Prolonged rote learning produces delayed memory facilitation and metabolic changes in the hippocampus of the ageing human brain

[Research progress of effect of Tai Chi on cognitive function in the elderly based on neuroelectrophysiological techniques and brain imaging techniques]

With the increasing prominence of population aging, the cognitive decline of the elderly has gradually become a hotspot of clinical research. As a traditional rehabilitation exercise, Tai Chi has been proved to have a positive effect on improving cognitive function and delaying cognitive decline in the elderly. However, the related brain function mechanism is still unclear. In this paper, we collected studies which observed the changes of Tai Chi on brain regions related to cognitive function in the elderly using magnetic resonance imaging (MRI), electroencephalogram (EEG) and functional near-infrared spectroscopy (fNIRS). We summarized relevant studies from perspective of structural and functional changes in the brain. The results showed that Tai Chi may delay and improve cognitive decline in the elderly by reshaping the structure and function of brain regions related to cognitive function such as memory, attention and execution. The effect of Tai Chi for cognitive function may be associated with positive regulation of cardiovascular function, emotion and meditation level of the elderly. In addition, the improvement of cognitive function further enhances the balance of the elderly. We also found that practice time, frequency and intensity of Tai Chi could be factors influencing the improvement of cognitive function and brain function in the elderly.

Increased Hippocampus-Medial Prefrontal Cortex Resting-State Functional Connectivity and Memory Function after Tai Chi Chuan Practice in Elder Adults

Previous studies provide evidence that aging is associated with the decline of memory function and alterations in the hippocampal (HPC) function, including functional connectivity to the medial prefrontal cortex (mPFC). In this study, we investigated if longitudinal (12-week) Tai Chi Chuan and Baduanjin practice can improve memory function and modulate HPC resting-state functional connectivity (rs-FC). Memory function measurements and resting-state functional magnetic resonance imaging (rs-fMRI) were applied at the beginning and the end of the experiment. The results showed that (1) the memory quotient (MQ) measured by the Wechsler Memory Scale-Chinese Revision significantly increased after Tai Chi Chuan and Baduanjin practice as compared with the control group, and no significant difference was observed in MQ between the Tai Chi Chuan and Baduanjin groups; (2) rs-FC between the bilateral hippocampus and mPFC significantly increased in the Tai Chi Chuan group compared to the control group (also in the Baduanjin group compared to the control group, albeit at a lower threshold), and no significant difference between the Tai Chi Chuan and Baduanjin groups was observed; (3) rs-FC increases between the bilateral hippocampus and mPFC were significantly associated with corresponding memory function improvement across all subjects. Similar results were observed using the left or right hippocampus as seeds. Our results suggest that both Tai Chi Chuan and Baduanjin may be effective exercises to prevent memory decline during aging.

Differential brain shrinkage over 6 months shows limited association with cognitive practice

The brain shrinks with age, but the timing of this process and the extent of its malleability are unclear. We measured changes in regional brain volumes in younger (age 20-31) and older (age 65-80) adults twice over a 6 month period, and examined the association between changes in volume, history of hypertension, and cognitive training. Between two MRI scans, 49 participants underwent intensive practice in three cognitive domains for 100 consecutive days, whereas 23 control group members performed no laboratory cognitive tasks. Regional volumes of seven brain structures were measured manually and adjusted for intracranial volume. We observed significant mean shrinkage in the lateral prefrontal cortex, the hippocampus, the caudate nucleus, and the cerebellum, but no reliable mean change of the prefrontal white matter, orbital-frontal cortex, and the primary visual cortex. Individual differences in change were reliable in all regions. History of hypertension was associated with greater cerebellar shrinkage. The cerebellum was the only region in which significantly reduced shrinkage was apparent in the experimental group after completion of cognitive training. Thus, in healthy adults, differential brain shrinkage can be observed in a narrow time window, vascular risk may aggravate it, and intensive cognitive activity may have a limited effect on it.