Large-Scale Object Topography in Occipito-Temporal Cortex

Konkle & Caramazza

The neural responses for animate and inanimate objects show a large-scale organization across occipito-temporal cortex in a medial-to-lateral arrangement. Recently, a similar large-scale organization was also found for objects with big and small real-world sizes. How are these two orthogonal object dimensions represented together across the cortex?

12 participants undergoing functional neuroimaging were shown images of big animals, big objects, small animals, and small objects presented in a blocked design. To directly compare the large-scale animacy and size organizations, we used a new “coarse MVPA” approach in which 20 spherical regions-of-interest were arrayed across parahippocampal, fusiform, lateral occipital, and medial occipital cortex.

The results show that (i) the medial-to-lateral responses of objects vs animals are part of an even larger-scale alternating organization along this continuous band of cortex, (ii) big vs small differences apply more strongly within the inanimate domain, and (iii) the ventral surface of cortex has at least three (not two) peaks of selectivity, for big objects, all animals, and small objects, ordered from medial to lateral.

This analysis technique provides a novel method for exploring and quantifying large-scale organization. Given the recent insights regarding the topographic organization of motor and pre-motor cortex, we suggest that a full characterization of large-scale object topography will prove to be valuable for understanding the overaching neural code for object representation.

Konkle, T., & Caramazza, A. (2012). Large-Scale Object Topography In Occipito-Temporal Cortex. Poster presented at the Concepts, Actions, and Objects annual meeting, May 24-27, Rovereto, Italy.