Determine the effect of targeted high-definition tDCS on reducing post-stroke upper limb motor impairments
Description: Significant motor impairments occur in 80% of individuals after moderate to severe stroke, and impact the body side to the lesioned hemisphere. Typical motor impairments involve loss of dexterity with highly-prevalent upper limb flexion synergy. Flexion synergy interacts with weakness and abnormal joint postures, resulting in functional limitations, such as inability to reach, open the hand and manipulate objects. Advances in treating flexion synergy impairments have been hampered by a lack of precision rehabilitation. Previous studies suggest and support the role of cortico-reticulospinal tract (CRST) hyperexcitability in post-stroke flexion synergy. CRST hyperexcitability is often caused by damage to the corticospinal tract (CST). The PI hypothesizes that: 1) inhibiting the contralesional dorsal premotor cortex (cPMd) will directly reduce the CRST hyperexcitability and thus, reduce the expression of the flexion synergy; 2) facilitating the ipsilesional primary motor cortex (iM1) will improve the excitability of the damaged CST, therefore reducing the CRST hyperexcitability and the flexion synergy. Recent studies demonstrated that tDCS could be a promising and safe approach to modulate cortical excitability. However, the effect of conventional tDCS is limited as it uses large size “sponge” electrodes, making it difficult to target a specific region of interest in the brain for testing the hypothesis. To address the limitation of conventional tDCS that non-specifically activates many brain areas, the PI proposes to use a novel targeted high-definition tDCS (THD-tDCS) to specifically modulate the targeted cortical regions for testing his hypothesis, via the following aims: Aim 1. Evaluate the effect of cathodal THD-tDCS over the cPMd on reducing the CRST hyperexcitability and the expression of flexion synergy. Aim 2. Evaluate the effect of anodal THD-tDCS over the iM1 on improving the excitability of the CST, and determine whether this, thus, also reduces the CRST hyperexcitability and the flexion synergy. Aim 3. Evaluate the confluence effect of bilateral THD-tDCS, i.e., simultaneous cathodal stimulation over the cPMd and anodal over the iM1. The proposed work will facilitate the development of targeted interventions to enhance the recovery of the injured motor system after stroke. PI’s effort follows the AHA mission and if successful, will ultimately result in beneficial reductions in motor impairments for hemiparetic stroke survivors.
Funder: American Heart Association
Amount: $231,000
Funding type: fellowship
Funder scheme: Career Development Award
Start date: 2022-07-01
End date: 2025-06-30
Investigators: Yuan Yang, Yuan Yang
Institution: The Carle Foundation Hospital
Funded outputs count: 15
Funder award ID: 932980
OpenAlex ID: G1312981629