The relationship between corticospinal excitability during motor imagery and motor imagery ability.

It is commonly reported that transcranial magnetic stimulation (TMS) of the motor cortex during action observation and motor imagery results in increases in the amplitude of motor evoked potentials (MEPs) in muscles specific to the observed or imagined action. This study aimed to determine whether MEP amplitude was related to the motor imagery ability of participants. Participants were 15 healthy, right-handed adults (five male), with a mean age of 29.7 years. Motor imagery ability was measured using the Vividness of Movement Imagery Questionnaire-2 (VMIQ-2) and a hand rotation task. TMS was delivered during observation and imagery of a finger-thumb opposition sequence and MEPs were measured in the abductor pollicis brevis. Significant increases in MEP amplitude, from baseline, were recorded during observation and imagery conditions. The change in amplitude to both observation and imagery was expressed as a percentage of baseline amplitude. There was a significant correlation between MEP change for the imagery condition and imagery ability, with greater change linked to more vivid images and faster response times. The relationship between MEP change for the observation condition and imagery ability was less salient. This is the first study to show that the strength of corticospinal activation during imagery, which may be a determinant of the effectiveness of imagery training, is related to imagery ability in the general population, and has implications for clinical programs.

Investigating central mechanisms underlying the effects of action observation and imagery through transcranial magnetic stimulation.

Sport and exercise psychologists provide some interventions for clients based on limited direct evidence and partial understanding of the mechanisms that underpin their efficacy. The authors review a recent technique, transcranial magnetic stimulation (TMS), which offers a tested procedure for investigating cortical activity during observation and imagery processes. They provide a detailed description of the TMS protocol and highlight some of the key studies that inform sport and exercise psychology research. Finally, the authors offer some thoughts on the direct application to practice.