Shared and Distinct High-Dimensional Object Spaces in Human and Macaque Inferotemporal Cortex

Abstract

Human and macaque studies of inferotemporal cortex (IT) have shaped our understanding of object vision, yet the extent of their representational alignment and the precise nature of this correspondence have remained unclear. To address these questions, we applied multivariate cross-species alignment to large-scale macaque multi-unit recordings and human fMRI responses to the same 8,640 naturalistic object images. The resulting shared space revealed a surprisingly rich, high-dimensional geometry that extended well beyond coarse correspondences such as animacy and shape and included a wide range of interpretable visual and conceptual dimensions, as well as specific conjunctions of the two. Unexpectedly, the space also uncovered a shared neural signature for orthography-related content, consistent with precursor mechanisms in macaques. Contrasting the within-species spaces revealed systematic differences in the expression of living and artificial categories, conspecific content, and visual versus conceptual structure. Together, these findings uncover a high-dimensional shared object space along with species-specific divergences, clarifying the scope and limits of cross-species comparability.