The hippocampus and prefrontal cortex (PFC) are both critical for learning and memory-guided behavior, with the hippocampus necessary for rapid episodic learning and memory, and PFC playing an integral role in long- term memory, retrieval, working memory and decision making. Coordination of neural activity between these regions is necessary for these cognitive processes, however, it is still unclear what features of neural activity mediate interactions for communication of memory-related information, and the explicit roles of these activity patterns in learning, retrieval and decision making. This proposal will investigate the roles of prominent physiological network patterns by combining behavioral methods in rats, high-density recording, and a novel closed-loop optogenetic perturbation technique that can detect network patterns in real-time and disrupt inter- regional coordination. First, we will simultaneously and continuously monitor activity of neural populations in the hippocampus and PFC over the course of learning of a novel spatial memory task. Previous work suggests that two prominent patterns can mediate hippocampal-prefrontal interactions; coherence during theta oscillations associated with place cell activity, and coordinated reactivation of behavioral experiences during awake sharp-wave ripples (SWRs). We will test if awake SWR reactivation during initial exploration supports memory formation by establishing associations between hippocampal-prefrontal neurons, and if theta coherence mediates retrieval of these associations during later exploitation to support ongoing decision making. Next we will use real-time detection and closed-loop optogenetic perturbation to disrupt coordination during specific physiological patterns. We will test if disrupting coordinated reactivation using optogenetic perturbation of prefrontal reactivation during awake hippocampal SWRs impairs memory formation and behavioral learning. Further, we will test if disrupting phase-locked prefrontal spiking during theta coherence impairs retrieval and memory-guided decision making. Finally, we will investigate if reactivation during sleep and awake SWRs play different roles in learning. We will examine differences in prefrontal reactivation for awake vs. sleep SWRs, and test the causal role of sleep SWRs in consolidation by disrupting prefrontal reactivation during sleep. Together, these aims will provide an integrated, causal understanding of the role of prominent network activity patterns in hippocampal-prefrontal interactions necessary for learning and memory- guided behavior. This proposal will thus provide crucial insight into memory disorders associated with these regions such as dementia, PTSD, Alzhiemer's disease, and also neuropsychiatric disorders such as autism and schizophrenia.

Public Health Relevance

Relevance: Neural interactions between the hippocampus and prefrontal cortex are critical for learning and memory-guided behavior, and dysfunction in these processes is implicated in numerous memory disorders such as dementia, PTSD and Alzhiemer's disease, as well as in neuropsychiatric disorders such as autism and schizophrenia. This proposal aims to use novel methods to monitor neural activity and perturb inter-regional coordination during behavior to provide an integrated, causal understanding of the role of prominent physiological network activity patterns that support our ability to learn, recall, plan and choose. This project will thus provide crucial insight into neural mechanisms that underlie fundamental cognitive abilities, and contribute to an understanding of the pathophysiology of cognitive dysfunction in numerous disorders.

National Institute of Health (NIH)
National Institute of Mental Health (NIMH)
Research Project (R01)
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Neurobiology of Learning and Memory Study Section (LAM)
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Ferrante, Michele
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Brandeis University
Schools of Arts and Sciences
United States
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Maharjan, Dennis M; Dai, Yu Y; Glantz, Ethan H et al. (2018) Disruption of dorsal hippocampal - prefrontal interactions using chemogenetic inactivation impairs spatial learning. Neurobiol Learn Mem 155:351-360
Tang, Wenbo; Jadhav, Shantanu P (2018) Sharp-wave ripples as a signature of hippocampal-prefrontal reactivation for memory during sleep and waking states. Neurobiol Learn Mem :
Zielinski, Mark C; Tang, Wenbo; Jadhav, Shantanu P (2017) The role of replay and theta sequences in mediating hippocampal-prefrontal interactions for memory and cognition. Hippocampus :
Tang, Wenbo; Shin, Justin D; Frank, Loren M et al. (2017) Hippocampal-Prefrontal Reactivation during Learning Is Stronger in Awake Compared with Sleep States. J Neurosci 37:11789-11805