A Functional MRI Study of Three Motor Tasks in the Evaluation of Stroke Recovery

Abstract

Functional brain imaging studies have provided insights into the processes related to motor recovery after stroke. The comparative value of different motor activation tasks for probing these processes has received limited study. We hypothesized that dif ferent hand motor tasks would activate the brain differently in controls, and that this would affect control-patient comparisons. Functional magnetic resonance imaging (MRI) was used to evaluate nine control subjects and seven patients with good recov ery after a left hemisphere hemiparetic stroke. The volume of activated brain in bilat eral sensorimotor cortex and four other motor regions was compared during each of three tasks performed by the right hand: index finger tapping, four-finger tapping, and squeezing. In control subjects, activation in left sensorimotor cortex was found to be significantly larger during squeezing as compared with index-finger tapping. When com paring control subjects with stroke patients, patients showed a larger volume of acti vation in right sensorimotor cortex during index-finger tapping but not with four-fin ger tapping or squeezing. In addition, patients also showed a trend toward larger activation volume than controls within left supplementary motor area during index- finger tapping but not during the other tasks. Motion artifact was more common with squeezing than with the tapping tasks. The choice of hand motor tasks used during brain mapping can influence findings in control subjects as well as the differences identified between controls and stroke patients. The results may be useful for future studies of motor recovery after stroke. Key Words: Stroke—Motor recovery—Functional MRI.