How is object orientation represented in the brain? Behavioral error patterns reveal systematic tendencies to confuse certain orientations with one another. Using fMRI, we asked whether more confusable orientations are represented more similarly in object selective cortex (LOC). We compared two widely-used measures of neural similarity: multi-voxel pattern similarity (MVP-similarity) and Repetition Suppression. In LO, we found that multi-voxel pattern similarity was predicted by the confusability of two orientations. By contrast, Repetition Suppression effects in LO were unrelated to the confusability of orientations. To account for these differences between MVP-similarity and Repetition Suppression, we propose that MVP-similarity reflects the topographical distribution of neural populations, whereas Repetition Suppression depends on repeated activation of particular groups of neurons. This hypothesis leads to a unified interpretation of our results and may explain other dissociations between MVPA and Repetition Suppression observed in the literature.
Bibliographical noteFunding Information:
This work was supported by research funding from the Johns Hopkins University to S.P. We thank David Rothlein for providing the code used for the MVPA searchlight analysis, Jung Uk Kang and Harry Ngai for their assistance with data collection and analysis, and Kristen Johannes for constructive comments on the paper.
All Science Journal Classification (ASJC) codes
- Cognitive Neuroscience