Motor Planning, Initiation and Execution of Shoulder Abduction Against Gravity

by Christina Thomas, Brianna Johnson, Emma M. Baillargeon, Rosalind L.

Heckman Stroke affects the sensorimotor control of the upper extremity, limiting functional movements which require coordination between the shoulder and distal joints. StartReact has been used to investigate motor planning, independent of motor initiation and execution, but it is unclear if observed deficits in motor planning at the shoulder are due to task requirements or stroke-related impairments.

Our aim was to decouple these factors by studying motor planning of shoulder movement in participants who have not had a stroke. Participants performed unilateral shoulder abduction movements from two initial positions in response to auditory cues.

Muscle activity was recorded from the sternocleidomastoid (SCM) muscles as an indicator of startReact. Middle deltoid (DELT) activity and shoulder abduction position were also recorded.

We hypothesized that unilateral shoulder abduction could be triggered by a loud acoustic stimulus (LAS) used to study startReact.