Multifocal Transcranial Direct Current Stimulation to Modulate Motor Learning

Date
2025-03
Language
American English
Embargo Lift Date
Department
Committee Chair
Degree
Ph.D.
Degree Year
2025
Department
School of Health and Human Sciences
Grantor
Indiana University
Journal Title
Journal ISSN
Volume Title
Found At
Abstract

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that modulates neural excitability in targeted brain regions, influencing processes such as motor learning. While tDCS has been previously shown to benefit motor skill acquisition, much of this research has focused on relatively simple, unimanual tasks. Conversely, the effects of tDCS on more complex, bimanual motor tasks remain understudied, with existing findings often yielding mixed results. This inconsistency poses challenges for translating laboratory findings to functional, real-world motor skills, which frequently involve coordinated, two-handed movements and heightened cognitive demands. Emerging evidence suggests that multifocal tDCS paradigms, which simultaneously target multiple brain regions, may provide enhanced learning effects, particularly for complex motor tasks. Unlike traditional monofocal stimulation protocols that focus on the primary motor cortex (M1) or cerebellum individually, multifocal approaches may better address the neural dynamics underlying bimanual coordination and interhemispheric interactions. The purpose of this dissertation was to investigate the potential of multifocal tDCS to enhance motor learning in complex tasks, examining both unimanual and bimanual skill acquisition. This research involved a series of studies beginning with monofocal tDCS applied to M1 and the cerebellum during a non-dominant unimanual rhythm-timing task and culminating in a multifocal “tri-focal” stimulation protocol during a bimanual motor learning task. In Study One, we compared the effects of excitatory M1 stimulation against excitatory and inhibitory cerebellar and sham stimulation. While none of the monofocal tDCS conditions significantly enhanced learning compared to sham, small, non-significant trends were observed which informed the design of Study Two. Here, we observed that combining excitatory M1 stimulation with inhibitory cerebellar stimulation resulted in significant and robust improvements in motor learning. In Study Three, we found that bilateral M1 stimulation significantly enhanced the early stages of bimanual skill learning at lower intensities. However, Study Four revealed that increasing stimulation intensity or adding inhibitory cerebellar stimulation impaired bimanual learning. Together, these findings contribute to a growing understanding of how multifocal stimulation paradigms can be tailored to enhance motor learning in real-world tasks while underscoring the importance of carefully optimizing stimulation parameters to task-specific demands.

Description
IUI
item.page.description.tableofcontents
item.page.relation.haspart
Cite As
ISSN
Publisher
Series/Report
Sponsorship
Major
Extent
Identifier
Relation
Journal
Source
Alternative Title
Type
Thesis
Number
Volume
Conference Dates
Conference Host
Conference Location
Conference Name
Conference Panel
Conference Secretariat Location
Version
Full Text Available at
This item is under embargo {{howLong}}