Involvement of the right inferior parietal lobule in shape retrieval is modulated by prior tactile experience with objects

Abstract

Previous research has suggested a role of the posterior parietal cortex in shape retrieval from semantic memory (Oliver & Thompson-Schill, 2003). This study was designed to clarify the role of this region in shape retrieval. During fMRI scanning, subjects listened to the names of common objects and decided whether each one was mostly composed of curved edges or straight edges. The data from this shape retrieval task were modeled with a covariate for the affordance rating of each object, a familiarity covariate representing the degree to which these subjects were exposed to this object through any modality, and a covariate representing an estimate of the proportion of the time that was spent touching the object. Shape retrieval associated activity in the right inferior parietal lobule (IPL) was significantly modulated by the history of tactile interaction with objects such that objects with a richer tactile history showed a stronger shape retrieval effect in the right IPL. This effect was observed despite the presence of general exposure and object affordance in the model, indicating that the extent of tactile experience explains unique variance in the magnitude of the fMRI response in the IPL during shape retrieval. This effect supports domain-specific distributed models of memory in that prior experience with the object shapes its ultimate representation.