Effect Of Tai Chi Participation On Prefrontal Cortex Activation During Precision Fitting Task

Abstract

PURPOSE: The purpose of this study was to investigate the group effects on balance performance and prefrontal cortex (PFC) activation level when performing fitting task among Tai Chi (TC), older (OG), and young (YG) groups. METHODS: TC (67.5 ± 3.6 yrs), OG (66.9 ± 3.4 yrs) and YG (19.5 ± 0.6 yrs) were recruited. Each participant performed four different fitting tasks: (1) close-large (CL), (2) close-small (CS), (3) far-large (FL), and (4) far-small (FS) conditions. The order of opening size was random, but the distance was following from close to far conditions. Each task was required to repeat five times. Meanwhile, the center of pressure (CoP) was recorded by the force plate (2000 Hz, Kistler 9285BA), as well as the oxygenation levels of the PFC were recorded by the fNIRS device (50 Hz, Brite 24). Two three-way mixed models of ANOVA with repeated measure were used to examine the group, distance, and size effects on CoP measures and PFC activation, respectively. RESULTS: There was no significant group difference on time to complete. In the CL condition, TC and YG showed significantly smaller average CoP velocity (TC: 28.1 ± 11.4, YG: 26.6 ± 10.8, & OG: 42.8 ± 13.5 mm/s) in the Medial-Lateral (ML) direction than OG (p < .05). Additionally, in the CS condition, YG also presented smaller average CoP velocity than OG in the Anterior-Posterior (AP) direction (YG: 52.7 ± 17.0, & OG: 77.0 ± 30.1 mm/s) (p < .05). In the FS condition, YG exhibited smaller average CoP velocity than OG in the AP (YG: 43.1 ± 16.6, & OG: 61.8 ± 13.0 mm/s) and ML (YG: 27.0 ± 12.4, & OG: 61.8 ± 13.0 mm/s) directions (p < .05). In the FL and FS conditions, OG had significant larger activation levels in the right/left dorsolateral PFC (YG: 0.8 ± 0.9/0.3 ± 0.6, & OG: 1.8 ± 1.3/1.2 ± 0.8 μm), left dorsomedial PFC (YG: 0.3 ± 1.0, & OG: 1.0 ± 1.4 μm), and left ventrolateral PFC (YG: 0.5 ± 1.1, & OG: 1.9 ± 1.1 μm) than YG (p < .05). In addition, OG also had a higher activation level in the right dorsolateral PFC (TC: 0.8 ± 1.1 μm) than TC (p < .05). CONCLUSION: In the far condition, healthy older adults presented an alternative control strategy using additional PFC activation in fitting task compared to young adults. However, Tai Chi group adopted similar control strategy with young adults, thereby can be considered as a feasible intervention approach to reduce falling risks.