Position Selectivity in Scene- and Object-Responsive Occipitotemporal Regions

Abstract

Complex visual scenes preferentially activate several areas of the human brain, including the parahippocampal place area (PPA), the retrosplenial complex (RSC), and the transverse occipital sulcus (TOS). The sensitivity of neurons in these regions to the retinal position of stimuli is unknown, but could provide insight into their roles in scene perception and navigation. To address this issue, we used functional magnetic resonance imaging (fMRI) to measure neural responses evoked by sequences of scenes and objects confined to either the left or right visual hemifields. We also measured the level of adaptation produced when stimuli were either presented first in one hemifield and then repeated in the opposite hemifield or repeated in the same hemifield. Although overall responses in the PPA, RSC, and TOS tended to be higher for contralateral stimuli than for ipsilateral stimuli, all three regions exhibited position-invariant adaptation, insofar as the magnitude of adaptation did not depend on whether stimuli were repeated in the same or opposite hemifields. In contrast, object-selective regions showed significantly greater adaptation when objects were repeated in the same hemifield. These results suggest that neuronal receptive fields (RFs) in scene-selective regions span the vertical meridian, whereas RFs in object-selective regions do not. The PPA, RSC, and TOS may support scene perception and navigation by maintaining stable representations of large-scale features of the visual environment that are insensitive to the shifts in retinal stimulation that occur frequently during natural vision.

The distribution of category and location information across object-selective regions in human visual cortex

“…Similarly, the EBA preferred lower visual field stimuli to both foveal and upper visual field stimuli, which activated the region equally. These findings, like earlier reports of contralateral biases in object-selective regions (13)(14)(15)(16) do not fit within the fovea/periphery framework, and it is not clear how the computational-demands hypothesis (35) could account for them.…”

“…At the most general level, some of these regions demonstrate contralateral field biases (13)(14)(15)(16), and some of them [e.g., the parahippocampal place area (PPA)] respond more strongly to stimuli presented in the periphery, whereas others [e.g., the fusiform face area (FFA)] respond more strongly to foveal stimuli (17,18). Studies conducted with retinotopic mapping (19,20) have shown object-selective responses in certain retinotopically defined regions, although the degree to which these maps overlap object-selective cortex is not yet known.…”

“…Elevation. Although eccentricity biases (17,18) and contralateral biases (13)(14)(15)(16) have been reported for some higher-level category-selective areas, no studies to date have systematically tested for elevation biases in regions other than LO, which shows a lower visual field bias (13). Therefore, we compared mean response magnitude in each ROI for upper and lower field stimuli at equal eccentricities.…”

A Causal Role for the Extrastriate Body Area in Detecting People in Real-World Scenes

“…Inhibitory connections between the object and scene pathways could then account for the facilitatory effects observed in Mullin and Steeves (2011). The dual-pathway hypothesis is supported by fMRI studies showing that activity patterns in lateral occipitotemporal cortex contain information about within-scene objects, while patterns in scene-selective areas such as parahippocampal place area, TOS, and retrosplenial cortex contain information about global scene layout (Goh et al, 2004;Walther et al, 2011;Kravitz et al, 2011;MacEvoy and Epstein, 2011;Harel et al, 2013).…”

Interpreting fMRI data: maps, modules and dimensions

“…Studies using fMRI adaptation 5,20 have indicated that the FFA discriminates between different individual faces 36 and the LOC discriminates between individual object exemplars 37,38 . Adaptation studies have also shown that these regions are partly insensitive to size, position and spatial scale 39,40 but more sensitive to viewpoint and direction of illumination 37,41,42 . However, fMRI adaptation is an indirect measure of selectivity that might be linked only partially to neuronal selectivity 43 ; moreover, the extent to which the sensitivity of the ventral visual cortex to object exemplars can be explained through sensitivity for low-level stimulus properties such as luminance, contrast, line orientation or texture has not been systematically explored.…”