Year: 2012
Type: dissertation
Abstract: The importance of the hippocampus in the formation and retrieval of episodic \nmemory has been famously demonstrated in the case of patient H.M. Subsequent studies \nconducted in animal models have provided considerable insight into the specific \nfunctions of the individual components of the hippocampus. In the rodent, the pyramidal \nneurons of the CA1 and CA3 regions of the hippocampus have typically been associated \nwith the encoding of visuo-spatial cues and their utilization in navigation. These ‘place \ncells’ fire when the animal is in a specific part of its environment (its place field). \nHowever, these cells also encode non-spatial information from other sensory inputs, such \nas olfaction and audition. This study was conducted to find out how contextual odor cues \nare represented in the firing of CA1 place cells and whether these cues could drive stable \nspatial representations. \nOne group of mice was first extensively familiarized to a cylinder containing both \nvisual cues and preserved, self-generated odor cues. Then, after assessing place field \nstability across a six hour delay, the visual and odor cues were rotated in opposite \ndirections by ninety degrees (counter-rotated). Another group of mice was familiarized \nonly to the visual cues that were subsequently rotated. The next day stability and rotation were re-assessed in a novel cylinder. However, the odor cues of the two groups were \nswitched: the preserved odor cues of the first group were removed, and the odor cues of \nthe second group were now preserved across the three sessions. In a separate experiment, \na third group of animals was familiarized only to the odor cues. Firstly, we found that \ncontextual odor cues attenuated rotation with the visual cues, but only following \nextensive familiarization. Secondly, the removal of familiar odor cues impaired long-term \nstability of place fields. Third and finally, the self-generated odor cues alone were not \nsufficient for the generation of stable place fields in a free, open-field exploration \nparadigm. \nWe therefore conclude that although they are not as dominant as discrete visual \ncues, highly familiarized odor cues exert a significant effect on the representation of \nspace of the mouse CA1 place cell, illustrating the role of contextually relevant \ninformation in navigating an ever-changing world.
Author: Devdeep Aikath
Language: English
Topic: Memory and Neural Mechanisms
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Funder: University of Oregon
OpenAlex ID: W1552761081