Visual and Motor Mental Imagery After Brain Damage

Abstract

This chapter presents evidence from brain-damaged patients relevant to the debate concerning the neural underpinnings of visual and motor mental imagery capacities. For visual mental imagery, the domains of object shape and color, orthographic material, and spatial imagery (imaginal neglect) are examined. Concerning motor imagery, evidence is reviewed from patients with locked-in syndrome and vegetative state, Parkinson’s disease, vascular strokes, and limb amputations. Although both visual mental imagery and motor imagery have been postulated to draw on similar neural resources as the corresponding “actual” abilities (respectively, visual perception and motor acts), the available evidence from brain-damaged patients indicates that such a close correspondence only exists for motor imagery. Visual mental imagery, on the other hand, seems to rely on the activity of high-level visual processing. This possibility seems consistent with the proposed “active” character of imagery abilities, which would not necessarily require the functioning of sensory cortices devoted to the processing of external stimuli.