In the study of brain function, several recording methods are employed. The advantage of an electroencephalogram (EEG) is its high temporal resolution. Time-frequency analysis of EEG data can provide activity changes in the frequency band of millisecond-order. Beta band activity is believed to reflect information processing in the cortico-cortical connection. Therefore, we studied beta band changes in cortical oscillatory activity in the cerebral cortex in order to investigate changes in decision-making and inhibition during a visual oddball task. Eleven right-handed healthy subjects participated in this study. In the oddball task, the subjects were required to press a button when the target stimulus (go condition, 20% probability) was presented, whereas they were required to withhold their response when the standard stimulus (no-go condition) was presented. EEG data were recorded from the scalp using 128 channels. The data were analyzed by time-frequency analysis for each go and no-go condition. In both conditions, an increase in the beta band activity of approximately 15 Hz was observed in the frontal association area, beginning after stimulation, and this increase was observed in the left motor association area. The duration was clearly shorter in the no-go condition than that in the go condition. These results suggest that an increased beta band activity in the frontal association area may represent integrative processing of visual information and decision-making in both conditions, whereas it indicates inhibition in the no-go condition. Moreover, the shorter beta band activity in the motor association area during the no-go condition indicates increased GABA-mediated inhibition.
Contingent negative variation (CNV) is a negative brain potential recorded by averaging electroencephalogram derived from scalp electrodes during a period between warning and response stimulus (foreperiod) to which subjects perform motor and/or mental response. Main generators of CNV are reportedly supplementary motor cortex, premotor cortex, primary motor cortex, frontal cingulate area, thalamus, and basal ganglia. CNV is considered to be a complex of early and late component (early and late CNV, respectively). The early reportedly reflects orienting response to warning stimulus and the latter motor preparation and anticipatory attention to response stimulus. CNV shows no effect of trial repetition and has high reproducibility. Therefore, CNV is probably a useful index of the brain functions mentioned above. Since 1970s, a number of studies reported that late CNV is equivalent to movement-related cortical potential. Recently, late CNV and movement-related cortical potential are considered to be different phenomenon, in that the former reflects a process of motor programming and the latter a process related to motor execution. Using CNV as an index of change in attention direction, researches in a field of postural control have started investigating a relationship between brain activity and the strategies of postural control.
We have been investigated neck flexion effect on the brain activation. In the present paper, we showed the recording and analysis techniques of saccadic reaction time and sensory evoked potentials, which are indices of the brain activation. Furthermore, we indicated the following findings: (1) shortening mechanism of saccadic reaction time associated with maintaining neck flexion, (2) formation of that mechanism through saccadic training accompanied by maintenance of neck flexion, (3) age-related change in the shortening of the reaction time, and (4) neck flexion effect on latency and amplitude of sensory evoked potential.
The present study investigated the relationship between the activation in the motor cortex (MCx) and the cardiovascular responses during preparation for and after starting right handgrip exercise. We measured levels of oxygenated hemoglobin (oxyHb), deoxygenated hemoglobin (deoxyHb) and total hemoglobin (totalHb) in the MCx by near-infrared spectroscopy and simultaneously recorded heart rate (HR) and mean arterial blood pressure. We studied three experiment sessions and obtained any suggestions; (1) During the preparation period for exercise, the increases in HR and muscle flow rate were coupled with the increase in the MCx activation.(2) The differential values of the oxyHb concentration in the MCx were positively correlated with HR changes during the preparation period for exercise.(3) The MCx activities and sensory cortex responses after starting handgrip exercise are not affected by MCx activation or the increase in HR related to central command that develops during preparation for exercise.
The present study investigated the trunk and pelvis inclination movement angles in the frontal plane in single stance phase during stepping in place. Subjects were 26 healthy young adults. All measurements were taken with subjects standing barefoot on a force platform. Subjects performed the stepping for 120 s at 1 Hz frequency. The sum of the durations of double and single stance phases was approximately 1000 ms for each leg. Maximal inclination angle of the supporting leg in the frontal plane, and maximal hip and knee flexion angles did not differ significantly between the right and left single stance phase. These results clarified that right and left leg movements in the stepping were carried out symmetrically at 1 Hz frequency. The pelvis significantly inclined toward the supporting leg in the single stance phase. The trunk significantly inclined toward the supporting leg in the right stance phase, but not in the left. This indicated that the trunk inclination angle in the left stance phase was similar to that during quiet standing. The results suggested that the postural reference frame based on gravitational direction more strongly influenced balance during stepping in the left stance phase than in the right. No significant correlation was found between the trunk and leg inclination movement angles in both single stance phases, or between the right and left single stance phase in the trunk inclination movement angles. Individual variation in balance strategy between the trunk and leg in the frontal plane appears to occur during the stepping.
The effects of difficulty in voluntary postural change on contingent negative variation (CNV) and preparatory postural action were investigated. Subjects were 13 healthy young adults. A warning stimulus (S1) and then a response stimulus (S2) were presented with a 2-s time interval using two tone-bursts through earphones. Subjects voluntarily leaned their whole body forward to the target position from quiet standing (QS) in response to S2, and maintained the leaning posture for 3 s. The center of foot pressure in the anteroposterior direction (CoPy) was expressed as target position with percentage distance (%FL) to foot length from the heel. The target positions were 5 %FL posterior to extreme forward leaning (EFL-5) and the middle position (MID) between QS and EFL. CNV, CoPy and electromyograms (EMG) were analyzed between S1 and S2. Failure to maintain the target position was 14.1 ± 1.8% in EFL-5 and 0% in MID. This indicated the difficulty of maintaining EFL-5. Late CNV peaked just before S2, and then shifted toward a positive direction. The CNV peak timing was earlier in EFL-5 than MID. EMG activity of posterior muscles of the body slowly decreased just before S2. This would relate to the preparatory action for voluntary forward leaning motion. The timing of the start of the EMG decrease was earlier than CNV peak timing, and a high correlation was found between these timings. These findings suggest that attention to sensory information related to preparatory action in voluntary postural change is allocated earlier with more difficult postural changes.
This study investigated relativity of postural change into prone position and effect of bowel intestinal peristalsis activation, which may lead to the facilitation of defecation. The subjects included 21 healthy adults (≥ 65 years). The subjects maintained a supine position for 10 min, followed by a prone position for 30 min, and finally the supine position for 10 min. Each position was divided into 10-min intervals, and the intervals were referred to as Supine-Before, Prone I, II, III, and Supine-After. The bowel sounds and automatic nerve activities were used to investigate intestinal peristalsis (sympathetic index: LF/HF ratio, parasympathetic index: LogHF). We performed multiple comparisons of bowel sounds and autonomic nerve activity for all intervals. Bowel sounds tended to be reduced during the 30-min period when prone position was maintained. Among Supine-Before, Prone II, III, and Supine-After, a significant increase (p < 0.05) in bowel sounds was observed during Supine-After.
Since there was an increase in the power values of the bowel sounds during the 30 minutes when the Supine-After position was changed to the prone position. We believe that an autonomic nerve reflex and changes in blood flow related to the stimulation of the intestinal tract and the abdomen as a result of a change in the body position to the prone position influenced the acceleration of peristalsis. This research made it clear that peristalsis was accelerated by a change in posture to supine position from prone position, and this suggests that it would be effective in the facilitation of defecation.
The objective of this research is to abstract the evaluation standard of health behaviors, and analyze the characteristics specific to sex and age groups and reflect it to the health strategy for the citizens.
Based on the results of the health and nutrition research conducted on Niigata residents in 2007(valid responses: 748 people, 20 to 79 years old), we recomposed the standard for 20 items and analyzed the factors indicating health behaviors using factor analysis.
According to the age groups, elderly people have relatively good “sufficient level of sleep time and rhythm”. Also, “exercise consciousness and practicing light exercise” and “exercise consciousness and practicing medium to hard exercise”, which are related to physical activities, as they are older, both male and female have a higher tendency for high exercise consciousness and longer exercise time for light exercise. For medium to hard exercise, 20 to 39 years old male has a higher tendency for high exercise consciousness and longer exercise time. On the other hand, female in the same age group shows opposite result with a tendency for low exercise consciousness and shorter exercise time.
For the disease prevention subjecting the adolescent to middle age groups, we consider that it is necessary to promote the support strategy to give instruction for sleeping and resting, and to improve the environment for women to increase their exercise time. Also, for health and exercise instruction, we consider that it is effective to give practical instruction based on the stages of behavior change.
We examined the beta band appearance patterns in an electroencephalogram, which reflects the cortical activity and information processing, during a choice reaction task (CRT) performed before and after a brief period of high-intensity exercise.
To clear which beta band activity reflects information processing in the cerebral cortex, 12 healthy participants performed the CRT followed by a rest condition (RC). Then, the participants ran all out for a brief period. The RC consisted of gazing at a fixed point for 5 minutes. The CRT was performed using a visual stimulus of a 6-, 7-, and 8-points star. Participants were asked to push a button when the 6-points star appeared. A 128-channel electroencephalogram data, which was recorded from the scalp, was filtered through a 3-30 Hz bandpass, processed using a fast Fourier transform, and separated into the beta 1 and beta 2 bands. We compared the reaction time and distribution of both bands on each electrode measured before and after the exercise.
Distribution of the beta 1 band in all regions of the cerebral cortex was higher during the CRT than during the RC. The post-exercise reaction time was shorter than the pre-exercise reaction time and the post-exercise distribution of the beta 1 band increased in the left motor, left temporal, and bilateral occipital regions.
These results suggest that the beta 1 band activity reflects information processing in the cerebral cortex during the CRT and a brief period of high-intensity exercise activated the regions of the cerebral cortex relevant to information processing.
Many forearm muscles are responsible for producing a gripping force and the interaction of EMG activity in forearm muscles is unclear during gripping. The purpose of this study was to investigate the change in EMG activity in forearm muscles during sustained gripping. Six subjects participated in this study. They performed sustained gripping with their dominant hand at 50% maximal voluntary contraction (MVC) and MVC without restriction of the wrist (maximum one minute). Gripping force and EMG (flexor carpi ulnaris [FCU], flexor digitorum superficialis [FDS], and extensor carpi radialis [ECR]) were measured simultaneously and average gripping force, root mean square EMG (rmsEMG) and mean power frequency (MPF) every five seconds were calculated. The relationship between contraction time and EMG responses (coefficient) were investigated. Fatigue was defined as a 5% decline in gripping force from the target level during 50% MVC. In 50% MVC protocol, there was no difference in the coefficient of rmsEMG among the three muscles. But, the coefficient of MPF was different and decreasing MPF in ECR tended to be smaller than in FCU. Only the coefficient of MPF in ECR tended to correlate with time to fatigue. In MVC protocol, the coefficient of rmsEMG was different and a decreasing rmsEMG in ECR tended to be larger than in FDS. There was no difference in the coefficient of MPF among the three muscles. These results suggest that neural drive to ECR is larger during gripping. Therefore, we conclude that EMG activity of ECR plays an important role in gripping.
The aim of this study was to examine the effect of rapid ascent by aerial tramway, without physical exertion, to moderately high altitude on heart rate response during mountain hiking. Twenty-three healthy volunteers (27.9 ± 11 yr) arrived at the aerial tramway Base station (1,308 m) at midnight. After a few hours sleep they were transported by aerial tramway to the Top station (2,156 m) within 7 min. Then, they hiked 1.7 km to mountain Lodge (2,385 m). Heart rate (HR) was continuously measured during the hiking and HR from a section of steep slope was analyzed (815 m, 2,140-2,360 m, 31.2% incline). Anaerobic threshold (AT) was determined in 10 of the 23 subjects at sea level. HR increased with ascent to the altitude from Base to Lodge at rest. Change of HR between Top and Base was 112 ± 11% at rest (HRTop/Base). HRTop/Base positively correlated with blood lactate at TOP (LATop). No significant change was observed in blood pressure at the higher altitude. Mean HR response during exercise was 156 ± 17 beats/min on the steep slope, equivalent to 68.3% of their HR reserve (%HRR). The %HRR positively correlated with HRTop/Base and with LATop. Relative response of HR during steep slope (%ATHR) was 108 ± 18% which correlated with HRTop/Base and with LATop. Rapid ascent results in increased HR response during mountain hiking. This study suggests that rapid ascent to a higher altitude can cause marked cardio-respiratory responses during mountain hiking, even in moderately high altitude mountains.
Electroencephalographic (EEG) activity of a driver during limit driving condition on a circuit is not as well known as that of daily driving. A recent report demonstrated a significant positive correlation between lap time and β wave activity of the prefrontal cortex during solo driving on a circuit for a professional driver, whereas no significant correlation was found with α wave activity (Haranaka et al., 2010). In order to confirm the results obtained in the report, for 4 male subjects, during the first lap to the best lap, correlations between lap time and EEG activity of the prefrontal cortex while driving solo on a circuit were examined in this study. As a result, regarding correlations between lap time and β wave activity, a significant positive correlation (r = 0.693, p < 0.01), a strong positive correlation (r = 0.812), a weak positive correlation (r = 0.369), and a weak negative correlation (r = -340) were found. Regarding correlations between lap time and β/α, two significant positive correlations (r = 0.930, p < 0.1; r = 0.505, p < 0.05), and a weak positive correlation (r = 0.273) were found. However, no significant correlation was found between lap time and α wave activity. We hypothesize that the activity of the prefrontal cortex may be reflected by β wave activity more than by α wave activity, and the activity of the prefrontal cortex of a driver tends to decrease when the driver shows better driving skills during solo driving on a circuit.
In the present study, we investigated the effect of the visible section and the masking section’s ratio changing during the coincidence-anticipation timing task on the activity of the cerebral cortex. Subjects were eight healthy right-handed adult males. Subjects received the moving visual target with the stimulus runway visually masking (coincidence-anticipation timing tasks; the visible section: the masking section = 1 : 1, 1 : 2, 1 : 5) and, were asked to press the handheld pushbutton when the visual target arrived at an end each task. Electrodes were placed at 128 sites on the subjects’ scalp, and electroencephalograms (EEGs) were recorded during the coincidence-anticipation timing task. The EEGs were subjected to fast Fourier Transform in order to produce the power density in the beta (13-30 Hz) bands. The power in beta bands was expressed as a percentage of total power (3-30 Hz) in each task. The data were compared with each task.
The results showed that the percentage of beta band at 3-30 Hz increased significantly at the inferior frontal gyrus, the frontal pole, the middle temporal gyrus and the superior parietal lobules in the 1 : 1’s and the 1 : 2’s coincidence-anticipation timing task in the visible section compared with the 1 : 5’s coincidence-anticipation timing task. The results suggest that subjects during the 1 : 1’s and the 1 : 2’s coincidence-anticipation timing task in the visible section memorize shape and velocity of the moving visual target compared with the 1 : 5’s coincidence-anticipation timing task.
We investigated the decreasing effect of body asymmetry by wearing underwear with supporting function. Subjects were 14 healthy young women. They were requested to wear each combination of shirt and panty with (S) supporting function or without (N) it, in separate days for more than 6 hours per day, and then the stepping test for 1.5 minutes were performed with N-underwear. No significant differences were found among conditions in double stance and single stance phases. For pelvis inclination angle in the frontal plane, muscle activity and blood flow of gluteus medius, bilateral difference tended to decrease in all conditions with S-shirt or -panty. Especially, these were observed in subjects whose bilateral difference in N-underwear condition was larger than the mean + standard deviation (SD). Furthermore, these indices in S-shirt and -panty condition were smaller than the mean + SD for N-shirt and -panty condition. For trunk inclination angle in the frontal plane, muscle activities of erector spinae and trapezius, and blood flow in trapezius, bilateral difference with S-shirt or -panty tended to decrease, however, in a few subjects the considerable increase was also observed. In conclusion, the large bilateral differences in motion, muscle activity and blood flow tended to decrease by wearing S-shirt and/or -panty. Especially, the remarkable effect of the underwear with supporting function was found for the pelvis inclination angle, muscle activity and blood flow of gluteus medius.
This study described the development of the scale for measuring felt shoulder stiffness (SMFS). The questionnaire was 28 items selected from previous studies.
The factor analysis was conducted on responses from 506 students, and three factors were extracted and were identified: I) Numbness and a prickle; II) Dull pain of a deep part; III) Sense of congestion. All these factors had high degrees of internal consistency.
The scores of the “Numbness and a prickle” were significantly correlated with the Hostility action scores (r = 0.17). On the other hand, the scores of the “Dull pain of a deep part” were non-significantly correlated with the Hostility action scores, but were significantly correlated with the Depression scores (r = 0.27), and Anxiety scores (r = 0.27). The scores of the “Sense of congestion” were significantly correlated with the Hostility action scores (r = 0.24), the Depression scores (r = 0.23), and Anxiety scores (r = 0.16).
These results suggest that SFMS may be a reliable instrument for assessing shoulder stiffness in Japanese.
In the present study was examined the occurrence pattern of the EEG in the 3-30 Hz frequency band with the development of the brain of infants.
Time series experiments were performed 3 times every 3 or 4 months on 3 infants ranging from 7 months to 15 months after birth. The EEG was recorded from 128 scalp locations. Music stimulation was used in the experiment.
1) For 5-9 months of age, ratios of the occurrence of the theta, beta, and alpha band, at the opening of eyes following rest, were 38%, 19%, and 43%, respectively. For 10-15 months of age, these ratios at the opening of eyes following rest, were 38%, 21%, and 41%, respectively. 2) For 5-9 months of age, the ratios of the occurrence of the theta, alpha, and beta band, at the music stimulation, were 41%, 18%, and 41%, respectively. For 10-15 months of age, however, these ratios at the music stimulation, were 29%, 18%, and 53%, respectively. The ratio of the occurrence of the beta band remarkably increased to 53% at 10-15 months of age, while the theta band decreased to 29%. The alpha band remained unchanged in the meantime. 3) The occurrence pattern of the EEG in the infants at 5-9 months of age developed the shape of vertical stripes in each hemisphere. However, such occurrence pattern of vertical stripes completely disappeared at 10-15 months of age, and, in contrast, the occurrence pattern of the beta band changed in the cerebral cortex hemisphere, beginning to move to all around directions. These results suggest that neuronal networks of the association area in infants become active from approximately 10 months of age with the development.