Abstract
Research on the development of crossmodal (intersensory) perception of visual and haptic inputs suggests that communication within sensory systems develops earlier than communication across sensory systems. These behavioral changes reflect the development of neural substrates, but little is known about the neural mechanisms that underlie the developmental progression of haptic perception or visuohaptic interactions. To address this gap in knowledge, BOLD fMRI was measured during intramodal (visual-to-visual, haptic-to-haptic) and crossmodal (visual-to-haptic, haptic-to-visual) delayed match-to-sample recognition tasks with novel objects in children aged 7-8.5 years and in young adults. Tasks were further divided into encoding (sample) and matching (test) phases. During matching, adults and children demonstrated similar results. Whole-brain comparisons of intramodal and crossmodal object matching to rest revealed the network of known visuohaptic multisensory substrates, including the lateral occipital complex (LOC) and intraparietal sulcus (IPS). Comparisons of crossmodal versus intramodal conditions (i.e., (HV>VV) ͪ5; (HV>HH), (VH>VV) ͪ5; (VH>HH)) produced significant clusters in the same regions, and further, indicated specific effects of crossmodal directionality. In particular, haptic-to-visual matching tasks activated ventral regions (LOC) in both groups, while visual-to-haptic matching tasks activated dorsal regions (IPS) in adults only. Moreover, in the regions of interest as defined by contrasts with rest, crossmodal matching showed greater activation than intramodal matching. Specifically, results revealed this pattern in LOC during haptic-to-visual matching and in IPS during visual-to-haptic matching. Overall, children were highly similar to adults with the exception of some developmental differences in IPS. These results converge with existing findings on the multisensory nature of the IPS and LOC in adults, and extend our knowledge of the development of haptic perception and crossmodal integration. Critically, the results highlight the dominance of crossmodal over intramodal processing, as well as the different influences of test modality on the dorsal (IPS) and ventral (LOC) sites for visuohaptic object processing.
Meeting abstract presented at VSS 2013