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Guerreiro IC, Clopath C. Memory's gatekeeper: The role of PFC in the encoding of congruent events. Proc Natl Acad Sci U S A 2024; 121:e2403648121. [PMID: 39018188 PMCID: PMC11287283 DOI: 10.1073/pnas.2403648121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 06/17/2024] [Indexed: 07/19/2024] Open
Abstract
Theoretical models conventionally portray the consolidation of memories as a slow process that unfolds during sleep. According to the classical Complementary Learning Systems theory, the hippocampus (HPC) rapidly changes its connectivity during wakefulness to encode ongoing events and create memory ensembles that are later transferred to the prefrontal cortex (PFC) during sleep. However, recent experimental studies challenge this notion by showing that new information consistent with prior knowledge can be rapidly consolidated in PFC during wakefulness and that PFC lesions disrupt the encoding of congruent events in the HPC. The contributions of the PFC to memory encoding have therefore largely been overlooked. Moreover, most theoretical frameworks assume random and uncorrelated patterns representing memories, disregarding the correlations between our experiences. To address these shortcomings, we developed a HPC-PFC network model that simulates interactions between the HPC and PFC during the encoding of a memory (awake stage), and subsequent consolidation (sleeping stage) to examine the contributions of each region to the consolidation of novel and congruent memories. Our results show that the PFC network uses stored memory "schemas" consolidated during previous experiences to identify inputs that evoke congruent patterns of activity, quickly integrate it into its network, and gate which components are encoded in the HPC. More specifically, the PFC uses GABAergic long-range projections to inhibit HPC neurons representing input components correlated with a previously stored memory "schema," eliciting sparse hippocampal activity during exposure to congruent events, as it has been experimentally observed.
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Affiliation(s)
- Inês C. Guerreiro
- Department of Bioengineering, Imperial College London, LondonSW7 2AZ, United Kingdom
| | - Claudia Clopath
- Department of Bioengineering, Imperial College London, LondonSW7 2AZ, United Kingdom
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2
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Webler RD, Morales Carrasco C, Cooper SE, Chen M, Hunt CO, Hennessy S, Cao L, Lam C, Chiu A, Differding C, Todd E, Hendrickson TJ, Oathes DJ, Widge AS, Hermosillo RJ, Nelson SM, Fair DA, Lissek SM, Nahas Z. Causally Probing the Role of the Hippocampus in Fear Discrimination: A Precision Functional Mapping-Guided, Transcranial Magnetic Stimulation Study in Participants With Posttraumatic Stress Symptoms. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2024; 4:100309. [PMID: 38690260 PMCID: PMC11059300 DOI: 10.1016/j.bpsgos.2024.100309] [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: 11/26/2023] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 05/02/2024] Open
Abstract
Background Fear overgeneralization is a promising pathogenic mechanism of clinical anxiety. A dominant model posits that hippocampal pattern separation failures drive overgeneralization. Hippocampal network-targeted transcranial magnetic stimulation (HNT-TMS) has been shown to strengthen hippocampal-dependent learning/memory processes. However, no study has examined whether HNT-TMS can alter fear learning/memory. Methods Continuous theta burst stimulation was delivered to individualized left posterior parietal stimulation sites derived via seed-based connectivity, precision functional mapping, and electric field modeling methods. A vertex control site was also stimulated in a within-participant, randomized controlled design. Continuous theta burst stimulation was delivered prior to 2 visual discrimination tasks (1 fear based, 1 neutral). Multilevel models were used to model and test data. Participants were undergraduates with posttraumatic stress symptoms (final n = 25). Results Main analyses did not indicate that HNT-TMS strengthened discrimination. However, multilevel interaction analyses revealed that HNT-TMS strengthened fear discrimination in participants with lower fear sensitization (indexed by responses to a control stimulus with no similarity to the conditioned fear cue) across multiple indices (anxiety ratings: β = 0.10, 95% CI, 0.04 to 0.17, p = .001; risk ratings: β = 0.07, 95% CI, 0.00 to 0.13, p = .037). Conclusions Overgeneralization is an associative process that reflects deficient discrimination of the fear cue from similar cues. In contrast, sensitization reflects nonassociative responding unrelated to fear cue similarity. Our results suggest that HNT-TMS may selectively sharpen fear discrimination when associative response patterns, which putatively implicate the hippocampus, are more strongly engaged.
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Affiliation(s)
- Ryan D. Webler
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | | | - Samuel E. Cooper
- Department of Psychiatry and Behavioral Sciences, University of Texas at Austin, Austin, Texas
| | - Mo Chen
- Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota
| | - Christopher O. Hunt
- Center of Excellence for Stress and Mental Health, VA San Diego, San Diego, California
| | - Sierra Hennessy
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | - Lancy Cao
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | - Carol Lam
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | - Allen Chiu
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | - Cash Differding
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | - Erin Todd
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | - Timothy J. Hendrickson
- Masonic Institute for the Developing Brain, University of Minnesota, Minneapolis, Minnesota
- Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota
| | - Desmond J. Oathes
- Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Alik S. Widge
- Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota
| | - Robert J.M. Hermosillo
- Masonic Institute for the Developing Brain, University of Minnesota, Minneapolis, Minnesota
| | - Steven M. Nelson
- Masonic Institute for the Developing Brain, University of Minnesota, Minneapolis, Minnesota
| | - Damien A. Fair
- Masonic Institute for the Developing Brain, University of Minnesota, Minneapolis, Minnesota
| | - Shmuel M. Lissek
- Department of Psychology, University of Minnesota, Minneapolis, Minnesota
| | - Ziad Nahas
- Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota
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3
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Sherman BE, Turk-Browne NB, Goldfarb EV. Multiple Memory Subsystems: Reconsidering Memory in the Mind and Brain. PERSPECTIVES ON PSYCHOLOGICAL SCIENCE 2024; 19:103-125. [PMID: 37390333 PMCID: PMC10756937 DOI: 10.1177/17456916231179146] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2023]
Abstract
The multiple-memory-systems framework-that distinct types of memory are supported by distinct brain systems-has guided learning and memory research for decades. However, recent work challenges the one-to-one mapping between brain structures and memory types central to this taxonomy, with key memory-related structures supporting multiple functions across substructures. Here we integrate cross-species findings in the hippocampus, striatum, and amygdala to propose an updated framework of multiple memory subsystems (MMSS). We provide evidence for two organizational principles of the MMSS theory: First, opposing memory representations are colocated in the same brain structures; second, parallel memory representations are supported by distinct structures. We discuss why this burgeoning framework has the potential to provide a useful revision of classic theories of long-term memory, what evidence is needed to further validate the framework, and how this novel perspective on memory organization may guide future research.
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Affiliation(s)
| | | | - Elizabeth V Goldfarb
- Department of Psychology, Yale University
- Wu Tsai Institute, Yale University
- Department of Psychiatry, Yale University
- National Center for PTSD, West Haven, USA
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4
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Atak S, Boye A, Peciña S, Liu ZX. High-Fat-Sugar Diet is Associated with Impaired Hippocampus-Dependent Memory in Humans. Physiol Behav 2023; 268:114225. [PMID: 37150429 DOI: 10.1016/j.physbeh.2023.114225] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/28/2023] [Accepted: 05/04/2023] [Indexed: 05/09/2023]
Abstract
Overconsumption of high-fat and high-sugar (HFS) diet may affect the hippocampus, and consequently, memory functions. Yet, converging evidence is needed to demonstrate that the type of memory affected by HFS diet consumption is indeed hippocampus dependent. Moreover, the extent to which HFS diet can also affect executive functioning, and indirectly affect memory requires further examination. In this online study, we asked 349 young adults to report their HFS diet consumption and complete a word memory task, the Everyday Memory Questionnaire, and importantly two memory tasks that have been shown to robustly engage the hippocampus, i.e., the Pattern Separation and Associative Memory Tasks. Participants also completed two executive functioning tasks, the Trail Making Task (TMT) and the Stroop Task. These measures assess attention/cognitive flexibility and the ability to inhibit cognitive interference, respectively. After controlling for confounding variables, we found that participants who reported higher level consumption of a HFS diet performed worse on the Pattern Separation Task and that higher HFS intake was significantly associated with poorer TMT task performance and longer Stroop average reaction time (RT). TMT and Stroop RT scores indicative of reduced executive function also partially mediated the relationship between HFS diet and memory performance on the pattern separation task. Taken together, our results provide converging evidence that HFS diet may impair hippocampus-dependent memory. HFS diet may also affect executive functioning and indirectly impair memory function. The findings are consistent with human subject and animal studies and call for further investigations on the psychological and neural mechanisms underlying the dietary effects on cognitive processes.
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Affiliation(s)
- Selen Atak
- Department of Behavioral Sciences, The University of Michigan-Dearborn, Dearborn, Michigan, USA
| | - Alyssa Boye
- Department of Behavioral Sciences, The University of Michigan-Dearborn, Dearborn, Michigan, USA
| | - Susana Peciña
- Department of Behavioral Sciences, The University of Michigan-Dearborn, Dearborn, Michigan, USA
| | - Zhong-Xu Liu
- Department of Behavioral Sciences, The University of Michigan-Dearborn, Dearborn, Michigan, USA.
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5
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Amer T, Davachi L. Extra-hippocampal contributions to pattern separation. eLife 2023; 12:82250. [PMID: 36972123 PMCID: PMC10042541 DOI: 10.7554/elife.82250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 03/21/2023] [Indexed: 03/29/2023] Open
Abstract
Pattern separation, or the process by which highly similar stimuli or experiences in memory are represented by non-overlapping neural ensembles, has typically been ascribed to processes supported by the hippocampus. Converging evidence from a wide range of studies, however, suggests that pattern separation is a multistage process supported by a network of brain regions. Based on this evidence, considered together with related findings from the interference resolution literature, we propose the 'cortico-hippocampal pattern separation' (CHiPS) framework, which asserts that brain regions involved in cognitive control play a significant role in pattern separation. Particularly, these regions may contribute to pattern separation by (1) resolving interference in sensory regions that project to the hippocampus, thus regulating its cortical input, or (2) directly modulating hippocampal processes in accordance with task demands. Considering recent interest in how hippocampal operations are modulated by goal states likely represented and regulated by extra-hippocampal regions, we argue that pattern separation is similarly supported by neocortical-hippocampal interactions.
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Affiliation(s)
- Tarek Amer
- Department of Psychology, University of Victoria, Victoria, Canada
| | - Lila Davachi
- Department of Psychology, Columbia University, New York, United States
- Nathan Kline Research Institute, Orangeburg, United States
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6
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Xie W, Cappiello M, Yassa MA, Ester E, Zaghloul KA, Zhang W. The entorhinal-DG/CA3 pathway in the medial temporal lobe retains visual working memory of a simple surface feature. eLife 2023; 12:83365. [PMID: 36861959 PMCID: PMC10019891 DOI: 10.7554/elife.83365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 03/01/2023] [Indexed: 03/03/2023] Open
Abstract
Classic models consider working memory (WM) and long-term memory as distinct mental faculties that are supported by different neural mechanisms. Yet, there are significant parallels in the computation that both types of memory require. For instance, the representation of precise item-specific memory requires the separation of overlapping neural representations of similar information. This computation has been referred to as pattern separation, which can be mediated by the entorhinal-DG/CA3 pathway of the medial temporal lobe (MTL) in service of long-term episodic memory. However, although recent evidence has suggested that the MTL is involved in WM, the extent to which the entorhinal-DG/CA3 pathway supports precise item-specific WM has remained elusive. Here, we combine an established orientation WM task with high-resolution fMRI to test the hypothesis that the entorhinal-DG/CA3 pathway retains visual WM of a simple surface feature. Participants were retrospectively cued to retain one of the two studied orientation gratings during a brief delay period and then tried to reproduce the cued orientation as precisely as possible. By modeling the delay-period activity to reconstruct the retained WM content, we found that the anterior-lateral entorhinal cortex (aLEC) and the hippocampal DG/CA3 subfield both contain item-specific WM information that is associated with subsequent recall fidelity. Together, these results highlight the contribution of MTL circuitry to item-specific WM representation.
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Affiliation(s)
- Weizhen Xie
- Surgical Neurology Branch, National Institute of Neurological Disorders and StrokeBethesdaUnited States
- Department of Psychology, University of California, RiversideRiversideUnited States
- Department of Psychology, University of MarylandCollege ParkUnited States
| | - Marcus Cappiello
- Department of Psychology, University of California, RiversideRiversideUnited States
| | - Michael A Yassa
- Center for the Neurobiology of Learning and Memory, School of Biological Sciences, University of California, IrvineIrvineUnited States
| | - Edward Ester
- Department of Psychology, University of NevadaRenoUnited States
| | - Kareem A Zaghloul
- Surgical Neurology Branch, National Institute of Neurological Disorders and StrokeBethesdaUnited States
| | - Weiwei Zhang
- Department of Psychology, University of California, RiversideRiversideUnited States
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7
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Löffler H, Gupta DS. A Model of Pattern Separation by Single Neurons. Front Comput Neurosci 2022; 16:858353. [PMID: 35573263 PMCID: PMC9103200 DOI: 10.3389/fncom.2022.858353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/07/2022] [Indexed: 12/02/2022] Open
Abstract
For efficient processing, spatiotemporal spike patterns representing similar input must be able to transform into a less similar output. A new computational model with physiologically plausible parameters shows how the neuronal process referred to as “pattern separation” can be very well achieved by single neurons if the temporal qualities of the output patterns are considered. Spike patterns generated by a varying number of neurons firing with fixed different frequencies within a gamma range are used as input. The temporal and spatial summation of dendritic input combined with theta-oscillating excitability in the output neuron by subthreshold membrane potential oscillations (SMOs) lead to high temporal separation by different delays of output spikes of similar input patterns. A Winner Takes All (WTA) mechanism with backward inhibition suffices to transform the spatial overlap of input patterns to much less temporal overlap of the output patterns. The conversion of spatial patterns input into an output with differently delayed spikes enables high separation effects. Incomplete random connectivity spreads the times up to the first spike across a spatially expanded ensemble of output neurons. With the expansion, random connectivity becomes the spatial distribution mechanism of temporal features. Additionally, a “synfire chain” circuit is proposed to reconvert temporal differences into spatial ones.
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Affiliation(s)
- Hubert Löffler
- Independent Scholar, Bregenz, Austria
- *Correspondence: Hubert Löffler,
| | - Daya Shankar Gupta
- College of Science and Humanities, Camden County College, Husson University, Bangor, ME, United States
- Department of Biology, Camden County College, Blackwood, NJ, United States
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8
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Sheng J, Zhang L, Liu C, Liu J, Feng J, Zhou Y, Hu H, Xue G. Higher-dimensional neural representations predict better episodic memory. SCIENCE ADVANCES 2022; 8:eabm3829. [PMID: 35442734 PMCID: PMC9020666 DOI: 10.1126/sciadv.abm3829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
Episodic memory enables humans to encode and later vividly retrieve information about our rich experiences, yet the neural representations that support this mental capacity are poorly understood. Using a large fMRI dataset (n = 468) of face-name associative memory tasks and principal component analysis to examine neural representational dimensionality (RD), we found that the human brain maintained a high-dimensional representation of faces through hierarchical representation within and beyond the face-selective regions. Critically, greater RD was associated with better subsequent memory performance both within and across participants, and this association was specific to episodic memory but not general cognitive abilities. Furthermore, the frontoparietal activities could suppress the shared low-dimensional fluctuations and reduce the correlations of local neural responses, resulting in greater RD. RD was not associated with the degree of item-specific pattern similarity, and it made complementary contributions to episodic memory. These results provide a mechanistic understanding of the role of RD in supporting accurate episodic memory.
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9
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Robertson EM. Memory leaks: information shared across memory systems. Trends Cogn Sci 2022; 26:544-554. [DOI: 10.1016/j.tics.2022.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 10/18/2022]
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10
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Zheng L, Gao Z, McAvan AS, Isham EA, Ekstrom AD. Partially overlapping spatial environments trigger reinstatement in hippocampus and schema representations in prefrontal cortex. Nat Commun 2021; 12:6231. [PMID: 34711830 PMCID: PMC8553856 DOI: 10.1038/s41467-021-26560-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 10/11/2021] [Indexed: 01/17/2023] Open
Abstract
When we remember a city that we have visited, we retrieve places related to finding our goal but also non-target locations within this environment. Yet, understanding how the human brain implements the neural computations underlying holistic retrieval remains unsolved, particularly for shared aspects of environments. Here, human participants learned and retrieved details from three partially overlapping environments while undergoing high-resolution functional magnetic resonance imaging (fMRI). Our findings show reinstatement of stores even when they are not related to a specific trial probe, providing evidence for holistic environmental retrieval. For stores shared between cities, we find evidence for pattern separation (representational orthogonalization) in hippocampal subfield CA2/3/DG and repulsion in CA1 (differentiation beyond orthogonalization). Additionally, our findings demonstrate that medial prefrontal cortex (mPFC) stores representations of the common spatial structure, termed schema, across environments. Together, our findings suggest how unique and common elements of multiple spatial environments are accessed computationally and neurally.
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Affiliation(s)
- Li Zheng
- grid.134563.60000 0001 2168 186XDepartment of Psychology, University of Arizona, 1503 E. University Blvd., Tucson, AZ 85721 USA ,grid.134563.60000 0001 2168 186XEvelyn McKnight Brain Institute, University of Arizona, 1503 E. University Blvd., Tucson, AZ 85721 USA
| | - Zhiyao Gao
- grid.5685.e0000 0004 1936 9668Department of Psychology, University of York, Heslington, York YO10 5DD UK
| | - Andrew S. McAvan
- grid.134563.60000 0001 2168 186XDepartment of Psychology, University of Arizona, 1503 E. University Blvd., Tucson, AZ 85721 USA ,grid.134563.60000 0001 2168 186XEvelyn McKnight Brain Institute, University of Arizona, 1503 E. University Blvd., Tucson, AZ 85721 USA
| | - Eve A. Isham
- grid.134563.60000 0001 2168 186XDepartment of Psychology, University of Arizona, 1503 E. University Blvd., Tucson, AZ 85721 USA ,grid.134563.60000 0001 2168 186XEvelyn McKnight Brain Institute, University of Arizona, 1503 E. University Blvd., Tucson, AZ 85721 USA
| | - Arne D. Ekstrom
- grid.134563.60000 0001 2168 186XDepartment of Psychology, University of Arizona, 1503 E. University Blvd., Tucson, AZ 85721 USA ,grid.134563.60000 0001 2168 186XEvelyn McKnight Brain Institute, University of Arizona, 1503 E. University Blvd., Tucson, AZ 85721 USA
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11
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Wynn JS, Liu ZX, Ryan JD. Neural Correlates of Subsequent Memory-Related Gaze Reinstatement. J Cogn Neurosci 2021; 34:1547-1562. [PMID: 34272959 DOI: 10.1162/jocn_a_01761] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Mounting evidence linking gaze reinstatement-the recapitulation of encoding-related gaze patterns during retrieval-to behavioral measures of memory suggests that eye movements play an important role in mnemonic processing. Yet, the nature of the gaze scanpath, including its informational content and neural correlates, has remained in question. In this study, we examined eye movement and neural data from a recognition memory task to further elucidate the behavioral and neural bases of functional gaze reinstatement. Consistent with previous work, gaze reinstatement during retrieval of freely viewed scene images was greater than chance and predictive of recognition memory performance. Gaze reinstatement was also associated with viewing of informationally salient image regions at encoding, suggesting that scanpaths may encode and contain high-level scene content. At the brain level, gaze reinstatement was predicted by encoding-related activity in the occipital pole and BG, neural regions associated with visual processing and oculomotor control. Finally, cross-voxel brain pattern similarity analysis revealed overlapping subsequent memory and subsequent gaze reinstatement modulation effects in the parahippocampal place area and hippocampus, in addition to the occipital pole and BG. Together, these findings suggest that encoding-related activity in brain regions associated with scene processing, oculomotor control, and memory supports the formation, and subsequent recapitulation, of functional scanpaths. More broadly, these findings lend support to scanpath theory's assertion that eye movements both encode, and are themselves embedded in, mnemonic representations.
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Affiliation(s)
| | | | - Jennifer D Ryan
- Rotman Research Institute at Baycrest Health Sciences.,University of Toronto
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12
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Abstract
In addition to the role that our visual system plays in determining what we are seeing right now, visual computations contribute in important ways to predicting what we will see next. While the role of memory in creating future predictions is often overlooked, efficient predictive computation requires the use of information about the past to estimate future events. In this article, we introduce a framework for understanding the relationship between memory and visual prediction and review the two classes of mechanisms that the visual system relies on to create future predictions. We also discuss the principles that define the mapping from predictive computations to predictive mechanisms and how downstream brain areas interpret the predictive signals computed by the visual system. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Nicole C Rust
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104;
| | - Stephanie E Palmer
- Department of Organismal Biology and Anatomy, University of Chicago, Illinois 60637;
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13
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Webler RD, Berg H, Fhong K, Tuominen L, Holt DJ, Morey RA, Lange I, Burton PC, Fullana MA, Radua J, Lissek S. The neurobiology of human fear generalization: meta-analysis and working neural model. Neurosci Biobehav Rev 2021; 128:421-436. [PMID: 34242718 DOI: 10.1016/j.neubiorev.2021.06.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 05/04/2021] [Accepted: 06/23/2021] [Indexed: 02/06/2023]
Abstract
Fear generalization to stimuli resembling a conditioned danger-cue (CS+) is a fundamental dynamic of classical fear-conditioning. Despite the ubiquity of fear generalization in human experience and its known pathogenic contribution to clinical anxiety, neural investigations of human generalization have only recently begun. The present work provides the first meta-analysis of this growing literature to delineate brain substrates of conditioned fear-generalization and formulate a working neural model. Included studies (K = 6, N = 176) reported whole-brain fMRI results and applied generalization-gradient methodology to identify brain activations that gradually strengthen (positive generalization) or weaken (negative generalization) as presented stimuli increase in CS+ resemblance. Positive generalization was instantiated in cingulo-opercular, frontoparietal, striatal-thalamic, and midbrain regions (locus coeruleus, periaqueductal grey, ventral tegmental area), while negative generalization was implemented in default-mode network nodes (ventromedial prefrontal cortex, hippocampus, middle temporal gyrus, angular gyrus) and amygdala. Findings are integrated within an updated neural account of generalization centering on the hippocampus, its modulation by locus coeruleus and basolateral amygdala, and the excitation of threat- or safety-related loci by the hippocampus.
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Affiliation(s)
- Ryan D Webler
- Department of Psychology, University of Minnesota, 75 E River Rd, Minneapolis, MN, 55455, USA
| | - Hannah Berg
- Department of Psychology, University of Minnesota, 75 E River Rd, Minneapolis, MN, 55455, USA
| | - Kimberly Fhong
- Department of Psychology, University of Minnesota, 75 E River Rd, Minneapolis, MN, 55455, USA
| | - Lauri Tuominen
- The Royal's Institute of Mental Health Research, University of Ottawa, 1145 Carling Avenue, Ottawa, Ontario, K1Z 7K4, Canada
| | - Daphne J Holt
- Department of Psychiatry, Massachusetts General Hospital/Harvard Medical School, 55 Fruit Street, Boston, MA, 02114, USA
| | - Rajendra A Morey
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, Duke University Medical Center, Durham, NC, 27710, USA; VA Mid-Atlantic Mental Illness Research Education and Clinical Center, 508 Fulton Street, Durham VAMC, Durham, VA Medical Center, Durham, NC, 27705, USA; Duke-UNC Brain Imaging and Analysis Center, Duke University, 40 Duke Medicine Circle, Durham, NC, USA
| | - Iris Lange
- Department of Psychiatry and Psychology, School for Mental Health and Neuroscience, EURON, Maastricht University Medical Centre, Duboisdomein 30, 6229 GT, Maastricht, the Netherlands
| | - Philip C Burton
- Department of Psychology, University of Minnesota, 75 E River Rd, Minneapolis, MN, 55455, USA
| | - Miquel Angel Fullana
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), CIBERSAM, Campus Casanova, Casanova, 143, 08036, Barcelona, Spain; Adult Psychiatry and Psychology Department, Institute of Neurosciences, Hospital Clínic, Casanovas 143, 08036, Barcelona, Spain
| | - Joaquim Radua
- Adult Psychiatry and Psychology Department, Institute of Neurosciences, Hospital Clínic, Casanovas 143, 08036, Barcelona, Spain; Early Psychosis: Interventions and Clinical-detection (EPIC) Laboratory, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 16 De Crespigny Park, London, SE5 8AF, UK; Department of Clinical Neuroscience, Centre for Psychiatric Research and Education, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Shmuel Lissek
- Department of Psychology, University of Minnesota, 75 E River Rd, Minneapolis, MN, 55455, USA.
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14
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Sakon JJ, Suzuki WA. Neural evidence for recognition of naturalistic videos in monkey hippocampus. Hippocampus 2021; 31:916-932. [PMID: 34021646 DOI: 10.1002/hipo.23335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/26/2021] [Accepted: 04/17/2021] [Indexed: 11/11/2022]
Abstract
The role of the hippocampus in recognition memory has long been a source of debate. Tasks used to study recognition that typically require an explicit probe, where the participant must make a response to prove they remember, yield mixed results on hippocampal involvement. Here, we tasked monkeys to freely view naturalistic videos, and only tested their memory via looking times for two separate novel versus repeat video conditions on each trial. Notably, a large proportion (>30%) of hippocampal neurons differentiated these videos via changes in firing rates time-locked to the duration of their presentation on screen, and not during the delay period between them as would be expected for working memory. Many of these single neurons (>15%) contributed to both retrieval conditions, and differentiated novel from repeat videos across trials with trial-unique content, suggesting they detect familiarity. The majority of neurons contributing to the classifier showed an enhancement in firing rate on repeat compared with novel videos, a pattern which has not previously been shown in hippocampus. These results suggest the hippocampus contributes to recognition memory via familiarity during free-viewing.
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Affiliation(s)
- John J Sakon
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wendy A Suzuki
- Center for Neural Science, New York University, New York, New York, USA
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15
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Pinpointing the neural signatures of single-exposure visual recognition memory. Proc Natl Acad Sci U S A 2021; 118:2021660118. [PMID: 33903238 DOI: 10.1073/pnas.2021660118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Memories of the images that we have seen are thought to be reflected in the reduction of neural responses in high-level visual areas such as inferotemporal (IT) cortex, a phenomenon known as repetition suppression (RS). We challenged this hypothesis with a task that required rhesus monkeys to report whether images were novel or repeated while ignoring variations in contrast, a stimulus attribute that is also known to modulate the overall IT response. The monkeys' behavior was largely contrast invariant, contrary to the predictions of an RS-inspired decoder, which could not distinguish responses to images that are repeated from those that are of lower contrast. However, the monkeys' behavioral patterns were well predicted by a linearly decodable variant in which the total spike count was corrected for contrast modulation. These results suggest that the IT neural activity pattern that best aligns with single-exposure visual recognition memory behavior is not RS but rather sensory referenced suppression: reductions in IT population response magnitude, corrected for sensory modulation.
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16
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Pofahl M, Nikbakht N, Haubrich AN, Nguyen T, Masala N, Distler F, Braganza O, Macke JH, Ewell LA, Golcuk K, Beck H. Synchronous activity patterns in the dentate gyrus during immobility. eLife 2021; 10:65786. [PMID: 33709911 PMCID: PMC7987346 DOI: 10.7554/elife.65786] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/11/2021] [Indexed: 01/25/2023] Open
Abstract
The hippocampal dentate gyrus is an important relay conveying sensory information from the entorhinal cortex to the hippocampus proper. During exploration, the dentate gyrus has been proposed to act as a pattern separator. However, the dentate gyrus also shows structured activity during immobility and sleep. The properties of these activity patterns at cellular resolution, and their role in hippocampal-dependent memory processes have remained unclear. Using dual-color in vivo two-photon Ca2+ imaging, we show that in immobile mice dentate granule cells generate sparse, synchronized activity patterns associated with entorhinal cortex activation. These population events are structured and modified by changes in the environment; and they incorporate place- and speed cells. Importantly, they are more similar than expected by chance to population patterns evoked during self-motion. Using optogenetic inhibition, we show that granule cell activity is not only required during exploration, but also during immobility in order to form dentate gyrus-dependent spatial memories.
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Affiliation(s)
- Martin Pofahl
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - Negar Nikbakht
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - André N Haubrich
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - Theresa Nguyen
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - Nicola Masala
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - Fabian Distler
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - Oliver Braganza
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - Jakob H Macke
- Machine Learning in Science, Cluster of Excellence "Machine Learning", University of Tübingen, Germany & Department Empirical Inference, Max Planck Institute for Intelligent Systems, Tübingen, Germany
| | - Laura A Ewell
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - Kurtulus Golcuk
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany
| | - Heinz Beck
- Institute for Experimental Epileptology and Cognition Research, University of Bonn, Bonn, Germany.,Deutsches Zentrum für Neurodegenerative Erkrankungen e.V, Bonn, Germany
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17
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Besnard A, Miller SM, Sahay A. Distinct Dorsal and Ventral Hippocampal CA3 Outputs Govern Contextual Fear Discrimination. Cell Rep 2021; 30:2360-2373.e5. [PMID: 32075769 PMCID: PMC7050277 DOI: 10.1016/j.celrep.2020.01.055] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 11/05/2019] [Accepted: 01/17/2020] [Indexed: 01/12/2023] Open
Abstract
Considerable work emphasizes a role for hippocampal circuits in governing contextual fear discrimination. However· the intra- and extrahippocampal pathways that route contextual information to cortical and subcortical circuits to guide adaptive behavioral responses are poorly understood. Using terminal-specific optogenetic silencing in a contextual fear discrimination learning paradigm· we identify opposing roles for dorsal CA3-CA1 (dCA3-dCA1) projections and dorsal CA3-dorsolateral septum (dCA3-DLS) projections in calibrating fear responses to certain and ambiguous contextual threats· respectively. Ventral CA3-DLS (vCA3-DLS) projections suppress fear responses in both certain and ambiguous contexts· whereas ventral CA3-CA1 (vCA3-vCA1) projections promote fear responses in both these contexts. Lastly· using retrograde monosynaptic tracing· ex vivo electrophysiological recordings· and optogenetics,· we identify a sparse population of DLS parvalbumin (PV) neurons as putative relays of dCA3-DLS projections to diverse subcortical circuits. Taken together· these studies illuminate how distinct dCA3 and vCA3 outputs calibrate contextual fear discrimination. Besnard et al. show that dorsal and ventral hippocampal CA3 projections to CA1 and dorsolateral septum (DLS) play distinct roles in calibration of contextual fear discrimination. DLS parvalbumin inhibitory neurons receive monosynaptic dorsal CA3 inputs and modulate fear responses in a context-specific manner.
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Affiliation(s)
- Antoine Besnard
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Samara M Miller
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Amar Sahay
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; BROAD Institute of Harvard and MIT, Cambridge, MA 02142, USA.
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18
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Griffiths TD, Lad M, Kumar S, Holmes E, McMurray B, Maguire EA, Billig AJ, Sedley W. How Can Hearing Loss Cause Dementia? Neuron 2020; 108:401-412. [PMID: 32871106 PMCID: PMC7664986 DOI: 10.1016/j.neuron.2020.08.003] [Citation(s) in RCA: 161] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 07/31/2020] [Accepted: 08/05/2020] [Indexed: 12/11/2022]
Abstract
Epidemiological studies identify midlife hearing loss as an independent risk factor for dementia, estimated to account for 9% of cases. We evaluate candidate brain bases for this relationship. These bases include a common pathology affecting the ascending auditory pathway and multimodal cortex, depletion of cognitive reserve due to an impoverished listening environment, and the occupation of cognitive resources when listening in difficult conditions. We also put forward an alternate mechanism, drawing on new insights into the role of the medial temporal lobe in auditory cognition. In particular, we consider how aberrant activity in the service of auditory pattern analysis, working memory, and object processing may interact with dementia pathology in people with hearing loss. We highlight how the effect of hearing interventions on dementia depends on the specific mechanism and suggest avenues for work at the molecular, neuronal, and systems levels to pin this down.
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Affiliation(s)
- Timothy D Griffiths
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK; Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London WC1N 3AR, UK; Human Brain Research Laboratory, Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
| | - Meher Lad
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - Sukhbinder Kumar
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - Emma Holmes
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London WC1N 3AR, UK
| | - Bob McMurray
- Departments of Psychological and Brain Sciences, Communication Sciences and Disorders, Otolaryngology, University of Iowa, Iowa City, IA 52242, USA
| | - Eleanor A Maguire
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London WC1N 3AR, UK
| | | | - William Sedley
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne NE2 4HH, UK
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19
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Genetic Alzheimer’s Disease Risk Affects the Neural Mechanisms of Pattern Separation in Hippocampal Subfields. Curr Biol 2020; 30:4201-4212.e3. [DOI: 10.1016/j.cub.2020.08.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/30/2020] [Accepted: 08/11/2020] [Indexed: 01/13/2023]
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20
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Besnard A, Sahay A. Enhancing adult neurogenesis promotes contextual fear memory discrimination and activation of hippocampal-dorsolateral septal circuits. Behav Brain Res 2020; 399:112917. [PMID: 32949641 DOI: 10.1016/j.bbr.2020.112917] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/01/2020] [Accepted: 09/09/2020] [Indexed: 12/21/2022]
Abstract
Hippocampal circuitry is continuously modified by integration of adult-born dentate granule cells (DGCs). Prior work has shown that enhancing adult hippocampal neurogenesis decreases interference or overlap or conflict between ensembles of similar contexts and promotes discrimination of a shock-associated context from a similar, neutral context. However, the impact of enhanced integration of adult-born neurons on hippocampal network activity or downstream circuits such as the dorsolateral septum that mediate defensive behavioral responses is poorly understood. Here, we first replicated our finding that genetic expansion of the population of adult-born dentate granule cells (8 weeks and younger) promotes contextual fear discrimination. We found that enhanced contextual fear discrimination is associated with greater c-Fos expression in discrete hippocampal subfields along the proximo-distal and dorsoventral axis. Examination of the dorsolateral septum revealed an increase in activation of somatostatin expressing neurons consistent with recent characterization of these cells as calibrators of defensive behavior. Together, these findings begin to shed light on how genetically enhancing adult hippocampal neurogenesis affects activity of hippocampal-dorsolateral septal circuits.
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Affiliation(s)
- Antoine Besnard
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Harvard Stem Cell Institute, Cambridge, MA, 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Amar Sahay
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Harvard Stem Cell Institute, Cambridge, MA, 02138, USA; Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA; BROAD Institute of Harvard and MIT, Cambridge, MA, 02142, USA.
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21
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Dahan L, Rampon C, Florian C. Age-related memory decline, dysfunction of the hippocampus and therapeutic opportunities. Prog Neuropsychopharmacol Biol Psychiatry 2020; 102:109943. [PMID: 32298784 DOI: 10.1016/j.pnpbp.2020.109943] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 04/01/2020] [Accepted: 04/01/2020] [Indexed: 12/13/2022]
Abstract
While the aging of the population is a sign of progress for societies, it also carries its load of negative aspects. Among them, cognitive decline and in particular memory loss is a common feature of non-pathological aging. Autobiographical memories, which rely on the hippocampus, are a primary target of age-related cognitive decline. Here, focusing on the neurobiological mechanisms of memory formation and storage, we describe how hippocampal functions are altered across time in non-pathological mammalian brains. Several hallmarks of aging have been well described over the last decades; among them, we consider altered synaptic communication and plasticity, reduction of adult neurogenesis and epigenetic alterations. Building on the neurobiological processes of cognitive aging that have been identified to date, we review some of the strategies based on lifestyle manupulation allowing to address age-related cognitive deficits.
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Affiliation(s)
- Lionel Dahan
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse Cedex 9, France
| | - Claire Rampon
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse Cedex 9, France
| | - Cédrick Florian
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, Toulouse Cedex 9, France.
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22
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Impairment of Pattern Separation of Ambiguous Scenes by Single Units in the CA3 in the Absence of the Dentate Gyrus. J Neurosci 2020; 40:3576-3590. [PMID: 32234778 DOI: 10.1523/jneurosci.2596-19.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 03/05/2020] [Accepted: 03/10/2020] [Indexed: 12/13/2022] Open
Abstract
Theoretical models and experimental evidence have suggested that connections from the dentate gyrus (DG) to CA3 play important roles in representing orthogonal information (i.e., pattern separation) in the hippocampus. However, the effects of eliminating the DG on neural firing patterns in the CA3 have rarely been tested in a goal-directed memory task that requires both the DG and CA3. In this study, selective lesions in the DG were made using colchicine in male Long-Evans rats, and single units from the CA3 were recorded as the rats performed visual scene memory tasks. The original scenes used in training were altered during testing by blurring to varying degrees or by using visual masks, resulting in maximal recruitment of the DG-CA3 circuits. Compared with controls, the performance of rats with DG lesions was particularly impaired when blurred scenes were used in the task. In addition, the firing rate modulation associated with visual scenes in these rats was significantly reduced in the single units recorded from the CA3 when ambiguous scenes were presented, largely because DG-deprived CA3 cells did not show stepwise, categorical rate changes across varying degrees of scene ambiguity compared with controls. These findings suggest that the DG plays key roles not only during the acquisition of scene memories but also during retrieval when modified visual scenes are processed in conjunction with the CA3 by making the CA3 network respond orthogonally to ambiguous scenes.SIGNIFICANCE STATEMENT Despite the behavioral evidence supporting the role of the dentate gyrus in pattern separation in the hippocampus, the underlying neural mechanisms are largely unknown. By recording single units from the CA3 in DG-lesioned rats performing a visual scene memory task, we report that the scene-related modulation of neural firing was significantly reduced in the DG-lesion rats compared with controls, especially when the original scene stimuli were ambiguously altered. Our findings suggest that the dentate gyrus plays an essential role during memory retrieval and performs a critical computation to make categorical rate modulation occur in the CA3 between different scenes, especially when ambiguity is present in the environment.
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23
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Wynn JS, Ryan JD, Buchsbaum BR. Eye movements support behavioral pattern completion. Proc Natl Acad Sci U S A 2020; 117:6246-6254. [PMID: 32123109 PMCID: PMC7084073 DOI: 10.1073/pnas.1917586117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The ability to recall a detailed event from a simple reminder is supported by pattern completion, a cognitive operation performed by the hippocampus wherein existing mnemonic representations are retrieved from incomplete input. In behavioral studies, pattern completion is often inferred through the false endorsement of lure (i.e., similar) items as old. However, evidence that such a response is due to the specific retrieval of a similar, previously encoded item is severely lacking. We used eye movement (EM) monitoring during a partial-cue recognition memory task to index reinstatement of lure images behaviorally via the recapitulation of encoding-related EMs or gaze reinstatement. Participants reinstated encoding-related EMs following degraded retrieval cues and this reinstatement was negatively correlated with accuracy for lure images, suggesting that retrieval of existing representations (i.e., pattern completion) underlies lure false alarms. Our findings provide evidence linking gaze reinstatement and pattern completion and advance a functional role for EMs in memory retrieval.
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Affiliation(s)
- Jordana S Wynn
- Department of Psychology, University of Toronto, Toronto, ON M55 3G3, Canada;
- Rotman Research Institute, Baycrest Hospital, Toronto, ON M6A 2E1, Canada
| | - Jennifer D Ryan
- Department of Psychology, University of Toronto, Toronto, ON M55 3G3, Canada
- Rotman Research Institute, Baycrest Hospital, Toronto, ON M6A 2E1, Canada
| | - Bradley R Buchsbaum
- Department of Psychology, University of Toronto, Toronto, ON M55 3G3, Canada
- Rotman Research Institute, Baycrest Hospital, Toronto, ON M6A 2E1, Canada
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24
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Abstract
An exciting experiment by Zheng et al. (2019) in this issue of Neuron identifies neural signatures of successful and unsuccessful emotional memory discrimination. By examining human intracranial recordings with high spatial and temporal resolution, this study provides a novel link between rodent and human research on pattern separation.
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25
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Miller SM, Sahay A. Functions of adult-born neurons in hippocampal memory interference and indexing. Nat Neurosci 2019; 22:1565-1575. [PMID: 31477897 PMCID: PMC7397477 DOI: 10.1038/s41593-019-0484-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/30/2019] [Indexed: 12/22/2022]
Abstract
The dentate gyrus-CA3 circuit of the hippocampus is continuously modified by the integration of adult-born dentate granule cells (abDGCs). All abDGCs undergo a prolonged period of maturation, during which they exhibit heightened synaptic plasticity and refinement of electrophysiological properties and connectivity. Consistent with theoretical models and the known functions of the dentate gyrus-CA3 circuit, acute or chronic manipulations of abDGCs support a role for abDGCs in the regulation of memory interference. In this Review, we integrate insights from studies that examine the maturation of abDGCs and their integration into the circuit with network mechanisms that support memory discrimination, consolidation and clearance. We propose that adult hippocampal neurogenesis enables the generation of a library of experiences, each registered in mature abDGC physiology and connectivity. Mature abDGCs recruit inhibitory microcircuits to support pattern separation and memory indexing.
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Affiliation(s)
- Samara M Miller
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
- Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Amar Sahay
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA.
- Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.
- Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
- BROAD Institute of Harvard and MIT, Cambridge, Massachusetts, USA.
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