Positive Technology Journal

Kinesthetic but not visual imagery assists in normalizing the CNV in Parkinson's disease.

Clin Neurophysiol. 2006 Oct;117(10):2308-14

Authors: Lim VK, Polych MA, Holländer A, Byblow WD, Kirk IJ, Hamm JP

OBJECTIVE: This study investigated whether kinesthetic and/or visual imagery could alter the contingent negative variation (CNV) for patients with Parkinson's disease (PD). METHODS: The CNV was recorded in six patients with PD and seven controls before and after a 10min block of imagery. There were two types of imagery employed: kinesthetic and visual, which were evaluated on separate days. RESULTS: The global field power (GFP) of the late CNV did not change after the visual imagery for either group, nor was there a significant difference between the groups. In contrast, kinesthetic imagery resulted in significant group differences pre-, versus post-imagery GFPs, which was not present prior to performing the kinesthetic imagery task. In patients with PD, the CNV amplitudes post-, relative to pre-kinesthetic imagery, increased over the dorsolateral prefrontal regions and decreased in the ipsilateral parietal regions. There were no such changes in controls. CONCLUSIONS: A 10-min session of kinesthetic imagery enhanced the GFP amplitude of the late CNV for patients but not for controls. SIGNIFICANCE: While the study needs to be replicated with a greater number of participants, the results suggest that kinesthetic imagery may be a promising tool for investigations into motor changes, and may potentially be employed therapeutically, in patients with Parkinson's disease.

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.