Abstract
Date Presented 03/23/24
This study explores how noninvasive brain stimulation of the left and right posterior parietal cortex influences bilateral fine motor control. Results suggest distinct effects on speed and accuracy to help understand fine motor control modulation.
Primary Author and Speaker: Sydney C. Sharp
Additional Authors and Speakers: Brooke Dexheimer
The left posterior parietal cortex (PPC) is suggested to be a critical brain region for motor learning in bilateral upper extremities (BUE). Stimulating the PPC in healthy controls with a non-invasive form of brain stimulation, high-definition transcranial direct current stimulation (HD-tDCS) has been shown to improve motor learning transfer from the dominant hand (DH) to non-dominant hand (NDH) during non-functional reaching tasks. However, it remains unclear how this brain region contributes to motor learning in BUE during functional tasks. Our aim is to investigate the differential roles of left and right PPC on functional fine motor control during 1) DH tracing, and 2) transfer of fine motor learning to the NDH, using HD-tDCS. In this double-blind randomized controlled trial, we used convenience sampling to recruit right handed healthy controls between the ages of 18 and 40. 15 participants were randomized to receive either left PPC, right PPC, or sham stimulation of HD-tDCS. During stimulation, they completed tracing tasks on a touchscreen app with their DH. Following the stimulation, they completed the same tracing task with their NDH. We quantified performance via average trial duration and average tracing error. Preliminary results suggest that right PPC stimulation appears to result in faster average trial duration and increased average tracing error when participants switched to their NDH. Left PPC stimulation resulted in slower average trial duration in the DH when compared to sham stimulation but similar average tracing error in both the DH and NDH. Stimulation applied to the left or right PPC appears to differentially affect speed and accuracy of functional fine motor control in the DH and NDH suggesting that both brain regions have a role in bilateral fine motor control. Additionally, HD-tDCS applied to specific brain regions to modulate fine motor control may have future clinical implications, but additional research is necessary.
References
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Hirayama, K., Koga, T., Takahashi, T., & Osu, R. (2021). Transcranial direct current stimulation of the posterior parietal cortex biases human hand choice. Scientific Reports, 11(1). 10.1038/s41598-020-80611-8
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