| The decline of cognitive function with age is a major problem affecting the life of the elderly.The positive effects of exercise on the cognitive function have been confirmed in literatures,but the proper intensity and type of exercise for the elderly has not been fully determined.As a traditional Chinese sport,Tai Chi Chuan is very suitable for the elderly in terms of its popularity and exercise intensity.Tai Chi Chuan also has positive effects on cognitive function because of mind-body movements.This thesis used functional near-infrared spectroscopy to study the differences between Tai Chi exercise and other exercise on brain function in the elderly.The differences between different modes of Tai Chi exercise and longterm effects of Tai Chi exercise on brain function were also investigated.In the first experiment,6 participants,aged 60-70 years,who were all proficient in Tai Chi,first underwent a baseline Stroop test,after which they took three Stroop tests in randomized order,(a)after sitting rest(control),(b)after performing Tai Chi,and(c)after a bout of brisk walking.During these four Stroop tests cortical hemodynamic changes in the prefrontal area were monitored with fNIRS.Both Tai Chi and brisk walking enhanced the cortical oxygenation,leading to improved Stroop cognitive performance.Tai Chi induced a greater Stroop-task-related bilateral cortical activation in the ventrolateral prefrontal cortex area,whereas brisk walking induced a greater Stroop-task-related bilateral cortical activation in the dorsolateral prefrontal cortex area.In addition,DLPFC,as a bottom-up executive control region,showed stronger synergy with other brain regions after Tai chi exercise.This study may offer a glimpse of the neural processes underlying the improvement of older people's executive function through Tai Chi and brisk walking,at an age when they face a reduced choice of healthpromoting activities.In the second experiment,15 experienced Tai Chi practitioners and 15 novice Tai Chi practitioners were invited to participate.The cortical hemodynamic changes in the prefrontal area were monitored with fNIRS during 10 minutes of resting,10 min Tai Chi meditation,and 10 min motor imagery.Tai Chi meditation induced cortical activation in the prefrontal cortex area,while Tai Chi motor imagery induced significant activity in the prefrontal cortex and premotor cortex area.Experienced Tai Chi practitioners showed significant activation in multiple regions of the prefrontal cortex in different modes compared with novice Tai Chi practitioners.The DLPFC,as one of most important regions related to the cognitive function,is the main region activated in the midbrain in the present study.Moreover,subjects' brain functional connections were mainly in the DLPFC region and connected with other brain regions,and the proportion of connections with the DLPFC region increased after exercise.This study may help understanding how Tai Chi can influence cognitive function,and may help understanding "mind-body" and "Chi" of Tai Chi movement. |
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