High-level representations in human occipito-temporal cortex are indexed by distal connectivity

Abstract

Human object recognition is dependent on occipito-temporal cortex, but a complete understanding of the complex functional architecture of this area must account for how it is connected to the wider brain. Converging functional magnetic resonance imaging evidence shows that univariate responses to different categories of information (e.g. faces, bodies, & non-human objects) are strongly related to, and potentially shaped by, functional and structural connectivity to the wider brain. However, to date, there have been no systematic attempts to determine how distal connectivity and complex local high-level responses in occipito-temporal cortex (i.e. multivoxel response patterns) are related. Here, we show that distal functional connectivity is related to, and can reliably index, high-level representations for several visual categories (i.e. tools, faces, & places) within occipito-temporal cortex; that is, voxel sets that are strongly connected to distal brain areas show higher pattern discriminability than less well-connected sets do. We further show that, in several cases, pattern discriminability is higher in sets of well-connected voxels than sets defined by 'local' activation (e.g. strong amplitude responses to faces in fusiform face area). Together, these findings demonstrate the important relationship between the complex functional organization of occipito-temporal cortex and wider brain connectivity.

Overlapping but distinct: Distal connectivity dissociates hand and tool processing networks

“…In this view, local representations do depend on local computations, feedforward and feedback connections, as described before, but also, and importantly, on connections from distal regions that share categorical preference (and that pertain to the same level of representation). That is, local representations are constrained by connectivity with other brain areas at the same level in the visual processing hierarchy (Almeida et al, 2013;Chen et al, 2017;Garcea et al, 2019;Hutchison et al, 2014;Hutchison & Gallivan, 2018;Lee et al, 2019;, 2011Walbrin & Almeida, 2021). In support of this view, representations in a tool-preferring region (the left medial fusiform gyrus; mFUG) within the ventral temporal cortex (VTC) are causally dependent on computations in remote but functionally connected tool-preferring regions within parietal cortex (the Inferior Parietal Lobule; IPL; Lee et al, 2019; see also Ruttorf et al, 2019;Garcea et al, 2019).…”