Behavioural indexes of movement imagery ability are associated with the magnitude of corticospinal adaptation following movement imagery training.

Movement imagery (MI) is a cognitive process wherein an individual simulates themselves performing a movement in the absence of physical movement. The current paper reports an examination of the relationship between behavioural indexes of MI ability and the magnitude of corticospinal adaptation following MI training. Behavioural indexes of MI ability included data from a questionnaire (MIQ-3), a mental chronometry task, and a hand laterality judgment task. For the measure of corticospinal adaptation, single-pulse transcranial magnetic stimulation (TMS) was administered to elicit thumb movements to determine the representation of thumb movements before and after MI training. MI training involved participants imagining themselves moving their thumb in the opposite direction to the dominant direction of the TMS-evoked movements prior to training. Pre/post-training changes in the direction and velocity of TMS-evoked thumb movements indicated the magnitude of adaptation following MI training. The two main findings were: 1) a positive relationship was found between the MIQ-3 and the pre/post-training changes in the direction of TMS-evoked thumb movements; and 2) a negative relationship between the mental chronometry measure and both measures of corticospinal adaptation following MI training. These results indicate that both ease of imagery and timing of imagery could predict the magnitude of neuroplastic adaptation following MI training. Thus, both these measures may be considered when assessing imagery ability and determining who might benefit from MI interventions.

Motor system activation during motor imagery is positively related to the magnitude of cortical plastic changes following motor imagery training.

Motor imagery (MI) is a cognitive motor process wherein a person consciously imagines themselves performing a movement. Previous transcranial magnetic stimulation (TMS) studies have demonstrated that physical and observational training can elicit neuroplastic adaptations in the cortical representation of movement. It has been shown that these cortical adaptations can also occur following MI training. These changes are thought to occur because of a training-dependent potentiation (i.e. increased excitability) of the trained movement representation. To test this hypothesis, the current experiment assessed the relationship between motor cortex excitability during MI and the magnitude of motor cortical adaptations following MI training. Prior to training, single-pulse TMS was used to determine the dominant direction of TMS-evoked thumb movements. The pre/post-training change in the direction of TMS-evoked thumb movements as well as the change in the first peak velocity of these thumb movements was used as an indication of the magnitude of adaptation following MI training. During the training session, participants imagined themselves moving their thumb in the opposite direction of the pre-determined dominant direction. Single-pulse TMS was also used to determine the amplitude of motor evoked potentials (MEPs) during imagined thumb movements. A strong positive relationship was found between MEP amplitude during MI of thumb movements and both measures of motor cortical adaptation following MI training. These results support the hypothesis that activation of the corticospinal motor system during MI of movements is related to the magnitude of motor cortical adaptations following MI training.

Rapid motor cortical plasticity can be induced by motor imagery training.

Previous behavioural research has revealed that motor imagery (MI) can be an effective technique to generate and enhance motor learning and rehabilitation. This MI-enhanced motor performance may emerge because MI shares overlapping neural networks with movement execution and observation and leads to the activation and neuro-plasticity of the motor system. Neurophysiological studies using transcranial magnetic stimulation (TMS) have shown that physical and observational practice can elicit use-dependent, neuro-plastic changes in the cortical representation of movement. The purpose of the current experiment was to determine if similar changes in cortical representation of thumb movements could be elicited with MI training. Single-pulse TMS was provided over primary motor cortex to generate involuntary thumb movements before and after each of five training blocks. The dominant direction (flexion or extension) of TMS-evoked thumb movements was used as an index of the representation of thumb movements in primary motor cortex. During training, participants either imagined moving (experimental MI group) or physically moved (control PT group) their thumbs in the direction opposite to the dominant direction of their TMS-evoked thumb movements determined in the pre-training assessment. Both PT and MI training resulted in increases in the percentage of TMS-evoked thumb movements in the trained direction. These changes were apparent for the MI group after 900 imagery trials, whereas the changes were detectable in the PT group after 300 trials. These results indicate that MI can induce plastic changes similar to those of physical training, although more trials may be needed for these changes to occur.

Independent Development of Imagination and Perception of Fitts' Law in Late Childhood and Adolescence.

Recent neurophysiological and behavioral research suggests perception-action systems are tightly coupled. Accordingly, Fitts' law has been observed when individuals execute, perceive, and imagine actions. Developmental research has found that (a) children demonstrate Fitts' law in imagined actions and (b) imagined movement time (MT) becomes closer to actual MT as age increases. However, action execution, imagination, and perception have yet to be assessed together in children. The authors investigated how imagined and perceived MTs related to actual MTs in children and adolescents. It was found that imagined MTs were longer than execution MTs were. Perception MTs were lower than execution MTs for children and more consistent with execution MTs for adolescents. These results suggest potential mechanistic differences in action imagination and perception.