Is there an amodal “semantic” area in the left posterior temporal lobe?
Year: 2018
Type: preprint
Abstract: Portions of the left posterior temporal lobe are widely believed to comprise a “convergence zone” for integrating information from various sensory modalities and therefore for accessing high-level semantic information. It is an open question whether the network in this posterior temporal lobe region is coding/processing abstract, amodal information or whether neural codes retain sensory modality-tied representations. A recent functional MRI study (Xu et al. 2009, PNAS, 106, 20664-20669) seems to support the amodal account: using standard univariate general linear model (GLM) analyses, the left posterior temporal lobe region was equally activated during the processing of visually presented meaningful symbolic hand gestures and auditorily presented spoken glosses of those same gestures, relative to meaningless control gestures/speech, thus showing no preferential response according to modality of presentation of the same information. However, standard univariate analyses may not be sensitive to the micro-organization of the region of interest. In the present study we reanalyzed the same dataset using a region of interest (ROI)-based multivariate pattern classification method to assess modality sensitivity in the posterior temporal lobe ROI. We found that the pattern of activity in the ROI significantly discriminated between the visual and auditory conditions, including the meaningless control conditions. Moreover, mapping of the prediction coefficients onto the voxels within the ROI demonstrated a gradient of preference among modalities, where the gesture preferring voxels were distributed more medial and posterior, and the speech preferring voxels were distributed more lateral and anterior. These findings suggest that the left posterior temporal region is not coding information in an amodal format, at least broadly, but contains sub-regions that are sensitive to each individual modality.
Authors: Feng Rong, Jiang Xu, Karen Emmorey, Allen R. Braun, Gregory Hickok
Language: English
Subfield: Experimental and Cognitive Psychology
Field: Psychology
Domain: Social Sciences
Open Access status: green
OpenAlex ID: W4229492130