Demographic data.

Demographic data.

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Chronic cannabis use has been shown to block long-term depression of GABA-glutamate synapses in the striatum, which is likely to reduce the extent to which endogenous cannabinoids modulate GABA- and glutamate-related neuronal activity. The current study aimed at investigating the effect of this process on striatal dopamine levels by studying the sp...

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... Indeed, reduction in sEBR following dopamine antagonist administration as well as an increase after dopamine agonist administration was observed [18][19][20][21]. sEBR was also linked to changes in dopamine regulation in several neurological and psychiatric disorders [22][23][24], including substance use disorders [25,26]. Previous studies have also shown a relationship between sEBR and cognitive functions such as attention and cognitive flexibility [27]. ...
... However, problematic use (as assessed in the current study) and true clinical impairment due to problematic behavior, while overlapping, are still two different concepts and potentially should cause different levels of functional alterations. Previously shown changes of sEBR in addicted subjects [25,26] might be due to a relatively stronger impairment in dopamine functioning. Importantly, excessive internet use also incorporates a range of online activities including gambling, gaming, streaming, pornography, impulsive buying, and social networking, which if used excessively might be considered problematic [58]. ...
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Increasing availability of the internet has resulted in the increased prevalence of problematic online behaviors. Reliable and affordable neurobiological and psychological biomarkers that distinguish problematic internet use (PIU) from functional online activities are of utmost importance. Previous studies have shown a relationship between spontaneous eye blinking rate (sEBR) and changes in dopamine regulation in neurological and psychiatric disorders, including substance use disorders. In this study, we utilized sEBR to examine the potential link between individual differences in dopaminergic neurotransmission and PIU. In sum, 62 subjects participated in this study (median age 25, IQR 6 years, 34 females). The Problematic Internet Use Questionnaire (PIUQ-9), Beck Depression Inventory (BDI-II), Beck Anxiety Inventory (BAI), Clark–Beck Obsessive–Compulsive Inventory (CBOCI) and Barratt Impulsiveness Scale (BIS-11) were used for psychological assessment. The sEBRs were assessed with an electrooculogram recorded from above and below the left eye and from the right and left outer canthi. The group with PIU (PIUQ-9 > 20) expressed higher levels of impulsivity and compulsive behavior symptoms than the control group. In the group with PIU, impulsivity levels were inversely related to sEBR, and a trend of negative association of sEBR with compulsive behavior was observed. Future research should enroll subjects with high levels of PIU and strongly expressed psychopathology levels to further address the utility of sEBR as a potential biomarker.
... • Clarification of the metabolic profiles of secondary plant ingredients [50][51][52]; ...
... Clarification of the metabolic profiles of secondary plant ingredients [50][51][52]; • Use of secondary plant ingredients for therapeutic application for animals and humans [53][54][55][56][57][58][59]; • Use for defense against undesired plants, bacteria, and fungi [60,61]; • Application for improving material properties. ...
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The transition towards a bio-based world is a challenging undertaking. This perspective paper, from an engineering point of view, aims to provide an overview of existing projects and academic disciplines highlighting the potential benefit of increased interdisciplinary exchanges. Furthermore, the current utilization of biomass to produce biogas is discussed, including an economic assessment, showing the need for new strategies of biomass valorization. One solution could be the development of separation processes for the isolation of secondary plant metabolites, which have been especially valuable for pharmaceutical applications, e.g., taxotere ® and artemisinin. The economic feasibility is demonstrated in a case study, evaluating the purification potential of curcuminoids from Curcuma longa L. Subsequently, the conclusion discusses the limitations of large-scale industrial applications and the need for new separation techniques as a step towards a bio-based world.
... • Severe reduction of visual acuity and/or visual field of any cause, refractive errors not correctable with glasses and hearing loss, because the involved subjects had to observe some scenes from a movie, including audio, as well as to mentally read a text. • Other causes that can influence spontaneous eye blinking were excluded: drug assumption (Karson 1983, Lawrence and Redmond 1991, Kowal et al 2011, sleep deficiency/insomnia in the week before participation in the study (Deuschl and Goddemeier 1998) and nicotine assumption (Evinger et al 1993). • Use of contact lenses to avoid factors that could potentially interfere with the physiological variation in the corneo-retinal potential that changes when the eyelid passes through the eye. ...
... The VEOG is not suitable for recording blinking when there is a structural alteration of the cornea and/or retinal pigment epithelium caused by pathology, or when there is a deficit of eye and eyelid movements (Denney andDenney 1984, Stern et al 1984). In this study all those conditions were excluded, as well as other causes that could influence spontaneous blinking that were previously reported in section 2.1, such as taking medication (Karson 1983, Lawrence and Redmond 1991, Kowal et al 2011, psychiatric disorders (Stevens 1978, Ebert et al 1996, Byrne et al 2016, lack of sleep (Deuschl and Goddemeier 1998), nicotine consumption (Evinger et al 1993), ambient brightness (Denney and Denney 1984) and the vertical eye position during recording (VanderWerf et al 2003). ...
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Objective: Hypomimia is a common and early symptom of Parkinson's disease (PD), which reduces the ability of PD patients to manifest emotions. Currently, it is visually evaluated by the neurologist during neurological examinations for PD diagnosis, as described in task 3.2 of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS). Since such an evaluation is semi-quantitative and affected by inter-variability, this paper aims to measure the physiological parameters related to eye blink and facial expressions extracted from a vertical electro-oculogram (VEOG) and facial surface electromyography (fsEMG) to differentiate PD patients from healthy control subjects (HCs). Approach: The spontaneous eye blink rate-minute (sEBR), its maximum amplitude (BMP), and facial cutaneous muscle activity were measured in 24 PD patients and 24 HCs while the subjects looked at a visual-tester composed of three main parts: static vision, dynamic vision and reading silently. Specificity and sensitivity for each parameter were calculated. Main results: The VEOG and the fsEMG allowed the identification of some parameters related to eye blink and facial expressions (i.e. sEBR, BMP, frontal and peribuccal muscular activities), being able to distinguish between PD patients and HCs with high sensitivity and specificity. Significance: The demonstration that the combination of parameters related to eye blink and facial expressions can discriminate (with high accuracy) between PD patients versus HCs, thus resulting in a useful tool to support the neurologist in objective assessment of hypomimia for improving PD diagnosis.
... The Spontaneous Eye Blink Rate (SEBR) has been used as a non-invasive marker to index DA production with a lower blink rate associated with lower DA production (Karson, 1988;Taylor et al., 1999). Kowal et al. (2011) have shown that abstinent chronic cannabis users blink almost half as many times per minute as controls, providing further indirect evidence of a hypodopaminergic state in chronic users who are abstinent from cannabis. Therefore finally, we collected SEBR to index DA production in cannabis users and compare it to controls. ...
... At the Callaghan campus, the number of blinks on the videos recorded during the 6 min of the experiment was counted by two independent observers and averaged for each participant. Total number of blinks collected for each participant was then divided by 6 (Kowal et al., 2011), and compared between groups, using independent t test. ...
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RationaleCannabis use impairs visual attention; however, it is unclear whether cannabis use also impairs low level visual processing or whether low level visual deficits can be related to lower dopaminergic functioning found in cannabis users. Objectives To investigate whether spatiotemporal contrast sensitivity and motion discrimination under normal and low luminance conditions differ in cannabis users and non-users. Methods Control (n = 20) and cannabis (n = 21) participants completed a visual acuity test, a saliva test and self-report measures. Spatial and temporal contrast thresholds, motion coherence thresholds for translational and radial motion and the spontaneous eye blink rate were then collected. ResultsCannabis users showed decreased spatial contrast sensitivity under low luminance conditions and increased motion coherence thresholds under all luminance levels tested compared to non-users. No differences in temporal contrast sensitivity were found between the groups. Frequency of cannabis use correlated significantly and negatively with contrast sensitivity, both spatial and temporal, in the cannabis group and higher motion coherence thresholds for radial motion were also associated with more frequent cannabis use in this group. The eye blink rate was significantly lower in cannabis users compared to non-users. Conclusions The present study shows that cannabis use is associated with deficits in low level visual processing. Such deficits are suggested to relate to lower dopamine, in a similar manner as in clinical populations. The implications for driving safety under reduced visibility (e.g. night) in abstaining cannabis users are discussed.
... Three participants were kept in the analyses despite minor data loss (exploitable data: 3.5, 4.4 and 4.5 min). One gambler was further excluded because he met the DSM-IV-TR criteria for past year marijuana dependence, which is known to influence sEBR measures (Kowal et al., 2011). As a result, the final sample comprised 20 participants (mean age: 38.2, age range: 22-54, gamblers: n=11, controls: n=9). ...
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Dopamine is central to a number of cognitive functions and brain disorders. Given the cost of neurochemical imaging in humans, behavioral proxy measures of dopamine have gained in popularity in the past decade, such as spontaneous eye blink rate (sEBR). Increased sEBR is commonly associated with increased dopamine function based on pharmacological evidence and patient studies. Yet, this hypothesis has not been validated using in vivo measures of dopamine function in humans. In order to fill this gap, we measured sEBR and striatal dopamine synthesis capacity using [18F]DOPA PET in 20 participants (9 healthy individuals and 11 pathological gamblers). Our results, based on frequentist and Bayesian statistics, as well as region-of-interest and voxel-wise analyses, argue against a positive relationship between sEBR and striatal dopamine synthesis capacity. They show that, if anything, the evidence is in favor of a negative relationship. These results, which complement findings from a recent study that failed to observe a relationship between sEBR and dopamine D2 receptor availability, suggest that caution and nuance are warranted when interpreting sEBR in terms of a proxy measure of striatal dopamine. This article is protected by copyright. All rights reserved.
... Parkinson's patients have decreased EBR [33] and decreased DA activity in the nigral area of the braina dopamine producing area associated with the disease [34] as well as degenerated striatal DA activity [35]. Decreased EBR has also been seen in chronic cannabis users [36] and recreational cocaine users [37] -a drug which disinhibits dopamine neurons, especially with chronic use [37]. Together, these studies demonstrate spontaneous eye blink rates are a reliable biomarker for DA activity. ...
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Previous research suggests that eye blink rates (EBR) can be used as an index for dopamine activity (DA) and therefore a potential marker of creative aptitude. In addition, another putative index of creativity has been linked to the neurotransmitter serotonin (5-HT) and eye blink duration (EBD). The current pilot study aimed to investigate whether both EBR and EBD could be used as predictors of creativity and if mood would influence these measures. Vertical electrooculograms were gathered from 12 participants, during three conditions, to enable subsequent EBR and EBD to be calculated. The three conditions comprised eyes open baseline, viewing images from the International Affective Picture System (IAPS) of positive and finally negative valence. Dispositional measures of creativity were measured post task using the Creative Styles Questionnaire-revised. Higher EBR was significantly related to higher scores on subcategories 'Use of Techniques' and 'Use of Other People'. In addition, shorter EBD significantly correlated with higher scores of global creativity, 'Use of Techniques' and 'Use of the Senses'. Results confirm that EBR and EBD can be used as predictors for creativity and may reflect DA/5-HT activity. Implications of the results are discussed in relation to specific characteristics, techniques and underlying mechanisms of creativity and how neurotransmitters drive such ability.
... Three participants were kept in the analyses despite minor data loss (exploitable data: 3.5, 4.4 and 4.5 min). One gambler was further excluded because he met the DSM-IV-TR criteria for past year marijuana dependence, which is known to influence sEBR measures (Kowal et al., 2011). As a result, the final sample comprised 20 participants (mean age: 38.2, age range: 22-54, gamblers: n=11, controls: n=9). ...
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Dopamine is central to a number of cognitive functions and brain disorders. Given the cost of neurochemical imaging in humans, behavioral proxy measures of dopamine have gained in popularity in the past decade, such as spontaneous eye blink rate (sEBR). Increased sEBR is commonly associated with increased dopamine function based on pharmacological evidence and patient studies. Yet, this hypothesis has not been validated using in vivo measures of dopamine function in humans. In order to fill this gap, we measured sEBR and striatal dopamine synthesis capacity using [ ¹⁸ F]DOPA PET in 20 participants (9 healthy individuals and 11 pathological gamblers). Our results, based on frequentist and Bayesian statistics, as well as region-of-interest and voxel-wise analyses, argue against a positive relationship between sEBR and striatal dopamine synthesis capacity. They show that, if anything, the evidence is in favor of a negative relationship. These results, which complement findings from a recent study that failed to observe a relationship between sEBR and dopamine D2 receptor availability, suggest that caution and nuance are warranted when interpreting sEBR in terms of a proxy measure of striatal dopamine.
... Parkinson's disease and 107 schizophrenia), or a history of using drugs known to affect the dopamine system 108 (e.g. cocaine) (Chen et al., 1996;Colzato et al., 2008;Kowal et al., 2011;109 Fitzpatrick et al., 2012). This evidence is complicated by the fact that aberrant 110 EBR is also present in non-dopamine specific conditions such as intellectual 111 disability and traumatic brain injury (Goldberg et al., 1987;Daugherty et al., 1993;112 Konrad et al., 2003), suggesting that EBR is influenced by and reflective of 113 multiple brain processes (see Jongkees and Colzato, 2016 for a more thorough 114 review of evidence relating EBR to dopamine). ...
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Spontaneous eye blink rate (EBR) has been proposed as a noninvasive, inexpensive marker of dopamine functioning. Support for a relation between EBR and dopamine function comes from observations that EBR is altered in populations with dopamine dysfunction and EBR changes under a dopaminergic manipulation. However, the evidence across the literature is inconsistent and incomplete. A direct correlation between EBR and dopamine function has so far been observed only in nonhuman animals. Given significant interest in using EBR as a proxy for dopamine function, this study aimed to verify a direct association in healthy, human adults. Here we measured EBR in healthy human subjects whose dopamine D2 receptor (DRD2) availability was assessed with positron emission tomography (PET)-[18F]fallypride to examine the predictive power of EBR for DRD2 availability. Effects of the dopamine agonist bromocriptine on EBR also were examined to determine the responsiveness of EBR to dopaminergic stimulation and, in light of the hypothesized inverted-U profile of dopamine effects, the role of DRD2 availability in EBR responsivity to bromocriptine. Results from 20 subjects (age 33.6 ± 7.6 years, 9F) showed no relation between EBR and DRD2 availability. EBR also was not responsive to dopaminergic stimulation by bromocriptine, and individual differences in DRD2 availability did not modulate EBR responsivity to bromocriptine. Given that EBR is hypothesized to be particularly sensitive to DRD2 function, these findings suggest caution in using EBR as a proxy for dopamine function in healthy humans.
... The vertical Electrooculogram (EOG) was used to detect eye blink rates, by recording the voltage difference between two electrodes placed above and below the left eye (which were applied after the skin was scrubbed with Nuprep Skin Prep Gel, Weaver and Company, Aurora, CO). Recordings did not take place after 5 p.m., because spontaneous EBR is generally stable during daytime, but increases in the evening (Barbato et al., 2000;Kowal et al., 2011). Data analysis was performed with Brain Vision Analyzer (Brain Products GmbH, Munich, Germany). ...
Article
Although the existence of ‘choking under pressure’ is well-supported by research, its biological underpinnings are less clear. In this research, we examined two individual difference variables that may predict whether people are likely to perform poorly in high-incentive conditions: baseline eye blink rate (EBR; reflecting dopamine system functioning) and baseline anterior hemispheric asymmetry (an indicator of goal-directed vs. stimulus driven processing). Participants conducted a switch task under control vs. incentive conditions. People low in EBR were generally capable of improving their performance when incentives were at stake, whereas people high in EBR were not. Hemispheric asymmetry did not predict performance. These findings are consistent with the idea that suboptimal performance in high-stakes conditions may stem from the neuromodulatory effects of dopamine.
... The usual blink rate is about once every three seconds, or about 20 times per minute (e.g., Mackintosh, Kumar, & Kitamura, 1983). In the absence of a serious medical illness (e.g., Parkinson's disease) or chronic cannabis or cocaine use, in which blink rates are attenuated due in part to disruptions in the dopaminergic system (Colzato, Van Den Wildenberg, & Hommel, 2008;Deuschl & Goddemeier, 1998;Kowal, Colzato, & Hommel, 2011), if someone blinks, for example, twice per minute, it suggests that the individual is either intensely concentrating on something (e.g., Karson, Freed, Kleinman, Bigelow, & Wyatt, 1981), is feeling a sense of danger, or both. In mental health settings, if a person's blink rate is low and he or she is uncommunicative, one possible inference is that the person is preoccupied with and concentrating on suicide and, because death is fearsome, is attempting to "stare it down." ...
Article
When perceiving a dangerous predation threat, mammalian and other species activate antipredator defensive reactions. These include the seemingly paradoxical—but compatible—activation of overarousal (e.g., agitation, insomnia) and “shutdown” (e.g., mutism, withdrawal) states. Acute suicidal crises, too, are characterized by the co-occurrence of overarousal and shutdown behaviors. In the minutes, hours, and days prior to one’s death by suicide, it is not uncommon for one to be simultaneously agitated and socially withdrawn, states that resemble antipredator defensive reactions. In this article, we present empirical, clinical, and philosophical grist for our conjecture that antipredator defensive reactions may serve as a useful way to understand the phenomenology of a serious suicidal crisis, and we reflect on the implications that soon-to-be suicide decedents are simultaneously killer and victim.