# Shift from Unilateral to Bilateral Sensory-Motor Connectivity in Chronic Hemiparetic Stroke

> **NIH NIH R01** · UNIVERSITY OF OKLAHOMA · 2022 · $343,655

## Abstract

Abstract. The emergence of abnormal movement synergies following a stroke presents a major limitation to the
recovery of independent function by constraining voluntary movements to stereotypical muscle coactivation
patterns. The resulting expression of the flexion synergy limits arm/hand function, like reaching and hand opening;
and has also been reported to be linked to hyperactive stretch reflexes or spasticity. Previous studies found that
flexion synergy and spasticity are associated with the recruitment of contralesional descending cortico-
bulbospinal pathways. However, how the somatosensory system adapts to this change in the use of motor
pathways and the role of adaptive sensory feedback to the abnormal motor control of the paretic arm remain
largely unknown. The ascending sensory pathways that convey somatosensation from the paretic arm project
contralaterally to the primary sensory cortex in the lesioned hemisphere. Our preliminary data, however,
suggests that, in individuals that express the flexion synergy and spasticity, this sensory information is
subsequently transferred to the contralesional hemisphere, a process that may support the manifestation of the
abnormal movement patterns in hemiparetic stroke. The overall goal of the proposed research is to examine
the pathophysiology of this maladaptive hemispheric somatosensory “shift” and its relationship to the upper
limb motor impairments following a hemiparetic stroke. The results will lead to a greater understanding of
abnormal limb synergies and spasticity by closing the sensorimotor loop, which should provide a novel means
by which to therapeutically prevent and mitigate the emergence and expression of upper limb motor impairments,
following a stroke. The proposed research aims to test the following key hypotheses in our specific aims:
Following a unilateral motor stroke, a hemispheric shift in somatosensory processing provides sensory feedback
to support the maladaptive hemispheric shift in the motor system. This hemispheric sensory shift not only
influences volitional movement control which contributes to the expression of the flexion synergy (Aim 1), but
also the transcortical loop of the stretch reflex that is related to the hyperactive stretch reflexes (or spasticity)
and the increased onset delay of the long-latency stretch reflex (Aim 2). Furthermore, the hemispheric sensory
shift, as a result of neuroplasticity in an injured brain, can occur in the absence of motor output; and this sensory
shift can indicate the extent of motor deficits (Aim 3). By testing these hypotheses, the proposed research will
improve our understanding of the role of sensory feedback in post-stroke motor impairments. This should allow
for the determination of motor deficits from a new sensory perspective for more impaired individuals or
acute/subacute patients who have difficulty performing motor tasks. Furthermore, the knowledge gained in this
study will facilitate the future development of target...

## Key facts

- **NIH application ID:** 10499357
- **Project number:** 1R01HD109157-01
- **Recipient organization:** UNIVERSITY OF OKLAHOMA
- **Principal Investigator:** Yuan Yang
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $343,655
- **Award type:** 1
- **Project period:** 2022-09-19 → 2027-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10499357

## Citation

> US National Institutes of Health, RePORTER application 10499357, Shift from Unilateral to Bilateral Sensory-Motor Connectivity in Chronic Hemiparetic Stroke (1R01HD109157-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10499357. Licensed CC0.

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