[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to examine the effects of a single bout of walking on mood, psychophysiologic responses, and executive function in elderly adults.
Twenty healthy, elderly adults (10 women and 10 men; mean age 70.50 ± 3.4 years) participated in this study. Mood, as assessed by the Profile of Mood States, and salivary α-amylase activity were examined before and after walking. Executive functions were also evaluated by the Wisconsin Card Sorting Test.
Negative feeling scores such as tension-anxiety, anger-hostility, and confusion significantly improved after walking. No significant differences were found for either salivary α-amylase activities or Wisconsin Card Sorting Test scores before and after walking. However, the changes in salivary α-amylase activity before and after walking correlated positively with the number of total errors and perseverative errors of Nelson in the Wisconsin Card Sorting Test.
These results suggest that moderate exercise, such as self-paced one-time walking, induces beneficial psychologic effects in elderly adults. Meanwhile, the significant increase in salivary α-amylase activity after walking might temporarily cause deterioration of executive function.
[Show abstract][Hide abstract] ABSTRACT: Previous studies have demonstrated centrifugal modulation of somatosensory cortical responses before the onset of self-initiated or externally-initiated voluntary movement. To elucidate the centrifugal regulation just before an imperative signal initiating a movement, we examined changes in short- and long-latency somatosensory evoked potentials (SEPs) just before an imperative signal in a forewarned reaction time task. Twelve healthy adults participated in this study. An auditory warning signal was followed 2 s later by a visual imperative signal. An electrical stimulus to elicit SEPs was presented to the right median nerve 200 ms before the imperative signal. The subjects were instructed to extend the right second digit when the visual stimulus was presented (reaction condition), to silently count the number of visual stimuli (visual attention condition), or to silently count the number of the electrical stimuli (somatosensory attention condition). The control condition involved no task. The amplitudes of the frontal N30, parietal P30 and central N60 were significantly reduced in the reaction condition compared to the control, visual attention and somatosensory attention conditions. The short-latency SEP components earlier than 30 msec after somatosensory stimulation were not significantly modified by visual and somatosensory attention. The amplitude of the N140 was significantly enhanced in the reaction condition compared to the other three conditions. In conclusion, short-latency neural responses are suppressed by the centrifugal influence just before a timed movement, whereas long-latency activity around the 140-ms latency is enhanced.
[Show abstract][Hide abstract] ABSTRACT: The amplitudes of the event-related brain potentials (ERPs) have been associated with the amount of attentional resources. The present study investigated whether force production type (increasing or decreasing force) in a visuomotor force tracking task modulates the ERPs elicited in a somatosensory oddball task performed simultaneously, whether stimulus-response coupling assessed by a single-trial analysis of P300 latency is modulated by the concurrent performance of the tasks, and whether dynamic visuomotor coordination rather static coordination is sensitive to the ERP modulation. In the dual-task condition, the subjects tracked a target line moving on the display with another line representing the force generated by the grip of their left hand, while executing the somatosensory oddball task with the right hand. In the oddball-only condition, the oddball task only was performed. The amplitude of the P300 elicited in the oddball task was decreased in the dual-task condition compared with the oddball-only condition, and further decreased in the force-decreasing phase compared with the increasing phase, but was not altered by the concurrently performed isometric contraction. P100, N140, reaction time (RT), and error rate were not influenced by force production type. A correlation analysis of single-trial P300 latency and RT showed that the dual-task condition produced a stronger coupling of the P300 and RT. In summary, different force production types requiring dynamic visuomotor coordination alter a modality-nonspecific late stage of somatosensory processing but have less of an effect on early stages. During the performance of the dual task, stimulus-response coupling in the somatosensory discrimination task becomes stronger to compensate for a lack of resources and/or due to snap decisions owing to sufficient resources.
Experimental Brain Research 11/2011; 216(4):575-84. DOI:10.1007/s00221-011-2961-z · 2.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We examined the modulation of event-related brain potentials (ERPs) and the accuracy of sensori-motor coordination on short-term repetition of the concurrent performance of a somatosensory discrimination (oddball) task and a visuo-motor tracking task.
The subjects concurrently performed visuomotor tracking and somatosensory oddball tasks. In the dual-task condition, the subjects performed the visuomotor tracking and somatosensory oddball tasks concurrently for about an hour. In the oddball-only condition, they performed just the oddball task for the same period.
Tracking performance improved with task repetition. The amplitude of the P300 elicited by somatosensory stimulation in the oddball-only condition decreased significantly with task repetition, whereas in the dual-task condition, it showed a complex pattern of change. The earlier responses were decreased in amplitude in the dual-task condition compared to the oddball-only condition, and gradually decreased with task repetition in both conditions.
Dynamic changes in ERPs and task performance with dual-task repetition support the idea that dual-task repetition produces changes in resource allocation following the automation of stimulus processing in addition to so-called habituation.
This study also provides evidence for use of ERP amplitudes as physiological indices of functionally different types of resources.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 10/2011; 123(6):1123-30. DOI:10.1016/j.clinph.2011.10.001 · 3.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Effects of long-term motor practice on movement-related brain activities were investigated by measuring from the scalp, movement-related cortical potentials (MRCP) associated with self-paced right (dominant) and left (non-dominant) brisk handgrip movements with a 20% maximal voluntary contraction (MVC) in 8 elite kendo players (kendo group) and 8 healthy young adults (control group). The kendo players had engaged in regular practice since childhood. Three components of MRCP were obtained from all subjects. These components relating to the preparation (Bereitschaftspotential: BP and negative slope: NS') and initiation (motor potential: MP) of the movements were compared between the two groups. The BP onset time for a non-dominant handgrip task was significantly earlier in the control group than in the kendo group. Moreover, BP onset time appeared significantly earlier preceding the non-dominant handgrip task as compared with the dominant one only in the control group. Furthermore, MP amplitudes in the kendo group were significantly larger than in the control group. These findings suggest that long-term motor practice affects brain activities, leading to practice-dependent modulations in the cortical areas involved in the preparation and initiation of self-paced non-dominant handgrip movements in kendo players.
[Show abstract][Hide abstract] ABSTRACT: The present study investigated the effects of acute aerobic exercise on cognitive brain functions of older adults. Twenty-four males (12 older and 12 younger adults) performed a modified flanker task during a baseline session (no exercise) and after light and moderate cycling exercise in counterbalanced order on different days while measures of task performance and the P3 component of an event-related brain potential were collected. The results indicated that, for both age groups, reaction time following moderate exercise was shorter relative to the other sessions, and P3 latencies following both light and moderate exercise were shorter compared with the baseline session. In contrast, P3 amplitude increased only following moderate exercise in younger adults. These findings suggest that light and moderate exercises improve cognitive function across the adult lifespan, although the mechanisms underlying the effects of observed acute aerobic exercise on cognitive function may be age dependent.
The Journals of Gerontology Series B Psychological Sciences and Social Sciences 05/2009; 64(3):356-63. DOI:10.1093/geronb/gbp030 · 3.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The interactive effect of exercise intensity and task difficulty on human cognitive processing was investigated using the P3 component of an event-related brain potential (ERP). Exercise intensity was established using Borg's rating of perceived exertion (RPE) scale, and task difficulty was manipulated using a modified flanker task comprised of incongruent and neutral trials. Twelve participants (22 to 30 y) performed the flanker task during a baseline session, and again after light (RPE: 11), moderate (RPE: 13), and hard (RPE: 15) cycling exercise. Results indicated that the P3 amplitude increases across task conditions following light and moderate cycling, but not during hard cycling, relative to baseline, suggesting that P3 amplitude may change in an inverted U fashion by as a result of acute exercise intensity. Additionally, the expected delay in P3 latency for incongruent relative to neutral trials was observed during the baseline condition. However, following acute exercise these task condition differences diminished across exercise intensities. Moreover, reaction times following all exercise conditions were shorter when compared to the baseline condition. These findings suggest that P3 latency is more sensitive to task difficulty manipulated by a flanker task than behavioral measures, and P3 latency during trials requiring greater executive control processes might be more sensitive to the effects of acute exercise than tasks requiring minimal effort.
International Journal of Psychophysiology 09/2007; 65(2):114-21. DOI:10.1016/j.ijpsycho.2007.04.001 · 2.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We investigated to what extent the facilitation of the soleus (Sol) Hoffmann (H-) reflex during a phasic voluntary wrist flexion (Jendrássik maneuver, JM) can be modulated by graded plantar flexion force and conditioning wrist flexion force.
The subjects were asked to perform phasic wrist flexion under a reaction time condition. Sol H-reflex was evoked by stimulating the right tibial nerve at various time intervals (50-400ms) after the 'Go' signal for initiating JM while the ankle was at rest and while plantarflexing. The level of tonic plantar flexion force (isometric contraction of 10, 20 and 30% of maximal EMG) and conditioning wrist flexion (isometric contraction of 30, 50 and 80% of maximum voluntary contraction) during JM was graded systematically.
Although JM facilitation could be seen 80-120ms after the flexor carpi radialis (FCR) EMG onset even while plantarflexing, the magnitude of JM facilitation under plantar flexion was significantly decreased compared to that at rest. The degree of decrease in JM facilitation did not depend on the level of plantar flexion force. In contrast, the degree of JM facilitation was proportional to the level of wrist flexion force while the ankle was at rest and while plantarflexing, though the amount of JM facilitation significantly decreased while plantarflexing.
JM facilitation of Sol H-reflex is decreased while performing tonic voluntary contraction of the homonymous muscle. The degree of decrease in JM facilitation is independent of the level of homonymous muscle contraction, but depends on the level of remote FCR contraction. In clinical application, when we intend to elicit a maximum stretch reflex by JM, full relaxation of homonymous muscle should be carefully confirmed.
Our results provide evidence for better understanding of the features of JM and insight into its clinical application.
[Show abstract][Hide abstract] ABSTRACT: We examined the effects of habitual moderate exercise on central information processing in older individuals using the reaction time (RT) and P3 component of event-related brain potentials (ERP). The present study was designed to assess cognitive function by comparing groups of 20 older individuals (69.20 +/- 1.3 years active group) who regularly engage in moderate physical activity with 20 subjects (66.90 +/- 1.1 years inactive group) who do comparatively little exercise. Subjects performed a somatosensory oddball task composed of pressing a button with their right foot as fast as possible following an electrical stimulus applied to the right index finger, and not responding to an electrical stimulus applied to the left index finger. Electroencephalogram (EEG) was recorded at the frontal (Fz), central (Cz), and parietal (Pz) sites according to the International 10-20 system referenced to linked earlobes. The RT was faster for the active group than for the inactive group, and the P3 amplitude of the active group was significantly larger than that of the inactive group. Moreover, the P3 amplitude for the active group was maximum at Pz and significantly larger than at Fz and Cz, but for the inactive group it was identical between Fz and Pz. The results suggest that habitual moderate exercise exerts positive influences in older adults not only on response processing, but also on cognitive processing.
The Japanese Journal of Physiology 03/2005; 55(1):29-36. DOI:10.2170/jjphysiol.R2068 · 1.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Modulation of transmission in group I muscle afferent pathways to the somatosensory cortex and those to the alpha-motoneuron were investigated during active leg pedaling. Cerebral somatosensory evoked potentials (SEPs) and Soleus (Sol) H-reflexes following posterior tibial nerve stimulation were recorded at four different pedaling phases. The subjects were asked to perform pedaling at three different cadences (30, 45 and 60 rpm with 0.5 kp, cadence task; C-task) and with three different workloads (at 45 rpm with 0.0, 0.5 and 1.0 kp, load task; L-task). In both C- and L-tasks, Sol H-reflexes were modulated in a phase-dependent manner, showing an increase in the power phase and a decrease in the recovery phase. In contrast, the early SEP (P30-N40) components were modulated in a phase-dependent manner when the cadence and load were low. When focusing on the power phases, significant cadence- and load-dependent modulations of the P30-N40 were found, and inversely graded with the cadence and load. The H-reflex was found to be significantly decreased at the highest cadence, i.e., cadence-dependent modulation. In contrast, the H-reflex during the L-task was found to be proportional to the load. The correlation analysis between the size of H-reflex and the amount of background (BG) electromyographic (EMG) activity demonstrated that the H-reflex in the power phase did not depend on the BG EMG in either C- or L-task. These findings suggested that transmission of muscle afferents along the ascending pathways to the cerebral cortex and the spinal cord is independently controlled in accordance with the biomechanical constraints of active pedaling.
Brain Research 01/2005; 1029(2):272-85. DOI:10.1016/j.brainres.2004.09.054 · 2.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of the present study was to investigate the influence of exercise intensity on arousal level.
Twelve subjects (22-33 years) performed a S1-S2 reaction time task consisting of warning stimulus (S1) and imperative stimulus (S2) in a control condition, and again after low, medium, and high intensity pedaling exercises. During this task, contingent negative variation (CNV) and spontaneous electroencephalogram before S1 were measured as indicators for arousal level.
CNV amplitude after high intensity pedaling exercise was significantly smaller than after medium pedaling exercise. Compared to the control condition, relative power value of alpha waves increased after the high intensity exercise.
These results suggested that arousal level was reduced after high intensity exercise and reached a state near optimal level after medium intensity exercise. The findings also suggested that changes in CNV amplitude by differences in exercise intensity followed an inverted-U shaped dose response curve.
The present study supported the view that CNV amplitude and arousal level followed an inverted-U relationship. It is concluded that differences in exercise intensity influenced arousal level.
[Show abstract][Hide abstract] ABSTRACT: The amount of attentional resources allocated to a task is determined by the intrinsic demands, also denoted as task load or difficulty of the task. Effects of resource allocation on the somatosensory N140 and P300 were investigated in an inter-modal situation using a dual-task methodology.
Under a dual-task condition, subjects concurrently performed a visuomotor tracking task and a somatosensory oddball task, while they performed just the oddball task under an oddball-only condition. In the tracking task, the subjects tracked the target line, which was presented on an oscilloscope and automatically moved, with the line which represented their own force generated by grip movement with the left hand. Tracking speed (experiment 1) and tracking predictability (experiment 2) were manipulated to vary task difficulty. N140, P300, and reaction time (RT) in the oddball task and tracking accuracy in the tracking task were measured.
The P300 and N140 amplitudes were reduced in the dual-task condition compared to those in the oddball-only condition. The fastest tracking speed produced lower tracking accuracy and later RT. However, the tracking speed did not affect the P300 or N140 amplitudes. In contrast, the P300 amplitude was smaller when the change in tracking direction was unpredictable than when it was predictable, without any differences in tracking accuracy or RT, N140.
The differences in behaviors among N140, P300, and RT following manipulation of task difficulty support the multiple-resource hypothesis, which defines functionally separate pools of resources.
The present study may show that the P300 amplitude reflects modality-unspecific resource at more central level, and that the N140 amplitude involves perceptual resource.
[Show abstract][Hide abstract] ABSTRACT: We investigated modulation of the short- and long-latency somatosensory evoked potentials (SEPs) in a forewarned reaction time task.
A pair of warning (auditory) and imperative stimuli (somatosensory) was presented with a 2 s interstimulus interval. In movement condition, subjects responded by grip movement with the ipsilateral hand to the somatosensory stimulation when the imperative stimulus was presented. In counting condition, they silently counted the number of imperative stimuli. The SEPs in response to the imperative stimuli were recorded.
Frontal N30 and central N60 amplitudes were significantly smaller in the movement than in the counting or rest conditions. None of the short-latency components differed between the counting and rest conditions. In contrast to the short-latency components, P80 was significantly larger in the counting than in the rest condition, and showed a further increase from the counting to the movement condition. The N140 amplitude was significantly larger in the movement than the rest condition, but was not changed between the counting and the rest conditions.
The attenuation of the frontal N30 and central N60, and the enhancement of the P80 and possibly the N140 resulted from the centrifugal mechanism. The present findings may show the different effects of voluntary movement on the early and subsequent cortical processing of the relevant somatosensory information requiring a behavioral response.
The present study demonstrated the differential modulation of short- and long-latency components of SEPs in a forewarned reaction time task.
[Show abstract][Hide abstract] ABSTRACT: The influence of exercise intensity on information processing in the central nervous system was investigated using P300 and no-go P300 event-related potentials. Twelve subjects (22-33 years) performed a go/no-go reaction time task in a control condition, and again after high-, medium-, and low-intensity pedaling exercises. Compared to the control condition, P300 amplitude decreased after high-intensity pedaling exercise and increased after medium-intensity pedaling exercise. There was no change after low-intensity pedaling exercise. These results suggested that the amount of attentional resources devoted to a given task decreased after high-intensity exercise and increased after medium-intensity exercise. The findings also suggest that changes in P300 amplitude are an inverted U-shaped behavior of differences in exercise intensity. In addition, no-go P300 amplitude showed the same changes as P300 amplitude at different exercise intensities. This indicates that differences in exercise intensity influenced not only the intensity of processing the requirement for a go response, but also processing of the need for a no-go response. It is concluded that differences in exercise intensity influenced information processing in the CNS.
[Show abstract][Hide abstract] ABSTRACT: We investigated the changes in the somatosensory P100 and N140 during passive (reading) versus active tasks (counting, button pressing) and oddball (target=20%, standard=80%) versus deviant alone conditions (standards were omitted).
Nine healthy subjects performed the 3 tasks (reading, counting and button pressing) under two conditions. Standard and target electrical stimuli were presented in a random order to the index or middle fingers of the left hand at a constant 800 ms interstimulus interval in the oddball conditions. In the deviant alone conditions, only target stimuli were presented with the same timing as in the oddball conditions.
The N140 amplitude increased for the deviant alone stimuli compared with the oddball standard and target stimuli regardless of whether the task was passive or active, indicating passive shifts of attention related to temporal infrequency. The P100 amplitude also increased for the deviant alone stimuli compared with the oddball standard and target stimuli in both passive and active tasks, but the enhancement seemed to be even smaller than that of the N140 amplitude.
The somatosensory N140 passively increased even if subjects tried to attend actively to the stimulus source when the deviant alone condition was used. This change in N140 amplitude may be related to a strong orienting effect against a 'silent' background.
The present study provided evidence that the N140 is an indicator of passive attention against a silent background when the deviant alone condition or long interstimulus interval was used.
[Show abstract][Hide abstract] ABSTRACT: The modulation of the somatosensory N140 was examined in a selective attention task where a control condition was applied and the interstimulus interval (ISI) was varied. Electrical stimuli were randomly presented to the left index (p=0.4) and middle fingers (p=0.1), and right index (p=0.4) and middle fingers (p=0.1). In the attend-right condition, subjects were instructed to count silently the number of infrequent target stimuli presented to the right middle finger, and to the left middle finger in the attend-left condition. They had no task in the control condition. Each condition was performed with two different sets of ISI (mean 400 vs. 800 ms). The somatosensory N140 elicited by frequent standard stimuli was analyzed. The N140 amplitude was larger for the attended ERP compared to the control and unattended ERPs. This attention effect was more marked at the frontal electrodes compared to the temporal electrodes contralateral to the stimulation side. Furthermore, the attention effect at the frontal electrode was larger when the ISI was 800 ms than when it was 400 ms. The N140 amplitude did not differ between the control and unattended ERPs, which might show that a small processing negativity (PN) occurred during the control condition or difference in vigilance level between them. In conclusion, the early lateral ("temporal") and late midline ("frontal") components of the N1 (N140) show different behavior, and thus may have different functional significance. Enhancement of the attention effect at the frontal electrode in the longer ISI condition supports the hypothesis that it is related to stronger, voluntary maintenance of the attentional trace.
Cognitive Brain Research 04/2004; 19(1):33-9. DOI:10.1016/j.cogbrainres.2003.10.016 · 3.77 Impact Factor