1
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Kolibius LD, Josselyn SA, Hanslmayr S. On the origin of memory neurons in the human hippocampus. Trends Cogn Sci 2025; 29:421-433. [PMID: 40037964 DOI: 10.1016/j.tics.2025.01.013] [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: 09/03/2024] [Revised: 01/22/2025] [Accepted: 01/27/2025] [Indexed: 03/06/2025]
Abstract
The hippocampus is essential for episodic memory, yet its coding mechanism remains debated. In humans, two main theories have been proposed: one suggests that concept neurons represent specific elements of an episode, while another posits a conjunctive code, where index neurons code the entire episode. Here, we integrate new findings of index neurons in humans and other animals with the concept-specific memory framework, proposing that concept neurons evolve from index neurons through overlapping memories. This process is supported by engram literature, which posits that neurons are allocated to a memory trace based on excitability and that reactivation induces excitability. By integrating these insights, we connect two historically disparate fields of neuroscience: engram research and human single neuron episodic memory research.
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Affiliation(s)
- Luca D Kolibius
- Department of Biomedical Engineering, Columbia University, New York City, NY, USA.
| | - Sheena A Josselyn
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Department of Psychology, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Simon Hanslmayr
- School of Psychology and Neuroscience and Centre for Neurotechnology, University of Glasgow, Glasgow, UK; Centre for Neurotechnology, University of Glasgow, Glasgow, UK.
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2
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Wahlheim CN, Zacks JM. Memory updating and the structure of event representations. Trends Cogn Sci 2025; 29:380-392. [PMID: 39668061 PMCID: PMC12103877 DOI: 10.1016/j.tics.2024.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2024] [Revised: 11/16/2024] [Accepted: 11/18/2024] [Indexed: 12/14/2024]
Abstract
People form memories of specific events and use those memories to make predictions about similar new experiences. Living in a dynamic environment presents a challenge: How does one represent valid prior events in memory while encoding new experiences when things change? There is evidence for two seemingly contradictory classes of mechanism: One differentiates outdated event features by making them less similar or less accessible than updated event features. The other integrates updated features of new events with outdated memories, and the relationship between them, into a structured representation. Integrative encoding may occur when changed events trigger inaccurate predictions based on remembered prior events. We propose that this promotes subsequent recollection of events and their order, enabling adaptation to environmental changes.
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Affiliation(s)
- Christopher N Wahlheim
- Department of Psychology, The University of North Carolina at Greensboro, Greensboro, NC 27402, USA.
| | - Jeffrey M Zacks
- Department of Psychological & Brain Sciences, Washington University in Saint Louis, Saint Louis, MO 63130, USA.
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3
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Abstract
Since one of its first descriptions 70 years ago, rapid eye movement sleep has continually inspired and excited new generations of sleep researchers. Despite significant advancements in understanding its neurocircuitry, underlying mechanisms and microstates, many questions regarding its function, especially beyond the early neurodevelopment, remain unanswered. This opinion review delves into some of the unresolved issues in rapid eye movement sleep research, highlighting the ongoing need for comprehensive exploration in this fascinating field.
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Affiliation(s)
- Liborio Parrino
- Sleep Medicine CenterUniversity of ParmaParmaItaly
- Neurology UnitParma University HospitalParmaItaly
| | - Ivana Rosenzweig
- Sleep and Brain Plasticity Centre, Department of Neuroimaging, Institute of PsychiatryPsychology and Neuroscience (IoPPN), King's College LondonLondonUK
- Sleep Disorders CentreGuy's and St Thomas' NHS Foundation TrustLondonUK
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4
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Higuchi Y, Oblak E, Nakamura H, Yamada M, Shibata K. The role of memory in affirming-the-consequent fallacy. iScience 2025; 28:111889. [PMID: 40008358 PMCID: PMC11850161 DOI: 10.1016/j.isci.2025.111889] [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: 05/19/2024] [Revised: 10/09/2024] [Accepted: 01/22/2025] [Indexed: 02/27/2025] Open
Abstract
People tend to recognize that a transitive relation remains true even when its order is reversed. This affirming-the-consequent fallacy is thought to be uniquely related to human intelligence. It is generally thought that this fallacy is a byproduct of explicit reasoning at the moment of recognition of the reversed order. Here, we provide evidence suggesting a reconsideration of this account using an implicit memory paradigm, which minimizes the involvement of explicit reasoning. Specifically, we tested a two-stage memory model: (1) when a sequence of events is encoded, the memory of the reversed sequence is formed, resulting in the affirming-the-consequent fallacy, and (2) the memories of the forward and reversed sequences are integrated over time, reinforcing the fallacy. Results of behavioral and functional magnetic resonance imaging experiments were consistent with this memory-based model. Our findings suggest that the affirming-the-consequent fallacy may begin unwittingly when individuals memorize a transitive relation.
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Affiliation(s)
- Yoko Higuchi
- RIKEN Center for Brain Science, RIKEN, Wako, Saitama, Japan
- Department of Cognitive and Information Sciences, Chiba Institute of Technology, Narashino, Chiba, Japan
| | - Ethan Oblak
- RIKEN Center for Brain Science, RIKEN, Wako, Saitama, Japan
| | - Hiroko Nakamura
- Japan Society for the Promotion of Science, Chiyoda, Tokyo, Japan
- School of Science and Engineering, Tokyo Denki University, Adachi, Tokyo, Japan
| | - Makiko Yamada
- Institute for Quantum Life Science, National Institute for Quantum Science and Technology, Inage, Chiba, Japan
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5
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Cho I, Leger KR, Valoumas I, Mair RW, Goh JOS, Gutchess A. How age and culture impact the neural correlates of memory retrieval. COGNITIVE, AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2025; 25:45-62. [PMID: 39776064 PMCID: PMC12066026 DOI: 10.3758/s13415-024-01245-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/12/2024] [Indexed: 01/11/2025]
Abstract
Culture can shape memory, but little research has investigated age effects. The present study examined the neural correlates of memory retrieval for old, new, and similar lures in younger and older Americans and Taiwanese. A total of 207 participants encoded pictures of objects and, during fMRI scanning, completed a surprise object recognition task testing discrimination of similar and new from old items. Results show that age and culture impact discrimination of old from new items. Taiwanese performed worse than Americans, with age effects more pronounced for Taiwanese. The cultural differences in the engagement of left inferior frontal gyrus (LIFG) in younger adults (i.e., greater activity for old [for Taiwanese] or new items [for Americans]) were eliminated with age. The results are interpreted as reflecting cultural differences in orientation to novelty versus familiarity for younger, but not older, adults, with the LIFG supporting interference resolution at retrieval. Support is not as strong for cultural differences in pattern separation processes. Although Americans had higher levels of memory discrimination than Taiwanese, neither cultural nor age differences were found in hippocampal activity, which is surprising given the region's role in pattern separation. The findings suggest ways in which cultural life experiences and concomitant information processing strategies can contribute to consistent effects of age across cultures or contribute to different trajectories with age in terms of memory.
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Affiliation(s)
- Isu Cho
- Department of Psychology, Brandeis University, Waltham, MA, USA.
- Department of Psychology, Sungkyunkwan University, 25-2, Seonggyungwan-Ro, Jongno-Gu, Seoul, Republic of Korea, 03063.
| | - Krystal R Leger
- Department of Psychology, Brandeis University, Waltham, MA, USA
| | | | - Ross W Mair
- Center for Brain Science, Harvard University, Cambridge, MA, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA
| | - Joshua Oon Soo Goh
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei City, Taiwan
- Department of Psychology, National Taiwan University, Taipei City, Taiwan
- Neurobiology and Cognitive Science Center, National Taiwan University, Taipei City, Taiwan
- Center of Artificial Intelligence and Advanced Robotics, National Taiwan University, Taipei City, Taiwan
| | - Angela Gutchess
- Department of Psychology, Brandeis University, Waltham, MA, USA
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Jennen L, Mazereel V, Vancampfort D, Qiao Z, Vansteelandt K, Dupont P, Lecei A, van Winkel R. The effects of acute exercise on emotional pattern separation in adolescents and young adults. Neuroimage 2025; 305:120959. [PMID: 39631572 DOI: 10.1016/j.neuroimage.2024.120959] [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: 03/19/2024] [Revised: 10/25/2024] [Accepted: 11/29/2024] [Indexed: 12/07/2024] Open
Abstract
Acute exercise has been associated with cognitive improvements, particularly in memory processes linked to the hippocampus, such as the ability to discriminate between similar stimuli, called hippocampal pattern separation. This can be assessed behaviorally with a mnemonic discrimination task and neurally with functional magnetic resonance imaging (fMRI). Additionally, previous research has shown an emotional modulatory effect on pattern separation, involving the amygdala. In this randomized between-subject study, we investigated whether a 10-minute bout of moderate-intensity exercise, compared to rest, could enhance pattern separation of neutral and emotional images in a group of healthy adolescents and young adults (n=53). Our results showed no significant effects of exercise on either mnemonic discrimination performance or neural activity in the hippocampus and amygdala. Additionally, arterial spin labeling (ASL) confirmed that there were no significant differences in cerebral blood flow between exercise and rest. We did observe worse discrimination for images with a higher similarity level and worse discrimination for highly similar positive images compared to negative and neutral images. However, there were no significant correlations between behavioral outcomes and neural activity. Exploratory analysis revealed a neural signal consistent with pattern completion in the bilateral CA1 and left CA3, but no evidence of pattern separation. Future studies should optimize the exercise characteristics necessary to robustly enhance pattern separation.
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Affiliation(s)
- Lise Jennen
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON5b Herestraat 49, bus 1029, 3000, Leuven, Belgium.
| | - Victor Mazereel
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON5b Herestraat 49, bus 1029, 3000, Leuven, Belgium; University Psychiatric Center KU Leuven, Leuvensesteenweg 517, 3070, Leuven-Kortenberg, Belgium
| | - Davy Vancampfort
- University Psychiatric Center KU Leuven, Leuvensesteenweg 517, 3070, Leuven-Kortenberg, Belgium; KU Leuven Department of Rehabilitation Sciences, ON4 Herestraat 49, bus 1510, 3000, Leuven, Belgium
| | - Zhiling Qiao
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON5b Herestraat 49, bus 1029, 3000, Leuven, Belgium
| | - Kristof Vansteelandt
- University Psychiatric Center KU Leuven, Leuvensesteenweg 517, 3070, Leuven-Kortenberg, Belgium
| | - Patrick Dupont
- KU Leuven, Department of Neurosciences, Laboratory for Cognitive Neurology, ON5 Herestraat 49, bus 1020, 3000, Leuven, Belgium
| | - Aleksandra Lecei
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON5b Herestraat 49, bus 1029, 3000, Leuven, Belgium
| | - Ruud van Winkel
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON5b Herestraat 49, bus 1029, 3000, Leuven, Belgium; University Psychiatric Center KU Leuven, Leuvensesteenweg 517, 3070, Leuven-Kortenberg, Belgium
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7
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Zhao M, Xin Y, Deng H, Zuo Z, Wang X, Bi Y, Liu N. Object color knowledge representation occurs in the macaque brain despite the absence of a developed language system. PLoS Biol 2024; 22:e3002863. [PMID: 39466847 PMCID: PMC11542842 DOI: 10.1371/journal.pbio.3002863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2024] [Revised: 11/07/2024] [Accepted: 09/21/2024] [Indexed: 10/30/2024] Open
Abstract
Animals guide their behaviors through internal representations of the world in the brain. We aimed to understand how the macaque brain stores such general world knowledge, focusing on object color knowledge. Three functional magnetic resonance imaging (fMRI) experiments were conducted in macaque monkeys: viewing chromatic and achromatic gratings, viewing grayscale images of their familiar fruits and vegetables (e.g., grayscale strawberry), and viewing true- and false-colored objects (e.g., red strawberry and green strawberry). We observed robust object knowledge representations in the color patches, especially the one located around TEO: the activity patterns could classify grayscale pictures of objects based on their memory color and response patterns in these regions could translate between chromatic grating viewing and grayscale object viewing (e.g., red grating-grayscale images of strawberry), such that classifiers trained by viewing chromatic gratings could successfully classify grayscale object images according to their memory colors. Our results showed direct positive evidence of object color memory in macaque monkeys. These results indicate the perceptually grounded knowledge representation as a conservative memory mechanism and open a new avenue to study this particular (semantic) memory representation with macaque models.
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Affiliation(s)
- Minghui Zhao
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yumeng Xin
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Haoyun Deng
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Zhentao Zuo
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoying Wang
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
- IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China
| | - Yanchao Bi
- State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China
- IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China
- Beijing Key Laboratory of Brain Imaging and Connectomics, Beijing Normal University, Beijing, China
- Chinese Institute for Brain Research, Beijing, China
| | - Ning Liu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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8
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Mitchnick KA, Marlatte H, Belchev Z, Gao F, Rosenbaum RS. Differential contributions of the hippocampal dentate gyrus and CA1 subfield to mnemonic discrimination. Hippocampus 2024; 34:278-283. [PMID: 38501294 DOI: 10.1002/hipo.23604] [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: 08/04/2023] [Revised: 02/27/2024] [Accepted: 03/06/2024] [Indexed: 03/20/2024]
Abstract
Evidence suggests that individual hippocampal subfields are preferentially involved in various memory-related processes. Here, we demonstrated dissociations in these memory processes in two unique individuals with near-selective bilateral damage within the hippocampus, affecting the dentate gyrus (DG) in case BL and the cornu ammonis 1 (CA1) subfield in case BR. BL was impaired in discriminating highly similar objects in memory (i.e., mnemonic discrimination) but exhibited preserved overall recognition of studied objects, regardless of similarity. Conversely, BR demonstrated impaired general recognition. These results provide evidence for the DG in discrimination processes, likely related to underlying pattern separation computations, and the CA1 in retention/retrieval.
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Affiliation(s)
- Krista A Mitchnick
- Department of Psychology, York University, Toronto, Ontario, Canada
- Rotman Research Institute at Baycrest Hospital, Toronto, Ontario, Canada
| | - Hannah Marlatte
- Rotman Research Institute at Baycrest Hospital, Toronto, Ontario, Canada
- Department of Psychology, University of Toronto, Toronto, Ontario, Canada
| | - Zorry Belchev
- Rotman Research Institute at Baycrest Hospital, Toronto, Ontario, Canada
- Department of Psychology, University of Toronto, Toronto, Ontario, Canada
| | - Fuqiang Gao
- Cognitive Neurology Research Group, Sunnybrook Hospital, Toronto, Ontario, Canada
| | - R Shayna Rosenbaum
- Department of Psychology, York University, Toronto, Ontario, Canada
- Rotman Research Institute at Baycrest Hospital, Toronto, Ontario, Canada
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9
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Cho I, Leger KR, Valoumas I, Mair RW, Goh JOS, Gutchess A. Effects of Age on Cross-Cultural Differences in the Neural Correlates of Memory Retrieval. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.25.591227. [PMID: 38712235 PMCID: PMC11071622 DOI: 10.1101/2024.04.25.591227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Culture can shape memory, but little research investigates age effects. The present study examines the neural correlates of memory retrieval for old, new, and similar lures in younger and older Americans and Taiwanese. Results show that age and culture impact discrimination of old from new items. Taiwanese performed worse than Americans, with age effects more pronounced for Taiwanese. Americans activated the hippocampus for new more than old items, but pattern of activity for the conditions did not differ for Taiwanese, nor did it interact with age. The engagement of left inferior frontal gyrus (LIFG) differed across cultures. Patterns of greater activity for old (for Americans) or new (for Taiwanese) items were eliminated with age, particularly for older Americans. The results are interpreted as reflecting cultural differences in orientation to novelty vs. familiarity for younger, but not older, adults, with the LIFG supporting interference resolution at retrieval. Support is not as strong for cultural differences in pattern separation processes. Although Americans had higher levels of memory discrimination than Taiwanese and engaged the LIFG for correct rejections more than false alarms, the patterns of behavior and neural activity did not interact with culture and age. Neither culture nor age impacted hippocampal activity, which is surprising given the region's role in pattern separation. The findings suggest ways in which cultural life experiences and concomitant information processing strategies can contribute to consistent effects of age across cultures or contribute to different trajectories with age in terms of memory.
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10
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Kolibius LD, Roux F, Parish G, Ter Wal M, Van Der Plas M, Chelvarajah R, Sawlani V, Rollings DT, Lang JD, Gollwitzer S, Walther K, Hopfengärtner R, Kreiselmeyer G, Hamer H, Staresina BP, Wimber M, Bowman H, Hanslmayr S. Hippocampal neurons code individual episodic memories in humans. Nat Hum Behav 2023; 7:1968-1979. [PMID: 37798368 PMCID: PMC10663153 DOI: 10.1038/s41562-023-01706-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/23/2023] [Indexed: 10/07/2023]
Abstract
The hippocampus is an essential hub for episodic memory processing. However, how human hippocampal single neurons code multi-element associations remains unknown. In particular, it is debated whether each hippocampal neuron represents an invariant element within an episode or whether single neurons bind together all the elements of a discrete episodic memory. Here we provide evidence for the latter hypothesis. Using single-neuron recordings from a total of 30 participants, we show that individual neurons, which we term episode-specific neurons, code discrete episodic memories using either a rate code or a temporal firing code. These neurons were observed exclusively in the hippocampus. Importantly, these episode-specific neurons do not reflect the coding of a particular element in the episode (that is, concept or time). Instead, they code for the conjunction of the different elements that make up the episode.
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Affiliation(s)
- Luca D Kolibius
- Department of Biomedical Engineering, Columbia University, New York, NY, USA.
- Centre for Cognitive Neuroimaging, School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK.
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK.
| | - Frederic Roux
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK
| | - George Parish
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK
| | - Marije Ter Wal
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK
| | - Mircea Van Der Plas
- Centre for Cognitive Neuroimaging, School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK
| | - Ramesh Chelvarajah
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK
- Complex Epilepsy and Surgery Service, Neurosciences Centre, Queen Elizabeth Hospital Birmingham, Birmingham, UK
| | - Vijay Sawlani
- Complex Epilepsy and Surgery Service, Neurosciences Centre, Queen Elizabeth Hospital Birmingham, Birmingham, UK
| | - David T Rollings
- Complex Epilepsy and Surgery Service, Neurosciences Centre, Queen Elizabeth Hospital Birmingham, Birmingham, UK
| | - Johannes D Lang
- Epilepsy Center, Department of Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Stephanie Gollwitzer
- Epilepsy Center, Department of Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Katrin Walther
- Epilepsy Center, Department of Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Rüdiger Hopfengärtner
- Epilepsy Center, Department of Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Gernot Kreiselmeyer
- Epilepsy Center, Department of Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Hajo Hamer
- Epilepsy Center, Department of Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Bernhard P Staresina
- Department of Experimental Psychology, University of Oxford, Oxford, UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK
| | - Maria Wimber
- Centre for Cognitive Neuroimaging, School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK
| | - Howard Bowman
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK
- Centre for Cognitive Neuroscience and Cognitive Systems and the School of Computing, University of Kent, Canterbury, UK
| | - Simon Hanslmayr
- Centre for Cognitive Neuroimaging, School of Psychology and Neuroscience, University of Glasgow, Glasgow, UK.
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, UK.
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11
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Jensen A, Karpov G, Collin CA, Davidson PSR. Executive Function Predicts Older Adults' Lure Discrimination Difficulties on the Mnemonic Similarity Task. J Gerontol B Psychol Sci Soc Sci 2023; 78:1642-1650. [PMID: 37330622 DOI: 10.1093/geronb/gbad091] [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: 01/12/2023] [Indexed: 06/19/2023] Open
Abstract
OBJECTIVES Older adults often have difficulty remembering the details of recently encountered objects. We previously found this with the Mnemonic Similarity Task (MST). Surprisingly, the older adults' MST Lure Discrimination Index (LDI) was significantly correlated with visual acuity but not with memory or executive function. Here we ran a replication with new, larger samples of young (N = 45) and older adults (N = 70). We then combined the original and replication older adult samples (N = 108) to critically examine the relative contributions of visual acuity, memory, and executive function composite scores to LDI performance using dominance analysis. This provided, to our knowledge, the first direct statistical comparison of all 3 of these factors and their interactions on LDI. METHODS Participants completed the MST and a battery assessing visual acuity, memory, and executive function. We examined age group differences on MST performance in the new (i.e., replication) young and older adult samples and performed multiple regression and dominance analysis on the combined older adult sample. RESULTS Consistent with previous findings, the older adults showed significantly poorer LDI but preserved item recognition. LDI was significantly correlated with both memory and executive function but not with visual acuity. In the combined older adult sample, all 3 composites predicted LDI, but dominance analysis indicated that executive function was the most important predictor. DISCUSSION Older adults' MST LDI difficulty may be predicted by their executive function and visual acuity. These factors should be considered when interpreting older adults' MST performance.
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Affiliation(s)
- Adelaide Jensen
- School of Psychology, University of Ottawa, Ottawa, Ontario, Canada
| | - Galit Karpov
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, New Jersey, USA
| | - Charles A Collin
- School of Psychology, University of Ottawa, Ottawa, Ontario, Canada
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12
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Quian Quiroga R, Boscaglia M, Jonas J, Rey HG, Yan X, Maillard L, Colnat-Coulbois S, Koessler L, Rossion B. Single neuron responses underlying face recognition in the human midfusiform face-selective cortex. Nat Commun 2023; 14:5661. [PMID: 37704636 PMCID: PMC10499913 DOI: 10.1038/s41467-023-41323-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 08/28/2023] [Indexed: 09/15/2023] Open
Abstract
Faces are critical for social interactions and their recognition constitutes one of the most important and challenging functions of the human brain. While neurons responding selectively to faces have been recorded for decades in the monkey brain, face-selective neural activations have been reported with neuroimaging primarily in the human midfusiform gyrus. Yet, the cellular mechanisms producing selective responses to faces in this hominoid neuroanatomical structure remain unknown. Here we report single neuron recordings performed in 5 human subjects (1 male, 4 females) implanted with intracerebral microelectrodes in the face-selective midfusiform gyrus, while they viewed pictures of familiar and unknown faces and places. We observed similar responses to faces and places at the single cell level, but a significantly higher number of neurons responding to faces, thus offering a mechanistic account for the face-selective activations observed in this region. Although individual neurons did not respond preferentially to familiar faces, a population level analysis could consistently determine whether or not the faces (but not the places) were familiar, only about 50 ms after the initial recognition of the stimuli as faces. These results provide insights into the neural mechanisms of face processing in the human brain.
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Affiliation(s)
- Rodrigo Quian Quiroga
- Hospital del Mar Research Institute (IMIM), Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
- Centre for Systems Neuroscience, University of Leicester, Leicester, UK.
- Ruijin hospital, Shanghai Jiao Tong university school of medicine, Shanghai, China.
| | - Marta Boscaglia
- Centre for Systems Neuroscience, University of Leicester, Leicester, UK
| | - Jacques Jonas
- Université de Lorraine, CNRS, CRAN, F-54000, Nancy, France
- Université de Lorraine, CHRU-Nancy, Service de Neurologie, F-54000, Nancy, France
| | - Hernan G Rey
- Centre for Systems Neuroscience, University of Leicester, Leicester, UK
| | - Xiaoqian Yan
- Université de Lorraine, CNRS, CRAN, F-54000, Nancy, France
| | - Louis Maillard
- Université de Lorraine, CNRS, CRAN, F-54000, Nancy, France
- Université de Lorraine, CHRU-Nancy, Service de Neurologie, F-54000, Nancy, France
| | - Sophie Colnat-Coulbois
- Université de Lorraine, CNRS, CRAN, F-54000, Nancy, France
- Université de Lorraine, CHRU-Nancy, Service de Neurochirurgie, F-54000, Nancy, France
| | - Laurent Koessler
- Université de Lorraine, CNRS, CRAN, F-54000, Nancy, France
- Université de Lorraine, CHRU-Nancy, Service de Neurologie, F-54000, Nancy, France
| | - Bruno Rossion
- Université de Lorraine, CNRS, CRAN, F-54000, Nancy, France.
- Université de Lorraine, CHRU-Nancy, Service de Neurologie, F-54000, Nancy, France.
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13
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Han CZ, Donoghue T, Cao R, Kunz L, Wang S, Jacobs J. Using multi-task experiments to test principles of hippocampal function. Hippocampus 2023; 33:646-657. [PMID: 37042212 PMCID: PMC10249632 DOI: 10.1002/hipo.23540] [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: 03/23/2023] [Revised: 03/30/2023] [Accepted: 03/31/2023] [Indexed: 04/13/2023]
Abstract
Investigations of hippocampal functions have revealed a dizzying array of findings, from lesion-based behavioral deficits, to a diverse range of characterized neural activations, to computational models of putative functionality. Across these findings, there remains an ongoing debate about the core function of the hippocampus and the generality of its representation. Researchers have debated whether the hippocampus's primary role relates to the representation of space, the neural basis of (episodic) memory, or some more general computation that generalizes across various cognitive domains. Within these different perspectives, there is much debate about the nature of feature encodings. Here, we suggest that in order to evaluate hippocampal responses-investigating, for example, whether neuronal representations are narrowly targeted to particular tasks or if they subserve domain-general purposes-a promising research strategy may be the use of multi-task experiments, or more generally switching between multiple task contexts while recording from the same neurons in a given session. We argue that this strategy-when combined with explicitly defined theoretical motivations that guide experiment design-could be a fruitful approach to better understand how hippocampal representations support different behaviors. In doing so, we briefly review key open questions in the field, as exemplified by articles in this special issue, as well as previous work using multi-task experiments, and extrapolate to consider how this strategy could be further applied to probe fundamental questions about hippocampal function.
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Affiliation(s)
- Claire Z. Han
- Department of Biomedical Engineering, Columbia University
| | | | - Runnan Cao
- Department of Radiology, Washington University in St. Louis
| | - Lukas Kunz
- Department of Epileptology, University of Bonn Medical Center, Bonn, Germany
| | - Shuo Wang
- Department of Radiology, Washington University in St. Louis
| | - Joshua Jacobs
- Department of Biomedical Engineering, Columbia University
- Department of Neurological Surgery, Columbia University
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14
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Amer T, Davachi L. Extra-hippocampal contributions to pattern separation. eLife 2023; 12:e82250. [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] [MESH Headings] [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 VictoriaVictoriaCanada
| | - Lila Davachi
- Department of Psychology, Columbia UniversityNew YorkUnited States
- Nathan Kline Research InstituteOrangeburgUnited States
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15
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Quian Quiroga R. An integrative view of human hippocampal function: Differences with other species and capacity considerations. Hippocampus 2023; 33:616-634. [PMID: 36965048 DOI: 10.1002/hipo.23527] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 02/11/2023] [Accepted: 03/09/2023] [Indexed: 03/27/2023]
Abstract
We describe an integrative model that encodes associations between related concepts in the human hippocampal formation, constituting the skeleton of episodic memories. The model, based on partially overlapping assemblies of "concept cells," contrast markedly with the well-established notion of pattern separation, which relies on conjunctive, context dependent single neuron responses, instead of the invariant, context independent responses found in the human hippocampus. We argue that the model of partially overlapping assemblies is better suited to cope with memory capacity limitations, that the finding of different types of neurons and functions in this area is due to a flexible and temporary use of the extraordinary machinery of the hippocampus to deal with the task at hand, and that only information that is relevant and frequently revisited will consolidate into long-term hippocampal representations, using partially overlapping assemblies. Finally, we propose that concept cells are uniquely human and that they may constitute the neuronal underpinnings of cognitive abilities that are much further developed in humans compared to other species.
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Affiliation(s)
- Rodrigo Quian Quiroga
- Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- Centre for Systems Neuroscience, University of Leicester, Leicester, UK
- Department of neurosurgery, clinical neuroscience center, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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16
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The effects of variable encoding contexts on item and source recognition. Mem Cognit 2023; 51:391-403. [PMID: 35980546 DOI: 10.3758/s13421-022-01353-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2022] [Indexed: 11/08/2022]
Abstract
How repeated encoding affects retention of item details is an unresolved question. The Competitive Trace theory (Yassa & Reagh, Frontiers in Behavioral Neuroscience, 7, 107, 2013) assumes that even slight variations in encoding contexts across item repetitions induce competition among non-overlapping contextual traces, leading to semanticization and decontextualized memory traces. However, empirical support for this assumption is mixed. In extension of previous research, the current study attempted to increase the competition between contextual traces by increasing encoding context variability. In three experiments we tested how repeated encoding in the same context or different contexts affects target recognition, similar lure discrimination, and source memory. Participants viewed images of objects once, three times in the same or three times in different contexts. Context variability was implemented through variations in background color or encoding tasks. Repeated encoding improved memory for item details, independent of context variability. Background color was poorly remembered but answering different encoding questions for repeated items impaired recollection of specific encoding tasks, in comparison to encoding items only once or repeatedly with the same encoding task. Our findings show that repetitions enhance memory for perceptual details but can impair memory for contextual elements, a dissociation that needs to be considered by the Competitive Trace Theory and other consolidation theories.
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17
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Quilty-Dunn J, Porot N, Mandelbaum E. The best game in town: The reemergence of the language-of-thought hypothesis across the cognitive sciences. Behav Brain Sci 2022; 46:e261. [PMID: 36471543 DOI: 10.1017/s0140525x22002849] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mental representations remain the central posits of psychology after many decades of scrutiny. However, there is no consensus about the representational format(s) of biological cognition. This paper provides a survey of evidence from computational cognitive psychology, perceptual psychology, developmental psychology, comparative psychology, and social psychology, and concludes that one type of format that routinely crops up is the language-of-thought (LoT). We outline six core properties of LoTs: (i) discrete constituents; (ii) role-filler independence; (iii) predicate-argument structure; (iv) logical operators; (v) inferential promiscuity; and (vi) abstract content. These properties cluster together throughout cognitive science. Bayesian computational modeling, compositional features of object perception, complex infant and animal reasoning, and automatic, intuitive cognition in adults all implicate LoT-like structures. Instead of regarding LoT as a relic of the previous century, researchers in cognitive science and philosophy-of-mind must take seriously the explanatory breadth of LoT-based architectures. We grant that the mind may harbor many formats and architectures, including iconic and associative structures as well as deep-neural-network-like architectures. However, as computational/representational approaches to the mind continue to advance, classical compositional symbolic structures - that is, LoTs - only prove more flexible and well-supported over time.
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Affiliation(s)
- Jake Quilty-Dunn
- Department of Philosophy and Philosophy-Neuroscience-Psychology Program, Washington University in St. Louis, St. Louis, MO, USA. , sites.google.com/site/jakequiltydunn/
| | - Nicolas Porot
- Africa Institute for Research in Economics and Social Sciences, Mohammed VI Polytechnic University, Rabat, Morocco. , nicolasporot.com
| | - Eric Mandelbaum
- Departments of Philosophy and Psychology, The Graduate Center & Baruch College, CUNY, New York, NY, USA. , ericmandelbaum.com
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18
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Billig AJ, Lad M, Sedley W, Griffiths TD. The hearing hippocampus. Prog Neurobiol 2022; 218:102326. [PMID: 35870677 PMCID: PMC10510040 DOI: 10.1016/j.pneurobio.2022.102326] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/08/2022] [Accepted: 07/18/2022] [Indexed: 11/17/2022]
Abstract
The hippocampus has a well-established role in spatial and episodic memory but a broader function has been proposed including aspects of perception and relational processing. Neural bases of sound analysis have been described in the pathway to auditory cortex, but wider networks supporting auditory cognition are still being established. We review what is known about the role of the hippocampus in processing auditory information, and how the hippocampus itself is shaped by sound. In examining imaging, recording, and lesion studies in species from rodents to humans, we uncover a hierarchy of hippocampal responses to sound including during passive exposure, active listening, and the learning of associations between sounds and other stimuli. We describe how the hippocampus' connectivity and computational architecture allow it to track and manipulate auditory information - whether in the form of speech, music, or environmental, emotional, or phantom sounds. Functional and structural correlates of auditory experience are also identified. The extent of auditory-hippocampal interactions is consistent with the view that the hippocampus makes broad contributions to perception and cognition, beyond spatial and episodic memory. More deeply understanding these interactions may unlock applications including entraining hippocampal rhythms to support cognition, and intervening in links between hearing loss and dementia.
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Affiliation(s)
| | - Meher Lad
- Translational and Clinical Research Institute, Newcastle University Medical School, Newcastle upon Tyne, UK
| | - William Sedley
- Translational and Clinical Research Institute, Newcastle University Medical School, Newcastle upon Tyne, UK
| | - Timothy D Griffiths
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK; Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, UK; Human Brain Research Laboratory, Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, USA
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19
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Safron A, Çatal O, Verbelen T. Generalized Simultaneous Localization and Mapping (G-SLAM) as unification framework for natural and artificial intelligences: towards reverse engineering the hippocampal/entorhinal system and principles of high-level cognition. Front Syst Neurosci 2022; 16:787659. [PMID: 36246500 PMCID: PMC9563348 DOI: 10.3389/fnsys.2022.787659] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 09/02/2022] [Indexed: 11/24/2022] Open
Abstract
Simultaneous localization and mapping (SLAM) represents a fundamental problem for autonomous embodied systems, for which the hippocampal/entorhinal system (H/E-S) has been optimized over the course of evolution. We have developed a biologically-inspired SLAM architecture based on latent variable generative modeling within the Free Energy Principle and Active Inference (FEP-AI) framework, which affords flexible navigation and planning in mobile robots. We have primarily focused on attempting to reverse engineer H/E-S "design" properties, but here we consider ways in which SLAM principles from robotics may help us better understand nervous systems and emergent minds. After reviewing LatentSLAM and notable features of this control architecture, we consider how the H/E-S may realize these functional properties not only for physical navigation, but also with respect to high-level cognition understood as generalized simultaneous localization and mapping (G-SLAM). We focus on loop-closure, graph-relaxation, and node duplication as particularly impactful architectural features, suggesting these computational phenomena may contribute to understanding cognitive insight (as proto-causal-inference), accommodation (as integration into existing schemas), and assimilation (as category formation). All these operations can similarly be describable in terms of structure/category learning on multiple levels of abstraction. However, here we adopt an ecological rationality perspective, framing H/E-S functions as orchestrating SLAM processes within both concrete and abstract hypothesis spaces. In this navigation/search process, adaptive cognitive equilibration between assimilation and accommodation involves balancing tradeoffs between exploration and exploitation; this dynamic equilibrium may be near optimally realized in FEP-AI, wherein control systems governed by expected free energy objective functions naturally balance model simplicity and accuracy. With respect to structure learning, such a balance would involve constructing models and categories that are neither too inclusive nor exclusive. We propose these (generalized) SLAM phenomena may represent some of the most impactful sources of variation in cognition both within and between individuals, suggesting that modulators of H/E-S functioning may potentially illuminate their adaptive significances as fundamental cybernetic control parameters. Finally, we discuss how understanding H/E-S contributions to G-SLAM may provide a unifying framework for high-level cognition and its potential realization in artificial intelligences.
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Affiliation(s)
- Adam Safron
- Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Cognitive Science Program, Indiana University, Bloomington, IN, United States
- Institute for Advanced Consciousness Studies, Santa Monica, CA, United States
| | - Ozan Çatal
- IDLab, Department of Information Technology, Ghent University—imec, Ghent, Belgium
| | - Tim Verbelen
- IDLab, Department of Information Technology, Ghent University—imec, Ghent, Belgium
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20
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Schaeffer JD, Chek CJW. Recollection, familiarity, and behavioural pattern separation: A correlational study. Memory 2022; 30:1248-1257. [DOI: 10.1080/09658211.2022.2101665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- James D. Schaeffer
- Department of Psychology, Stephen F. Austin State University, Nacogdoches, TX, USA
| | - Carmen Jia-Wen Chek
- Department of Psychology and Counseling, University of Texas at Tyler, Tyler, TX, USA
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21
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Face identity coding in the deep neural network and primate brain. Commun Biol 2022; 5:611. [PMID: 35725902 PMCID: PMC9209415 DOI: 10.1038/s42003-022-03557-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 06/01/2022] [Indexed: 01/01/2023] Open
Abstract
A central challenge in face perception research is to understand how neurons encode face identities. This challenge has not been met largely due to the lack of simultaneous access to the entire face processing neural network and the lack of a comprehensive multifaceted model capable of characterizing a large number of facial features. Here, we addressed this challenge by conducting in silico experiments using a pre-trained face recognition deep neural network (DNN) with a diverse array of stimuli. We identified a subset of DNN units selective to face identities, and these identity-selective units demonstrated generalized discriminability to novel faces. Visualization and manipulation of the network revealed the importance of identity-selective units in face recognition. Importantly, using our monkey and human single-neuron recordings, we directly compared the response of artificial units with real primate neurons to the same stimuli and found that artificial units shared a similar representation of facial features as primate neurons. We also observed a region-based feature coding mechanism in DNN units as in human neurons. Together, by directly linking between artificial and primate neural systems, our results shed light on how the primate brain performs face recognition tasks.
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22
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Abstract
SignificanceEpisodic memories represent the "what," "when," and "where" of specific episodes. In epilepsy patients, we detected single-unit activity reflecting episodic memory only in the hippocampus. This neural signal is sparsely coded and pattern-separated, consistent with predictions from neurocomputational models. We also detected single-unit activity reflecting a generic memory signal, coding whether an item is old or new without item-specific episodic information. Similar to concept cells, this generic repetition/novelty neural signal was found in multiple brain regions, including the hippocampus. In contrast, the item-specific signal was found only in the hippocampus. Our results indicate the coexistence of two memory signals in the human brain and suggest that the sparsely coded, hippocampus-specific signal is fundamental, whereas the often-studied generic signal is derivative.
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23
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You Y, Novak LR, Clancy KJ, Li W. Pattern differentiation and tuning shift in human sensory cortex underlie long-term threat memory. Curr Biol 2022; 32:2067-2075.e4. [PMID: 35325599 PMCID: PMC9090975 DOI: 10.1016/j.cub.2022.02.076] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 01/18/2022] [Accepted: 02/28/2022] [Indexed: 12/12/2022]
Abstract
The amygdala-prefrontal-cortex circuit has long occupied the center of the threat system,1 but new evidence has rapidly amassed to implicate threat processing outside this canonical circuit.2-4 Through nonhuman research, the sensory cortex has emerged as a critical substrate for long-term threat memory,5-9 underpinned by sensory cortical pattern separation/completion10,11 and tuning shift.12,13 In humans, research has begun to associate the human sensory cortex with long-term threat memory,14,15 but the lack of mechanistic insights obscures a direct linkage. Toward that end, we assessed human olfactory threat conditioning and long-term (9 days) threat memory, combining affective appraisal, olfactory psychophysics, and functional magnetic resonance imaging (fMRI) over a linear odor-morphing continuum (five levels of binary mixtures of the conditioned stimuli/CS+ and CS- odors). Affective ratings and olfactory perceptual discrimination confirmed (explicit) affective and perceptual learning and memory via conditioning. fMRI representational similarity analysis (RSA) and voxel-based tuning analysis further revealed associative plasticity in the human olfactory (piriform) cortex, including immediate and lasting pattern differentiation between CS and neighboring non-CS and a late onset, lasting tuning shift toward the CS. The two plastic processes were especially salient and lasting in anxious individuals, among whom they were further correlated. These findings thus support an evolutionarily conserved sensory cortical system of long-term threat representation, which can underpin threat perception and memory. Importantly, hyperfunctioning of this sensory mnemonic system of threat in anxiety further implicates a hitherto underappreciated sensory mechanism of anxiety.
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Affiliation(s)
- Yuqi You
- Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 32306, USA.
| | - Lucas R Novak
- Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 32306, USA
| | - Kevin J Clancy
- Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 32306, USA
| | - Wen Li
- Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 32306, USA.
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24
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Bach DR. Aversive conditioning: Principles of memory storage in sensory cortex. Curr Biol 2022; 32:R426-R428. [DOI: 10.1016/j.cub.2022.03.068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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25
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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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26
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Jennen L, Mazereel V, Lecei A, Samaey C, Vancampfort D, van Winkel R. Exercise to spot the differences: a framework for the effect of exercise on hippocampal pattern separation in humans. Rev Neurosci 2022; 33:555-582. [PMID: 35172422 DOI: 10.1515/revneuro-2021-0156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/16/2022] [Indexed: 12/12/2022]
Abstract
Exercise has a beneficial effect on mental health and cognitive functioning, but the exact underlying mechanisms remain largely unknown. In this review, we focus on the effect of exercise on hippocampal pattern separation, which is a key component of episodic memory. Research has associated exercise with improvements in pattern separation. We propose an integrated framework mechanistically explaining this relationship. The framework is divided into three pathways, describing the pro-neuroplastic, anti-inflammatory and hormonal effects of exercise. The pathways are heavily intertwined and may result in functional and structural changes in the hippocampus. These changes can ultimately affect pattern separation through direct and indirect connections. The proposed framework might guide future research on the effect of exercise on pattern separation in the hippocampus.
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Affiliation(s)
- Lise Jennen
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON V Herestraat 49, bus 1029, 3000 Leuven, Belgium
| | - Victor Mazereel
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON V Herestraat 49, bus 1029, 3000 Leuven, Belgium.,University Psychiatric Center KU Leuven, Leuvensesteenweg 517, 3070 Leuven-Kortenberg, Belgium
| | - Aleksandra Lecei
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON V Herestraat 49, bus 1029, 3000 Leuven, Belgium
| | - Celine Samaey
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON V Herestraat 49, bus 1029, 3000 Leuven, Belgium
| | - Davy Vancampfort
- University Psychiatric Center KU Leuven, Leuvensesteenweg 517, 3070 Leuven-Kortenberg, Belgium.,KU Leuven Department of Rehabilitation Sciences, ON IV Herestraat 49, bus 1510, 3000, Leuven, Belgium
| | - Ruud van Winkel
- KU Leuven, Department of Neurosciences, Center for Clinical Psychiatry, ON V Herestraat 49, bus 1029, 3000 Leuven, Belgium.,University Psychiatric Center KU Leuven, Leuvensesteenweg 517, 3070 Leuven-Kortenberg, Belgium
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27
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Widloski J, Foster DJ. Flexible rerouting of hippocampal replay sequences around changing barriers in the absence of global place field remapping. Neuron 2022; 110:1547-1558.e8. [PMID: 35180390 PMCID: PMC9473153 DOI: 10.1016/j.neuron.2022.02.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/30/2021] [Accepted: 02/01/2022] [Indexed: 01/12/2023]
Abstract
Flexibility is a hallmark of memories that depend on the hippocampus. For navigating animals, flexibility is necessitated by environmental changes such as blocked paths and extinguished food sources. To better understand the neural basis of this flexibility, we recorded hippocampal replays in a spatial memory task where barriers as well as goals were moved between sessions to see whether replays could adapt to new spatial and reward contingencies. Strikingly, replays consistently depicted new goal-directed trajectories around each new barrier configuration and largely avoided barrier violations. Barrier-respecting replays were learned rapidly and did not rely on place cell remapping. These data distinguish sharply between place field responses, which were largely stable and remained tied to sensory cues, and replays, which changed flexibly to reflect the learned contingencies in the environment and suggest sequenced activations such as replay to be an important link between the hippocampus and flexible memory.
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Affiliation(s)
- John Widloski
- Helen Wills Neuroscience Institute and Department of Psychology, University of California, Berkeley, CA 94720, USA
| | - David J Foster
- Helen Wills Neuroscience Institute and Department of Psychology, University of California, Berkeley, CA 94720, USA.
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28
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Genon S, Bernhardt BC, La Joie R, Amunts K, Eickhoff SB. The many dimensions of human hippocampal organization and (dys)function. Trends Neurosci 2021; 44:977-989. [PMID: 34756460 DOI: 10.1016/j.tins.2021.10.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 09/06/2021] [Accepted: 10/05/2021] [Indexed: 11/19/2022]
Abstract
The internal organization of hippocampal formation has been studied for more than a century. Although early accounts emphasized its subfields along the medial-lateral axis, findings in recent decades have highlighted also the anterior-to-posterior (i.e., longitudinal) axis as a key contributor to this brain region's functional organization. Hence, understanding of hippocampal function likely demands characterizing both medial-to-lateral and anterior-to-posterior axes, an approach that has been concretized by recent advances in in vivo parcellation and gradient mapping techniques. Following a short historical overview, we review the evidence provided by these approaches in brain-mapping studies, as well as the perspectives they open for addressing the behavioral relevance of the interacting organizational axes in healthy and clinical populations.
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Affiliation(s)
- Sarah Genon
- Institute of Neuroscience and Medicine, Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany; Institute of Systems Neuroscience, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
| | | | - Renaud La Joie
- Memory and Aging Center, Weill Institute for Neuroscience, University of California, San Francisco, San Francisco, CA, USA
| | - Katrin Amunts
- Institute of Neuroscience and Medicine, Structural and Functional Organisation of the Brain (INM-1), Research Centre Jülich, Jülich, Germany; C. & O. Vogt Institute for Brain Research, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University, Düsseldorf, Germany
| | - Simon B Eickhoff
- Institute of Neuroscience and Medicine, Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany; Institute of Systems Neuroscience, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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29
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Willems T, Henke K. Imaging human engrams using 7 Tesla magnetic resonance imaging. Hippocampus 2021; 31:1257-1270. [PMID: 34739173 PMCID: PMC9298259 DOI: 10.1002/hipo.23391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 10/07/2021] [Accepted: 10/08/2021] [Indexed: 12/15/2022]
Abstract
The investigation of the physical traces of memories (engrams) has made significant progress in the last decade due to optogenetics and fluorescent cell tagging applied in rodents. Engram cells were identified. The ablation of engram cells led to the loss of the associated memory, silent memories were reactivated, and artificial memories were implanted in the brain. Human engram research lags behind engram research in rodents due to methodological and ethical constraints. However, advances in multivariate analysis techniques of functional magnetic resonance imaging (fMRI) data and machine learning algorithms allowed the identification of stable engram patterns in humans. In addition, MRI scanners with an ultrahigh field strength of 7 Tesla (T) have left their prototype state and became more common around the world to assist human engram research. Although most engram research in humans is still being performed with a field strength of 3T, fMRI at 7T will push engram research. Here, we summarize the current state and findings of human engram research and discuss the advantages and disadvantages of applying 7 versus 3T fMRI to image human memory traces.
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Affiliation(s)
- Tom Willems
- Institute of Psychology, University of Bern, Bern, Switzerland
| | - Katharina Henke
- Institute of Psychology, University of Bern, Bern, Switzerland
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The spontaneous location recognition task for assessing spatial pattern separation and memory across a delay in rats and mice. Nat Protoc 2021; 16:5616-5633. [PMID: 34741153 DOI: 10.1038/s41596-021-00627-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 09/02/2021] [Indexed: 11/08/2022]
Abstract
Keeping similar memories distinct from one another is a critical cognitive process without which we would have difficulty functioning in everyday life. Memories are thought to be kept distinct through the computational mechanism of pattern separation, which reduces overlap between similar input patterns to amplify differences among stored representations. At the behavioral level, impaired pattern separation has been shown to contribute to memory deficits seen in neuropsychiatric and neurodegenerative diseases, including Alzheimer's disease, and in normal aging. This protocol describes the use of the spontaneous location recognition (SLR) task in mice and rats to behaviorally assess spatial pattern separation ability. This two-phase spontaneous memory task assesses the extent to which animals can discriminate and remember object locations presented during the encoding phase. Using three configurations of the task, the similarity of the to-be-remembered locations can be parametrically manipulated by altering the spatial positions of objects-dissimilar, similar or extra similar-to vary the load on pattern separation. Unlike other pattern separation tasks, SLR varies the load on pattern separation during encoding, when pattern separation is thought to occur. Furthermore, SLR can be used in standard rodent behavioral facilities with basic expertise in rodent handling. The entire protocol takes ~20 d from habituation to testing of the animals on all three task configurations. By incorporating breaks between testing, and varying the objects used as landmarks, animals can be tested repeatedly, increasing experimental power by allowing for within-subjects manipulations.
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Krotkova OA, Kuleva AY, Galkin MV, Kaverina MY, Strunina YV, Danilov GV. Memory Modulation Factors in Hippocampus Exposed to Radiation. Sovrem Tekhnologii Med 2021; 13:6-13. [PMID: 34603759 PMCID: PMC8482834 DOI: 10.17691/stm2021.13.4.01] [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: 12/03/2020] [Indexed: 11/14/2022] Open
Abstract
Although the key scene of the hippocampus in memory processes is obvious, the specificity of its participation in information processing is far from being established. Current advanced neuroimaging enables to operate with precise morphometric parameters. The aim of the study was to reveal fine memory rearrangements under mechanical impact on the hippocampus by a neoplasm and radiation exposure in the course of therapy. Materials and Methods We used a homogeneous sample of 28 patients with parasellar meningiomas adjacent to hippocampus. In 10 patients (5 with left-sided and 5 with right-sided meningiomas), the tumor was located near the hippocampus but exhibited no mechanical effect on it. In 18 patients (10 with left-sided and 8 with right-sided tumors), the neoplasm compressed the adjacent hippocampus. The control group consisted of 39 healthy subjects. All three groups were comparable in age, education, and gender characteristics. In order to control tumor growth, the patients underwent radiotherapy when the hippocampus involuntary was exposed to a dose comparable to that in the tumor (30 sessions with a single focal dose of 1.8 Gy, total dose - 54.0 Gy).Based on the literature data on hippocampus involved in mnestic processes, a special methodology to investigate memory was developed. Incorrect responses the subjects made when identifying previously memorized images were classified as neutralizing the novelty factor of an identified stimulus or as wrongly emphasizing its novelty. Results At the first observation point (before radiation therapy) all groups underwent a complete standardized neuropsychological examination and performed a battery of cognitive tests. The overall results of the tests assessing attention, memory, thinking processes, and neurodynamic indicators corresponded to standard values. A mild brain compression by the tumor without brain tissue destruction was not accompanied by focal neuropsychological symptoms and deficit manifestations in the cognitive sphere. However, as early as in the first observation point, the number of "pattern separation" errors in the clinical group was significantly higher than that in healthy subjects.The second observation point (immediately after radiotherapy) and the third observation point - 6 months after the treatment - showed that, in general, the patients' cognitive sphere condition was not deteriorating, and in a number of parameters was characterized by positive dynamics, apparently associated with some tumor reduction due to the therapy provided. However, the distribution of errors in the original method significantly changed. When previously memorized stimuli were recognized, the errors neutralizing the novelty factor of the evaluated stimulus increased, while the number of errors with overestimating the stimuli novelty decreased.All tendencies hypothetically (according to the published data) associated with the changes in functional activity of the hippocampus were more pronounced in the subgroup of patients with mechanical impact of the tumor on hippocampus. Conclusion The continuous flow of impressions any person has at any moment of his activity is most likely marked by the hippocampus in a continuum "old-similar-new". The present study has shown that mechanical impact on the hippocampus combined with radiation exposure changes the range of assessments towards the prevailing labeling "old, previously seen, already known".
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Affiliation(s)
- O A Krotkova
- Senior Researcher, Rehabilitation Unit; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
| | - A Y Kuleva
- PhD Student; Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5A Butlerova St., Moscow, 117485, Russia
| | - M V Galkin
- Researcher, Radiotherapy Department; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
| | - M Y Kaverina
- Junior Researcher, Rehabilitation Unit; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
| | - Y V Strunina
- Managing Engineer; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
| | - G V Danilov
- Scientific Secretary; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia; Associate Professor, Neurosurgery Department; N.N. Burdenko National Medical Research Center for Neurosurgery, Ministry of Health of the Russian Federation, 16, 4 Tverskaya-Yamskaya St., Moscow, 125047, Russia
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Quian Quiroga R. Still challenging the pattern separation dogma: 'quiero retruco'. Trends Cogn Sci 2021; 25:923-924. [PMID: 34598878 DOI: 10.1016/j.tics.2021.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 08/24/2021] [Indexed: 11/25/2022]
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Rolls ET. On pattern separation in the primate, including human, hippocampus. Trends Cogn Sci 2021; 25:920-922. [PMID: 34598879 DOI: 10.1016/j.tics.2021.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/04/2021] [Accepted: 07/08/2021] [Indexed: 11/26/2022]
Affiliation(s)
- Edmund T Rolls
- Oxford Centre for Computational Neuroscience, Oxford, UK; Department of Computer Science, University of Warwick, Coventry, UK.
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Duplicate Detection of Spike Events: A Relevant Problem in Human Single-Unit Recordings. Brain Sci 2021; 11:brainsci11060761. [PMID: 34201115 PMCID: PMC8228483 DOI: 10.3390/brainsci11060761] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/29/2021] [Accepted: 06/01/2021] [Indexed: 11/21/2022] Open
Abstract
Single-unit recordings in the brain of behaving human subjects provide a unique opportunity to advance our understanding of neural mechanisms of cognition. These recordings are exclusively performed in medical centers during diagnostic or therapeutic procedures. The presence of medical instruments along with other aspects of the hospital environment limit the control of electrical noise compared to animal laboratory environments. Here, we highlight the problem of an increased occurrence of simultaneous spike events on different recording channels in human single-unit recordings. Most of these simultaneous events were detected in clusters previously labeled as artifacts and showed similar waveforms. These events may result from common external noise sources or from different micro-electrodes recording activity from the same neuron. To address the problem of duplicate recorded events, we introduce an open-source algorithm to identify these artificial spike events based on their synchronicity and waveform similarity. Applying our method to a comprehensive dataset of human single-unit recordings, we demonstrate that our algorithm can substantially increase the data quality of these recordings. Given our findings, we argue that future studies of single-unit activity recorded under noisy conditions should employ algorithms of this kind to improve data quality.
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How Are Memories Stored in the Human Hippocampus? Trends Cogn Sci 2021; 25:425-426. [PMID: 33820659 DOI: 10.1016/j.tics.2021.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 03/07/2021] [Indexed: 11/20/2022]
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Suthana N, Ekstrom AD, Yassa MA, Stark C. Pattern Separation in the Human Hippocampus: Response to Quiroga. Trends Cogn Sci 2021; 25:423-424. [PMID: 33820660 DOI: 10.1016/j.tics.2021.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/06/2021] [Accepted: 02/08/2021] [Indexed: 12/12/2022]
Affiliation(s)
- Nanthia Suthana
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA 90095, USA; Department of Neurosurgery, David Geffen School of Medicine and Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA 90095, USA; Department of Psychology, University of California, Los Angeles, CA 90095, USA; Department of Bioengineering, University of California, Los Angeles, CA 90095, USA.
| | - Arne D Ekstrom
- Psychology Department, University of Arizona, Tucson, AZ 85721, USA; Evelyn McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, USA
| | - Michael A Yassa
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA 92697, USA; Center for the Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA 92697, USA
| | - Craig Stark
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA 92697, USA; Center for the Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA 92697, USA
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