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

Abstract

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 (5 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.

Developmental improvements in reaching correction efficiency are associated with an increased ability to represent action mentally

“…Indeed, the time taken to imagine a movement correlates closely with subsequent execution times (Decety et al, 1989;Sirigu et al, 1996), with awkward and more physically demanding actions taking longer to imagine (Butson, Hyde, Steenbergen, & Williams, 2014;de Lange, Roelofs, & Toni, 2008;Munzert, Lorey, & Zentgraf, 2009). This relative functional equivalence is coupled with corresponding neurophysiological similarities, with neuroimaging studies indicating that imagined movements activate similar neural networks to those activated in actual movement (Jeannerod, 2001;Munzert et al, 2009) and corticospinal pathways (e.g., Williams, Pearce, Loporto, Morris, & Holmes, 2012). Consequently, it is largely assumed that MI provides insight into one's ability to accurately form and monitor the kinds of internal motor representations that support purposive action (de Lange et al, 2008;Jeannerod, 2001;Munzert et al, 2009).…”

In the absence of physical practice, observation and imagery do not result in updating of internal models for aiming

“…With respect to the latter hypothesis, there is evidence that imagery ability mediates corticospinal activation during action observation. The amplitude of motor evoked potentials, as measured during transcranial magnetic stimulation of a finger-thumb opposition task, was found to be correlated with validated measures of imagery ability (Williams et al 2012). …”

Effector-independent brain activity during motor imagery of the upper and lower limbs: An fMRI study

“…A previous study reported that a gender difference was observed in brain activity during a mental rotation task [42]. Furthermore, since motor imagery ability would affect brain activity during motor imagery [46], we did not record motor imagery ability. In the future, we need to clarify whether effector-independent activity during motor imagery was different between male and female subjects or was affected by motor imagery ability.…”