title: Increased Visual Stimulation Systematically Decreases Activity in Lateral Intermediate Cortex.
abstract: Previous studies have attributed multiple diverse roles to the posterior superior temporal cortex (STC), both visually driven and cognitive, including part of the default mode network (DMN). Here, we demonstrate a unifying property across this multimodal region. Specifically, the lateral intermediate (LIM) portion of STC showed an unexpected feature: a progressively decreasing fMRI response to increases in visual stimulus size (or number). Such responses are reversed in sign, relative to well-known responses in classic occipital temporal visual cortex. In LIM, this "reversed" size function was present across multiple object categories and retinotopic eccentricities. Moreover, we found a significant interaction between the LIM size function and the distribution of subjects' attention. These findings suggest that LIM serves as a part of the DMN. Further analysis of functional connectivity, plus a meta-analysis of previous fMRI results, suggests that LIM is a heterogeneous area including different subdivisions. Surprisingly, analogous fMRI tests in macaque monkeys did not reveal a clear homolog of LIM. This interspecies discrepancy supports the idea that self-referential thinking and theory of mind are more prominent in humans, compared with monkeys.
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA Department of Radiology, Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Shahin
authors.initials: S
authors.lastname: Nasr
authors.affiliation: Laboratory of Neuro and Psychophysiology, KU Leuven Medical School, 3000 Leuven, Belgium.
authors.forename: Heiko
authors.initials: H
authors.lastname: Stemmann
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA Department of Radiology, Harvard Medical School, Charlestown, MA 02129, USA Laboratory of Neuro and Psychophysiology, KU Leuven Medical School, 3000 Leuven, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Vanduffel
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA Department of Radiology, Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Roger B H
authors.initials: RB
authors.lastname: Tootell
mesh_terms: D000328:Adult; D000818:Animals; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D013045:Species Specificity; D013702:Temporal Lobe / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: DMN; fMRI; homology; size response function; temporal cortex