Stéphane Bouchard

Self-efficacy in the thermal biofeedback treatment of migraine sufferers

Despite the demonstrated efficacy of thermal biofeedback (TBF) for the treatment of migraine headaches, therapeutic mechanisms underlying this widely used therapy remain poorly understood. Previous investigations of electromyograph (EMG) biofeedback treatment of tension-type headache have suggested that reductions in headache activity may be mediated primarily by changes in perceived self-efficacy, rather than actual self-regulation ability. The present study examined perceived self-efficacy as a potential therapeutic mechanism in TBF using an experimental manipulation of perceived success. Twenty-seven females meeting International Headache Society (IHS) diagnostic criteria for migraine headache were randomly assigned to one of two TBF conditions. Subjects were shown bogus computer-generated graphs that ostensibly demonstrated that subjects displayed either superior (high success condition) or inferior (moderate success condition) hand-warming skills relative to a fictitious normative sample. Although the manipulation of perceived success produced significant group differences on measures of perceived self-efficacy, the groups did not experience significantly different reductions in headache activity or medication consumption. The present findings suggest that perceived self-efficacy, as measured in the present study, may not be a significant mediator of TBF treatment outcome.

EMG-to-torque dynamic relationship for elbow constant angle contractions

The purpose of this work was to determine the optimal EMG-torque relationship using four different EMG processors in conjunction with different system identification (ID) techniques for dynamically torque varying elbow constant angle contractions. Comparing predicted torque with actual elbow torque, it was found that either multiple EMG channels or EMG signal whitening lead to the best relationship. The choice of the system ID model had limited effect on performance.