EFFECTS OF TEMPORARY INACTIVATION OF DORSAL HIPPOCAMPUS ON EXPLICITLY NONSPATIAL, UNIMODAL, CONTEXTUAL FEAR LEARNING By

ii ABSTRACT OF THE THESIS Effects of temporary inactivation of dorsal hippocampus on explicitly nonspatial, Several studies have reported that dorsal hippocampal damage attenuates the of recently acquired contextual fear conditioning. "Context" is often operationalized as the conditioning chamber in which CS-US pairings occurred. However, the hippocampus is known to participate in spatial learning, presenting interpretative difficulties regarding the role of dorsal hippocampus in learning and memory. The current study examined the effects of temporary inactivation of DH on freezing, rearing, ambulating, grooming, and whisking behavior in an explicitly nonspatial contextual fear conditioning paradigm, where olfactory stimuli served as temporally and spatially diffuse contexts. Results indicate that temporary inactivation of DH produced both anterograde and retrograde deficits in contextually conditioned freezing, while sparing the acquisition and expression of freezing to a discrete auditory CS. Further, animals with DH inactivation froze modestly and similarly to the unsafe and safe contextual stimuli, while intact animals froze robustly to the unsafe, but not the safe, contextual stimulus. These data indicate that there is a decidedly nonspatial component to the role of DH in contextual conditioning, and suggest that olfactory contextual conditioning is a fruitful means of further exploring this function.