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Effects of Mental Fatigue on Brain Activity and Cognitive Performance: A Magnetoencephalography Study
Abstract
Background: Mental fatigue is prevalent in modern society. Since mental fatigue causes cognitive impairment and this has been one of the most significant causes of accidents, it is important to understand the neural mechanisms of mental fatigue related to cognitive performance and to develop appropriate methods for evaluating and overcoming mental fatigue. In this study, we quantified the effect of mental fatigue on neural activity and cognitive performance and evaluated the relationship between the change of brain activity and cognitive impairment induced by mental fatigue using magnetoencephalography.
Methods: Thirteen healthy male volunteers participated in this study. They performed mental fatigue-inducing task trials for 30 min. resting state magnetoencephalography measurements and cognitive tasks were performed before and after the fatigue-inducing task. Magnetoencephalography data were analyzed using narrow-band adaptive spatial filtering methods.
Results: Alpha-frequency band (8-13 Hz) power in the visual cortex decreased after performing the mental fatigue-inducing task. The decreased level in the alpha-frequency band power was positively associated with the impaired cognitive task performance.
Conclusions: These results demonstrate that performing the mental fatigue-inducing task causes over-activation of the visual cortex, manifested as the decreased alpha-frequency band power in this brain region, and the over-activation was associated with the cognitive impairment. Our results increase understanding of the neural mechanisms of mental fatigue and these may be utilized to develop new quantitative methods to assess mental fatigue.
... We used a modified version of the Stroop task, which comprised a cognitive task presentation involving traffic lights (placed on a letter corresponding to blue or red in Japanese), traffic signs of walkers (right or left), and turns (right or left) displayed on the screen of a laptop computer (Dynabook Satellite B35, Toshiba Co., Ltd., Tokyo) [24][25][26]. Participants were required to press the left button with their left index finger as soon as the letter meaning red appeared and to press the right button with their right index finger as soon as the letter meaning blue appeared, regardless of whether the light was red or blue, a traffic sign of walkers, or turns. Each trial appeared 100 ms after either button was pressed and was repeated until 15 min had elapsed. ...
... HF is mediated by the vagus nerve [29][30][31], whereas LF is derived from various sympathetic and vagal mechanisms [28,32]. Some review articles [24,33,34] have reported that LF reflects sympathetic nerve activity; therefore, it has been used as a marker. To stabilize the measurement, a 1-min pretest was performed before the main 3-min test. ...
... Thus, this task required significant cognitive effort from participants. Poor performance in cognitively demanding continuous tasks is frequently associated with fatigue or fatigue due to sleep loss, as previous studies have shown that acute mental fatigue increases error rates in traffic light tests [24,35] and Stroop tasks [36,37]. Particularly, fatigue due to a prolonged cognitive load has been demonstrated to impair attention control [38] and inhibit attention to irrelevant information [39], suggesting that fatigue can affect attentional performance. ...
Dark chocolate, rich in polyphenols, increases cerebral blood flow and improves cognitive function. This study aimed to determine whether the consumption of chocolate with a high concentration of polyphenols helps to maintain cognitive performance during cognitively demanding tasks. In this randomized, single-blinded, crossover, dose-comparison study, 18 middle-aged adults consumed two types of chocolate (25 g each), one with a high concentration (635.0 mg) and the other with a low concentration (211.7 mg) of cacao polyphenols, and performed a cognitive task requiring response inhibition and selective attention over two time periods (15–30 min and 40–55 min after consumption, respectively). Autonomic nerve function and subjective feelings, such as fatigue and concentration, were measured before food intake and after the second task to assess the participant's state. The results showed that the average reaction time between the first and second sessions was not significantly different for either high- or low-concentration chocolate consumption. However, the percentage of correct responses was similar in the first (96.7 %) and second (96.8 %) sessions for high-concentration chocolate consumption and significantly lower for low-concentration chocolate consumption in the second (96.4 %) session than in the first session (97.3 %). Autonomic nerve function showed a significant increase in sympathetic nerve activity after the second task with high-concentration chocolate consumption, while subjective feelings showed an increase in mental fatigue for both chocolate types but a significant decrease in concentration only after the second task with low-concentration chocolate consumption. These findings suggest that dark chocolate consumption contributes to the maintenance of performance and concentration in continuous and demanding cognitive tasks.
... Mental fatigue (MF) is a common psychophysiological phenomenon that occurs during prolonged demanding cognitive activities (Boksem, Meijman, & Lorist, 2005;Hockey, 2013;Van Cutsem, et al., 2017). It results from overusing the brain's capacity and resources (Tanaka, 2015), and has various manifestations, including feeling tired, worn out or lethargic, and having headaches (Hockey, 2013). ...
... Due to its impact on cognitive performance, MF typically has adverse effects on the performance of daily activities that require cognitive resources, making it less effective and efficient. In pertinent experimental studies, MF has been found to interfere with both executive and attentional functions (Borragan, Slama, Bartolomei, & Peigneux, 2017;Tanaka, 2015), as evidenced by longer times needed to process, plan, and respond to stimuli. MF also degrades the accuracy of responses in performing cognitive tasks, such as the Stroop task, the psychomotor vigilance task and the AXcontinuous performance task (Hachard, Noé, Ceyte, Trajin, & Paillard, 2020). ...
... For example, Lew and Qu (2014) found that mentally fatigued young adults displayed an increased risk of slipping when exposed to laboratory-induced slip-like perturbations. Based on such findings, it has been suggested that MF poses a risk for postural stability, potentially leading to accidents (Lew & Qu, 2014;Tanaka, 2015). ...
We examined the influence of mental fatigue on static balance control in healthy young adults to gain greater clarity about this issue than provided in previous research. Based on the prevailing assumption in pertinent literature, we hypothesized that mental fatigue leads to a reduced cognitive regulation of quiet upright standing, as reflected in center of pressure (COP) excursions. More specifically, we hypothesized that the influence of mental fatigue on balance control depends on the attentional effort required by the balance tasks being performed. To test these hypotheses, 44 young adults (24 women and 20 men) were quasi-randomly assigned to either an experimental group that was mentally fatigued (using the TloadDback-task with individualized settings) or a control group (who watched a documentary). Before and after the intervention the participants performed six balance tasks that differed in (attentional) control requirements, while their COP was being recorded. From these time-series sway variability, mean speed, and sample entropy were calculated and analyzed statistically. Additionally, mental fatigue was assessed using VAS scales. Statistical analyses confirmed that the balance tasks differed in control characteristics and that mental fatigue was elevated in the experimental group, but not in the control group. Nevertheless, no significant main effects of mental fatigue were found on any of the COP measures of interest, except for some non-robust and difficult to interpret interaction effects involving the factor group. These results suggest that, in young adults, postural control in static balance tasks is largely automatic and unaffected by mental fatigue.
... A study conducted by Johansson and Rönnbäck [18] on patients recovering from stroke suggested that mental fatigue following a stroke was associated with cognitive function impairment. Tanaka [33] observed that mental fatigue reduced cognitive performance by inducing over-activation of the visual cortex. Depression which is considered to be a curable condition has been cited as a risk factor of cognitive impairment largely due to its frequent association with mild cognitive impairment and dementia in several types of research [19,29]. ...
... Cognitive function impairment risk factors. Faramarzi et al.[20], Campbell et al.[59] and Xiu et al.[29] Lack of social supportFaramarzi et al.[20] and Yeh and Liu[60] Loneliness/living alone Faramarzi et al.[20] and Lara et al.[61] Mental fatigue Johansson and Rönnbäck[18], Jonasson et al.[62] and Tanaka[33] Sleep deprivation Alhola and Polo-Kantola[21], Killgore[63] and Spira et al.[64] Long working hour Virtanen et al.[65], Virtanen et al.[22] and Kajitani et al.[36] ...
Cognitive function impairment may seriously hamper the day-to-day activities of human beings. Investigating different risk factors of cognitive function impairment had been an area of immense interest among researchers that led to the identification of several factors. However, studies for estimating the importance of these factors are limited. In this study, an integrated multi-criteria decision-making (MCDM) approach is proposed for estimating the importance of the cognitive impairment risk factors (CIRFs) for cognitive function impairment. Twenty-three CIRFs were identified from the literature and they were grouped into four main category factors such as individual factors, medical factors, psycho-social factors, and occupational factors. The importance of the CIRFs was estimated through their rank which was determined using an integrated analytical hierarchy process (AHP) and entropy method, using pair-wise comparison matrices collected from a panel of ten experts. It was found that among the four main category factors, psycho-social factors and individual factors were the most and the least prominent respectively. Further, among the 23 CIRFs, long working hours which was a sub-factor of the occupational factors, and depression, a sub-factor of psycho-social factors, were the most and the least important respectively. The sturdiness and reliability of the ranking result were ascertained through sensitivity analysis.
... It should be noted that cognitive fatigue is not to be conflated with fatigue that arises from prolonged muscle activity (i.e., physical fatigue), emotional exhaustion (i.e., chronic fatigue) [8], sleep deprivation [9], or boredom [3]. Notably, cognitive fatigue has been demonstrated to have negative effects on executive functions, such as working memory, judgement, and attention [10][11][12][13]. Not surprisingly, cognitive fatigue increases the risk of accidents and errors in various missioncritical situations [14,15]. ...
... Alternatively, cognitive fatigue could also be objectively, but indirectly, inferred from a decrease in cognitive and behavioural performance over time [11,13,[28][29][30]. These performance metrics, such as accuracy and reaction time, are typically measured in the context of computerised versions of cognitive tasks, such as the Stroop task [31] or the Simon task [32]. ...
Cognitive fatigue is a psychological state characterised by feelings of tiredness and impaired cognitive functioning arising from high cognitive demands. This paper examines the recent research progress on the assessment of cognitive fatigue and provides informed recommendations for future research. Traditionally, cognitive fatigue is introspectively assessed through self-report or objectively inferred from a decline in behavioural performance. However, more recently, researchers have attempted to explore the biological underpinnings of cognitive fatigue to understand and measure this phenomenon. In particular, there is evidence indicating that the imbalance between sympathetic and parasympathetic nervous activity appears to be a physiological correlate of cognitive fatigue. This imbalance has been indexed through various heart rate variability indices that have also been proposed as putative biomarkers of cognitive fatigue. Moreover, in contrast to traditional inferential methods, there is also a growing research interest in using data-driven approaches to assessing cognitive fatigue. The ubiquity of wearables with the capability to collect large amounts of physiological data appears to be a major facilitator in the growth of data-driven research in this area. Preliminary findings indicate that such large datasets can be used to accurately predict cognitive fatigue through various machine learning approaches. Overall, the potential of combining domain-specific knowledge gained from biomarker research with machine learning approaches should be further explored to build more robust predictive models of cognitive fatigue.
... Mental fatigue, a result of overloading the working memory capacity (Borragán et al., 2017) and characteristic of high-altitude occupations (Kottke et al., 2015), is a common cause of accidents and errors (Tanaka, 2015), as well as being detrimental to performance and hence survival in environmental extremes. Briefly, mental fatigue has been defined as a psychobiological state, characterized by decreased cognitive performance, focus, motivation and mood disturbances (Marcora et al., 2009;McMorris et al., 2018;Van Cutsem., 2017a). ...
... In the current study however, we did not measure such mechanisms to help explain the null effect of mental fatigue and hypoxia on cognitive performance, thus, we can only speculate the mechanisms underpinning the performance outcome. In addition, previous research has presented a negative impact of mental fatigue on cognitive performance (Holtzer et al., 2011;Tanaka, 2015). However, despite mental fatigue scores significantly increasing from preexercise to post-exercise (prior to the TOH) no effect was observed. ...
This study investigated the individual and combined effects of mental fatigue (MF) and hypoxia (HYP) on physical and cognitive performance. Fifteen males (24 ± 3 years) completed one familiarization session and six experimental trials, including: 1) normoxia (0.209 FiO2) and no MF; 2) normoxia (0.209 FiO2) with MF; 3) mild normobaric HYP (0.13 FiO2) and no MF; 4) mild normobaric HYP (0.13 FiO2) with MF; 5) severe normobaric HYP (0.10 FiO2) and no MF; 6) severe normobaric HYP (0.10 FiO2) with MF. Each condition included a 15-min self-paced time trial, followed by a 60-s isometric maximal voluntary contraction of the biceps brachii. MF was induced using a 16-min individualized cognitive test prior to exercise performance. Following each time trial, participants performed the Tower of Hanoi cognitive test. A main effect of HYP was observed on average power output, oxygen consumption and muscle oxygenation (P ≤ 0.004), with no effect of MF (P ≥ 0.599). Voluntary activation of the biceps brachii was also reduced in HYP (68.42 ± 5.64%, P = 0.039). No effect of MF or HYP was observed on cognitive performance (P ≥ 0.138). HYP impacted physical performance, whilst MF had no effect on self-paced physical or cognitive performance.
... The experimental tasks are conducted in both individual and group formats, with a contagion effect in the latter potentially affecting the emotional responses [4]. Finally, the effect of fatigue related to the number of stimuli used is seldom controlled for, which would seem to be significant given its influence on cognitive performance and brain activity associated with the task in question [34,35]. ...
... SD = 2.2), only 4% referred to specific events (in the block corresponding to the RB, it was 8%). It should be noted that, in comparison to the present study, the number of songs was much higher, which might arguably have generated fatigue in the participants, as demonstrated in studies using visual stimuli [34,35]. ...
Aims
This study is based on two experiments, the first, with an exploratory character. The aim of which is to assess the capacity of native vs international pop songs (NAT vs INT) from two consecutive life stages, Reminiscence bump (RB) and the immediately subsequent period (No reminiscence bump, NORB) to elicit positive emotions and autobiographical memories.
Method
A total of 15 middle-aged adults and 15 older adults participated in Experiment 1 (E1). Emotionality, song familiarity and associated autobiographical memories were assessed. Each participant was exposed to 20 randomly selected age-specific songs. Pre-and post-test measures of mood state were also included. Experiment 2 (E2) focused on late adulthood, using a sample of 35 persons. The experimental design was similar to that used in E1. However, this second experiment also included an analysis of the types of autobiographical memories generated by the experimental task and a study of their relationship with the characteristics of the songs, their familiarity and the emotions they produced, and the number of trials. The aim was to delve into the effects that influence the effectiveness of the induction procedure, particularly as regards emotional positivity and memory specificity.
Results
Regarding age effect, E1 results varied: under some conditions, emotionality showed no difference between groups, others showed positive older adult bias. In E2, the analysis of the relationships between memory types and the selected variables suggests the latter are not useful predictors of differences between memory types. The study design yielded a relatively high level of memory specificity and emotional positivity.
Conclusion
The findings question positivity bias in the elderly. RB music produces different effects depending on age. Enculturation can be an important mediating factor in emotionality and memory. Finally, experimental design improves specific memory and positivity.
... It has been shown that MF impairs cognitive function and plays an important role in increasing error risk in the workplace (Sadeghniiat-Haghighi & Yazdi, 2015). In addition, MF is known to be detrimental factor to performance of different tasks (Tanaka, Ishii, & Watanabe, 2015), by altering the amount of physical effort people are willing to invest in an exercise workout (Brown & Bray, 2019) and exercise performance (MacMahon, Schücker, Hagemann, & Strauss, 2014;Martin, Meeusen, Thompson, Keegan, & Rattray, 2018). ...
... The impairment in cognitive performance from MF is correlated with brain over-activation (Tanaka et al., 2015). In addition, the increase in reaction time and number of errors after MF is associated with a reduction in the involvement of prefrontal cognitive control processes (Budini, Lowery, Durbaba, & De Vito, 2014;Lorist et al., 2000). ...
This study investigated the residual effects of mental fatigue induced by the 30-minute incongruent Stroop Color Word task on subjectively perceived fatigue, reaction time, and heart rate variability (HRV) in 20 adult volunteers (10 men; 10 women). Dependent variables were assessed before, immediately after, and at 15, 30, 45, and 60 minutes after two conditions: (a) a 30-minute incongruent Stroop Color Word task (mental fatigue condition); or (b) a 30-minute control condition. At pre-testing, there were no significant differences between experimental conditions for any variable. However, there was a residual effect of mental fatigue on psychological responses for up to ~15 minutes after the experimental manipulation (p < 0.01). For the reaction time task, significant differences were observed only immediately after the mental fatigue, compared to the control condition (p < 0.0001). There were no significant differences between experimental conditions for any parameters of HRV at any testing period. In addition, there were no significant gender related differences at any period or in either condition for any variable. The data suggest that mental fatigue can alter psychological responses for up to ~15 min after its induction, and mental fatigue may impair cognitive reaction time performance without changing autonomic cardiac responses.
... Fatigue is a psychobiological state caused by long periods of demanding cognitive activity and is classified into specific subjective, behavioral and physiological manifestations [17]. It is termed as a phenomenon of deteriorated capability and efficiency of mental or physical tasks, which is caused by carrying out excessive mental or physical tasks and illness [18]. Effects of fatigue on physical performance have recently been suggested. ...
... Also, mental fatigue results in cognitive impairment. Thus, it is of utmost importance to comprehend the neural mechanisms of mental exhaustion associated with cognitive performance and to propose appropriate methods for estimating and overcoming fatigue [18] Lack of sleep is frequently associated with major workplace accidents [19][20][21]. Marcora et al. [22] postulated that greater subjective ratings of fatigue and/or a drop in cognitive performance signify the presence of mental and/or driver fatigue [17]. ...
Technological advances in healthcare have saved innumerable patients and are continuously improving our quality of life. Fatigue among health indicators of individuals has become significant due to its association with cognitive performance and health outcomes and, is one of the major factors contributing to the degradation of performance in daily life. This review serves as a source of studies which helped in better understanding of fatigue and also gave significant detection methods and systematic approaches to figure out the impacts and causes of fatigue. Artificial intelligence was turned out to be one of the essential tactics to detect or monitor fatigue. Artificial neural network, wavelet transform, data analysis of mouse interaction and keyboard patterns, image analysis, kernel learning algorithms, relation of fatigue and anxiety, and heart rate data examination studies were used in this paper to precisely assess the source, factors and features which influenced the recognition of fatigue.
... Mental fatigue impacts performance in many professions (Boksem and Tops 2008;Gergelyfi et al. 2015) and is one of the most common causes of accidents and errors in the modern world (Lew and Qu 2014;Tanaka 2015). Research conducted on the characteristics of mental fatigue define it as a psychobiological state (Marcora, Staiano, and Manning 2009) that is characterised subjectively by a lack of energy and lethargy, and/or objectively as a reduction in the ability to complete cognitive tasks (Boksem and Tops 2008;Qian et al. 2015). ...
... Mental fatigue manifests as a result of utilising and overusing the brain's resources. This leads to a reduced competence of the brain to undertake cognitive workloads efficiently (Tanaka 2015). Due to the accumulative decrease in productivity and increase in errors, both physical (Marcora, Staiano, and Manning 2009;Smith et al. 2016) and cognitive performance can be reduced as a result of mental fatigue (Holtzer et al. 2010;Tanaka, Ishii, and Watanabe 2014). ...
Despite research indicating the negative impact that mental fatigue has on physical and cognitive performance, whether this is a result of mental fatigue or a state of under-arousal remains unclear. The current research aimed to explore the effectiveness of the methods being used to induce mental fatigue. Twelve participants attended six sessions in which two cognitive tests, the AX-continuous performance test (AX-CPT) and the TloadDback test, were compared for their effectiveness in inducing mental fatigue. Both tests were set at a standard processing speed (1.2 ms) for two conditions, and a further condition involved the individualisation of the TloadDback test. Participants presented significantly higher physiological and psychological arousal (p < 0.05) in the individualised dual task test compared to the AX-CPT. The individualised TloadDback test is a more effective method of inducing mental fatigue compared to the AX-CPT, as it sustains physiological arousal whilst inducing measurable reductions in mental resources.
Practitioner Summary: Mental fatigue negatively impacts physical and cognitive performance. It is unclear whether the current methods being used to induce mental fatigue are effective. This study compared different methods and confirmed that short, individualised and dual task tests are most effective for inducing mental fatigue whilst maintaining arousal.
... • Time: The duration of the cognitive fatigue induction task had to be a minimum of 30 minutes Holgado et al., 2020;Tanaka, 2015). If the duration was unclear or not reported then the study was excluded. ...
... Generally, this process encompasses facets such as language, memory, attention, reasoning, problemsolving, decision-making, and perception (Wang & Chiew, 2010). Cognitive fatigue may arise when the brain is taxed with mental activities beyond its capacity or prolonged engagement in cognitive tasks exceeding an individual's cognitive limits (Tanaka, 2015). Factors contributing to cognitive fatigue include exposure to digital screens, sleep deprivation, multitasking, lack of breaks, or excessive workloads (Small, 2020). ...
User interface design is a key priority in modern computer systems, especially when the users are non-technical. Due to the importance of designing more user-friendly interfaces, the focus has been increased on designing human-centred systems over functional-centred systems of the past. Any human-computer interface can cause different levels of cognitive fatigue in the user, which can cause significant mental stress, which is not healthy for the users. This study has used the critical literature review method and reviewed six theories/concepts related to the design of visual user interfaces which could potentially reduce user cognitive fatigue. The reviewed theories are attention restoration theory, cognitive load theory, Gestalt principles, Fitts's law, progressive disclosure and UX honeycomb. The current commercial purposes of interface design do not seem to consider the user's mental health or well-being when designing user interfaces and user experience. They only try to maximise user retention and engagement. The study findings advocate for a paradigm shift towards designing visual interfaces that prioritize human-centric principles, with a primary emphasis on promoting user mental health and well-being over commercial objectives of constant user retention and engagement. For example, attention restoration theory can be considered as one of the key theories which is helpful to design better interfaces which consider user health and well-being. However, there are challenges to the 2 designers to find the right equilibrium between user engagement and user well-being. Designers can use the findings, subject to further empirical validations.
... However, there was a lower ACC on the 2BACK task in the post task compared to the pre task in both MF_NOR and CON_NOR. A lower ACC in the post task when one is mentally fatigued is similar to previous research that states that mental fatigue has a negative effect on cognitive performance (Tanaka 2015;Van Cutsem et al. 2017;Wascher et al. 2014). However, in hypoxia, this decrease in cognitive performance was not present. ...
Mental fatigue (MF) and hypoxia impair cognitive performance through changes in brain hemodynamics. We want to elucidate the role of prefrontal cortex (PFC)-oxygenation in MF. Twelve participants (22.9 ± 3.5 years) completed four experimental trials, (1) MF in (normobaric) hypoxia (MF_HYP) (3.800 m; 13.5%O2), (2) MF in normoxia (MF_NOR) (98 m; 21.0%O2), (3) Control task in HYP (CON_HYP), (4) Control in NOR (CON_NOR). Participants performed a 2-back task, Digit Symbol Substitution test and Psychomotor Vigilance task before and after a 60-min Stroop task or an emotionally neutral documentary. Brain oxygenation was measured through functional Near Infrared Spectroscopy. Subjective feelings of MF and physiological measures (heart rate, oxygen saturation, blood glucose and hemoglobin) were recorded. The Stroop task resulted in increased subjective feelings of MF compared to watching the documentary. 2-back accuracy was lower post task compared to pre task in MF_NOR and CON_NOR, while no differences were found in the other cognitive tasks. The fraction of inspired oxygen did not impact feelings of MF. Although performing the Stroop resulted in higher subjective feelings of MF, hypoxia had no effect on the severity of self-reported MF. Additionally, this study could not provide evidence for a role of oxygenation of the PFC in the build-up of MF.
... On one hand, visual fatigue's effects on cognitive performance are multifaceted and not limited to cognitive impairment. Excessive visual stimulation and prolonged periods of concentration can lead to changes in brain activity that can affect an individual's memory, attention, and other cognitive functions [35,36]. Therefore, as visual fatigue increases, there is a significant decrease in an individual's cognitive ability. ...
This study investigates the effects of ambient illumination and negatively polarized text color on visual fatigue, exploring the issue of visual fatigue when using visual display terminals in low-illumination environments. The research methodology utilizes an experimental design to collect data on changes in pupil accommodation and blink rate through an eye tracker. Participants completed a reading task while exposed to various text colors and ambient light conditions to evaluate visual fatigue and cognitive performance. The study’s findings suggest that text color significantly affects visual fatigue, with red text causing the highest level of visual fatigue and yellow text causing the lowest level of visual fatigue. Improvements in ambient lighting reduce visual fatigue, but the degree of improvement varies depending on the text color. Additionally, cognitive performance is better when using yellow and white text but worse when using red text. Yellow text is the most effective choice for reducing visual fatigue under negative polarity. Increasing ambient lighting can also improve visual fatigue in low-illumination conditions. These findings will offer valuable guidance for designing visual terminal device interfaces, especially for low-illumination or night environments, to minimize visual fatigue and improve user experience.
... On one hand, visual fatigue's effects on cognitive performance are multifaceted and not limited to cognitive impairment. Excessive visual stimulation and prolonged periods of concentration can lead to changes in brain activity that can affect an individual's memory, attention, and other cognitive functions [35][36]. Therefore, as visual fatigue increases, there is a significant decrease in an individual's cognitive ability. ...
This study investigates the effects of ambient illumination and negatively polarized text color on visual fatigue, exploring the issue of visual fatigue when using visual display terminals in low-illumination environments. The research methodology utilized an experimental design to collect data on changes in pupil accommodation and blink rate through an eye tracker. Partici-pants completed a reading task while exposed to various text colors and ambient light conditions to evaluate visual fatigue and cognitive performance. The study's findings suggest that text color significantly affects visual fatigue, with red text causing the highest level of visual fatigue and yellow text causing the lowest level of visual fatigue. Improvements in ambient lighting reduce visual fatigue, but the degree of improvement varies depending on the text color. Additionally, cognitive performance is better when using yellow and white text but worse when using red text. Yellow text is the most effective choice for reducing visual fatigue under negative polarity. In-creasing ambient lighting can also improve visual fatigue in low-illumination conditions. These findings will offer valuable guidance for designing visual terminal device interfaces, especially for low-illumination or night environments, to minimize visual fatigue and improve the user ex-perience.
... However, human energy is limited, and farmers are mentally exhausted after a long information search. At this point, farmers are not only limited in their ability to process information but also develop cognitive impairments (Metzger & Flanagin,2013;Tanaka et al., 2015). More effort and a greater tendency for farmers to unconsciously ignore or filter helpful information or to treat information negatively result in increasingly narrow information or access-stop to information (Case et al., 2005;Chen et al., 2021b). ...
The rapid development of internet information technology creates opportunities for farmers to cross the information gap and adopt green prevention and control (GPC) technology. However, the causal relationship between internet use and GPC adoption is under-analyzed. This study aims to theoretically analyze the dark side of farmers’ internet use time in GPC adoption caused by information avoidance. Using survey data of rice farmers in Southern China, we empirically tested the inverted U-shaped relationship between farmers’ internet use time and adoption of GPC technology, which means the relationship is non-linear. Heterogeneity analysis showed that farmers with low social interaction or high specialization were more susceptible to information avoidance and less likely to adopt GPC technology. This paper opens the black box of ICT-based agricultural behavioral decisions and attaches importance to the “double-edged sword” effects of ICT usage in agriculture technology adoption. This study urges the government and relevant organizations to strengthen the construction of digital infrastructure and the governance of digital agricultural technology information and improve farmers’ digital literacy to alleviate the negative effects of information avoidance while promoting new technologies.
... On the other hand, task-induced fatigue can lead to a decrease in cognitive performance and is therefore termed cognitive performance fatigue (Behrens et al. 2023). This component of fatigue refers to the depletion of executive and attentional functions, for example as evidenced by longer times needed to process, plan, and respond to stimuli (Tanaka 2015;Borragan et al. 2017). Other typical manifestations are a degraded response accuracy and an increasing difficulty to focus on relevant information while suppressing irrelevant stimuli (Borragan et al. 2017). ...
We examined the influence of perceived cognitive fatigue on static balance control in healthy young adults to gain greater clarity about this issue than provided in previous research. Based on the prevailing assumption in pertinent literature, we hypothesized that the influence of cognitive fatigue on balance control depends on the attentional effort required by the balance tasks being performed. To test this hypothesis, 44 young adults (24 women and 20 men) were alternately assigned to either the experimental group that was cognitively fatigued (using the 16-min TloadDback-task with individualized settings) or the control group (who watched a documentary). Before and after the intervention, the participants performed six balance tasks that differed in (attentional) control requirements, while recording the center of pressure (COP). From these time series, sway variability, mean speed, and sample entropy were calculated and analyzed statistically. Additionally, perceived cognitive fatigue was assessed using VAS scales. Statistical analyses confirmed that the balance tasks differed in control characteristics and that cognitive fatigue was elevated in the experimental group, but not in the control group. Nevertheless, no significant main effects of cognitive fatigue were found on any of the COP measures of interest, except for some non-robust interaction effects related primarily to sample entropy. These results suggest that, in young adults, postural control in static balance tasks is largely automatic and unaffected by task-induced state fatigue.
... The level of Emotional Stability among the participants was average. Tanaka et al. (2015) conducted a study on thirteen volunteers in Japan who were subjected to Mental Fatigue through strenuous experiments that lasted thirty minutes. Findings revealed that Mental Fatigue leads to a decrease in cognitive performance, as well as cognition. ...
... This region corresponds to Brodmann Area 19 (V3/V3a), which is thought to be linked with visual fatigue. 59 Thus, a possible deficit in visual processing of stimuli could partially account for the reduced task accuracy. ...
Background:
Excessive heat exposure can lead to hyperthermia in humans, which impairs physical performance and disrupts cognitive function. While heat is a known physiological stressor, it is unclear how severe heat stress affects brain physiology and function.
Methods:
Eleven healthy participants were subjected to heat stress from prolonged exercise or warm water immersion until their rectal temperatures (Tre) attained 39.5°C, inducing exertional or passive hyperthermia, respectively. In a separate trial, blended ice was ingested before and during exercise as a cooling strategy. Data were compared to a control condition with seated rest (normothermic). Brain temperature (Tbr), cerebral perfusion, and task-based brain activity were assessed using magnetic resonance imaging techniques.
Results:
Tbr in motor cortex was found to be tightly regulated at rest (37.3°C ± 0.4°C) despite fluctuations in Tre. With the development of hyperthermia, Tbr increases and dovetails with the rising Tre. Bilateral motor cortical activity was suppressed during high-intensity plantarflexion tasks, implying a reduced central motor drive in hyperthermic participants (mean Tre: 38.5°C ± 0.1°C). Global gray matter perfusion and regional perfusion in sensorimotor cortex were reduced with passive hyperthermia. Executive function was poorer under a passive hyperthermic state, and this could relate to compromised visual processing as indicated by the reduced activation of left lateral-occipital cortex. Conversely, ingestion of blended ice before and during exercise alleviated the rise in both Tre and Tbr and mitigated heat-related neural perturbations.
Conclusion:
Severe heat exposure elevates Tbr, disrupts motor cortical activity and executive function, and this can lead to impairment of physical and cognitive performance.
... Since all these values are measured by sensors, they are subject to certain errors and do not change only based on the cognitive load. Other dependencies of The physiological measures are anxiety [9], arousal [35], physical activity [49], stress [12], fatigue [54], and light [48]. Since the pupil dilation is a possible candidate for real-time usage, many researchers investigated this feature [10,11,32,37]. ...
In this paper, we present a new feature that can be used to classify cognitive load based on pupil information. The feature consists of a temporal segmentation of the eye tracking recordings. For each segment of the temporal partition, a probability distribution of pupil size is computed and stored. These probability distributions can then be used to classify the cognitive load. The presented feature significantly improves the classification accuracy of the cognitive load compared to other statistical values obtained from eye tracking data, which represent the state of the art in this field. The applications of determining Cognitive Load from pupil data are numerous and could lead, for example, to pre-warning systems for burnouts. Link: https://es-cloud.cs.uni-tuebingen.de/d/8e2ab8c3fdd444e1a135/?p=%2FCognitiveLoadFeature&mode=list
... In order to effectively manage fatigue, it is first necessary to be able to detect it. Research has shown that fatigue is closely related to drowsiness and sleepiness, which can be identified with the correct combination of physiological and psychological biosignals [12], [41]. The tools required to measure these signals effectively are obtrusive and are impractical for daily monitoring. ...
The need for proper fatigue detection and mitigation is made clear in research, with failure to detect fatigue resulting in significant societal health repercussions. Currently, there are limited hardware systems dedicated to the monitoring of fatigue-related biometrics. The devices that do attempt to provide this information are often impractical due to their size, required expertise and cost constraints. Access to these technologies by a broader population is therefore limited. Wearable health devices could provide a more practical solution. A data capture system was designed and implemented that records PPG and in-ear EEG information. The device was created to be inexpensive and portable. The in-ear EEG results obtained showed the detection of a statistically significant difference in alpha attenuation levels, which are closely associated with the state of alertness or drowsiness. While the acquired heart rate and blood oxygen saturation measurements showed a close correlation with an FDA approved pulse oximeter. Although the number of trials conducted was limited, the results show promising performance. This project is a stepping stone in the pursuit of an affordable fatigue monitoring solution that can mitigate the human-cost incurred on account of fatigue.
... In addition, monitoring of mental fatigue is indicated through the visual analog scale (10 cm -magnitude: 0-1, no fatigue; 2-4, mild fatigue, 5-7, moderate fatigue, 8-10, several fatigues) 56,57 , and short-term Stroop Test using accuracy and especially the response time as indicators 7 . These tools are accessible and easy to apply compared to an electrophysiological resource sensitive to mental fatigue such as an electroencephalogram 58 . ...
Aim: This narrative review aimed to explore the effect of mental fatigue on physical, technical, and tactical performance in ball sports. Methods: Three Databases, PUBMED, SCOPUS, and SCIELO, were used to search for a scientific publication. The criterions adopted were: a) published in a peer-reviewed journal; b) adopted at least one manipulation check related to mental fatigue; c) mental fatigue induced by a cognitive task before the outcome task, and d) study participants were ball sports athletes. Result: The quality of this narrative review was rated at 11 (SANRA scale 0-12), and the papers analyzed were published between 2015 and 2022. Twenty-one experimental studies were included in this review. Most studies were in invasion sports (n = 13; 72%), and non-ecological tasks were used to induce mental fatigue (n = 15; 83%). Regarding performance in endurance tests, mentally fatigued athletes had performance impaired. However, when assessed during a small-sided or simulated game, data were inconclusive within the literature. Moreover, athletes presented attenuated perceptual skills (e.g., visual field). Consequently, this worsened motor skills, technical-tactical performances, and tactical behavior. Conclusions: Cognitively demanding tasks should be avoided before training and sports competitions because they can lead the athlete to mental fatigue and impair performance. This impairment is identified in physical performance (endurance tasks) and technical and tactical performance. Finally, it is recommended that athletes do not perform tasks that cause mental fatigue 2 h before the sports event.
... This mental state is a result of cognitive "overloading" by engaging in cognitively demanding activities for a prolonged period of time [1,[3][4][5][6][7]. Previous research has found that cognitive fatigue was associated with negative effects on cognitive functioning, such as working memory, judgement, and attention [8][9][10][11]. Hence, cognitive fatigue may result in more mistakes and, consequentially, the risk of accidents [12,13]. Hence, advancing assessment methods of cognitive fatigue is imperative in managing such risk, especially in critical situations. ...
Cognitive fatigue is a mental state characterised by feelings of tiredness and impaired cognitive functioning due to sustained cognitive demands. Frequency-domain heart rate variability (HRV) features have been found to vary as a function of cognitive fatigue. However, it has yet to be determined whether HRV features derived from electrocardiogram data with a low sampling rate would remain sensitive to cognitive fatigue. Bridging this research gap is important as it has substantial implications for designing more energy-efficient and less memory-hungry wearables to monitor cognitive fatigue. This study aimed to examine (1) the level of agreement between frequency-domain HRV features derived from lower and higher sampling rates, and (2) whether frequency-domain HRV features derived from lower sampling rates could predict cognitive fatigue. Participants (N = 53) were put through a cognitively fatiguing 2-back task for 20 min whilst their electrocardiograms were recorded. Results revealed that frequency-domain HRV features derived from sampling rate as low as 125 Hz remained almost perfectly in agreement with features derived from the original sampling rate at 2000 Hz. Furthermore, frequency domain features, such as normalised low-frequency power, normalised high-frequency power, and the ratio of low- to high-frequency power varied as a function of increasing cognitive fatigue during the task across all sampling rates. In conclusion, it appears that sampling at 125 Hz is more than adequate for frequency-domain feature extraction to index cognitive fatigue. These findings have significant implications for the design of low-cost wearables for detecting cognitive fatigue.
... It was seen that the level of decrease on power belonging to alpha frequency band in the visual cortex had positive correlation with weak performance of cognitive task (2-back test). It was indicated that performing the duty causing mental fatigue caused extreme activation in visual cortex and that it was related to cognitive disorder [18]. ...
Stress and mental fatigue are in existence constantly in daily life, and decrease our productivity while performing our daily routines. The purpose of this study was to analyze the states of stress and mental fatigue using data fusion while e-sport activity. In the study, ten volunteers performed e-sport duty which required both physical and mental effort and skills for 2 min. Volunteers’ electroencephalogram (EEG), galvanic skin response (GSR), heart rate variability (HRV), and eye tracking data were obtained before and during game and then were analyzed. In addition, the effects of e-sports were evaluated with visual analogue scale and d2 attention tests. The d2 tests are performed after the game, and the game has a positive effect on attention and concentration. EEG from the frontal region indicates that the game is partly caused by stress and mental fatigue. HRV analysis showed that the sympathetic and vagal activities created by e-sports on people are different. By evaluating HRV and GSR together, it was seen that the emotional processes of the participants were stressed in some and excited in others. Data fusion can serve a variety of purposes such as determining the effect of e-sports activity on the person and the appropriate game type.Graphical abstract
... Participants were all tested according to the same time frames. A psychomotor visual vigilance task (Dorrian et al., 2004) was administered during the 20-min tACS blocks in order to control for the known state-dependent effects associated with alpha oscillations (Dinges and Powell, 1985;Dorrian et al., 2004;Lim and Dinges, 2008;Mierau et al., 2017) as well as for fatigue and vigilance (Craig et al., 2012;Tanaka, 2015). The task was identical across stimulation conditions. ...
Transcranial alternating current stimulation, a non-invasive brain stimulation technique, has been used to increase alpha (8–12 Hz) power, the latter being associated with various brain functions and states. Heterogeneity among stimulation parameters across studies makes it difficult to implement reliable transcranial alternating current stimulation protocols, explaining the absence of consensus on optimal stimulation parameters to modulate the alpha rhythm. This project documents the differential impact of controlling for key transcranial alternating current stimulation parameters, namely the intensity, the frequency and the stimulation site (anterior versus posterior). Phase 1:20 healthy participants underwent 4 different stimulation conditions. In each experimental condition, stimulation via 2 electrodes was delivered for 20 min. Stimulation conditions were administered at PO7-PO8 or F3-F4 at individual’s alpha frequency, or at individual’s theta frequency or sham. Stimulation intensity was set according to each participant’s comfort following a standardized unpleasantness scale (≤ 40 out of 100) and could not exceed 6 mA. All conditions were counterbalanced. Phase 2: participants who tolerated higher intensity of stimulation (4–6 mA) underwent alpha-frequency stimulation applied over PO7–PO8 at 1 mA to investigate within-subject modulation of stimulation response according to stimulation intensity. Whether set over posterior or anterior cortical sites, alpha-frequency stimulation showed greater increase in alpha power relative to stimulation at theta frequency and sham stimulation. Posterior alpha-frequency stimulation showed a greater increase in alpha power relative to the adjacent frequency bands over frontal and occipito-parietal brain areas. Low intensity (1 mA) posterior alpha stimulation showed a similar increase in alpha power than at high (4–6 mA) intensity when measured immediately after stimulation. However, when tested at 60 min or 120 min, low intensity stimulation was associated with significantly superior alpha power increase relative to high intensity stimulation. This study shows that posterior individual’s alpha frequency stimulation at higher intensities is well tolerated but fails to increase stimulation aftereffects recorded within 2 h of stimulation on brain oscillations of the corresponding frequency band. In sharp contrast, stimulating at 1 mA (regardless of phosphene generation or sensory perception) effectively and selectively modulates alpha power within that 2-h time window, thus validating that it as a reliable stimulus intensity for future studies. This study also shows that posterior alpha-frequency stimulation preferentially modulates endogenous brain oscillations of the corresponding frequency band. Moreover, our data suggest that posterior alpha-frequency transcranial alternating current stimulation is a reliable and precise non-invasive brain stimulation technique for persistent modulation of both frontal and occipito-parietal alpha power.
... Pupil dilation was found to be higher for more challenging tasks [11,26]. Not only task demands have been found to influence the pupil diameter, but also factors like anxiety [7], stress [10], and fatigue [37]. A study done by Just and Carpenter [20], showcased that pupil responses can be an indicator of the effort to understand and process information. ...
... Furthermore, prolonged performance of demanding tasks leads to cognitive fatigue, which is characterized by a subjective dimension -i.e. feeling of exhaustion, impression of worsened ability and decreased willingness to engage in mental activities (Hockey, 2011;van der Linden et al., 2003) -and an objective dimension, with an actual decrease of task performance (Bailey et al., 2007;Tanaka, 2015;van der Linden et al., 2003). However, it is still unclear what is the origin of cognitive costs (i.e., what is costly about cognitive processing?), how to specify them quantitatively, and whether cognitive costs and cognitive fatigue have some adaptive value. ...
In statistics and machine learning, model accuracy is traded off with complexity, which can be viewed as the amount of information extracted from the data. Here, we discuss how cognitive costs can be expressed in terms of similar information costs, i.e. as a function of the amount of information required to update a person’s prior knowledge (or internal model) to effectively solve a task. We then examine the theoretical consequences that ensue from this assumption. This framework naturally explains why some tasks – for example, unfamiliar or dual tasks – are costly and permits to quantify these costs using information-theoretic measures. Finally, we discuss brain implementation of this principle and show that subjective cognitive costs can originate either from local or global capacity limitations on information processing or from increased rate of metabolic alterations. These views shed light on the potential adaptive value of cost-avoidance mechanisms.
... To avoid the surgical procedures, there are four popular non-invasive measurement methods for acquiring the brain information: functional magnetic resonance imaging (fMRI) [6], magnetoencephalography (MEG) [7], electroencephalogram (EEG) [8], and functional near-infrared spectroscopy (fNIRS) [9,10]. Due to the advantage of the good temporal resolution, portable, and low cost, EEG shows unique usability superiority for the BCI-based control system in comparison to the other type of brain techniques (i.e., MEG, fMRI, and fNIRS) [11]. ...
The goal of this study was to develop and validate a hybrid brain-computer interface (BCI) system for home automation control. Over the past decade, BCIs represent a promising possibility in the field of medical (e.g., neuronal rehabilitation), educational, mind reading, and remote communication. However, BCI is still difficult to use in daily life because of the challenges of the unfriendly head device, lower classification accuracy, high cost, and complex operation. In this study, we propose a hybrid BCI system for home automation control with two brain signals acquiring electrodes and simple tasks, which only requires the subject to focus on the stimulus and eye blink. The stimulus is utilized to select commands by generating steady-state visually evoked potential (SSVEP). The single eye blinks (i.e., confirm the selection) and double eye blinks (i.e., deny and re-selection) are employed to calibrate the SSVEP command. Besides that, the short-time Fourier transform and convolution neural network algorithms are utilized for feature extraction and classification, respectively. The results show that the proposed system could provide 38 control commands with a 2 s time window and a good accuracy (i.e., 96.92%) using one bipolar electroencephalogram (EEG) channel. This work presents a novel BCI approach for the home automation application based on SSVEP and eye blink signals, which could be useful for the disabled. In addition, the provided strategy of this study-a friendly channel configuration (i.e., one bipolar EEG channel), high accuracy, multiple commands, and short response time-might also offer a reference for the other BCI controlled applications.
... Those individuals in the active group performed a spatial N-back test for 25 minutes. The N-back task is a difficult working memory task previously validated as a sufficient tool to induce cognitive fatigue (Tanaka, Ishii & Watanabe, 2015). Twenty-five minutes was chosen based on pilot work to be a sufficient amount of time to create mental fatigue in participants and because it temporally aligned well with Tanaka and colleagues who showed strong evidence of cognitive fatigue after 30 minutes. ...
Esports offer a new and unique opportunity for fans. Not only can fans watch professional players, but they can experience the game directly as players themselves. In this paper, we explore esports fan identity at the intersection of viewer and player in Overwatch, League of Legends and FIFA forums, considering a spectrum and influence of geek to sports orientation. We explore differences and similarities between these esports fandoms in regard to expression of knowledge, identification with professional players, and the search for legitimacy. These groups generally use knowledge and skill to demonstrate legitimacy, as a form of (sub)cultural capital. Fans display concerns about where they fit in regard to both traditional sports and other esports. However, whereas in traditional sports, outgroups are defined as membership in rival teams, in esports, outgroup status is conferred to casuals. Esports fandom is tribal in the sense that it is a method for fans to display tribal affiliation as “real” game players against the newer, lower level players.
... It is characterised by decreased energy, motivation and difficulty concentrating or difficulty in maintaining sustained attention and remain alert to relevant stimuli appearing at unpredictable time points over long periods of time. Fatigue is usually accompanied by a sense of discomfort, desire to rest and reduced motivation (Tanaka, Ishii, Watanabe, 2015;Kitani T, et al. 2011). There are many types of different works such as driving, monitoring tasks which require operators to maintain sustained attention on multiple objects for prolonged periods of times. ...
Nowadays, there is a great need to investigate the effects of fatigue on physical as well as mental performance. The issues that are generally associated with extreme fatigue are that one can easily lose one's focus while performing any particular activity whether it is physical or mental as well as this decreases one's motivation to complete efficiently and successfully the task at hand. In the same line of thought, myriads research studies posited the negative effects of fatigue on mental performance, and most techniques to induce fatigue require normally long-time and repetitive visual search tasks. In this study, a visual search algorithm task was devised and customised using performance measures such as d' (d-prime) and Speed Accuracy Trade-Off (SATF) as well as ROC analysis for classifier performance. The visual search algorithm consisted of distractors (L) and a target (T) whereby human participants had to press appropriate keyboard button as fast as possible if they notice a target or not upon presentation of a visual stimuli. It was administered to human participants under laboratory conditions, and the reaction times as well as accuracy of the participants were monitored. It was found that the testimage Size35Int255 was the best image to be used in terms of sensitivity and AUC (area under curve).
... Prior psychology research shows that mental fatigue is associated with declines in performance across multiple domains of executive function. 17 Both multitasking and forced task switching, which typically increase as shift duration (and patient burden) increases, have been shown to decrease performance. 18 When viewed in light of the findings of our study, these lines of evidence ...
Background
Understanding factors that drive admissions is critical to containing cost and optimising hospital operations. We hypothesised that, due to multiple factors, emergency physicians would be more likely to admit a patient seen later in their shift.
Methods
Retrospective study examining all patient visits at a large academic hospital from July 2010 to July 2016. Patients with missing data (n=191) were excluded. 294 031 emergency department (ED) visits were included in the final analysis. The exposure of interest was the time during the shift at which a patient was first evaluated by the clinician, and outcome was hospital admission. We used a generalised estimating equation with physician as the clustering level to adjust for patient age, gender, Emergency Severity Index (ESI, 1=most severe illness, 5=least severe illness) and 24 hours clock time. We also conducted a stratified analysis by three ESI categories.
Results
From the 294 031 ED visits, 5977 were seen in the last hour of the shift. Of patients seen in the last shift hour, 43% were admitted versus 39% seen at any other time during the shift. There was a significant association between being evaluated in the last hour (RR 1.03, 95% CI 1.01 to 1.06) and last quarter (RR 1.02, 1.01 to 1.03) of shift and the likelihood of admission. Patients with an ESI Score of 4–5 saw the largest effect sizes (RR 1.62, 0.996–2.635 for last hour and RR 1.24, 0.996–1.535 for last quarter) but these were not statistically significant. Additionally, there was a trend towards increased likelihood of admission later in shift; the relative risk of admission was 1.04 in hour 6, (1.02–1.05), 1.03 in hour 7 (1.01–1.05), 1.04 in hour 8 (1.01–1.06) and 1.06 in hour 9 (1.013–1.101).
Conclusions
There is a small but significant association between a patient being evaluated later in an emergency physician’s shift and their likelihood of being admitted to the hospital.
... If not nugatory, this gradually also creates a situation where fatigue compensating effort results in a successively more vulnerable states of overdraft fatigue during the day at work, NFR. In addition to being a vulnerable state of mental fatigue, compensatory effort may alter the functioning of the brain in the direction of the effort being both very costly and inefficient (e.g., Durning et al. 2013;Tanaka et al. 2015). This costly adaptation of the fatigued brain alone constitutes strong arguments for internal ("at work") successive recovery. ...
Objective
To examine three levels of need for recovery (NFR) after work in relation to effort from work demands, demand compensatory strategies, effort-moderating or -reversing resources, and health including health behaviors. A further purpose was to examine occupational characteristics determining NFR.
Methods
5000 engineers, carpenters, nurses, and home care nurses were invited to participate. NFR k-means clusters were calculated from 1289 participants. The effect from three levels of NFR regarding demands, compensatory strategies, resources at work, health, and health behaviors was examined using analysis of variance (ANOVA) and post hoc analysis. Prevalence ratios (PRs) of suboptimal health for three levels of NFR were calculated using Poisson regression. Linear stepwise multiple regression predictors explaining NFR were examined also occupation wise.
Results
NFR centroids at 5.8/33, 13.1/33, and 21.0/33 points were identified. ANOVA showed corresponding effects from NFR levels on work demands and compensatory strategies. The inversed proportion concerned levels of resources at work. Only the low NFR cluster negated regular health effects. The other two cluster groups also repeatedly worked while ill and presented PRs concerning health effects from 1.9 to 3.9 when compared to the low NFR group. Making good quality work, recovery opportunities, and thinking of work when off work were the most important predictors of NFR among 1289 participants with also occupation-wise interpretable profiles.
Conclusions
Three levels of NFR meant corresponding levels of work demands, work-demand compensatory strategies, and unfavorable health behaviors. An inversed proportion of resources related to the same levels of NFR. Low NFR meant no regular health effects which could guide limit values regarding salutary NFR. Important predictors of NFR were resources making a good quality work, recovery opportunities, and reversely effort from rumination when off work. Occupation-wise predictors could guide interventions.
... Per the 2014 study by Ishii et al., it is a potential impairment of cognitive function, and in modern society, it is one of the most significant causes of accidents [22]. Mental fatigue induces a decline in cognitive processes such as planning, response inhibition, executive attention, sustained attention, goal-directed attention, alternating attention, divided attention, and conflict-controlling selective attention [23][24]. At a given moment, there is a finite amount of fuel being provided to the brain in the form of glucose or neurotransmitters. ...
Micro-learning is an educational teaching method used to train users on multiple platforms. This article will provide a brief introduction to the concepts of short-term and long-term memory, and explain how micro-learning can be used to increase retention in learners. Micro-lessons can aid in negating the Ebbinghaus forgetting curve and can use reintroduction to keep retention at significantly higher levels. This process also speeds up the learning process overall because students avoid the phenomenon of mental fatigue. The article cites studies suggesting mental fatigue can cause serious cognitive decline in individual performance. By breaking complex courses into manageable smaller lessons, micro-learning preserves the neurotransmitter cascade for steady neurochemical performance. By using mobile devices, students can pause and continue their micro-lessons with ease. The mobile application also gives them the opportunity to continually check on their performance, and adjust their learning accordingly. Micro-learning on mobile devices also keeps engagement levels high because it utilizes different forms of media to keep users captivated.
... Finally, Martin et al. (2016) used the 30-min Stroop protocol when they found that athletic status determines the influence of MF on 20-min TT performance. Unlike these previous studies, however, we added the performance of the N-back task intermittently during the Stroop to reduce singulartask disengagement thereby decreasing the likelihood of a reduction in MF-inducing stimulus during the latter stages of the test (Tanaka et al. 2015). Nevertheless, it is important to recognise that the 30-min cognitive challenge that we employed might not have been long enough to achieve the psychobiologic perturbation necessary to impair subsequent exercise performance. ...
It has been reported that mental fatigue decreases exercise performance during high-intensity constant-work-rate exercise (CWR) and self-paced time trials (TT) in recreationally-trained individuals. The purpose of this study was to determine whether performance is impaired following a prolonged cognitive task in individuals trained for competitive sport. Ten trained competitive athletes (ATH) and ten untrained healthy men (UNT) completed a 6-min severe-intensity CWR followed by a 6-min cycling TT immediately following cognitive tasks designed to either perturb (Stroop colour-word task and N-back task; PCT) or maintain a neutral (documentary watching; CON) mental state. UNT had a higher heart rate (75 ± 9 v. 69 ± 7 bpm; P = 0.002) and a lower positive affect PANAS score (19.9 ± 7.5 v. 24.3 ± 4.6; P = 0.036) for PCT compared to CON. ATH showed no difference in heart rate, but had a higher negative affect score for PCT compared to CON (15.1 ± 3.7 v. 12.2 ± 2.7; P = 0.029). Pulmonary O2 uptake during CWR was not different between PCT and CON for ATH or UNT. Work completed during TT was not different between PCT and CON for ATH (PCT 103 ± 12 kJ; CON 102 ± 12 kJ; P > 0.05) or UNT (PCT 75 ± 11 kJ; CON 74 ± 12 kJ; P > 0.05). Compared to CON, during PCT, UNT showed unchanged psychological stress responses, whereas ATH demonstrated increased psychological stress responses. However, regardless of this distinction, exercise performance was not affected by PCT in either competitive athletes or untrained individuals.
... Furthermore, prolonged performance of demanding tasks leads to cognitive fatigue, which is characterized by a subjective dimensioni.e. feeling of exhaustion, impression of worsened ability and decreased willingness to engage in mental activities (Hockey, 2011;van der Linden et al., 2003) and an objective dimension, with an actual decrease of task performance (Bailey et al., 2007;Tanaka, 2015;van der Linden et al., 2003). ...
In statistics and machine learning, model accuracy is traded off with complexity, which can be viewed as the amount of information extracted from the data. Here, we discuss how cognitive costs can be expressed in terms of similar information costs, i.e. as a function of the amount of information required to update a person's prior knowledge (or internal model) to effectively solve a task. We then examine the theoretical consequences that ensue from this assumption. This framework naturally explains why some tasks - for example, unfamiliar or dual tasks - are costly and permits to quantify these costs using information-theoretic measures. Finally, we discuss brain implementation of this principle and show that subjective cognitive costs can originate either from local or global capacity limitations on information processing or from increased rate of metabolic alterations. These views shed light on the potential adaptive value of cost-avoidance mechanisms.
... Mental fatigue can lead to over-activation in brain activity, which is related to reduced cognitive performance [6]. Severe fatigue over an extended period can lead to workers taking sick leave and disability leave [7]. ...
... While the existence of a cost to cognition appears intuitively obvious, its origin remains unknown (Kurzban et al., 2013;Shenhav et al., 2017;Westbrook and Braver, 2015). What is clear, however, is that prolonged cognitive engagement leads to the subjective feeling of fatigue (Ackerman and Kanfer, 2009;Campagne et al., 2004;Deluca, 2005) and can also deteriorate performance (Holtzer et al., 2011;Schwid et al., 2003;Tanaka, 2015), sometimes referred to as objective fatigue (Bailey et al., 2007). The nature of these behavioral manifestations of cognitive fatigue is diverse, including disruption of inhibition mechanisms (Kato et al., 2009), planning (Lorist, 2008;Lorist et al., 2000;van der Linden et al., 2003), processing of new information (Massar et al., 2010), attention (Boksem et al., 2006;Dorrian et al., 2007;Holtzer et al., 2011;Lim et al., 2010), working memory (Gergelyfi et al., 2015) or task switching (Borragán et al., 2017). ...
Mentally demanding tasks feel effortful and are usually avoided. Furthermore, prolonged cognitive engagement leads to mental fatigue, consisting of subjective feeling of exhaustion and decline in performance. Despite the intuitive characterization of fatigue as an increase in subjective effort perception, the effect of fatigue on effort cost has never been tested experimentally. To this end, sixty participants in 2 separate experiments underwent a forced-choice working memory task following either a fatigue-inducing (i.e. cognitive task involving working memory, conflict and switch costs) or a control manipulation. We measured fatigue in terms of subjective feeling and performance decrement and assessed effort in terms of subjective perception and task avoidance. Subjects exhibited only weak avoidance of the working memory task, with stronger influence of reward than task difficulty on their decisions. In addition, we found that task avoidance did not systematically change following the fatigue manipulation but that variations in task avoidance correlated with fatigue-induced performance decline. The other measures of fatigue and effort were unrelated to each other. Our findings suggest that subjective fatigue may develop independently of task avoidance and suggest an "anticipatory regulation" model in which fatigue urges subjects to stop in anticipation of possible, future adverse consequences.
Mental fatigue has shown to be one of the root causes of decreased productivity and overall cognitive performance, by decreasing an individual’s ability to inhibit responses, process information and concentrate. The effects of mental fatigue have led to occupational errors and motorway accidents. Early detection of mental fatigue can prevent the escalation of symptoms that may lead to chronic fatigue syndrome and other disorders. To date, in clinical settings, the assessment of mental fatigue and stress is done through self-reported questionnaires. The validity of these questionnaires is questionable, as they are highly subjective measurement tools and are not immune to response biases. This review examines the wider presence of mental fatigue in the general population and critically compares its various detection techniques ( i.e ., self-reporting questionnaires, heart rate variability, salivary cortisol levels, electroencephalogram, and saccadic eye movements). The ability of these detection tools to assess inhibition responses (which are sensitive enough to be manifested in a fatigue state) is specifically evaluated for a reliable marker in identifying mentally fatigued individuals. In laboratory settings, antisaccade tasks have been long used to assess inhibitory control and this technique can potentially serve as the most promising assessment tool to objectively detect mental fatigue. However, more studies need to be conducted in the future to validate and correlate this assessment with other existing measures of mental fatigue detection. This review is intended for, but not limited to, mental health professionals, digital health scientists, vision researchers, and behavioral scientists.
Background
Mental fatigue is a common and potentially debilitating state that can affect individuals’ health and quality of life. In some cases, its manifestation can precede or mask early signs of other serious mental or physiological conditions. Detecting and assessing mental fatigue can be challenging nowadays as it relies on self-evaluation and rating questionnaires, which are highly influenced by subjective bias. Introducing more objective, quantitative, and sensitive methods to characterize mental fatigue could be critical to improve its management and the understanding of its connection to other clinical conditions.
Objective
This paper aimed to study the feasibility of using keystroke biometrics for mental fatigue detection during natural typing. As typing involves multiple motor and cognitive processes that are affected by mental fatigue, our hypothesis was that the information captured in keystroke dynamics can offer an interesting mean to characterize users’ mental fatigue in a real-world setting.
Methods
We apply domain transformation techniques to adapt and transform TypeNet, a state-of-the-art deep neural network, originally intended for user authentication, to generate a network optimized for the fatigue detection task. All experiments were conducted using 3 keystroke databases that comprise different contexts and data collection protocols.
Results
Our preliminary results showed area under the curve performances ranging between 72.2% and 80% for fatigue versus rested sample classification, which is aligned with previously published models on daily alertness and circadian cycles. This demonstrates the potential of our proposed system to characterize mental fatigue fluctuations via natural typing patterns. Finally, we studied the performance of an active detection approach that leverages the continuous nature of keystroke biometric patterns for the assessment of users’ fatigue in real time.
Conclusions
Our results suggest that the psychomotor patterns that characterize mental fatigue manifest during natural typing, which can be quantified via automated analysis of users’ daily interaction with their device. These findings represent a step towards the development of a more objective, accessible, and transparent solution to monitor mental fatigue in a real-world environment.
In this paper we study the feasibility of employing keystroke biometrics for mental fatigue detection during natural typing. For this task, we employ TypeNet, a state-of-the-art deep neuronal network, originally intended for user authentication at large scale using keystroke dynamics. We adapted TypeNet for fatigue detection by leveraging the information embedded in TypeNet for person recognition, and applying that information to a different but related task as it is fatigue detection by employing domain adaptation techniques. All experiments were conducted using three keystroke databases that comprise different contexts and data collection protocols. Our preliminary results showed performances ranging between 72.2% and 80.0% for fatigue versus rested sample classification, which is aligned with previously published models on daily alertness and circadian cycles. This demonstrates the potential of our proposed system to characterize mental fatigue fluctuations via natural typing patterns. Finally, we studied the feasibility of an active detection approach that utilizes the continuous monitoring of keystroke biometric patterns for the real-time assessment of subject fatigue.
e-learning platforms have a huge potential in the transfer and monitoring of curricula and learning content in surgical training programs; e-learning environments should be validated with the same rigor as virtual reality simulators. e-learning should not be seen as an alternative to traditional face-to-face training, but rather as a tool to improve and facilitate the learning process. e-content should refer to knowledge already acquired, should allow learners to interact with the proposed materials and to solve problems in order to better retain new information. Furthermore, the integration of proficiency-based progression methodology could drastically improve the results of these new training methodologies, both in terms of quality and time. Learners’ performance should be continuously assessed formatively with feedback to the trainees. At the end of the e-learning component of the curriculum, a summative assessment should be carried out, allowing only students who have reached the required performance level to progress to the next part of the curriculum.Keywordse-learningProficiency-based progression trainingPBPRobotic trainingMinimally invasive surgical training
Background: Fatigue is a general term used to describe an overall feeling of tiredness. It is one of the most common complaints of people seen in primary health care. Several previous studies have evaluated the effects of fatigue on cognitive function in various clinical and population settings and yielded different results. This study aimed to investigate the effect of fatigue on cognitive performance in neurology residents of Faculty of Medicine of Universitas Sumatera UtaraMethods: This was a crosssectional study involving all of the neurology residents of faculty of medicine universitas Sumatera Utara who fulfilled the inclusion criteria. This study was conducted on November until December 2020. Fatigue was assessed using fatigue severity scale and cognitive performance was assessed using Stroop test. The data was analyse using regression linear testResults: Total subject in this study was 42 subjects consisted of 26 female and 16 male with mean age of 32.02±3.45 years. The mean of FSS score was 33.71±7.41 and the mean of Stroop test score was 46.37±9.16 second. Using regression linear test we found fatigue affect cognitive function with p=0.002; R=0.470 and R2=0.221 and after stratification analysis based on sex of the subjects found that fatigue affect cognitive function in female subjects with p=0.013; R=0.482 and R2=0.232. According to age of the subject, fatigue affect cognitive function in subject >30 years old with p=0.001; R=0.635; R2=0.403Conclusions: There is significant effect of fatigue on cognitive performance. Particularly in women and age >30 years old.
Abstract: In our Education system an increasing importance being given to the grades and relative performance of students in academics, it comes with a lot more pressure for students to deal with. The education system puts an unnatural amount of emphasis on memorizing answers. Scoring high marks is the main objective and that is padded with pressure from all sides, from peers, teachers and parents. The present education system does not allow a child to relax and learn or think about what he or she learnt. The pressure of preparation for assignments, Projects, daily home works creates a high degree of mental tiredness in many students, especially in those who are unable to perform at a level that matches the potential they have shown in less stressful situations. The present study resembles the cognitive fatigue of adolescent school students, causes, signs and symptoms, and the ways to ease the cognitive fatigue.
(PDF) Cognitive Fatigue of Adolescent School Students. Available from: https://www.researchgate.net/publication/351128382_Cognitive_Fatigue_of_Adolescent_School_Students [accessed Apr 28 2021].
Background:
Cognitive failure is associated with memory and concentration problems. Previously, a prevalence of one third was found in a general sarcoidosis population. The aim of this study was to assess if neurosarcoidosis patients are at higher risk for developing everyday cognitive failure using the Cognitive Failure Questionnaire (CFQ) and to determine what factors were associated with cognitive failure.
Methods:
A cross-sectional web-based survey was conducted from April to May 2017 in a national sample of neurosarcoidosis patients. The survey asked about complaints and included 3 questionnaires (Fatigue Assessment Scale [FAS], Small Fiber Neuropathy Screening List [SFNSL] and CFQ. Data were compared to a general sarcoidosis population.
Results:
Of the 152 patients who completed the survey, 131 had neurosarcoidosis. The mean CFQ score was significantly higher in the neurosarcoidosis (45.6±20.7) compared to the general sarcoidosis population (36.2±15.9; p< 0.0001). High CFQ scores (≥43) were found in 55.7% and 33.9%, respectively (p<0.0001). The FAS score (OR 21.4) and SFNSL score (OR 4.3) were the strongest positive predictors of a high CFQ score.
Conclusion:
Cognitive failure is a significant problem in neurosarcoidosis. More than half of the patients reported cognitive deficits, compared to one third of a general sarcoidosis population. Fatigue and small fiber neuropathy play a role in cognitive failure.
Öz: Bilişsel yorgunluk (BY) egzersiz ve sporda performansa etki eden faktörlerden biri olarak değerlendirilmektedir. Bu derlemenin amacı bilişsel yorgunluk kavramını, bilişsel yorgunluğun nasıl oluşturulduğunu, nasıl değerlendirildiğini açıklamak ve konuyla ilgili çalışmaların sonuçlarını tartışmak ve böylece gelecekteki araştırmalar için önerilerde bulunabilmektir. Bu nedenle literatürdeki çalışmalar farklı veri tabanlarında taranmış ve BY ile ilgili yapılmış araştırmalar; "a) dayanıklılık performansı, b) anaerobik güç, maksimal kuvvet ve sürat performansı ve c) spora özgü beceriler, motor ve bilişsel performansa etkileri" başlıkları altında açıklanmıştır. Sonuçlara göre BY'nin egzersiz ve spor performasını olumsuz etkilediği görülmüştür. BY genel olarak dayanıklılık, spora özgü beceri, motor performans ve karar verme süreçlerinde bozulma yaratmış ancak maksimal veya maksimal üstü aktivitelerde performansı etkilememiştir. BY'nin performans üzerindeki olumsuz etkilerinin; algılanan zorluktaki artışa, beyindeki nörotransmitter dağılımına ve motivasyon düzeyindeki azalmaya bağlı olduğu düşünülmektedir. Gelecek çalışmalarda BY'ye neden olan bilişsel işler sırasındaki nöro-fizyolojik değişimler daha detaylı incelenebilir ve BY'nin etkilerinin nasıl elimine edebileceği üzerinde duralabilir. Abstract: Cognitive fatigue (CF) is considered as one of the factors affecting performance in exercise and sports. The purpose of this review is to explain the concept of cognitive fatigue, how cognitive fatigue is formed, how it is evaluated, and to discuss the results of studies related to the subject and thus to make suggestions for future research. For this reason, the studies in the literature have been searched in different databases and listed as effects on; "a) endurance performance, b) anaerobic power, maximal strength and speed performance, and c) sport-specific skills, motor and cognitive performance". According to the results, it was observed that BY had a negative effect on exercise and sports performance. In general, it caused impairments in endurance, motor performance, and sport-specific skills and decision-making, but did not affect performance in maximal or supramaximal activities. The negative effects of CF on performance are thought to be due to the increase in perception of effort, neurotransmitter distribution in the brain, and decreased level of motivation. In future studies, neurophysiological changes during cognitive tasks that lead to CF can be examined in more detail, and could be focused on how to eliminate the effects of BD. GİRİŞ Sporda kondisyon hazır olma durumudur ve performansı etkileyen tüm parametrelerin tekrar edilebilen en üst düzeylerini ifade eder. Sporda performans ise, müsabaka ve/veya antrenman sırasında ortaya konan ürün, yapılan iştir, ancak kazanma temelli düşünüldüğünde sporcuların mevcut kondisyonlarını müsabaka sırasında yansıtabilme başarıları olarak tanımlanmaktadır. Başarı için kondisyon ile performansın mümkün olan en üst seviyede ve birbirine yakın
Depression is a debilitating mental health problem in which inner conflict plays a major role. How a person experiences and resolves inner conflict has been well developed in cognitive dissonance theory. The use of dissonance theory has remained mostly limited to the field of social psychology and the link between depression and dissonance theory is largely unexplored. By researching the application of cognitive dissonance theory to experiences of individuals with depression it may be possible to expand our understanding of depression. The overall aim of this study was to explore how the process of depression might be related to the mechanism of cognitive dissonance. The objectives of the study were: to identify and compare episodes of cognitive dissonance in two participant groups (depressed and nondepressed), to analyse how different elements of cognitive dissonance are experienced by participants, and finally to develop a conceptual model that illustrates the potential relationship between depression and dissonance.
Abstract. Background: Cognitive failure is associated with memory and concentration problems. Previously,
a prevalence of one third was found in a general sarcoidosis population. The aim of this study was to assess if
neurosarcoidosis patients are at higher risk for developing everyday cognitive failure using the Cognitive Failure
Questionnaire (CFQ) and to determine what factors were associated with cognitive failure. Methods: A crosssectional
web-based survey was conducted from April to May 2017 in a national sample of neurosarcoidosis
patients. The survey asked about complaints and included 3 questionnaires (Fatigue Assessment Scale [FAS],
Small Fiber Neuropathy Screening List [SFNSL] and CFQ. Data were compared to a general sarcoidosis population.
Results: Of the 152 patients who completed the survey, 131 had neurosarcoidosis. The mean CFQ score
was significantly higher in the neurosarcoidosis (45.6±20.7) compared to the general sarcoidosis population
(36.2±15.9; p< 0.0001). High CFQ scores (≥43) were found in 55.7% and 33.9%, respectively (p<0.0001). The
FAS score (OR 21.4) and SFNSL score (OR 4.3) were the strongest positive predictors of a high CFQ score.
Conclusion: Cognitive failure is a significant problem in neurosarcoidosis. More than half of the patients reported
cognitive deficits, compared to one third of a general sarcoidosis population. Fatigue and small fiber neuropathy
play a role in cognitive failure. (Sarcoidosis Vasc Diffuse Lung Dis 2019; 36: 2-10)
An enhanced facilitation system caused by motivational input plays an important role in supporting performance during physical fatigue. We tried to clarify the neural mechanisms of the facilitation system during physical fatigue using magnetoencephalography (MEG) and a classical conditioning technique. Twelve right-handed volunteers participated in this study. Participants underwent MEG recording during the imagery of maximum grips of the right hand guided by metronome sounds for 10 min. Thereafter, fatigue-inducing maximum handgrip trials were performed for 10 min; the metronome sounds were started 5 min after the beginning of the handgrip trials. The metronome sounds were used as conditioned stimuli and maximum handgrip trials as unconditioned stimuli. The next day, they were randomly assigned to two groups in a single-blinded, two-crossover fashion to undergo two types of MEG recordings, that is, for the control and motivation sessions, during the imagery of maximum grips of the right hand guided by metronome sounds for 10 min. The alpha-band event-related desynchronizations (ERDs) of the motivation session relative to the control session within the time windows of 500 to 700 and 800 to 900 ms after the onset of handgrip cue sounds were identified in the sensorimotor areas. In addition, the alpha-band ERD within the time window of 400 to 500 ms was identified in the right dorsolateral prefrontal cortex (Brodmann's area 46). The ERD level in the right dorsolateral prefrontal cortex was positively associated with that in the sensorimotor areas within the time window of 500 to 700 ms. These results suggest that the right dorsolateral prefrontal cortex is involved in the neural substrates of the facilitation system and activates the sensorimotor areas during physical fatigue.
Background
Fatigue has a multi-factorial nature. We examined the effects of two types of mental fatigue on spontaneous oscillatory brain activity using magnetoencephalography (MEG).
Methods
Participants were randomly assigned to two groups in a single-blinded, crossover fashion to perform two types of mental fatigue-inducing experiments. Each experiment consisted of a 30-min fatigue-inducing 0- or 2-back test session and two evaluation sessions performed just before and after the fatigue-inducing mental task session.
Results
After the 0-back test, decreased alpha power was indicated in the right angular gyrus and increased levels in the left middle and superior temporal gyrus, left postcentral gyrus, right superior frontal gyrus, left inferior frontal gyrus, and right medial frontal gyrus. After the 2-back test, decreased alpha power was indicated in the right middle and superior frontal gyrus and increased levels in the left inferior parietal and superior parietal lobules, right parahippocampal gyrus, right uncus, left postcentral gyrus, left middle frontal gyrus, and right inferior frontal gyrus. For beta power, increased power following the 0-back test was indicated in the left middle temporal gyrus, left superior frontal gyrus, left cingulate gyrus, and left precentral gyrus. After the 2-back test, decreased power was suggested in the left superior frontal gyrus and increased levels in the left middle temporal gyrus and left inferior parietal lobule. Some of these brain regions might be associated with task performance during the fatigue-inducing trials.
Conclusions
Two types of mental fatigue may produce different alterations of the spontaneous oscillatory MEG activities. Our findings would provide new perspectives on the neural mechanisms underlying mental fatigue.
BACKGROUND: Fatigue can be classified as mental and physical depending on its cause, and each type of fatigue has a multi-factorial nature. We examined the effect of mental fatigue on the central nervous system using electroencephalography (EEG) in eighteen healthy male volunteers.Methods
After enrollment, subjects were randomly assigned to two groups in a single-blinded, crossover fashion to perform two types of mental fatigue-inducing experiments. Each experiment consisted of four 30-min fatigue-inducing 0- or 2-back test sessions and two evaluation sessions performed just before and after the fatigue-inducing sessions. During the evaluation session, the participants were assessed using EEG. Eleven electrodes were attached to the head skin, from positions F3, Fz, F4, C3, Cz, C4, P3, Pz, P4, O1, and O2.ResultsIn the 2-back test, the beta power density on the Pz electrode and the alpha power densities on the P3 and O2 electrodes were decreased, and the theta power density on the Cz electrode was increased after the fatigue-inducing mental task sessions. In the 0-back test, no electrodes were altered after the fatigue-inducing sessions.Conclusions
Different types of mental fatigue produced different kinds of alterations of the spontaneous EEG variables. Our findings provide new perspectives on the neural mechanisms underlying mental fatigue.
Fatigue is a common problem in modern society. We attempted to identify moderate- to long-term fatigue-related alterations in the central nervous system using cognitive tasks and electroencephalography (EEG) measures. The study group consisted of 17 healthy male participants. After saliva samples were collected to measure copy number of human herpesvirus (HHV)-6 DNA to assess the level of moderate- to long-term fatigue, subjects were evaluated using EEG, with their eyes open for 2 min, then closed for 1 min sitting quietly. Thereafter, they completed cognitive task trials to evaluate simple selective attention for 3 min (Task 1) and conflict-controlling selective attention for 6 min (Task 2, which included Stroop trials). The percent error of Task 2 for Stroop trials was positively associated with the copy number of saliva HHV-6 DNA, although the simple selective attention measures in Task 1 did not differ significantly. EEG power densities (especially the alpha power density) during the eye-closed condition were negatively associated with the saliva HHV-6 DNA level. Impaired high-level information processing such as that required for conflict-controlling selective attention in the central nervous system may be a characteristic feature of moderate- to long-term fatigue.
The traditional belief is that brain oscillations are important for human long-term memory, because they induce synchronized firing between cell assemblies which shapes synaptic plasticity. Therefore, most prior studies focused on the role of synchronization for episodic memory, as reflected in theta (∼5 Hz) and gamma (>40 Hz) power increases. These studies, however, neglect the role that is played by neural desynchronization, which is usually reflected in power decreases in the alpha and beta frequency band (8–30 Hz). In this paper we present a first idea, derived from information theory that gives a mechanistic explanation of how neural desynchronization aids human memory encoding and retrieval. Thereby we will review current studies investigating the role of alpha and beta power decreases during long-term memory tasks and show that alpha and beta power decreases play an important and active role for human memory. Applying mathematical models of information theory, we demonstrate that neural desynchronization is positively related to the richness of information represented in the brain, thereby enabling encoding and retrieval of long-term memories. This information via desynchronization hypothesis makes several predictions, which can be tested in future experiments.
Mental fatigue has a wide range of effects on cognitive, behavioral, and motivational measures. It can be expected that specific effects in which fatigue becomes manifest is dependent on the nature of fatigue-inducing activity (e.g., level of control and working memory demands). This study examined how fatigue caused by tasks that differ on the level of working memory demands (0-Back, 2-Back) affects brain function (novelty processing, P3a) and performance (driving). Results showed that fatigue did not affect driving performance. Fatigue did reduce P3a amplitude, but only after 2-Back. P3a was also reduced during driving. The effects of fatigue and driving on P3a were additive. In summary, both driving and fatigue reduced P3a amplitude. Driving effects were always present. Fatigue effects on novelty processing were dependent on the cognitive demands of the fatigue-inducing task.
Performance decrements attributed to mental fatigue have been found to be especially pronounced in tasks that involve the voluntary control of attention. Here we explored whether mental fatigue from prolonged time on task (TOT) also impairs temporal preparation for speeded action in a simple reaction-time task. Temporal preparation is enabled by a warning signal presented before the imperative stimulus and usually results in shorter reaction time (RT). When the delay between warning and imperative stimuli - the foreperiod (FP) - varies between trials, responses are faster with longer FPs. This pattern has been proposed to arise from either voluntary attentional processes (temporal orienting) or automatic trial-to-trial learning (trace conditioning). The former account suggests a selective RT increase on long-FP trials with fatigue; the latter account suggests no such change. Over a work period of 51 min, we found the typical increase in overall RT but no selective RT increase after long FPs. This additivity indicates that TOT-induced mental fatigue generally reduces cognitive efficiency but leaves temporal preparation under time uncertainty unaffected. We consider this result more consistent with the trace-conditioning account of temporal preparation.
A visual analogue scale to evaluate fatigue severity (VAS-F) was developed and tested in a sample of 75 healthy individuals and a sample of 57 patients undergoing medical evaluation for sleep disorders. The scale consists of 18 items related to fatigue and energy, has simple instructions, and is completed with minimal time and effort. The VAS-F compares favorably with the Stanford Sleepiness Scale and the Profile of Mood States, and its internal consistency reliabilities are high. Healthy subjects demonstrated significant differences between their evening and morning scores on the VAS-F, while sleep-disordered patients did not.
The emergence of a unified cognitive moment relies on the coordination
of scattered mosaics of functionally specialized brain regions. Here we review
the mechanisms of large-scale integration that counterbalance the distributed
anatomical and functional organization of brain activity to enable the emergence
of coherent behaviour and cognition. Although the mechanisms involved in large-scale
integration are still largely unknown, we argue that the most plausible candidate
is the formation of dynamic links mediated by synchrony over multiple frequency
bands.
We tested whether behavioural manifestations of mental fatigue may be linked to compromised executive control, which refers to the ability to regulate perceptual and motor processes for goal-directed behaviour. In complex tasks, compromised executive control may become manifest as decreased flexibility and sub-optimal planning. In the study we use the Wisconsin Card Sorting Test (WCST) and the Tower of London (TOL), which respectively measure flexibility (e.g., perseverative errors) and planning. A simple memory task was used as a control measure. Fatigue was induced through working for 2 h on cognitively demanding tasks. The results showed that compared to a non-fatigued group, fatigued participants displayed more perseveration on the WCST and showed prolonged planning time on the TOL. Fatigue did not affect performance on the simple memory task. These findings indicate compromised executive control under fatigue, which may explain the typical errors and sub-optimal performance that are often found in fatigued people.
Fatigue is a serious issue for the rail industry, increasing inefficiency and accident risk. The performance of 20 train drivers in a rail simulator was investigated at low, moderate and high fatigue levels. Psychomotor vigilance (PVT), self-rated performance and subjective alertness were also assessed. Alertness, PVT reaction times, extreme speed violations (>25% above the limit) and penalty brake applications increased with increasing fatigue level. In contrast, fuel use, draft (stretch) forces and braking errors were highest at moderate fatigue levels. Thus, at high fatigue levels, errors involving a failure to act (errors of omission) increased, whereas incorrect responses (errors of commission) decreased. The differential effect of fatigue on error types can be explained through a cognitive disengagement with the virtual train at high fatigue levels. Interaction with the train reduced dramatically, and accident risk increased. Awareness of fatigue-related performance changes was moderate at best. These findings are of operational concern.
Objective: Fatigue decreases efficiency in performing daily tasks, and this is a common symptom in modern society. It would thus be of great value to clarify the mechanism underlying fatigue and to develop efficient methods to evaluate fatigue. We examined cognitive function associated with two types of mental fatigue. Methods: Twenty healthy volunteers were randomised to perform rest or fatigue-inducing mental task session (0-back or 2-back test session) for 30 min in a 3-way crossover design. Just before and after each session, participants completed cognitive task trials to evaluate simple and conflict-controlling selective attention (response inhibition). Results: Changes in the reaction time of simple selective attention task after the 2-back test session were longer and changes after the 0-back test session had a trend toward being longer than those after the rest session. In addition, changes in the percent error for Stroop effect after the 2-back test session were significantly higher than those after the rest session, although those after the 0-back test session were not. Conclusions: Different types of mental fatigue produced different styles of deteriorated cognitive performances. Impaired selective attention may be a specific feature of mental fatigue, and a higher mental load may introduce a greater level of impaired conflict control or response inhibition.
Mental fatigue can be defined as a psychobiological state caused by prolonged periods of demanding cognitive activity and manifests as a reduced efficiency in cognitive performance. Mental fatigue is one of the most significant causes of accidents in modern society. Therefore, understanding the neural mechanisms of mental fatigue is important. However, the neural mechanisms of mental fatigue are not fully understood. In this study, we investigated the neural activity that results from mental fatigue caused by a continuous attention load. We used magnetoencephalography (MEG) to evaluate the neural activities during the attention task. Ten healthy male volunteers participated in this study. They performed a continuous attention task lasting 10 minutes. Subjective ratings of mental fatigue, mental stress, boredom, and sleepiness were performed just after the task trial. MEG data were analyzed using narrow-band adaptive spatial filtering methods. An increase in the beta-frequency band (13–25 Hz) power in the right inferior and middle frontal gyri (Brodmann's areas 44 and 9, respectively) was caused by the mental fatigue. The increase in the beta-frequency band power in the right middle frontal gyrus was negatively associated with the self-reported level of mental stress and was positively associated with those of boredom and sleepiness. These results demonstrate that performing a continuous mental fatigue-inducing task causes changes in the activation of the prefrontal cortex, and manifests as an increased beta-frequency power in this brain area as well as sleepiness. Our results contribute to greater understanding of the neural mechanisms of mental fatigue.
We sought to clarify the neural effect of mental fatigue on physical fatigue using magnetoencephalography (MEG) and classical conditioning techniques. Eleven right-handed volunteers participated in this study. On the first day, participants performed fatigue-inducing maximum handgrip trials for 10 min; metronome sounds were started 5 min after the beginning of the trials. We used metronome sounds as conditioned stimuli and maximum handgrip trials as unconditioned stimuli to cause physical fatigue. On the next day, MEG recordings during the imagery of maximum grips of the right hand guided by the metronome sounds were performed for 10 min just before (control session) and after (mental fatigue session) a 30-min fatigue-inducing mental task session. In the right anterior cingulate cortex (Brodmann's area 23), the alpha-band event-related synchronization of the mental fatigue session relative to the control session within the time window of 500–600 ms after the onset of handgrip cue sounds was identified. We demonstrated that mental fatigue suppresses activities in the right anterior cingulate cortex during physical fatigue.
Central inhibition plays an important role in physical performance during physical fatigue. We tried to clarify the neural mechanism of central inhibition during physical fatigue using magnetoencephalography (MEG) and a classical conditioning technique. Twelve right-handed volunteers participated in this study. Participants underwent MEG recording during the imagery of maximum grips of the right hand guided by metronome sounds for 10min. Thereafter, fatigue-inducing maximum handgrip trials were performed for 10min; the metronome sounds were started 5min after the beginning of the handgrip trials. We used metronome sounds as conditioned stimuli and maximum handgrip trials as unconditioned stimuli to cause central inhibition. The next day, MEG recording during the imagery of maximum grips of the right hand guided by metronome sounds were measured for 10min. Levels of the fatigue sensation in the right hand and sympathetic nerve activity on the second day were significantly higher than those on the first day. In the right dorsolateral prefrontal cortex (Brodmann's area 46), the alpha-band event-related desynchronization (ERD) of the second MEG session relative to the first session with the time window of 200 to 300ms after the onset of handgrip cue sounds was identified. The ERD level in this brain region was positively associated with the change in subjective level of right hand fatigue after the conditioning session and was negatively associated with that of sympathetic nerve activity. We demonstrated that the right dorsolateral prefrontal cortex is involved in the neural substrates of central inhibition during physical fatigue.
Three-dimensional MRI imaging techniques offer new possibilities for qualitative and quantitative studies of gross neuroanatomy, functional neuroanatomy and for neurosurgical planning. The digital nature of the data allows for the reconstruction of realistic three-dimensional models of an individual brain which can be sliced at arbitrary orientations for optimal visual inspection of often complex neuroanatomy and pathology. This is particularly relevant in the assessment of potential neuroanatomical correlates of temporal lobe epilepsy. Re-formatting of contiguous thinly sliced (1–2 mm thick) volumetric MRI data along planes parallel and perpendicular to the temporal plane allow finer visual discrimination and greater standardisation in qualitative procedures than previously possible. Perhaps more exciting are the applications of quantitative analysis where, for instance, accurate measurements of hippocampus and/or amygdala volumes provide important indicators of unilateral mesial temporal sclerosis which compare favourably with EEG and more invasive methods of lateralising the epileptogenic focus (Jack et al., 1990; Cascino et al., 1991; Watson et al, 1992; Cendes et al., 1993 a,b). For instance, by combining volumetric measurements of both hippocampus and amygdala, Cendes et al., (Chapter 9) quote correct lateralisation of focus in 93 of 100 temporal lobe epilepsy cases. The study of epilepsy arising from cortical abnormalities has been limited in the past by the difficulties of visualising the cortical surface from a set of conventional two-dimensional MRI slices. New acquisition techniques with gradient echo as opposed to spin echo techniques allow for an improved signal-to-noise ratio in thin slices in times compatible with clinical examinations. Whole brain coverage with thin slice data is now possible, such that partial volume effects are minimised with consequent improvements in fine detail. Numerous authors have reported dramatic improvements in the assessment of cortical dysplasia and grey matter heterotopias, particularly for more subtle abnormalities (Palmini et al., 1991a,b,c; Barkovich and Kjos, 1992a,b,c). The impact of this improved raw data when combined with new techniques for generating three-dimensional surface renderings in reasonably interactive circumstances is yet to be fully realised but initial experience is promising. At present, most studies have relied upon visual inspection to identify abnormalities in gyration on three-dimensional surface-rendered MRI. Such methods are quite acceptable for gross pathologies but, in a manner similar to mesial temporal volumetrics, the identification of more subtle distortions may require quantitative analysis of left/right differences and comparison of individual gyral surface area or gyral/sulcal locations with previously established population norms. Cook et al., (Chapter 47) have approached the problem by application of fractal analysis to two-dimensional MRI images from normal and frontal lobe epilepsy (FLE) patients. The grey-white matter interface was extracted by image processing procedures as a continuous contour and the fractal dimension, an index of contour complexity, derived. Results indicate that 10 of 16 FLE patients had a fractal index more than 3 standard deviations (3SD) below normal. In its present form, the method provides a non-specific indicator of cortical abnormality, yielding an overall index of complexity rather than identifying specific abnormalities, and is implemented in two dimensions rather than three dimensions. Nevertheless, it illustrates the potential of quantitative analysis for detecting aberrant cortical morphology. For a more directed analysis of cortical folding, a model of normal neuroanatomical variability, expressed in three-dimensional coordinates, is necessary. Keyserlingk and co-workers have developed methods for digitising sulcal patterns from post-mortem brains and constructed a map, with cuboid elements of 4 mm or 8 mm edge length, of major sulcal anatomy from 30 such brains (Keyserlingk et al., 1983, 1985, 1988; Niemann et al, 1988). The advent of high resolution MRI scanning offers finer spatial and contrast resolution in normal brain in vivo. At the Montreal Neurological Institute, MRI and PET imaging techniques are combined with three-dimensional graphics and computational analysis in the study of functional neuroanatomy of cognitive and sensorimotor processing. As part of this “brain mapping” programme, we have collected a database of over 300 MRI volumes from young normal subjects and are presently engaged in a series of projects whose long-term goal is the construction of a probabilistic description of normal neuroanatomy derived from high-resolution (1 mm thick slices) MRI data. In this chapter we briefly describe the current brain mapping environment at our institute and the current development of the MRI atlas project in both volumetric and surface domains.
This paper reviews the association between neurobiologically-based sleepiness/fatigue and human-error related accidents. It concludes that fatigue contributes to human error and accidents in technology-rich, industrialized societies in terms of human, environmental and economic impacts. The cultural utilization of time as expressed in 24-h work operations, combined with the widespread use of automation, will continue to escalate in the next century, further increasing the risks of fatigue-related accidents, as more people conduct vigilance-based activities at times other than the traditional daytime work hours. Fatigue management and prevention of fatigue-related catastrophes need to become a sustained priority for government, industries, labour, and the public. Scientific data are urgently needed on the most likely areas in which sleepiness-related performance failures contribute to accidents, and on the effectiveness of a wide range of potentially useful countermeasures.
During sustained periods of a taxing cognitive workload, humans typically display time-on-task (TOT) effects, in which performance gets steadily worse over the period of task engagement. Arterial spin labeling (ASL) perfusion functional magnetic resonance imaging (fMRI) was used in this study to investigate the neural correlates of TOT effects in a group of 15 subjects as they performed a 20-min continuous psychomotor vigilance test (PVT). Subjects displayed significant TOT effects, as seen in progressively slower reaction times and significantly increased mental fatigue ratings after the task. Perfusion data showed that the PVT activates a right lateralized fronto-parietal attentional network in addition to the basal ganglia and sensorimotor cortices. The fronto-parietal network was less active during post-task rest compared to pre-task rest, and regional CBF decrease in this network correlated with performance decline. These results demonstrate the persistent effects of cognitive fatigue in the fronto-parietal network after a period of heavy mental work and indicate the critical role of this attentional network in mediating TOT effects. Furthermore, resting regional CBF in the thalamus and right middle frontal gyrus prior to task onset was predictive of subjects' subsequent performance decline, suggesting that resting CBF quantified by ASL perfusion fMRI may be a useful indicator of performance potential and a marker of the level of fatigue in the neural attentional system.
The effects of mental fatigue on the availability of cognitive resources and associated response-related processes were examined using event-related brain potentials. Subjects performed a Go/NoGo task for 60 min. Reaction time, number of errors, and mental fatigue scores all significantly increased with time spent on the task. The NoGo-P3 amplitude significantly decreased with time on task, but the Go-P3 amplitude was not modulated. The amplitude of error-related negativity (Ne/ERN) also decreased with time on task. These results indicate that mental fatigue attenuates resource allocation and error monitoring for NoGo stimuli. The Go- and NoGo-P3 latencies both increased with time on task, indicative of a delay in stimulus evaluation time due to mental fatigue. NoGo-N2 latency increased with time on task, but NoGo-N2 amplitude was not modulated. The amplitude of response-locked lateralized readiness potential (LRP) significantly decreased with time on task. Mental fatigue appears to slows down the time course of response inhibition, and impairs the intensity of response execution.
Fatigue is a common symptom in modern society. In order to clarify the mechanisms underlying fatigue, we examined the association between central nervous system fatigue and autonomic nerve activity.
The study group consisted of 20 healthy subjects. They performed the 2-back test for 30 min to induce fatigue. Just before and after the fatigue-inducing session, they completed the advanced trail making test (ATMT) for 30 min as a fatigue-evaluating task session. In order to measure autonomic nerve activity, electrocardiograms were monitored continuously throughout the experiment.
After the fatigue-inducing task session, impaired task performance was demonstrated based on the total trial number and error counts of the ATMT. During the task session, although task performance as measured using the accuracy and the mean reaction time of the 2-back test was almost unchanged, electrocardiographic R-R wave interval analyses showed a decreased high-frequency component power and an increasing trend in the low-frequency component power/high-frequency component power ratio.
Decreased vagal nerve activity and increased sympathetic nerve activity are associated with central nervous system fatigue.
PET and fMRI experiments have previously shown that several brain regions in the frontal and parietal lobe are involved in working memory maintenance. MEG and EEG experiments have shown parametric increases with load for oscillatory activity in posterior alpha and frontal theta power. In the current study we investigated whether the areas found with fMRI can be associated with these alpha and theta effects by measuring simultaneous EEG and fMRI during a modified Sternberg task This allowed us to correlate EEG at the single trial level with the fMRI BOLD signal by forming a regressor based on single trial alpha and theta power estimates. We observed a right posterior, parametric alpha power increase, which was functionally related to decreases in BOLD in the primary visual cortex and in the posterior part of the right middle temporal gyrus. We relate this finding to the inhibition of neuronal activity that may interfere with WM maintenance. An observed parametric increase in frontal theta power was correlated to a decrease in BOLD in regions that together form the default mode network. We did not observe correlations between oscillatory EEG phenomena and BOLD in the traditional WM areas. In conclusion, the study shows that simultaneous EEG-fMRI recordings can be successfully used to identify the emergence of functional networks in the brain during the execution of a cognitive task.
The influence of mental fatigue, as induced by time on task, on top-down control involved in planning goal-directed behavior and conflict resolution was examined, using an S1-S2 paradigm. S2 stimuli consisted of compatible and incompatible stimuli, placing dissimilar demands on automatic and controlled processes involved in conflict solving. Information provided by explicit cues (S1) affected brain activity elicited during the S1-S2 interval. P2 and CNV effects were more pronounced if advance information was relevant for subsequent behavior (hand cue) than after a cue providing information about stimulus features of S2 (color cue). Brain activity elicited by cue information was significantly attenuated with time on task. The behavioral results showed that advance information facilitated processing of S2; reactions were faster if cue information was valid, especially in the hand cue condition. In this condition invalid information led to significant costs in the form of increased error rates, as well. Performance efficiency deteriorated with time on task and differences between validly and invalidly cued stimuli became smaller. Concerning the time course of the behavioral effect it seems that top-down processes indexed by the CNV are the most likely candidate to underlie the performance effects of mental fatigue. Time on task effects on the cue-P2 were unrelated to observed behavioral effects. These results showed that the influence of advance information on information processing diminished with increasing mental fatigue. No evidence was found that mental fatigue had differential effects on controlled and automatic processes involved in conflict solving.
The need for a simply applied quantitative assessment of handedness is discussed and some previous forms reviewed. An inventory of 20 items with a set of instructions and response- and computational-conventions is proposed and the results obtained from a young adult population numbering some 1100 individuals are reported. The separate items are examined from the point of view of sex, cultural and socio-economic factors which might appertain to them and also of their inter-relationship to each other and to the measure computed from them all. Criteria derived from these considerations are then applied to eliminate 10 of the original 20 items and the results recomputed to provide frequency-distribution and cumulative frequency functions and a revised item-analysis. The difference of incidence of handedness between the sexes is discussed.
Although recent neuroimaging studies suggest that prefrontal cortex (PFC) is involved in working memory (WM), the relationship between PFC activity and memory load has not yet been well-described in humans. Here we use functional magnetic resonance imaging (fMRI) to probe PFC activity during a sequential letter task in which memory load was varied in an incremental fashion. In all nine subjects studied, dorsolateral and left inferior regions of PFC were identified that exhibited a linear relationship between activity and WM load. Furthermore, these same regions were independently identified through direct correlations of the fMRI signal with a behavioral measure that indexes WM function during task performance. A second experiment, using whole-brain imaging techniques, both replicated these findings and identified additional brain regions showing a linear relationship with load, suggesting a distributed circuit that participates with PFC in subserving WM. Taken together, these results provide a "dose-response curve" describing the involvement of both PFC and related brain regions in WM function, and highlight the benefits of using graded, parametric designs in neuroimaging research.
In fMRI there are two classes of inference: one aims to make a comment about the "typical" characteristics of a population, and the other about "average" characteristics. The first pertains to studies of normal subjects that try to identify some qualitative aspect of normal functional anatomy. The second class necessarily applies to clinical neuroscience studies that want to make an inference about quantitative differences of a regionally specific nature. The first class of inferences is adequately serviced by conjunction analyses and fixed-effects models with relatively small numbers of subjects. The second requires random-effect analyses and larger cohorts.
An automated coordinate-based system to retrieve brain labels from the 1988 Talairach Atlas, called the Talairach Daemon (TD), was previously introduced [Lancaster et al., 1997]. In the present study, the TD system and its 3-D database of labels for the 1988 Talairach atlas were tested for labeling of functional activation foci. TD system labels were compared with author-designated labels of activation coordinates from over 250 published functional brain-mapping studies and with manual atlas-derived labels from an expert group using a subset of these activation coordinates. Automated labeling by the TD system compared well with authors' labels, with a 70% or greater label match averaged over all locations. Author-label matching improved to greater than 90% within a search range of +/-5 mm for most sites. An adaptive grey matter (GM) range-search utility was evaluated using individual activations from the M1 mouth region (30 subjects, 52 sites). It provided an 87% label match to Brodmann area labels (BA 4 & BA 6) within a search range of +/-5 mm. Using the adaptive GM range search, the TD system's overall match with authors' labels (90%) was better than that of the expert group (80%). When used in concert with authors' deeper knowledge of an experiment, the TD system provides consistent and comprehensive labels for brain activation foci. Additional suggested applications of the TD system include interactive labeling, anatomical grouping of activation foci, lesion-deficit analysis, and neuroanatomy education.
The effects of mental fatigue on planning and preparation for future actions were examined, using a task switching paradigm. Fatigue was induced by "time on task," with subjects performing a switch task continuously for 2 hr. Subjects had to alternate between tasks on every second trial, so that a new task set was required on every second trial. Manipulations of response-stimulus intervals (RSIs) were used to examine whether subjects prepared themselves for the task change. Behavioral measurements, event-related potentials (ERPs), and mood questionnaires were used to assess the effects of mental fatigue. Reaction times (RTs) were faster on trials in which no change in task set was required in comparison with switch trials, requiring a new task set. Long RSIs were used efficiently to prepare for the processing of subsequent stimuli. With increasing mental fatigue, preparation processes seemed to become less adequate and the number of errors increased. A clear poststimulus parietal negativity was observed on repetition trials, which reduced with time on task. This attention-related component was less pronounced in switch trials; instead, ERPs elicited in switch trials showed a clear frontal negativity. This negativity was also diminished by time on task. ERP differences between repetition and switch trials became smaller with increasing time on task.
The alpha rhythm in the EEG is 8-12 Hz activity present when a subject is awake with eyes closed. In this study, we used simultaneous EEG and fMRI to make maps of regions whose MRI signal changed reliably with modulation in posterior alpha activity. We scanned 11 subjects as they rested with eyes closed. We found that increased alpha power was correlated with decreased MRI signal in multiple regions of occipital, superior temporal, inferior frontal, and cingulate cortex, and with increased signal in the thalamus and insula. These results are consistent with animal experiments and point to the alpha rhythm as an index of cortical inactivity that may be generated in part by the thalamus. These results also may have important implications for interpretation of resting baseline in fMRI studies.
