Date of Award
2008
Degree Type
Thesis
Degree Name
Master of Science
Program
Neuroscience
Supervisor
Dr. Stefan Kohler
Second Advisor
Dr. Jody Culham
Third Advisor
Dr. Melvyn Goodale
Abstract
The prevailing view of the functions of the medial temporal lobe (MTL) holds that its structures are dedicated to declarative memory. Recent evidence challenges this position, suggesting that perirhinal cortex (PRc) in the MTL may also play a role in online processing of objects when perceptual discriminations of stimuli possessing highly overlapping visual features are required. Relevant neuropsychological findings in humans have been inconclusive, however, likely because studies have relied on patients with large, variable MTL lesions, resulting in inconsistent findings across studies. Also, perceptual and mnemonic tasks have not always been matched for difficulty. Here, we conducted an event-related fMRI experiment in 18 healthy participants to directly compare the role of PRc in perceptual discriminations and in recognition memory. We used sets of faces designed to have a large degree of feature overlap as stimuli. Prior to scanning, subjects were familiarized with a subset of faces. During scanning, all triais employed displays with three faces. The perceptual task required identification of an ‘oddball’, i.e. the face least similar to the other members in the display. The memory task involved forced-choice recognition of the previously studied face. Task difficulty was manipulated independently in the two conditions. When matched, there were no significant differences in PRc activation for the memory and perception trials. Instead, a conjunction analysis revealed a common region in right PRc whose activity was related to accuracy of both recognition memory and perceptual discriminations. This pattern differed from that of another region traditionally thought to be involved in the perceptual identification of faces, i.e., the fusiform face area (FFA), where activation was related to iii accuracy only in the easy perceptual condition. These findings show that the functional role of PRc is not limited to long-term declarative memory.
Recommended Citation
O’Neil, Edward B., "THE ROLE OF PERIRHINAL CORTEX IN RECOGNITION MEMORY AND PERCEPTUAL DISCRIMINATIONS" (2008). Digitized Theses. 4389.
https://ir.lib.uwo.ca/digitizedtheses/4389