Positive Technology Journal

Movement-specific enhancement of corticospinal excitability at subthreshold levels during motor imagery.

Exp Brain Res. 2006 Dec 8;

Authors: Li S

This study examined modulation of corticospinal excitability during both actual and imagined movements. Seven young healthy subjects performed actual (3-50% maximal voluntary contractions) and imagined index finger force production, and rest. Individual responses to focal transcranial magnetic stimulation (TMS) in four fingers (index, middle, ring, and little) were recorded for all three tested conditions. The force increments at the threshold of activation were predicted from regression analysis, representing the TMS-induced response at the threshold activation of the corticospinal pathways. The measured increment in the index finger during motor imagery was larger than that at rest, but smaller than the predicted increment at the threshold of activation. On the other hand, the measured increment in the uninstructed (middle, ring, and little), slave fingers during motor imagery was larger than that at rest, but not different from the predicted increment at the threshold of activation. These contrasting results suggest that the degree of imagery-induced enhancement in corticospinal excitability was significantly less than what could be predicted for threshold levels from regression analysis, but only for the index finger, and not the adjacent slave fingers. It is concluded that corticospinal excitability for the explicitly instructed index finger is specifically enhanced at subthreshold levels during motor imagery.

Motor imagery practice in gait rehabilitation of chronic post-stroke hemiparesis: four case studies.

Int J Rehabil Res. 2006 Dec;29(4):351-356

Authors: Dunsky A, Dickstein R, Ariav C, Deutsch J, Marcovitz E

The aim of this series of pilot case studies was to examine the feasibility of enhancing the walking of individuals with post-stroke hemiparesis through the imagery practice of gait activities at home. Four persons with chronic hemiparesis received imagery gait practice, 3 days a week for 6 weeks. The intervention addressed gait impairments of the affected lower limb and task-specific gait training. Pre-intervention, mid-term, post-intervention and follow-up evaluations were performed. At 6 weeks from the beginning of treatment, the participants increased walking speed, stride length, cadence and single-support time on the affected lower limb, while decreasing double-support time. The findings appear to justify the institution of a larger-scale study in order to better delineate the contribution of motor imagery practice to gait performance in individuals with post-stroke hemiparesis.