درخت حوزه‌های تخصصی

Loss of balance and postural control are the main reasons for falls among the elderly adults that are considered as serious elderly health challenges with high impacts on the quality of life. The cerebellum is involved in postural control as one of the key neural structures that receives many inputs from the sensory systems. Cerebellar transcranial direct current stimulation (ctDCS) is a popular noninvasive and safe method enabling the adjustment of cerebellar activity. Therefore, we investigated the effect of ctDCS on postural control variables among elderly population with a history of stroke. Thirty elderly individuals (60-75 years) participated in this study. After preliminary assessments of postural control strategies by post urography at six sensory conditions, they received five 20-min sessions of active ctDCS at 2mA (intervention, n = 15) or sham stimulation (control, n = 15) in a random manner. At the end of the stimulation process, postural control strategies were reassessed. After adjustment for pre-test values using the ANCOVA test, an improvement of the subjects' performance in the first four conditions was observed in the intervention group compared with the control group (P < 0.05). However, in the fifth (P = 0.24) and sixth (P = 0.58) conditions, there were no significant differences between the groups. The results of this study showed the significant effect of ctDCS on the postural control strategies. These improvements were reflected by normalization of strategy of postural control in elderly adults.

A few second prior to an expected event, a systematic decrease in heart rate (HR), reflecting attentional processing is observed. Arousal variations however, restrain the interpretation of this decrement. The present study, aimed to investigate vigilance and arousal effects during a skilled performance separately, using separate measures for the two psychological states. HR and skin conductance level (SCL) were measured as an index of vigilance and arousal from 18 elite and 19 novices during 30 self-paced, self-initiated basketball free throws. Values of HR and SCL were calculated at half-second intervals from 10 s before to 10 s after each shot and were analyzed using repeated measures ANOVA. This helped to compare pre-shot and post-shot patterns of physiological changes separately in elites and novices. In elites, there was a slow reduction in SCL prior to, and a rebound increase immediately following the shot. These were smaller for novices. Similar findings were observed when good shots were compared to bad ones. The value for rebound after good shots reached 8 times more than the pre-shot value. A sharp increase in HR, up to 40 bpm was found 4 second before the shot, which returned to pre-shot value after 2s for elites; this did not return in novices. HR in bad shots was higher than good shots. Results indicate that the SCL reflect arousal level at the time of task and its pattern of variations reflects skill level. Although, HR was lower in good shots, the pattern of variation in HR reflected physical requirements of the task. Results were compared to previous findings and discussed in relation to the hypotheses explaining arousal and vigilance in human behavioral performance.