Probing somatotopic organization of motor cortex using a novel shoulder motor task and multi-echo fMRI

Motivation: Evolving views of motor cortex organization highlight a need for diverse, controlled motor-task fMRI studies to probe motor systems; while distal hand-grasp and finger-tapping tasks are commonly implemented with fMRI, proximal (e.g., shoulder) motor tasks have rarely been studied. Goal(s): We aimed to perform the first systematic fMRI study of controlled shoulder-abduction tasks, using multi-echo acquisition and analysis techniques. Approach: We used a novel device to study motor activity in healthy individuals who performed a shoulder-abduction task at varying torques. Results: While group-level cortical activity aligned with the traditional homunculus, subject-level results demonstrated individual variation. Impact: We demonstrate the feasibility of studying controlled, proximal upper extremity tasks with whole-brain multi-band multi-echo fMRI; this technique has the potential to elucidate group-level and subject-specific motor organization in healthy individuals and clinical populations with motor impairment.