Neural responses to visual scenes reveals inconsistencies between fMRI adaptation and multivoxel pattern analysis

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Abstract

Human observers can recognize real-world visual scenes with great efficiency. Cortical regions such as the parahippocampal place area (PPA) and retrosplenial complex (RSC) have been implicated in scene recognition, but the specific representations supported by these regions are largely unknown. We used functional magnetic resonance imaging adaptation (fMRIa) and multi-voxel pattern analysis (MVPA) to explore this issue, focusing on whether the PPA and RSC represent scenes in terms of general categories, or as specific scenic exemplars. Subjects were scanned while viewing images drawn from 10 outdoor scene categories in two scan runs and images of 10 familiar landmarks from their home college campus in two scan runs. Analyses of multi-voxel patterns revealed that the PPA and RSC encoded both category and landmark information, with a slight advantage for landmark coding in RSC. fMRIa, on the other hand, revealed a very different picture: both PPA and RSC adapted when landmark information was repeated, but category adaptation was only observed in a small subregion of the left PPA. These inconsistencies between the MVPA and fMRIa data suggests that these two techniques interrogate different aspects of the neuronal code. We propose three hypotheses about the mechanisms that might underlie adaptation and multi-voxel signals.

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