Shared mechanisms underlie mental imagery and motor planning

Area of Science:

• Cognitive Neuroscience
• Motor Control
• Virtual Reality

Background:

• Mental imagery and motor control share overlapping brain mechanisms, potentially involving the cerebellar forward model for sensory predictions.
• Previous studies show inconsistent correlations between individual mental and motor capacities, challenging the shared mechanism hypothesis.
• This inconsistency may stem from the forward model's role primarily in early motor adaptation, with the inverse model dominating later stages.

Purpose of the Study:

• To investigate the link between mental imagery and motor planning by manipulating sensory prediction using virtual embodiment.
• To test the hypothesis that increased forward-model involvement during sensorimotor adaptation enhances the overlap between motor planning and mental imagery.
• To explore virtual reality as a tool to probe and potentially improve the convergence of physical and mental capacities.

Main Methods:

• Participants (n=48) performed mental and manual rotation tasks in an immersive virtual reality environment.
• A test group experienced altered sensorimotor dynamics (virtual hand twice as fast as physical hand) via speed re-mapping.
• Mental imagery capacity was assessed pre- and post-blocks of manual rotation; motor planning duration was measured as time to motion onset.

Main Results:

• Virtual sensorimotor alteration significantly increased the correlation between mental imagery and motor planning (r=0.9, p<0.0001).
• Participants in the altered reality group showed greater improvement in mental imagery performance after motor tasks.
• The manipulation primarily affected motor planning to align with imagery mechanisms, supporting increased forward-model engagement.

Conclusions:

• Virtual embodiment, by inducing sensorimotor conflict, enhances the functional overlap between motor planning and mental imagery.
• Findings support the predictive forward model as a core mechanism underlying both motor control and mental imagery.
• Virtual sensorimotor alteration offers a novel method to increase physical-mental convergence and has potential applications in cognitive evaluation and treatment.