Oxyopia Abstract

February 12, 2004
Thursday, 12 Noon
489 Minor Hall

Ione Fine, MD
Doheny Retina Institute Keck School of Medicine, University of Southern California
Host: Marty Banks

Title

"The role of experience in complex form processing"

Abstract

I will describe two sets of experiments examining the role of visual experience in complex form processing:

To examine how visual deprivation affects complex form processing we characterized visual processing in a patient (MM) whose sight was restored after suffering visual deprivation between the ages of 3 and 43. Deprivation resulted in severe losses in resolution, 3D shape perception, and object and face recognition. In contrast, MM’s performance on color and motion tasks was relatively normal. FMRI activity in MM’s motion processing areas was as great and covered as large an area as control observers, while images of faces and objects did not produce activity in areas near fusiform and lingual gyri associated with face and object processing. Long-term interruptions in visual experience seem to have particularly severe consequences for face and object processing, consistent with a continuing role for visual experience beyond early childhood in these areas.

To examine the role of visual experience in face selective tuning in visually normal adults we used a conjunction of analogous fMRI and psychophysical adaptation paradigms to examine whether mechanisms mediating face perception are jointly selective for both ethnicity and gender or selective for only one of these properties (e.g., tuned for ethnicity and unselective for gender). Consistent with a significant proportion of neurons being selective for both ethnicity and gender, we saw a release of adaptation for faces that differed in either ethnicity or gender from the adapting faces. These adaptation effects occurred selectively in the fusiform gyrus in areas overlapping with face selective areas defined using typical fusiform face area localizer scans. We did not find adaptation effects in V1 suggesting that selectivity for high level properties such as ethnicity and gender is driven by visual experience, rather than by low level visual properties.