Many theories of human long term memory assume that explicit memory for prior events relies on the medial temporal lobes (MTLs) and its subregions. In contrast, implicit memory, measured in tasks where experience with a prior item facilitates the subsequent identification or production of that item, is thought to rely on cortical regions outside of the MTL. However, it has recently been hypothesized that the perirhinal cortex, a region within the MTL, holds high level conceptual and perceptual representations irrespective of awareness or intention. In one recent study, we provided evidence that the perirhinal cortex is sensitive to certain forms of implicit memory. We demonstrated that amnesic stroke and temporal lobectomy patients exhibited impaired conceptual implicit memory, and in a separate experiment showed that perirhinal activations at encoding predicted subsequent conceptual implicit memory. The experiments proposed here seek to extend these previous findings. In the first experiment, a novel paradigm that measures both conceptual implicit memory and explicit familiarity-based recognition will be used to assess the role of the perirhinal cortex in these two tasks. Participants will be scanned during recognition and free association memory tasks that measure familiarity and conceptual implicit memory, respectively. In the second experiment we will test the hypothesis that sufficiently complex perceptual discriminations will recruit the perirhinal cortex during both the encoding and retrieval phases of a perceptual implicit memory task. Both experiments will utilize high-resolution fMRI and region of interest alignment derived from manual MRI brain tracing. Moreover, for the first experiment we will develop a unique fMRI sequence designed to counteract movement artifacts intrinsic to overt speech. Understanding the conditions under which the perirhinal cortex processes and represents conceptual and perceptual information is critical to understanding the role of the MTLs in long term memory and beyond. The insights from these studies can be applied to diagnose, understand, and treat memory deficits and mental disorders that adversely affect memory.

Public Health Relevance

The proposed project investigates the role of the perirhinal cortex in conceptual and perceptual implicit memory. The results of this project will have a direct impact on current models of long term memory and will be useful for developing interventions targeting long term memory deficits in patient populations (e.g., Schizophrenia, Alzheimer's disease, stroke).

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31MH096346-02
Application #
8391795
Study Section
Special Emphasis Panel (ZRG1-F02B-M (20))
Program Officer
Rosemond, Erica K
Project Start
2012-01-01
Project End
2013-09-30
Budget Start
2013-01-01
Budget End
2013-09-30
Support Year
2
Fiscal Year
2013
Total Cost
$28,837
Indirect Cost
Name
University of California Davis
Department
Psychology
Type
Schools of Arts and Sciences
DUNS #
047120084
City
Davis
State
CA
Country
United States
Zip Code
95618
Wang, Wei-Chun; Montchal, Maria E; Yonelinas, Andrew P et al. (2014) Hippocampal and parahippocampal cortex volume predicts recollection in schizophrenia. Schizophr Res 157:319-20
Wang, Wei-Chun; Ranganath, Charan; Yonelinas, Andrew P (2014) Activity reductions in perirhinal cortex predict conceptual priming and familiarity-based recognition. Neuropsychologia 52:19-26
Wang, Wei-Chun; Yonelinas, Andrew P; Ranganath, Charan (2013) Dissociable neural correlates of item and context retrieval in the medial temporal lobes. Behav Brain Res 254:102-7
Koen, Joshua D; Aly, Mariam; Wang, Wei-Chun et al. (2013) Examining the causes of memory strength variability: recollection, attention failure, or encoding variability? J Exp Psychol Learn Mem Cogn 39:1726-41