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Ritvo VJH, Nguyen A, Turk-Browne NB, Norman KA. Differentiation and Integration of Competing Memories: A Neural Network Model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.04.02.535239. [PMID: 37066178 PMCID: PMC10103961 DOI: 10.1101/2023.04.02.535239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
What determines when neural representations of memories move together (integrate) or apart (differentiate)? Classic supervised learning models posit that, when two stimuli predict similar outcomes, their representations should integrate. However, these models have recently been challenged by studies showing that pairing two stimuli with a shared associate can sometimes cause differentiation, depending on the parameters of the study and the brain region being examined. Here, we provide a purely unsupervised neural network model that can explain these and other related findings. The model can exhibit integration or differentiation depending on the amount of activity allowed to spread to competitors - inactive memories are not modified, connections to moderately active competitors are weakened (leading to differentiation), and connections to highly active competitors are strengthened (leading to integration). The model also makes several novel predictions - most importantly, that when differentiation occurs as a result of this unsupervised learning mechanism, it will be rapid and asymmetric, and it will give rise to anticorrelated representations in the region of the brain that is the source of the differentiation. Overall, these modeling results provide a computational explanation for a diverse set of seemingly contradictory empirical findings in the memory literature, as well as new insights into the dynamics at play during learning.
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Affiliation(s)
| | - Alex Nguyen
- Princeton Neuroscience Institute, Princeton University
| | | | - Kenneth A. Norman
- Department of Psychology, Princeton University
- Princeton Neuroscience Institute, Princeton University
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2
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Hao J, Wang T, Cao C, Li X, Li H, Gao H, Li J, Shen H, Chen G. LPCAT3 exacerbates early brain injury and ferroptosis after subarachnoid hemorrhage in rats. Brain Res 2024; 1832:148864. [PMID: 38484924 DOI: 10.1016/j.brainres.2024.148864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/19/2024] [Accepted: 03/11/2024] [Indexed: 03/18/2024]
Abstract
AIMS Lysophosphatidylcholine acyltransferase 3 (LPCAT3) is known to play a pivotal role in lipid metabolism, but its role in the early brain injury (EBI) following subarachnoid hemorrhage (SAH) remains unclear. This study provides insights into LPCAT3 expression alterations and functional implications in EBI following SAH. METHODS SAH models of adult male Sprague-Dawley (SD) rats were established by intravascular perforation. Lentivirus vectors were administered by intracerebroventricular injection (i.c.v.) to either induce LPCAT3 overexpression or knockdown 14 days before SAH induction. Western blot, immunofluorescence, Nissl staining, MDA detection, ROS detection, iron content detection, and short-term and long-term neurobehavioral tests were performed to investigate the effects of regulated-LPCAT3 after SAH. RESULTS LPCAT3 levels were found to be significantly elevated in SAH. Suppression of LPCAT3 expression via shRNA improved oxidative stress, reduced brain edema, alleviated behavioral and cognitive deficits following SAH and decreased neuronal death, while upregulating LPCAT3 expression showed opposing effects. CONCLUSION LPCAT3 is involved in SAH-induced EBI and associated with ferroptosis. Our findings provide a referential basis for potential therapeutic interventions aimed at alleviating EBI following SAH.
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Affiliation(s)
- Jiahui Hao
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou 215006, Jiangsu Province, China
| | - Tong Wang
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou 215006, Jiangsu Province, China
| | - Cheng Cao
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou 215006, Jiangsu Province, China; Department of Intensive Care Unit, The Affiliated Jiangyin Hospital of Nantong University, Jiangyin City 214400, Jiangsu Province, China; Department of Brain Center, The Affiliated Jiangyin Hospital of Nantong University, Jiangyin City 214400, Jiangsu Province, China
| | - Xiang Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou 215006, Jiangsu Province, China
| | - Haiying Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou 215006, Jiangsu Province, China
| | - Heng Gao
- Department of Brain Center, The Affiliated Jiangyin Hospital of Nantong University, Jiangyin City 214400, Jiangsu Province, China
| | - Jinquan Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou 215006, Jiangsu Province, China.
| | - Haitao Shen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou 215006, Jiangsu Province, China.
| | - Gang Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou 215006, Jiangsu Province, China
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Gao Z, Duberg K, Warren SL, Zheng L, Hinshaw SP, Menon V, Cai W. Reduced temporal and spatial stability of neural activity patterns predict cognitive control deficits in children with ADHD. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.29.596493. [PMID: 38854066 PMCID: PMC11160739 DOI: 10.1101/2024.05.29.596493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
This study explores the neural underpinnings of cognitive control deficits in ADHD, focusing on overlooked aspects of trial-level variability of neural coding. We employed a novel computational approach to neural decoding on a single-trial basis alongside a cued stop-signal task which allowed us to distinctly probe both proactive and reactive cognitive control. Typically developing (TD) children exhibited stable neural response patterns for efficient proactive and reactive dual control mechanisms. However, neural coding was compromised in children with ADHD. Children with ADHD showed increased temporal variability and diminished spatial stability in neural responses in salience and frontal-parietal network regions, indicating disrupted neural coding during both proactive and reactive control. Moreover, this variability correlated with fluctuating task performance and with more severe symptoms of ADHD. These findings underscore the significance of modeling single-trial variability and representational similarity in understanding distinct components of cognitive control in ADHD, highlighting new perspectives on neurocognitive dysfunction in psychiatric disorders.
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Affiliation(s)
- Zhiyao Gao
- Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Katherine Duberg
- Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Stacie L Warren
- Department of Psychology, University of Texas, Dallas, TX, USA
| | - Li Zheng
- Department of Psychology, University of Arizona, Tucson, AZ, USA
| | - Stephen P. Hinshaw
- Department of Psychology, University of California, Berkeley
- Department of Psychiatry & Behavioral Sciences, University of California, San Francisco
| | - Vinod Menon
- Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA
- Wu Tsai Neuroscience Institute, Stanford University, Stanford, CA, USA
- Department of Neurology & Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
- Maternal & Child Health Research Institute, Stanford, CA, USA
| | - Weidong Cai
- Department of Psychiatry & Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, USA
- Wu Tsai Neuroscience Institute, Stanford University, Stanford, CA, USA
- Maternal & Child Health Research Institute, Stanford, CA, USA
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4
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Bein O, Davachi L. Event Integration and Temporal Differentiation: How Hierarchical Knowledge Emerges in Hippocampal Subfields through Learning. J Neurosci 2024; 44:e0627232023. [PMID: 38129134 PMCID: PMC10919070 DOI: 10.1523/jneurosci.0627-23.2023] [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: 04/05/2023] [Revised: 11/10/2023] [Accepted: 11/16/2023] [Indexed: 12/23/2023] Open
Abstract
Everyday life is composed of events organized by changes in contexts, with each event containing an unfolding sequence of occurrences. A major challenge facing our memory systems is how to integrate sequential occurrences within events while also maintaining their details and avoiding over-integration across different contexts. We asked if and how distinct hippocampal subfields come to hierarchically and, in parallel, represent both event context and subevent occurrences with learning. Female and male human participants viewed sequential events defined as sequences of objects superimposed on shared color frames while undergoing high-resolution fMRI. Importantly, these events were repeated to induce learning. Event segmentation, as indexed by increased reaction times at event boundaries, was observed in all repetitions. Temporal memory decisions were quicker for items from the same event compared to across different events, indicating that events shaped memory. With learning, hippocampal CA3 multivoxel activation patterns clustered to reflect the event context, with more clustering correlated with behavioral facilitation during event transitions. In contrast, in the dentate gyrus (DG), temporally proximal items that belonged to the same event became associated with more differentiated neural patterns. A computational model explained these results by dynamic inhibition in the DG. Additional similarity measures support the notion that CA3 clustered representations reflect shared voxel populations, while DG's distinct item representations reflect different voxel populations. These findings suggest an interplay between temporal differentiation in the DG and attractor dynamics in CA3. They advance our understanding of how knowledge is structured through integration and separation across time and context.
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Affiliation(s)
- Oded Bein
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey 08540
| | - Lila Davachi
- Department of Psychology, Columbia University, New York, New York 10027
- Center for Clinical Research, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962
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5
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Mack ML, Love BC, Preston AR. Distinct hippocampal mechanisms support concept formation and updating. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580181. [PMID: 38405893 PMCID: PMC10888746 DOI: 10.1101/2024.02.14.580181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Learning systems must constantly decide whether to create new representations or update existing ones. For example, a child learning that a bat is a mammal and not a bird would be best served by creating a new representation, whereas updating may be best when encountering a second similar bat. Characterizing the neural dynamics that underlie these complementary memory operations requires identifying the exact moments when each operation occurs. We address this challenge by interrogating fMRI brain activation with a computational learning model that predicts trial-by-trial when memories are created versus updated. We found distinct neural engagement in anterior hippocampus and ventral striatum for model-predicted memory create and update events during early learning. Notably, the degree of this effect in hippocampus, but not ventral striatum, significantly related to learning outcome. Hippocampus additionally showed distinct patterns of functional coactivation with ventromedial prefrontal cortex and angular gyrus during memory creation and premotor cortex during memory updating. These findings suggest that complementary memory functions, as formalized in computational learning models, underlie the rapid formation of novel conceptual knowledge, with the hippocampus and its interactions with frontoparietal circuits playing a crucial role in successful learning. Significance statement How do we reconcile new experiences with existing knowledge? Prominent theories suggest that novel information is either captured by creating new memories or leveraged to update existing memories, yet empirical support of how these distinct memory operations unfold during learning is limited. Here, we combine computational modeling of human learning behaviour with functional neuroimaging to identify moments of memory formation and updating and characterize their neural signatures. We find that both hippocampus and ventral striatum are distinctly engaged when memories are created versus updated; however, it is only hippocampus activation that is associated with learning outcomes. Our findings motivate a key theoretical revision that positions hippocampus is a key player in building organized memories from the earliest moments of learning.
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6
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Zheng L, Gao Z, Doner S, Oyao A, Forloines M, Grilli MD, Barnes CA, Ekstrom AD. Hippocampal contributions to novel spatial learning are both age-related and age-invariant. Proc Natl Acad Sci U S A 2023; 120:e2307884120. [PMID: 38055735 PMCID: PMC10723126 DOI: 10.1073/pnas.2307884120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 10/30/2023] [Indexed: 12/08/2023] Open
Abstract
Older adults show declines in spatial memory, although the extent of these alterations is not uniform across the healthy older population. Here, we investigate the stability of neural representations for the same and different spatial environments in a sample of younger and older adults using high-resolution functional MRI of the medial temporal lobes. Older adults showed, on average, lower neural pattern similarity for retrieving the same environment and more variable neural patterns compared to young adults. We also found a positive association between spatial distance discrimination and the distinctiveness of neural patterns between environments. Our analyses suggested that one source for this association was the extent of informational connectivity to CA1 from other subfields, which was dependent on age, while another source was the fidelity of signals within CA1 itself, which was independent of age. Together, our findings suggest both age-dependent and independent neural contributions to spatial memory performance.
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Affiliation(s)
- Li Zheng
- Psychology Department, University of Arizona, Tucson, AZ85721
| | - Zhiyao Gao
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA94305
| | - Stephanie Doner
- Psychology Department, University of Arizona, Tucson, AZ85721
| | - Alexis Oyao
- Psychology Department, University of Arizona, Tucson, AZ85721
| | - Martha Forloines
- Alzheimer’s Disease Center, Department of Neurology, University of California, Davis, Sacramento, CA95816
| | - Matthew D. Grilli
- Psychology Department, University of Arizona, Tucson, AZ85721
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ85721
| | - Carol A. Barnes
- Psychology Department, University of Arizona, Tucson, AZ85721
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ85721
| | - Arne D. Ekstrom
- Psychology Department, University of Arizona, Tucson, AZ85721
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ85721
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7
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Zheng L, Gao Z, Doner S, Oyao A, Forloines M, Grilli MD, Barnes CA, Ekstrom AD. Hippocampal contributions to novel spatial learning are both age-related and age-invariant. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.28.546918. [PMID: 37425879 PMCID: PMC10326977 DOI: 10.1101/2023.06.28.546918] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Older adults show declines in spatial memory, although the extent of these alterations is not uniform across the healthy older population. Here, we investigate the stability of neural representations for the same and different spatial environments in a sample of younger and older adults using high-resolution functional magnetic resonance imaging (fMRI) of the medial temporal lobe. Older adults showed, on average, lower neural pattern similarity for retrieving the same environment and more variable neural patterns compared to young adults. We also found a positive association between spatial distance discrimination and the distinctiveness of neural patterns between environments. Our analyses suggested that one source for this association was the extent of informational connectivity to CA1 from other subfields, which was dependent on age, while another source was the fidelity of signals within CA1 itself, which was independent of age. Together, our findings suggest both age-dependent and independent neural contributions to spatial memory performance.
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Affiliation(s)
- Li Zheng
- Psychology Department, University of Arizona, Tucson, AZ 85719
| | - Zhiyao Gao
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305
| | - Stephanie Doner
- Psychology Department, University of Arizona, Tucson, AZ 85719
| | - Alexis Oyao
- Psychology Department, University of Arizona, Tucson, AZ 85719
| | - Martha Forloines
- Alzheimer s Disease Center, Department of Neurology, University of California, Davis, Sacramento, CA 95816
| | - Matthew D Grilli
- Psychology Department, University of Arizona, Tucson, AZ 85719
- Evelyn McKnight Brain Institute, University of Arizona, Tucson, AZ 85719
| | - Carol A Barnes
- Psychology Department, University of Arizona, Tucson, AZ 85719
- Evelyn McKnight Brain Institute, University of Arizona, Tucson, AZ 85719
| | - Arne D Ekstrom
- Psychology Department, University of Arizona, Tucson, AZ 85719
- Evelyn McKnight Brain Institute, University of Arizona, Tucson, AZ 85719
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8
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Geva-Sagiv M, Dimsdale-Zucker HR, Williams AB, Ranganath C. Proximity to boundaries reveals spatial context representation in human hippocampal CA1. Neuropsychologia 2023; 189:108656. [PMID: 37541615 DOI: 10.1016/j.neuropsychologia.2023.108656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 06/30/2023] [Accepted: 08/01/2023] [Indexed: 08/06/2023]
Abstract
Recollection of real-world events is often accompanied by a sense of being in the place where the event transpired. Convergent evidence suggests the hippocampus plays a key role in supporting episodic memory by associating information with the time and place it was originally encountered. This representation is reinstated during memory retrieval. However, little is known about the roles of different subfields of the human hippocampus in this process. Research in humans and non-human animal models has suggested that spatial environmental boundaries have a powerful influence on spatial and episodic memory, as well as hippocampal representations of contexts and events. Here, we used high-resolution fMRI to investigate how boundaries influence hippocampal activity patterns during the recollection of objects encountered in different spatial contexts. During the encoding phase, participants viewed objects once in a naturalistic virtual reality task in which they passively explored two rooms in one of two houses. Following the encoding phase, participants were scanned while they recollected items in the absence of any spatial contextual information. Our behavioral results demonstrated that spatial context memory was enhanced for objects encountered near a boundary. Activity patterns in CA1 carried information about the spatial context associated with each of these boundary items. Exploratory analyses revealed that recollection performance was correlated with the fidelity of retrieved spatial context representations in anterior parahippocampal cortex and subiculum. Our results highlight the privileged role of boundaries in CA1 and suggest more generally a close relationship between memory for spatial contexts and representations in the hippocampus and parahippocampal region.
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Affiliation(s)
- Maya Geva-Sagiv
- Center for Neuroscience, University of California, Davis, USA; Department of Psychology, University of California, Davis, CA, USA.
| | - Halle R Dimsdale-Zucker
- Center for Neuroscience, University of California, Davis, USA; Department of Psychology, Columbia University, USA
| | | | - Charan Ranganath
- Center for Neuroscience, University of California, Davis, USA; Department of Psychology, University of California, Davis, CA, USA
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9
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Leshinskaya A, Nguyen MA, Ranganath C. Integration of event experiences to build relational knowledge in the human brain. Cereb Cortex 2023; 33:9997-10012. [PMID: 37492008 DOI: 10.1093/cercor/bhad260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/22/2023] [Accepted: 06/23/2023] [Indexed: 07/27/2023] Open
Abstract
We investigated how the human brain integrates experiences of specific events to build general knowledge about typical event structure. We examined an episodic memory area important for temporal relations, anterior-lateral entorhinal cortex, and a semantic memory area important for action concepts, middle temporal gyrus, to understand how and when these areas contribute to these processes. Participants underwent functional magnetic resonance imaging while learning and recalling temporal relations among novel events over two sessions 1 week apart. Across distinct contexts, individual temporal relations among events could either be consistent or inconsistent with each other. Within each context, during the recall phase, we measured associative coding as the difference of multivoxel correlations among related vs unrelated pairs of events. Neural regions that form integrative representations should exhibit stronger associative coding in the consistent than the inconsistent contexts. We found evidence of integrative representations that emerged quickly in anterior-lateral entorhinal cortex (at session 1), and only subsequently in middle temporal gyrus, which showed a significant change across sessions. A complementary pattern of findings was seen with signatures during learning. This suggests that integrative representations are established early in anterior-lateral entorhinal cortex and may be a pathway to the later emergence of semantic knowledge in middle temporal gyrus.
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Affiliation(s)
- Anna Leshinskaya
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA
| | - Mitchell A Nguyen
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA
| | - Charan Ranganath
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA
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10
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Tambini A, Miller J, Ehlert L, Kiyonaga A, D’Esposito M. Structured memory representations develop at multiple time scales in hippocampal-cortical networks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.06.535935. [PMID: 37066263 PMCID: PMC10104124 DOI: 10.1101/2023.04.06.535935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Influential views of systems memory consolidation posit that the hippocampus rapidly forms representations of specific events, while neocortical networks extract regularities across events, forming the basis of schemas and semantic knowledge. Neocortical extraction of schematic memory representations is thought to occur on a protracted timescale of months, especially for information that is unrelated to prior knowledge. However, this theorized evolution of memory representations across extended timescales, and differences in the temporal dynamics of consolidation across brain regions, lack reliable empirical support. To examine the temporal dynamics of memory representations, we repeatedly exposed human participants to structured information via sequences of fractals, while undergoing longitudinal fMRI for three months. Sequence-specific activation patterns emerged in the hippocampus during the first 1-2 weeks of learning, followed one week later by high-level visual cortex, and subsequently the medial prefrontal and parietal cortices. Schematic, sequence-general representations emerged in the prefrontal cortex after 3 weeks of learning, followed by the medial temporal lobe and anterior temporal cortex. Moreover, hippocampal and most neocortical representations showed sustained rather than time-limited dynamics, suggesting that representations tend to persist across learning. These results show that specific hippocampal representations emerge early, followed by both specific and schematic representations at a gradient of timescales across hippocampal-cortical networks as learning unfolds. Thus, memory representations do not exist only in specific brain regions at a given point in time, but are simultaneously present at multiple levels of abstraction across hippocampal-cortical networks.
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Affiliation(s)
- Arielle Tambini
- Center for Biomedical Imaging and Neuromodulation, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY
- Department of Psychiatry, New York University Grossman School of Medicine, New York, NY
| | - Jacob Miller
- Wu Tsai Institute, Department of Psychiatry, Yale University, New Haven, CT
| | - Luke Ehlert
- Department of Neurobiology and Behavior, University of California. Irvine, CA
| | - Anastasia Kiyonaga
- Department of Cognitive Science, University of California, San Diego, CA
| | - Mark D’Esposito
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA
- Department of Psychology, University of California, Berkeley, CA
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Abstract
A schema refers to a structured body of prior knowledge that captures common patterns across related experiences. Schemas have been studied separately in the realms of episodic memory and spatial navigation across different species and have been grounded in theories of memory consolidation, but there has been little attempt to integrate our understanding across domains, particularly in humans. We propose that experiences during navigation with many similarly structured environments give rise to the formation of spatial schemas (for example, the expected layout of modern cities) that share properties with but are distinct from cognitive maps (for example, the memory of a modern city) and event schemas (such as expected events in a modern city) at both cognitive and neural levels. We describe earlier theoretical frameworks and empirical findings relevant to spatial schemas, along with more targeted investigations of spatial schemas in human and non-human animals. Consideration of architecture and urban analytics, including the influence of scale and regionalization, on different properties of spatial schemas may provide a powerful approach to advance our understanding of spatial schemas.
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12
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Fernandez C, Jiang J, Wang SF, Choi HL, Wagner AD. Representational integration and differentiation in the human hippocampus following goal-directed navigation. eLife 2023; 12:80281. [PMID: 36786678 PMCID: PMC9928422 DOI: 10.7554/elife.80281] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 01/29/2023] [Indexed: 02/15/2023] Open
Abstract
As we learn, dynamic memory processes build structured knowledge across our experiences. Such knowledge enables the formation of internal models of the world that we use to plan, make decisions, and act. Recent theorizing posits that mnemonic mechanisms of differentiation and integration - which at one level may seem to be at odds - both contribute to the emergence of structured knowledge. We tested this possibility using fMRI as human participants learned to navigate within local and global virtual environments over the course of 3 days. Pattern similarity analyses on entorhinal cortical and hippocampal patterns revealed evidence that differentiation and integration work concurrently to build local and global environmental representations, and that variability in integration relates to differences in navigation efficiency. These results offer new insights into the neural machinery and the underlying mechanisms that translate experiences into structured knowledge that allows us to navigate to achieve goals.
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Affiliation(s)
- Corey Fernandez
- Graduate Program in Neurosciences, Stanford UniversityStanfordUnited States,Wu Tsai Neurosciences Institute, Stanford UniversityStanfordUnited States
| | - Jiefeng Jiang
- Department of Psychological and Brain Sciences, University of IowaIowa CityUnited States
| | - Shao-Fang Wang
- Department of Psychology, Stanford UniversityStanfordUnited States
| | - Hannah Lee Choi
- Department of Psychology, Stanford UniversityStanfordUnited States
| | - Anthony D Wagner
- Wu Tsai Neurosciences Institute, Stanford UniversityStanfordUnited States,Department of Psychology, Stanford UniversityStanfordUnited States
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13
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Dimsdale-Zucker HR, Montchal ME, Reagh ZM, Wang SF, Libby LA, Ranganath C. Representations of Complex Contexts: A Role for Hippocampus. J Cogn Neurosci 2023; 35:90-110. [PMID: 36166300 PMCID: PMC9832373 DOI: 10.1162/jocn_a_01919] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The hippocampus plays a critical role in supporting episodic memory, in large part by binding together experiences and items with surrounding contextual information. At present, however, little is known about the roles of different hippocampal subfields in supporting this item-context binding. To address this question, we constructed a task in which items were affiliated with differing types of context-cognitive associations that vary at the local, item level and membership in temporally organized lists that linked items together at a global level. Participants made item recognition judgments while undergoing high-resolution fMRI. We performed voxel pattern similarity analyses to answer the question of how human hippocampal subfields represent retrieved information about cognitive states and the time at which a past event took place. As participants recollected previously presented items, activity patterns in the CA23DG subregion carried information about prior cognitive states associated with these items. We found no evidence to suggest reinstatement of information about temporal context at the level of list membership, but exploratory analyses revealed representations of temporal context at a coarse level in conjunction with representations of cognitive contexts. Results are consistent with characterizations of CA23DG as a critical site for binding together items and contexts in the service of memory retrieval.
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14
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Guo D, Yang J. Reactivation of schema representation in lateral occipital cortex supports successful memory encoding. Cereb Cortex 2022; 33:5968-5980. [PMID: 36520467 DOI: 10.1093/cercor/bhac475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 12/23/2022] Open
Abstract
Abstract
Schemas provide a scaffold onto which we can integrate new memories. Previous research has investigated the brain activity and connectivity underlying schema-related memory formation. However, how schemas are represented and reactivated in the brain, in order to enhance memory, remains unclear. To address this issue, we used an object–location spatial schema that was learned over multiple sessions, combined with similarity analyses of neural representations, to investigate the reactivation of schema representations of object–location memories when a new object–scene association is learned. In addition, we investigated how this reactivation affects subsequent memory performance under different strengths of schemas. We found that reactivation of a schema representation in the lateral occipital cortex (LOC) during object–scene encoding affected subsequent associative memory performance only in the schema-consistent condition and increased the functional connectivity between the LOC and the parahippocampal place area. Taken together, our findings provide new insight into how schema acts as a scaffold to support the integration of novel information into existing cortical networks and suggest a neural basis for schema-induced rapid cortical learning.
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Affiliation(s)
- Dingrong Guo
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behaviour and Mental Health, Peking University , 5 Yiheyuan Road, Beijing 100871, China
| | - Jiongjiong Yang
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behaviour and Mental Health, Peking University , 5 Yiheyuan Road, Beijing 100871, China
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Chen F, Cai J, Dai L, Lin Y, Yu L, Lin Z, Kang Y, Yu T, Wang D, Kang D. Altered hippocampal functional connectivity after the rupture of anterior communicating artery aneurysm. Front Aging Neurosci 2022; 14:997231. [DOI: 10.3389/fnagi.2022.997231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/17/2022] [Indexed: 11/09/2022] Open
Abstract
Background and purposeAneurysmal subarachnoid hemorrhage (SAH) predisposes hippocampal injury, a major cause of follow-up cognitive impairment. Our previous study has revealed an abnormal resting-state brain network in patients after the rupture of anterior communicating artery (ACoA) aneurysm. However, the functional connectivity (FC) characteristics of the hippocampus and its relationship with cognitive performance in these patients remain unknown.MethodsThis study ultimately included 26 patients and 19 age- and sex-matched controls who completed quality control for resting-state functional magnetic resonance imaging (fMRI). The mean time series for each side of the hippocampus was extracted from individuals and then a seed-to-voxel analysis was performed. We compared the difference in FC strength between the two groups and subsequently analyzed the correlations between abnormal FC and their cognitive performance.ResultsThe results of bilateral hippocampus-based FC analysis were largely consistent. Compared with the healthy controls, patients after the rupture of ACoA aneurysm exhibited significantly decreased FC between the hippocampus and other brain structures within the Papez circuit, including bilateral anterior and middle cingulate cortex (MCC), bilateral medial superior frontal gyrus, and left inferior temporal gyrus (ITG). Instead, increased FC between the hippocampus and bilateral insula was observed. Correlation analyses showed that more subjective memory complaints or lower total cognitive scores were associated with decreased connectivity in the hippocampus and several brain regions such as left anterior cingulate cortex (ACC) and frontotemporal cortex.ConclusionThese results extend our previous findings and suggest that patients with ruptured ACoA aneurysm exist hypoconnectivity between the hippocampus and multiple brain regions within the Papez circuit. Deactivation of the Papez circuit may be a crucial neural mechanism related to cognitive deficits in patients after the rupture of ACoA aneurysm.
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Xue G. From remembering to reconstruction: The transformative neural representation of episodic memory. Prog Neurobiol 2022; 219:102351. [PMID: 36089107 DOI: 10.1016/j.pneurobio.2022.102351] [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: 03/18/2022] [Revised: 08/23/2022] [Accepted: 09/05/2022] [Indexed: 11/29/2022]
Abstract
Although memory has long been recognized as a generative process, neural research of memory in recent decades has been predominantly influenced by Tulving's "mental time traveling" perspective and focused on the reactivation and consolidation of encoded memory representations. With the development of multiple powerful analytical approaches to characterize the contents and formats of neural representations, recent studies are able to provide detailed examinations of the representations at various processing stages and have provided exciting new insights into the transformative nature of episodic memory. These studies have revealed the rapid, substantial, and continuous transformation of memory representation during the encoding, maintenance, consolidation, and retrieval of both single and multiple events, as well as event sequences. These transformations are characterized by the abstraction, integration, differentiation, and reorganization of memory representations, enabling the long-term retention and generalization of memory. These studies mark a significant shift in perspective from remembering to reconstruction, which might better reveal the nature of memory and its roles in supporting more effective learning, adaptive decision-making, and creative problem solving.
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Affiliation(s)
- Gui Xue
- State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, PR China; Chinese Institute for Brain Research, Beijing 102206, PR China.
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Shao X, Liu W, Guo Y, Zhu B. Age Effects on Neural Discriminability and Monitoring Process During Memory Retrieval for Auditory Words. Front Aging Neurosci 2022; 14:884993. [PMID: 35928997 PMCID: PMC9343999 DOI: 10.3389/fnagi.2022.884993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 06/23/2022] [Indexed: 11/13/2022] Open
Abstract
After hearing a list of words (e.g., dream, awake, and bed), older adults tended to have more difficulty than younger adults in distinguishing targets (e.g., dream) from lures (e.g., sleep) and foils (e.g., pen) in a visual recognition test. Age-related reduction in neural discriminability in the visual cortex has been linked to deficits in memory discriminability of pictures. However, no study has examined age differences in auditory discrimination and prefrontal monitoring during true and false memory retrieval after hearing words. The current study used a visual recognition test following an auditory study of words and showed that older adults had lower true recognition and higher propensity for high-confidence false recognition compared to young adults. Using classification-based multivariate pattern analysis for functional neuroimaging data during memory retrieval, we found that neural activation patterns in the primary auditory cortex could be used to distinguish between auditorily-studied targets and unstudied lures in young adults, but not in older adults. Moreover, prefrontal monitoring for lures was weaker in older adults as compared to young adults. Individual differences analysis showed that neural discriminability in the primary auditory cortex was positively related to true recognition, whereas prefrontal activation for lures was negatively related to the propensity for high-confidence false recognition in young adults but not in older adults. Together, age differences in true and false memories following auditory study are associated with reduced neural discriminability in the primary auditory cortex and reduced prefrontal monitoring during retrieval.
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Affiliation(s)
- Xuhao Shao
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
- Institute of Developmental Psychology, Beijing Normal University, Beijing, China
- Beijing Key Laboratory of Brain Imaging and Connectomics, Beijing Normal University, Beijing, China
- IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China
| | - Wenzhi Liu
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
- School of Education, Cangzhou Normal University, Cangzhou, China
| | - Ying Guo
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
| | - Bi Zhu
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
- Institute of Developmental Psychology, Beijing Normal University, Beijing, China
- Beijing Key Laboratory of Brain Imaging and Connectomics, Beijing Normal University, Beijing, China
- IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China
- *Correspondence: Bi Zhu
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Shao X, Chen C, Loftus EF, Xue G, Zhu B. Dynamic changes in neural representations underlie the repetition effect on false memory. Neuroimage 2022; 259:119442. [PMID: 35788042 DOI: 10.1016/j.neuroimage.2022.119442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 06/19/2022] [Accepted: 06/30/2022] [Indexed: 11/18/2022] Open
Abstract
Restudying word lists (e.g., dream, awake, and bed) strengthens true memory of the studied words and reduces false memory for unstudied but semantically related lures (e.g., sleep). Yet, the neural mechanisms involved in this repetition effect on false memory remain unclear. Possible mechanisms involve item-specific and semantic neural representations at encoding, and the memory strength between encoding and retrieval. This study first replicated the behavioral results (Exp. 1) and then investigated various neural mechanisms by using slow event-related functional magnetic resonance imaging (fMRI) and representational similarity analysis (Exp. 2). Behavioral results confirmed that restudy improved true memory and reduced false memory. The fMRI results showed that restudy induced item-specific neural representations at encoding in the left occipital pole, but reduced neural overlap between semantic representations at encoding in the left temporal pole. Individual differences in these two encoding neural mechanisms were correlated with the behavioral measure of false memory, with greater restudy-induced representational changes at encoding (item-specific neural representations and reduced neural overlap between semantic representations) being associated with lower false memory. Moreover, restudy enhanced the memory strength between encoding and retrieval in the visuoparietal cortex but reduced it in the frontal cortex. These findings suggest that dynamic changes in neural representations underlie the repetition effect on false memory, supporting a dual-coding neural framework.
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Affiliation(s)
- Xuhao Shao
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875, China; Institute of Developmental Psychology, Beijing Normal University, Beijing 100875, China; Beijing Key Laboratory of Brain Imaging and Connectomics, Beijing Normal University, Beijing 100875, China; IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China
| | - Chuansheng Chen
- Department of Psychological Science, University of California, Irvine, CA 92697, United States
| | - Elizabeth F Loftus
- Department of Psychological Science, University of California, Irvine, CA 92697, United States
| | - Gui Xue
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875, China
| | - Bi Zhu
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875, China; Institute of Developmental Psychology, Beijing Normal University, Beijing 100875, China; Beijing Key Laboratory of Brain Imaging and Connectomics, Beijing Normal University, Beijing 100875, China; IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875, China.
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