The following three problems were examined: 1) Is there a great change of heel pressure distribution according to backward leaning? 2) Can this change be perceived accurately? 3) What is the relationship between the standing position at great change of heel pressure distribution and the skeletal structure of the foot? Twelve subjects with a mean age of 32.0 years (SD=12.3) participated in the study. The change of heel pressure distribution according to backward leaning was evaluated by simultaneously measuring the movement of the center of foot pressure and that of the center of heel pressure. The position of the lateral process of calcaneus and the highest point of the trochlear surface of body of talus were analyzed using an X-ray photograph. A great change in heel pressure distribution according to backward leaning was observed at 3.8 cm (SD=0.5), and the perceived position was 3.5 cm (SD=0.6). These two positions were significant different and also showed a significant correlation (r=0.91). The standing position at great change of heel pressure distribution correlated significantly with the position of the lateral process of calcaneus (r=0.86), and also with the position of the highest point of the trochlear surface of body of talus (r=0.71). We conclude that there is a great change of heel pressure distribution according to backward leaning, that this change is perceived accurately, and that there is a closely relationship between the standing position at great change of heel pressure distribution and the form of the foot.
We investigated the physiological and subjective responses associated with a speech task, measured at baseline, anticipation, speech, and post-speech conditions. We also examined the relationship between physiological and subjective responses during each condition. We employed R-R interval and finger skin temperature obtained by thermography as physiological measures. The Physiological Tension Scale and Cognitive Tension Scale extracted from the Relaxation Inventory (Crist, Rickard, Prentice-Dunn, & Barker, 1989) were used as subjective measures. Twenty-five healthy adults participated in this study. At the anticipation condition, participants showed significant increases of both Physiological Tension Scale and Cognitive Tension Scale scores, and decrease of finger skin temperature. During the speech task, Physiological Tension Scale and Cognitive Tension Scale scores increased while finger skin temperature decreased compared to the anticipation condition, and a remarkable decrease of R-R interval was observed. In the post-speech condition, the values of all measures reverted to baseline levels except finger skin temperature. Correlation study among the parameters showed that in the actual speech task, the relationship between finger skin temperature and R-R interval was intensified, and the relationship between subjective tension and physiological activation was slightly increased. The present results indicated increases of subjective tension and physiological tension during a speech task. Furthermore, the results suggested that physiological tension was not necessarily associated with actual change in heart rate. This study also revealed that finger skin temperature recorded by thermography was a more sensitive physiological indicator than R-R interval. Considering applicability and sensitivity, thermography may be a convenient instrument of physiological marker for the study of speech.
Near-infrared red spectroscopy (NIRS) is a noninvasive method that uses changes in cerebral blood volume (CBV) to measure relative changes in tissue concentration of oxygenated, deoxygenated and total hemoglobin. We used this technique to determine the cortical activation area during Japanese grammatical processing. To assess the relative changes in total hemoglobin, local changes in near-infrared absorption were measured simultaneously from seven points in both hemispheres. Nine subjects were presented target stimuli, and were asked to decide whether the attendant particle was “ga” or “wo” in Japanese grammatical tasks (experimental conditions), and whether the relative position was “front” or “back” in positioning tasks (baseline and control conditions). To control subvocal rehearsal and conceptual driven processing, the same Kanji character was presented visually as a target in the experimental and control conditions. Total hemoglobin increased in Broca's area when subjects made judgments in Japanese grammatical tasks, compared to positioning tasks. These results suggested that the task of deciding particles in Japanese grammatical processing might be an effective and objective method to assess language disorders.
We compared the saccadic reaction times during isometric contraction of bilateral shoulder girdle elevators and unilateral (right and left) shoulder girdle elevator in a sitting posture. Muscle contraction force was increased in 10% increments from 10% to 60% of the maximal voluntary contraction (MVC) of each side. Saccadic reaction time was determined as the latency to the beginning of eye movement toward a lateral target moved at random intervals in 20° amplitude jumps. Eye movement was measured using the electrooculographic technique. During bilateral contraction, the saccadic reaction time decreased until 30% MVC and then began to increase at 40% MVC. In both right and left contractions, saccadic reaction time decreased until 30% MVC similar to bilateral contraction, but remained constant from 30% to 50% MVC that differed from bilateral contraction, followed by a slight increase at 60% MVC. The saccadic reaction times at 50% and 60% MVC were significantly shorter during unilateral contraction compared to bilateral contraction. These results demonstrated that the saccadic reaction time produced by shoulder girdle elevator contraction is shortened at a wider range of muscular force during unilateral contraction than bilateral contraction, and that the saccadic reaction time did not differ significantly between right and left contraction.
Cardiovagal function declines with increasing age. We tested the hypothesis that age-related delay in cardiovagal reactivation is associated with age and habitual physical activity after cessation of exercise, and that is related to rapid cessation of central command in children and adults.
Cardiovagal reactivation was examined in 22 healthy children (8-9 yrs) and 98 adults (young group, 19-39 yrs; middle-aged group, 40-59 yrs; old group, 60-79 yrs) who were classified as either ‘sedentary’ or ‘habitual physical activity’, by using sequence analysis of the time constant of recovery heart rate (HRTC) and decay rate for 5 sec (HRDR) immediately after cessation of moderate pedaling exercise.
HRTC was progressively slower with increasing age. HRTC of the habitual physical activity and sedentary groups within age groups were different (young group, 37 ± 5.5 sec vs 57 ± 11.1 sec; middle-age group, 46 ± 11.5 sec vs 85 ± 28.4 sec; old group, 56 ± 15 sec vs 108 ± 37 sec; all p<0.05). HRTC in children were markedly faster than in the young habitual physical activity group (child group, 30 ± 5.1 sec; young group, 37 ± 5.5 sec; p<0.05). However, HRDR became progressively slower with increasing age. HRDR for the habitual physical activity and sedentary groups did not vary within age groups (young group, -1.67 ± 0.84 sec vs - 1.27 ± 0.69 sec; middle-age group, -1.3 ± 0.35 sec vs - 0.98 ± 0.34 sec; old group, -1.09 ± 0.62 sec vs - 1.08 ± 0.38 sec), but HRTC in the sedentary subjects decreased more slowly than in the habitual physical activity subjects. HRDR between the child group and both the middle-aged group and the old group were different in both habitual physical activity and sedentary subjects (p<0.05).
Our data demonstrate that HRTC in habitual physical activity subjects is well preserved with increasing age, while HRTC in sedentary subjects appears to be prolonged. These results suggest that habitual physical activity could be very useful for the maintenance of central cardiac regulation, such as central command and/or cardiovagal baroreflex sensitivity, and that decreased HRTC could be neuroautonomic control that helps to protect old subjects from cardiac diseases.
Scalp electroencephalograms (EEGs) were recorded from the prefrontal cortex in Japanese subjects while at rest and while playing computer games, and the subjects were classified into four types based on the β wave activity pattern. The games tested included tetris, action games, car race games, and the high-excitation-level role-playing games.
Normal-brain type : High β wave activity was recorded before these subjects started to play computer games, and the β wave activity showed no significant change even after subjects started to play the game. Visual-brain type : High β wave activity was recorded before the subjects started to play computer games, as in the normal-brain type subjects, but once the subject began to play, the activity of this wave decreased markedly. Semi-game- brain type : The resting β wave activity was already reduced to the level of the α wave activity, and the waveforms of the two overlapped. The semi-game-brain type subjects tended to be expressionless, forgetful and to show decreased concentration. Game-brain type : The resting β wave activity was consistently lower than the level of the α wave activity, or was even entirely undetectable. Persons of this type often reported, “I get into a rage (kireru) easily”. Many of these subjects also reported spending prolonged periods of time in a blank state of mind and finding it difficult to concentrate on anything. Many were also forgetful, unpunctual and often absent from school.
We investigated the effects of role-playing games on the β wave activity of a game-brain type subject. Even in the game-brain type subjects, playing of a role-playing game resulted in increased β wave activity up to the level noted in normal-brain type subjects. However, the β wave activity started to decline after the second round was played, and returned to the baseline game-brain type state by the fourth round.
The semi-game-brain type subjects showed an EEG pattern resembling that seen in patients with dementia.
Our data show that playing computer games results in depression of the neuronal activities of the prefrontal cortex. A game-brain type subject recovered to the visual-brain type after tossing three beanbags for 5 minutes a day continuously for six months. The β wave activity decreased markedly as soon as the subject started to play a computer game, and returned to the baseline level at the end of the game. This result shows that game-brain type subjects may benefit from exercises, such as tossing of three beanbags.
Major differences in histological, anatomical and physiological characteristics exist between the gastrocnemius and soleus muscles. The authors calculated the girth and subcutaneous fat thickness at the belly portion (G portion) and the musculotendinous junction portion (S portion) of the medial gastrocnemius, and then devised a method of calculating the ratio of gastrocnemius cross-sectional area to that of the other plantar flexors. The necessary parameters for the calculation were identified based on the analysis of the CT images of these portions. Consequently, the following findings were obtained. 1) The cross-sections of both portions could be approximated to a circle, and the subcutaneous thickness in each portion represented the average of all points along the circumference. 2) At G and S, the fat-free cross-sectional area excluding the gastrocnemius varied at a constant ratio. 3) The ratio of fat-free cross-sectional area excluding the gastrocnemius at G to the cross-sectional area of other plantar flexors showed small individual differences. These findings indicate that the girth and subcutaneous fat thickness measured at S and G may provide a relatively precise estimate of the ratio of gastrocnemius cross-sectional area to that of the other plantar flexors.