Effect of Transcranial Direct Current Bi-Hemispheric Stimulation on Fine Motor Activity of the Hand in Healthy Adults

Abstract

Background: Evidence states that transcranial direct current stimulation (tDCS) can alter cortical excitability (Cathodal stimulation hyperpolarizes, while anodal stimulation excites). This study compares bihemispheric tDCS to sham stimulation on fine motor activity in healthy adults. Methods: 24 healthy 18-30-year subjects were recruited at Nizam's Institute of Medical Sciences in Hyderabad, India, and split into experimental (tDCS bihemispheric stimulation) and control (sham) groups. The O'Connor Finger Dexterity Test (OCFDT) and Purdue Pegboard Test (PPBT) results were analysed for hand dexterity before and after stimulation. Results: Variables like age, height, weight, and BMI of the groups were taken. Significance of differences in Intra- and inter-group hand function dexterity tests (OCFDT, PPBT) test results were done, and a p-value of <0.05 was considered significant. Conclusion: The study found significant intra-group pre and post-differences in all components of OCFDT and assembly components of PPBT, but inter-group differences in other components of PPBT and OCFDT were insignificant. Results found were limited as tDCS can only stimulate the superficial cortex. In addition, the results in the sham group attributed to some amount of superficial stimulation in sham stimulation. Further research is needed to know the extent of stimulation effects and training effects to understand cortical activity differences in bi-hemispheric and sham stimulation, initial cognitive competence, motor planning, task practice, fine motor function feedback, intensity, electrode size, duration, number of sessions, stimulation site on tDCS effects. Keywords: Hand function, tDCS, Sham stimulation, Bi-hemispheric stimulation, Transcranial direct current stimulation,