Functional heterogeneity in the left lateral posterior parietal cortex during visual and haptic crossmodal dot-surface matching.

Jiajia Yang,Jinglong Wu,Yoshimichi Ejima,Hiroaki Shigemasu,Hiroshi Kadota,Yinghua Yu,Kiyoshi Nakahara,Takanori Kochiyama

doi:10.1002/brb3.2033

Abstract

BackgroundVision and touch are thought to contribute information to object perception in an independent but complementary manner. The left lateral posterior parietal cortex (LPPC) has long been associated with multisensory information processing, and it plays an important role in visual and haptic crossmodal information retrieval. However, it remains unclear how LPPC subregions are involved in visuo‐haptic crossmodal retrieval processing.MethodsIn the present study, we used an fMRI experiment with a crossmodal delayed match‐to‐sample paradigm to reveal the functional role of LPPC subregions related to unimodal and crossmodal dot‐surface retrieval.ResultsThe visual‐to‐haptic condition enhanced the activity of the left inferior parietal lobule relative to the haptic unimodal condition, whereas the inverse condition enhanced the activity of the left superior parietal lobule. By contrast, activation of the left intraparietal sulcus did not differ significantly between the crossmodal and unimodal conditions. Seed‐based resting connectivity analysis revealed that these three left LPPC subregions engaged distinct networks, confirming their different functions in crossmodal retrieval processing.ConclusionTaken together, the findings suggest that functional heterogeneity of the left LPPC during visuo‐haptic crossmodal dot‐surface retrieval processing reflects that the left LPPC does not simply contribute to retrieval of past information; rather, each subregion has a specific functional role in resolving different task requirements.

Highlights

Humans can effortlessly recognize objects using different sensory modalities
We initially identified the activation maps for regions involved in the haptic and visual matching phases
The results suggest that the specific region of the left anterior superior parietal lobule (SPL) specific to the haptic-to-Visual condition (hV) > visual-to-Visual condition (vV) condition showed a significant positive activation only in the hV condition, but the bilateral fusiform gyrus (FG) showed a significant positive activation in both the hV and vV conditions

Summary

| INTRODUCTION

Humans can effortlessly recognize objects using different sensory modalities (e.g., see or touch a tennis ball). Activation in the posterior part of the left inferior parietal lobule (IPL) mostly reflects recollection of specific details from the encoding phase (Sestieri et al, 2017), whereas the anterior superior parietal lobule (SPL) plays an important role in the manipulation and rearrangement of information in working memory (Koenigs et al, 2009) This evidence suggests that both functional and anatomical segregations of the LPPC are involved in unimodal memory retrieval. Since dot-surface perception weakly enables humans to determine whether the touched surface and the seen surface are the same, we asked the subjects to find the stimuli with the same or most similar dot-surface from the five stimuli during the matching phase This approach has the advantage of maintaining the constant encoding processing of unimodal and crossmodal conditions. It allowed us to assess the crossmodal memory retrieval modulation in the left LPPC by contrasting the matching phase of crossmodal conditions (hV and vH) to unimodal conditions (vV and hH)

| MATERIALS AND METHODS

| Procedures

Findings

| DISCUSSION

| CONCLUSION