Driving dreams: cortical activations during imagined passive and active whole body movement

It is unclear how subjects perceive and process self-motion cues in virtual reality environments. Movement could be perceived as passive, akin to riding in a car, or active, such as walking down the street. These two very different types of self-motion were studied here using motor imagery in fMRI. In addition, the relative importance of visual and proprioceptive training cues was examined. Stronger activations were found during proprioceptive motor imagery compared with visual motor imagery, suggesting that proprioceptive signals are important for successful imagined movement. No significant activations were found during active movement with proprioceptive training. Passive locomotion, however, was correlated with activity in an occipital-parietal and parahippocampal cortical network, which are the same regions found during navigation with virtual reality stimuli.