Learning, Memory and Decision Making in the Mammalian Brain
We use rodent models to investigate the physiological mechanisms that underlie information processing and coordinated interactions between multiple brain regions that are necessary for memory and cognition, with a particular focus on hippocampal – prefrontal cortical interactions. The hippocampus is known to be critical for episodic memories, and the prefrontal cortex is involved in executive control, working memory and decision making. Communication between the prefrontal executive system and the hippocampal memory system is key for learning, remembering, planning, prediction and memory-guided decision making. However, the nature of communication between these two regions, the underling neural mechanisms and causal contributions of this pivotal interaction remain largely unknown.
We address these questions using a combination of techniques, including behavior, large scale multielectrode recordings in awake behaving animals, real time detection and perturbation of neural activity patterns, targeted optogenetic interventions, and computational analysis. We have shown that hippocampal replay during awake sharp-wave ripples (SWRs) is critical for spatial memory, and SWRs are associated with coordinated reactivation of hippocampal-prefrontal neurons during memory-guided decision making. This approach thus allows us to characterize the neurophysiological basis of hippocampal-cortical interactions, and also to provide causal evidence linking specific forms of neural activity to behavior and cognition.
We posit that neural dynamics at the ensemble level and network coordination still remains a “missing link” that can bridge between molecular/ cellular processes and behavioral phenomena in our understanding of mechanisms that underlie cognitive function and dysfunction. Our findings provide a crucial foundation to investigate if impairments in physiological network patterns lead to deficits in memory and cognition in disorders that involve hippocampus and prefrontal cortex. Our research will thus provide crucial insight into several neurological and neuropsychiatric disorders involving these two key regions, such as dementia, Alzheimer’s disease, depression, autism and schizophrenia.
Major Findings and Discoveries
Awake Sharp-Wave Ripple Replay Of Mental Experiences Critical For Learning
Jadhav SP, Kemere C, German PW, Frank LM (2012), “Awake hippocampal sharp-wave ripples support spatial memory”, Science, 336(6087): 1454-1458. The hippocampus is essential for storing and
Coordinated Hippocampal-Prefrontal Replay Supports Spatial Learning And Memory-Guided Decision Making
Shin JD*, Tang W*, Jadhav SP (2019), “Dynamics of awake hippocampal-prefrontal replay for spatial learning and memory-guided decision making”, Neuron, 104(6), 1110-1125. This study builds on
Multiple Time-Scales Of Decision Making In Hippocampus And Prefrontal Cortex
Tang W*, Shin JD*, Jadhav SP (2021), “Multiple time-scales of decision making in the hippocampus and prefrontal cortex”, eLife, 10, e66227. In this study, we establish
Awake And Sleep Replay
Tang W, Shin JD, Frank LM, Jadhav SP (2017), “Hippocampal-prefrontal reactivation during learning is stronger in awake as compared to sleep states”, Journal of Neuroscience, 37(49):
Coherent Spatial Coding Mediated By Theta Oscillations
Zielinski MC*, Shin JD*, Jadhav SP (2019), “Coherent coding of spatial position mediated by theta oscillations in the hippocampus and prefrontal cortex”, Journal of Neuroscience, 39(23),
Hippocampal-Prefrontal Network For Memory-Guided Decision Making
Jadhav SP*, Rothschild G*, Roumis DR, Frank LM (2016), “Coordinated excitation and inhibition of prefrontal ensembles during awake hippocampal sharp-wave ripple events”, Neuron, 90(1):113-27. doi: 10.1016/j.neuron.2016.02.010
Taste Coding In The Hippocampus
Herzog LE, Pascual LM, Scott SJ, Mathieson ER, Katz DB, Jadhav SP (2019), “Interaction of taste and place coding in the hippocampus”, Journal of Neuroscience, 39(16),
Refinement And Reactivation Of A Taste-Responsive Hippocampal Network
Herzog LE, Katz DB, Jadhav SP (2020), “Refinement and reactivation of a taste-responsive hippocampal network”, Current Biology, 30, 1306-1311. This study followed up on the discovery