Abstract

SENIOR PROJECT ABSTRACT FORM

Project Title: The Excitability of the Motor Cortex for Planning Dexterous Manipulation

Student Name: Alison Llave

BASIS Advisor: Mr. Paul McClernon

On-Site Mentor: Dr. Marco Santello

Location: Neuroscience Motor Control Lab on ASU Tempe campus

Abstract

The objective of this project was to improve understanding of the relationship between the brain and finger movements. Since the brain is a complex organ of the body, the project was limited to study only two finger muscles: the abductor pollus brevis (thumb muscle) and the first dorsal interosseus (index finger muscle)--basic muscles in gripping. This study compared the planning of two different situations: When the subjects plan to position the fingers (P) vs. when the subject plan to position the fingers and to apply a grip force (P+F). The task requirement for the subjects was to position the fingers on the object or position and apply a force on the object according to the cue given. Before the subjects acted upon the cue, we measured the difference in excitability needed to move the fingers by comparing the motor-evoked potential (MEP) values. MEP values were recorded using an electromyogram (EMG), a device that measures the muscle activity from the finger movements. Transcranial magnetic stimulation (TMS) was used to see how much excitability was needed to stimulate movement in the fingers since excitability cannot be measured by the EMG alone during the planning phase without muscle movement. We hypothesized that P+F would require more excitability because of the additional difficulty it has compared to just P. Surprisingly, motor-evoked potential values were significantly higher when subjects only planned to position their fingers as opposed to planning to apply a force as well. This research can be applied to fine motor prosthesis, allowing for prosthetic limbs to smoothly communicate with the brain.