Contributions of Hippocampal Subsystems to Different Aspects of Episodic Memory

University Of California-Irvine, Irvine CA

Investigators

Abstract

People routinely organize the flow of experience in complex everyday environments into episodes that minimally contain information about what happened, where different items or events were located, and the order in which they occurred. The hippocampus plays a critical role in the brain’s formation of these episodic memories. Studies by the investigator and others found that rodents acquire simplified versions of ‘what’, ‘where’, and ‘when’ memory; subsequent neurobehavioral investigations identified hippocampal networks associated with each of these. The proposed experiments will determine if the animals also express two other critical features of human episodic memory – using context to retrieve a specific episode and one item to prompt recall of the next -- and then localize the underlying networks. Preliminary results suggest that rodents utilize both of these operations. A description of the network level operations underlying these functions would enable work on episodic memory’s contributions to higher order cognitive operations, including inferential thinking, that are vital to the human experience. It could also point the way to computerized learning systems that obviate known limitations on present versions of artificial intelligence. The proposed work will use modified forms of rodent learning paradigms developed in the applicant’s laboratory. These involve sequences of odors, cues that are of innate interest to the animals. The protocols do not require repetition or overt rewards and thus align with cardinal aspects of human episodic memory. The network-tracing portion of the work will employ chemogenetic techniques for transiently silencing specific pathways within the hippocampus and allied structures. Results will be evaluated with regard to a general hypothesis and associated computer models. In addition to the scientific advances, the project will provide an environment of training, mentoring and research activities for high school, undergraduate and graduate students. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.