Cognitive Effects on the Neurophysiology and Biomechanics of Stroke Recovery

Motor function recovery after stroke typically plateaus after six months. Case reports suggest that hypnosis has the potential to stimulate further recovery of function beyond this period. A pilot clinical investigation of hypnosis-aided recovery of motor function after stroke is presented. Baseline hand motor performance was quantified for six stroke subjects with a force-following task. Brain activity during the task was measured using functional magnetic resonance imaging (fMRI). After cognitive training with hypnosis for improved motor performance, subjects performed the task again. Reaction times and muscle contraction and relaxation rates improved significantly after hypnosis and changes persisted during follow up testing at two weeks. Hypnosis versus baseline fMRI results show increased activation extent in bilateral sensorimotor cortex with an ipsilateral shift in laterality. No significant differences were found in motor performance or fMRI results when the unaffected hand performed the task as a control condition. The autonomic physiology of hypnosis was studied by correlating heart rate variability (HRV) model parameters with hypnotic depth and motor performance changes. Modeling the low frequency (LF) and high frequency (HF) components in HRV as