The organization of action representations in lateral occipitotemporal cortex

Abstract

Neural representations for various types of information related to action are located in the left lateral occipitotemporal cortex (LOTC). Existing literature on basic and biological motion, bodies, body parts, tools, action perception and performance, but also action verbs demonstrated recruitment of the LOTC. This thesis investigates the architecture of this cortical area in more detail. To this aim, we carried out a direct comparison of different tasks within the same participants to examine how the different domains are represented in the LOTC in terms of their spatial and representational organization, and to relate this to the connectivity-based organization of the LOTC. We collected functional magnetic resonance imaging (fMRI) data from N = 21 participants for eight different localizer experiments (motion, biological motion, bodies & tools, body parts, action observation, action performance, verbs and high level retinotopic mapping) as well as resting-state functional magnetic resonance imaging data. First, using univariate analyses, we found that responses to the different domains were indeed located in the LOTC. Responses were arranged topographically, and subregions of LOTC were sparsley selective for only one domain. Subsequent multivariate analyses indicated a two-part organization of the LOTC where posterior-central regions show sensitivity to most contrasts and highly similar representations for body-related domains as well as spatial location information. By contrast, anterior regions were sensitive to verbs, action observation and performance, but showed no shared representations or spatial location information. Confirming the posterior-central and anterior subregion division, resting state functional connectivity analysis also indicated similar connectivity for posterior-central regions and different connections for anterior regions. The overlapping and shared representations in the posterior-central LOTC might indicate a hybrid map of superimposed feature representations enabling action understanding