Date of Award

Fall 2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biomedical Engineering

First Advisor

Brian D. Schmit

Second Advisor

Sheila Schindler-Ivens

Third Advisor

Kristina M. Ropella

Abstract

This study characterized the brain electrical activity during pedaling, a locomotor-like task, in humans. We postulated that phasic brain activity would be associated with active pedaling, consistent with a cortical role in locomotor tasks. 64 channels of electroencephalogram (EEG) and 10 channels of electromyogram (EMG) data were recorded from 10 neurologically-intact volunteers while they performed active and passive (no effort) pedaling on a custom-designed stationary bicycle. Ensemble average waveforms, two dimensional topographic maps and amplitude of the beta (13-35 Hz) frequency band were analyzed and compared between active and passive trials. The absolute amplitude (peak positive-peak negative) of the EEG waveform recorded at the Cz electrode tended to be higher in the passive than the active trials (paired t-test; p<0.01). Average power of the center beta-band frequency (20-25 Hz) in the active pedaling was significantly smaller than passive pedaling (Univariate ANOVA; p<0.01), consistent with beta desynchronization. A significant negative correlation was observed between the ensemble average EEG waveform for active trials and the composite EMG (summated EMG from both limbs for each muscle) of the rectus femoris (r = -0.77, p<0.01) the medial hamstrings (r = -0.85, p<0.01) and the tibialis anterior (r = -0.70, p <0.01) muscles. These results demonstrated that substantial sensorimotor processing occurs in the brain during pedaling in humans. Further, cortical activity seemed to be greatest during recruitment of the muscles critical for transitioning the legs from flexion to extension and vice versa. This is the first known study demonstrating the feasibility of EEG recording during pedaling, and owing to similarities between pedaling and bipedal walking, may provide valuable insight into brain activity during locomotion in humans.