Handedness effects of imagined fine motor movements

Previous studies of movement imagery have found inter-individual differences in the ability to imagine whole-body movements. The majority of these studies have used subjective scales to measure imagery ability, which may be confounded by other factors related to effort. Madan and Singhal [2013. Introducing TAMI: An objective test of ability in movement imagery. Journal of Motor Behavior, 45(2), 153–166. doi:10.1080/00222895.2013.763764] developed the Test of Ability in Movement Imagery (TAMI) to address these confounds by using a multiple-choice format with objectively correct responses. Here we developed a novel movement imagery questionnaire targeted at assessing movement imagery of fine-motor hand movements. This questionnaire included two subscales: Functionally-involved Movement (i.e., tool-related) and Isolated Movement (i.e., hand-only). Hand-dominance effects were observed, such that right-handed participants were significantly better at responding to right-hand questions compared to left-hand questions for both imagery types. A stronger handedness effect was observed for Functionally-involved Movement imagery, and it did not correlate with the Edinburgh Handedness Inventory. We propose that the Functionally-involved Movement imagery subscale provides an objective hand imagery test that induces egocentric spatial processing and a greater involvement of memory processes, potentially providing a better skill-based measure of handedness

Handedness effects on imagery of dominant‐ versus non‐dominant‐hand movements: An electroencephalographic investigation

Mental representations of our bodies are thought to influence how we interact with our surroundings. We can examine these mental representations through motor imagery, the imagination of movement using scalp EEG recordings. The visual modality of motor imagery emphasises ‘seeing’ the imagined movement and is associated with increased activity in the alpha rhythm (8–14 Hz) measured over the occipital regions. The kinaesthetic modality emphasises ‘feeling’ the movement and is associated with decreased activity in the mu rhythm (8–14 Hz) measured over the sensorimotor cortices. These two modalities can be engaged in isolation or together. We recorded EEG activity while 37 participants (17 left‐hand dominant) completed an objective hand motor imagery task. Left‐handers exhibited significant activity differences between occipital and motor regions only during imagery of right‐hand (non‐dominant‐hand) movements. This difference was primarily driven by less oscillatory activity in the mu rhythm, which may reflect a shift in imagery strategy wherein participants placed more effort into generating the kinaesthetic sensations of non‐dominant‐hand imagery. Spatial features of 8–14 Hz activity generated from principal component analysis (PCA) provide further support for a strategy shift. Right‐handers also exhibited significant differences between alpha and mu activity during imagery of non‐dominant movements. However, this difference was not primarily driven by either rhythm, and no differences were observed in the group's PCA results. Together, these findings indicate that individuals imagine movement differently when it involves their dominant versus non‐dominant hand, and left‐handers may be more flexible in their motor imagery strategies