The effect of transient visual deprivation on motor cortical excitability and motor learning : a pilot study

Abstract

Castro, Fabio, 2015. The Effect of Transient Visual Deprivation on Motor Cortical Excitability and Motor Learning. University of Jyväskylä, Department of Biology of Physical Activity, Master Thesis in Applied Biomechanics. 86 pp. We devised an experimental protocol to test the hypothesis that if the performer poses attention on the proprioceptive signals, in the form of awareness of the body in space, this could increase the corticospinal excitability and the overall performance. 10 right-handed volunteers were randomly assigned to either a group performing a skill training blindfolded (BLIND) or in normal (NORM) condition. The intervention included a visuomotor task-related skill training lasting five days. Neurophysiological measurements included input/output relationship (IO Curve) of the motor evoked potentials (MEPs) and short-interval intracortical inhibition (SICI), both measured with the transcranial magnetic stimulator, from the right Biceps Brachii muscle. The results showed no significant changes in any of the neurophysiological parameters, either between the groups or within the same group. However, the analysis revealed that in day 1, the BLIND group showed an increase in the corticospinal excitability compared with NORM. There was also a slight decrease in SICI for BLIND, and an increase in SICI for the NORM group. On day 5, there was a slight reduction in the corticospinal excitability for BLIND, coupled with a slight increase in SICI. For the NORM group, on day 1 there was a decrease in the corticospinal excitability, coupled with a decrease in the SICI as well. On day 5 the CSE increased, while the SICI decreased. The performance, expressed as mean error between the trial and the target line, showed that the BLIND group performed better in each day, with a strong significant difference on day 1 (difference between the groups: 3.07 ± 1.17, p < 0.01). On the other hand, the rate of performance improvement was significantly greater for the NORM group, compared with the BLIND group (difference between D1 and D5 for the NORM group: 3.70 ± 1.59, p < 0.01). It is concluded that a skill training performed blindfolded is undoubtedly beneficial for the performance, and that a modulation of the corticospinal excitability is indeed in place. Future study will be needed to clarify the exact mechanisms behind this modulation.