# Characterizing Hemisphere-Specific Deficits in Bimanual Motor Control After Stroke

> **NIH NIH F31** · UNIVERSITY OF SOUTHERN CALIFORNIA · 2020 · $37,820

## Abstract

PROJECT SUMMARY
Understanding the specific roles of the cerebral hemispheres for the control of bilateral movement is an important
goal of motor control research with implications for rehabilitation of neurological injury, especially stroke. For
instance, behavioral studies indicate that individuals with right hemisphere damage (RHD) exhibit a diminished
response to bilateral arm training compared to those with left hemisphere damage (LHD). Additionally, those
with RHD are less likely to use their more-affected arm alone or bilaterally with their less-affected arm. In order
to better understand the peculiar disadvantage suffered by individuals with RHD, this proposal seeks to examine
hemisphere-specific deficits in interlimb coordination during bimanual tasks by investigating an empirical
phenomenon known as interlimb coupling (IC). We will first characterize IC for discrete bimanual aiming tasks in
young control subjects. Based on this characterization, we will identify bimanual task conditions that elicit strong
IC in control subjects and quantify and compare IC deficits for these conditions between individuals with LHD
and RHD. Lastly, on the basis of the strong evidence supporting the role of the corpus callosum in mediating
interlimb interactions, we will quantify corpus callosal microstructure, quantify associations of this measure with
our measures of IC, and compare this relationship between chronic stroke survivors with LHD and RHD.
Hypothesis: According to the Dynamic Dominance Hypothesis, the two hemispheres assume specialized but
complementary roles in the two-component control of unimanual movement, with the left hemisphere responsible
for feedforward mechanisms of control (in the early phase of movement), while the right hemisphere is
responsible for feedback-mediated, end-point stabilization (in the late phase of movement).16
We hypothesize that interlimb coupling during bimanual tasks is influenced by hemispheric specialization. Thus,
after a stroke, deficits in IC, will be dissociable between individuals with left and right hemisphere damage, with
LHD exhibiting IC deficits in the early and RHD exhibiting IC deficits in the late phase of bilateral movements.
Aim 1: Characterize interlimb coupling during discrete bimanual aiming tasks.
Aim 2: Determine the influence of the side of stroke lesion on interlimb coupling.
Aim 3: Investigate the relationship between corpus callosum microstructure and interlimb coupling.
Studying fundamental neurobehavioral mechanisms and the identification of hemisphere-specific deficits of
bimanual movements after stroke is a necessary first step toward the development of interventions to
remediate these deficits. Successful accomplishment of these aims will advance our understanding of
hemisphere-specific mechanisms, and by doing so, lay groundwork for the development of targeted training
programs for stroke survivors with left- or right-hemisphere damage.

## Key facts

- **NIH application ID:** 9905315
- **Project number:** 5F31HD098796-02
- **Recipient organization:** UNIVERSITY OF SOUTHERN CALIFORNIA
- **Principal Investigator:** Rini Varghese
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $37,820
- **Award type:** 5
- **Project period:** 2019-04-01 → 2021-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9905315

## Citation

> US National Institutes of Health, RePORTER application 9905315, Characterizing Hemisphere-Specific Deficits in Bimanual Motor Control After Stroke (5F31HD098796-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9905315. Licensed CC0.

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