A putative model of multisensory object representation

Abstract

This review surveys the recent literature on visuo-haptic convergence in the perception of object form, with particular reference to the lateral occipital complex (LOC) and the intraparietal sulcus (IPS) and discusses how visual imagery or multisensory representations might underlie this convergence. Drawing on a recent distinction between object- and spatially-based visual imagery, we propose a putative model in which LOtv, a subregion of LOC, contains a modality-independent representation of geometric shape that can be accessed either bottom-up from direct sensory inputs or top-down from frontoparietal regions. We suggest that such access is modulated by object familiarity: spatial imagery may be more important for unfamiliar objects and involve IPS foci in facilitating somatosensory inputs to the LOC; by contrast, object imagery may be more critical for familiar objects, being reflected in prefrontal drive to the LOC.

Figure 1

Object-related regions in the visual and haptic modalities shown on an inflated right hemisphere (top: lateral view; bottom: ventral view). Visual object selectivity is relative to scrambled visual images; haptic object selectivity is relative to haptic textures. Visuo-haptic object selectivity in the lateral occipital complex (LOC) is found within the lateral occipito-temporal sulcus (delineating LOtv) and several foci in the intraparietal sulcus (IPS). (Modified from Amedi et al., 2001).