Dorsal and ventral cortical pathways for visuo-haptic shape integration revealed using fMRI

Abstract

Two sensory streams theories have had an important influence on sensory and sensorimotor research for the past several decades. Here we apply the perspective of two sensory streams to interactions between visual and haptic object shape processes. We specifically focus on the presence and pattern of multisensory integration or neuronal convergence in dorsal action pathways and ventral perception pathways. To investigate integration of visual and haptic processing streams, we assessed potential sites of visuo-haptic integration for a phenomenon called inverse effectiveness, that is, increased multisensory gain with decreasing stimulus salience. Unexpectedly, the opposite pattern, which we called enhanced effectiveness, was found. Nevertheless, finding enhanced effectiveness implies neuronal convergence of visual and haptic inputs in regions considered part of separable dorsal action and ventral perception visuo-haptic processing pathways.