Optimizing Transcranial Direct Current Stimulation for Motor Recovery From Severe Post-Stroke Hemiparesis

This study has 2 aims: i) determine whicl1 transcranial direct current stimulation (tDCS) electrode configuration is most effective in combination with motor training to promote motor recovery from severe post-stroke hemiparesis; and 2) begin to clarify the extent to which baseline transcranial magnetic stimulation (TMS) measures predict response to tDCS, as well as the effects of tDCS paired with motor training on TMS measures of motor cortical organization. To accomplish these aims. we will recruil36 human subjects with severe post-stroke hemiparesis and assign each subject to 1 of 4 tDCS conditions (anodal excitatory ipsilesional; cathodal ;nhibitory contralesional; a combination of anodal excitatory ipsilesional during cathodal Inhibitory contralesional; or sham). Each subject w!!l undergo a 20-mlnute stimulation session once a day for 10 days over a 2-week period. Each session will be followed by 3 hours of intensive, task-oriented upper extremity motor training. Outcome measures for this study include TMS motor cortical maps and standardized tesls of motor performance. We hypothesize that ail groups will show improvement in all measures; however, both the anodal excitatory ipsilesional group and the cathodal inhibitory contralesional group will show signlflcan!iy greater improvement compared w;th the other 2 groups. We wiil a!so find evidence clarifying whether the presence or absence of motor-evoked potentials (MEPs) has predictive value regarding which tOGS configuration would b'9 most effective for a particular subject.