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Pronier É, Morici JF, Girardeau G. The role of the hippocampus in the consolidation of emotional memories during sleep. Trends Neurosci 2023; 46:912-925. [PMID: 37714808 DOI: 10.1016/j.tins.2023.08.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/23/2023] [Accepted: 08/09/2023] [Indexed: 09/17/2023]
Abstract
Episodic memory relies on the hippocampus, a heterogeneous brain region with distinct functions. Spatial representations in the dorsal hippocampus (dHPC) are crucial for contextual memory, while the ventral hippocampus (vHPC) is more involved in emotional processing. Here, we review the literature in rodents highlighting the anatomical and functional properties of the hippocampus along its dorsoventral axis that underlie its role in contextual and emotional memory encoding, consolidation, and retrieval. We propose that the coordination between the dorsal and vHPC through theta oscillations during rapid eye movement (REM) sleep, and through sharp-wave ripples during non-REM (NREM) sleep, might facilitate the transfer of contextual information for integration with valence-related processing in other structures of the network. Further investigation into the physiology of the vHPC and its connections with other brain areas is needed to deepen the current understanding of emotional memory consolidation during sleep.
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Affiliation(s)
- Éléonore Pronier
- Institut du Fer à Moulin, Inserm U1270, Sorbonne Université, Paris, France
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2
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Whitmore NW, Paller KA. Sleep disruption by memory cues selectively weakens reactivated memories. Learn Mem 2023; 30:63-69. [PMID: 36921983 PMCID: PMC10027237 DOI: 10.1101/lm.053615.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 02/14/2023] [Indexed: 03/17/2023]
Abstract
A widely accepted view in memory research is that recently stored information can be reactivated during sleep, leading to memory strengthening. Two recent studies have shown that this effect can be reversed in participants with highly disrupted sleep. To test whether weakening of reactivated memories can result directly from sleep disruption, in this experiment we varied the intensity of memory reactivation cues such that some produced sleep arousals. Prior to sleep, participants (local community members) learned the locations of 75 objects, each accompanied by a sound naturally associated with that object. Location recall was tested before and after sleep, and a subset of the sounds was presented during sleep to provoke reactivation of the corresponding locations. Reactivation with sleep arousal weakened memories, unlike the improvement typically found after reactivation without sleep arousal. We conclude that reactivated memories can be selectively weakened during sleep, and that memory reactivation may strengthen or weaken memories depending on additional factors such as concurrent sleep disruption.
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Affiliation(s)
- Nathan W Whitmore
- Department of Psychology, Cognitive Neuroscience Program, Northwestern University, Evanston, Illinois 02139, USA
- Fluid Interfaces Group, Massachusetts Institute of Technology, Cambridge, Massachusetts 60208, USA
| | - Ken A Paller
- Department of Psychology, Cognitive Neuroscience Program, Northwestern University, Evanston, Illinois 02139, USA
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DiCola NM, Lacy AL, Bishr OJ, Kimsey KM, Whitney JL, Lovett SD, Burke SN, Maurer AP. Advanced age has dissociable effects on hippocampal CA1 ripples and CA3 high frequency events in male rats. Neurobiol Aging 2022; 117:44-58. [PMID: 35665647 PMCID: PMC9392897 DOI: 10.1016/j.neurobiolaging.2022.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 02/01/2023]
Abstract
Sharp wave/ripples/high frequency events (HFEs) are transient bursts of depolarization in hippocampal subregions CA3 and CA1 that occur during rest and pauses in behavior. Previous studies have reported that CA1 ripples in aged rats have lower frequency than those detected in young animals. While CA1 ripples are thought to be driven by CA3, HFEs in CA3 have not been examined in aged animals. The current study obtained simultaneous recordings from CA1 and CA3 in young and aged rats to examine sharp wave/ripples/HFEs in relation to age. While CA1 ripple frequency was reduced with age, there were no age differences in the frequency of CA3 HFEs, although power and length were lower in old animals. While there was a proportion of CA1 ripples that co-occurred with a CA3 HFE, none of the age-related differences in CA1 ripples could be explained by alterations in CA3 HFE characteristics. These findings suggest that age differences in CA1 are not due to altered CA3 activity, but instead reflect distinct mechanisms of ripple generation with age.
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Affiliation(s)
- Nicholas M. DiCola
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Alexa L. Lacy
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Omar J. Bishr
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Kathryn M. Kimsey
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Jenna L. Whitney
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Sarah D. Lovett
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Sara N. Burke
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA,Corresponding author at: University of Florida, Neuroscience, McKnight Brain Institute, P.O. Box 100244, 1149 Newell Dr, RM L1-100G, Gainesville, FL 32610, USA. (S.N. Burke)
| | - Andrew P. Maurer
- Evelyn F. McKnight McKnight Brain Institute, Department of Neuroscience, University of Florida, Gainesville, FL, USA,Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA,Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA,Corresponding author at: McKnight Brain Institute, 1149 Newell Dr, RM L1-100E, University of Florida, Gainesville, FL 32610, USA. (A.P. Maurer)
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Cocina F, Vitalis A, Caflisch A. Unsupervised Methods for Detection of Neural States: Case Study of Hippocampal-Amygdala Interactions. eNeuro 2021; 8:ENEURO.0484-20.2021. [PMID: 34544761 PMCID: PMC8577062 DOI: 10.1523/eneuro.0484-20.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 11/24/2022] Open
Abstract
The hippocampus and amygdala are functionally coupled brain regions that play a crucial role in processes involving memory and learning. Because interareal communication has been reported both during specific sleep stages and in awake, behaving animals, these brain regions can serve as an archetype to establish that measuring functional interactions is important for comprehending neural systems. To this end, we analyze here a public dataset of local field potentials (LFPs) recorded in rats simultaneously from the hippocampus and amygdala during different behaviors. Employing a specific, time-lagged embedding technique, named topological causality (TC), we infer directed interactions between the LFP band powers of the two regions across six frequency bands in a time-resolved manner. The combined power and interaction signals are processed with our own unsupervised tools developed originally for the analysis of molecular dynamics simulations to effectively visualize and identify putative, neural states that are visited by the animals repeatedly. Our proposed methodology minimizes impositions onto the data, such as isolating specific epochs, or averaging across externally annotated behavioral stages, and succeeds in separating internal states by external labels such as sleep or stimulus events. We show that this works better for two of the three rats we analyzed, and highlight the need to acknowledge individuality in analyses of this type. Importantly, we demonstrate that the quantification of functional interactions is a significant factor in discriminating these external labels, and we suggest our methodology as a general tool for large, multisite recordings.
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Affiliation(s)
- Francesco Cocina
- Biochemistry department, University of Zurich, Zurich, Switzerland CH-8057
| | - Andreas Vitalis
- Biochemistry department, University of Zurich, Zurich, Switzerland CH-8057
| | - Amedeo Caflisch
- Biochemistry department, University of Zurich, Zurich, Switzerland CH-8057
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Redish AD. Beyond replay: Introduction to the special issue on hippocampal replay. Hippocampus 2021; 30:3-5. [PMID: 31875338 DOI: 10.1002/hipo.23184] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A David Redish
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
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Processing of Hippocampal Network Activity in the Receiver Network of the Medial Entorhinal Cortex Layer V. J Neurosci 2020; 40:8413-8425. [PMID: 32978288 DOI: 10.1523/jneurosci.0586-20.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/10/2020] [Accepted: 09/20/2020] [Indexed: 11/21/2022] Open
Abstract
The interplay between hippocampus and medial entorhinal cortex (mEC) is of key importance for forming spatial representations. Within the hippocampal-entorhinal loop, the hippocampus receives context-specific signals from layers II/III of the mEC and feeds memory-associated activity back into layer V (LV). The processing of this output signal within the mEC, however, is largely unknown. We characterized the activation of the receiving mEC network by evoked and naturally occurring output patterns in mouse hippocampal-entorhinal cortex slices. Both types of glutamatergic neurons (mEC LVa and LVb) as well as fast-spiking inhibitory interneurons receive direct excitatory input from the intermediate/ventral hippocampus. Connections between the two types of excitatory neurons are sparse, and local processing of hippocampal output signals within mEC LV is asymmetric, favoring excitation of far projecting LVa neurons over locally projecting LVb neurons. These findings suggest a new role for mEC LV as a bifurcation gate for feedforward (telencephalic) and feedback (entorhinal-hippocampal) signal propagation.SIGNIFICANCE STATEMENT Patterned network activity in hippocampal networks plays a key role in the formation and consolidation of spatial memories. It is, however, largely unclear how information is transferred to the neocortex for long-term engrams. Here, we elucidate the propagation of network activity from the hippocampus to the medial entorhinal cortex. We show that patterned output from the hippocampus reaches both major cell types of deep entorhinal layers. These cells are, however, only weakly connected, giving rise to two parallel streams of activity for local and remote signal propagation, respectively. The relative weight of both pathways is regulated by local inhibitory interneurons. Our data reveal important insights into the hippocampal-neocortical dialogue, which is of key importance for memory consolidation in the mammalian brain.
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Paller KA, Creery JD, Schechtman E. Memory and Sleep: How Sleep Cognition Can Change the Waking Mind for the Better. Annu Rev Psychol 2020; 72:123-150. [PMID: 32946325 DOI: 10.1146/annurev-psych-010419-050815] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The memories that we retain can serve many functions. They guide our future actions, form a scaffold for constructing the self, and continue to shape both the self and the way we perceive the world. Although most memories we acquire each day are forgotten, those integrated within the structure of multiple prior memories tend to endure. A rapidly growing body of research is steadily elucidating how the consolidation of memories depends on their reactivation during sleep. Processing memories during sleep not only helps counteract their weakening but also supports problem solving, creativity, and emotional regulation. Yet, sleep-based processing might become maladaptive, such as when worries are excessively revisited. Advances in research on memory and sleep can thus shed light on how this processing influences our waking life, which can further inspire the development of novel strategies for decreasing detrimental rumination-like activity during sleep and for promoting beneficial sleep cognition.
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Affiliation(s)
- Ken A Paller
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, Illinois 60208, USA; , ,
| | - Jessica D Creery
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, Illinois 60208, USA; , ,
| | - Eitan Schechtman
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, Illinois 60208, USA; , ,
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