The general objective of this application is to study reorganization of network interactions following a common type of subcortical stroke (i.e. internal capsule) with mechanistic studies using noninvasive neurophysiology in humans. The goal is to obtain pilot data and to demonstrate the feasibility of the approach that combines transcranial magnetic stimulation (TMS) with reaching in an advanced exoskeleton robot. As reaching is an essential part of many daily activities, this approach will have beneficial impacts on the quality of life of these stroke patients.

The central hypothesis is that bilateral premotor cortical areas, dorsal (PMd) more so than ventral (PMv,) develops greater connectivity with primary motor cortex (M1) after stroke and thus better ability to produce motor outputs that support reaching with the paretic arm. When there is more damage to the corticospinal tract, contralesional areas will take on a greater role.

The relationship between connectivity, behavioral effects of stimulation and motor performance will be established. These findings will allow the investigators to formulate clear hypotheses about which premotor area should be modulated with TMS, depending on stroke extent and deficits in motor control, when reaching the stage of proposing a treatment trial. Increased knowledge of the dynamic changes of physiological interactions during various phases of reaching movements will allow a more defined study regarding the role of premotor areas in recovery of motor function after stroke, and a novel treatment protocol that delivers precisely timed stimulations during practice of reaching movements. Ultimately, the investigators can test these novel treatments in clinical trials and compare their impact to other, less specific, neuromodulatory methods such as transcranial direct current stimulation. This study will also lay the groundwork for collaboration in brain computer interface and non-human primate investigations in the mechanisms and treatment of motor deficits after stroke.