Dissertations, Theses, and Capstone Projects

Date of Degree

5-2019

Document Type

Dissertation

Degree Name

Ph.D.

Program

Biology

Advisor

Carolyn L. Pytte

Committee Members

Jeff Beeler

Dan McCloskey

Andre Fenton

Juan-Marcos Alarcon

Subject Categories

Behavioral Neurobiology | Cognitive Neuroscience | Molecular and Cellular Neuroscience | Systems Neuroscience

Keywords

Hippocampus, Memory, Lateralization, Split-Brain, Gene Expression, Neurogenesis

Abstract

The hippocampus is essential for memory and spatial navigation. Many theories have been proposed to explain how the hippocampus contributes to cognition; however, none has fully explained relevant neurophysiological and behavioral data. Hemispheric lateralization of hippocampal function has been reported in humans and in rodents, and lateralization of hippocampal neural circuitry has been reported in rodents. Most theories of hippocampal function fail to consider the hippocampus as a bilateral structure with hemispheric differences. Further, proposed theories of hippocampal lateralization have their own limitations in explaining empirical data concerning left/right function. Little is known about communication between the hippocampi across hemispheres. In addition, the information that we do have about hippocampal lateralization has been acquired in examination of CA3 or CA1, while less is known about the dentate gyrus. Here, my goal is to further our understanding of the hippocampus as a bilateral structure via novel theoretical and empirical contributions. In this dissertation, I will argue for a new model of bilateral hippocampal function, demonstrate a function of interhemispheric communication across hemispheres, and show that lateralization extends to the dentate gyrus. I will: formulate a model of left/right hippocampal function in Chapter 1; characterize lateralization in hippocampus-dependent learning and memory in Chapter 2; examine activity-dependent gene expression in the dentate gyrus across hemispheres in Chapter 3; and quantify adult neurogenesis in the left and right dentate gyrus in relation to experience in Chapter 4. The data collected in Chapters 2-4 are not tests of the model presented in Chapter 1. Rather, they are examinations of interhemispheric communication and lateralization that may be used in the future to produce more robust models of the bilateral hippocampus. Collectively, these contributions suggest that the mouse hippocampus is indeed lateralized and that the sharing of information across hemispheres enables some behaviors that are hippocampus-dependent.

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