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Open Access Publications from the University of California

Investigation of the Neural Basis of Order and Item Memory: Roles of Hippocampus, Prelimbic Cortex, and Perirhinal Cortex

  • Author(s): Feinberg, Leila Mangan
  • Advisor(s): Fortin, Norbert J
  • et al.

The field of research devoted to studying the neural basis of episodic memory is relatively new, and only very recently has been operationalized for study in non-human species. In this dissertation, episodic memory is operationally defined as memory for sequences of events in the spatial and/or temporal context in which they occurred. In a series of experiments, I examined memory for items and the order in which odor events occur over varying temporal domains. I used these approaches to help elucidate the roles of HC, PL, and PER in episodic memory. First, I used a novel odor recognition paradigm to probe item memory for social and non-social odors using varying retention intervals from 5 min to 48 hr. In this study, I found that HC lesions do not affect odor recognition memory for both odor types at all retention intervals. However, I found that PER lesions induced long-term memory deficits for social odors. These data implicate a role for PER in mnemonic processes for highly overlapping, but not distinctive, stimuli. Second, I designed a new behavioral paradigm to assess memory for sequences of odors. This ethologically-relevant task is a non-rewarded, incidentally encoded, trial-unique paradigm that can assess both order and item memory following the presentation of a sequence of odors. Using this method, I found that lesions to HC, PL, and PER, but not V2, induced specific deficits for order, but not item memory. Altogether, these data contribute to a larger understanding of the roles these structures play in temporal context, suggesting a critical role for HC, PL, and PER in sequence memory and ultimately episodic memory.

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