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Fenton AA. Remapping revisited: how the hippocampus represents different spaces. Nat Rev Neurosci 2024; 25:428-448. [PMID: 38714834 DOI: 10.1038/s41583-024-00817-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2024] [Indexed: 05/25/2024]
Abstract
The representation of distinct spaces by hippocampal place cells has been linked to changes in their place fields (the locations in the environment where the place cells discharge strongly), a phenomenon that has been termed 'remapping'. Remapping has been assumed to be accompanied by the reorganization of subsecond cofiring relationships among the place cells, potentially maximizing hippocampal information coding capacity. However, several observations challenge this standard view. For example, place cells exhibit mixed selectivity, encode non-positional variables, can have multiple place fields and exhibit unreliable discharge in fixed environments. Furthermore, recent evidence suggests that, when measured at subsecond timescales, the moment-to-moment cofiring of a pair of cells in one environment is remarkably similar in another environment, despite remapping. Here, I propose that remapping is a misnomer for the changes in place fields across environments and suggest instead that internally organized manifold representations of hippocampal activity are actively registered to different environments to enable navigation, promote memory and organize knowledge.
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Affiliation(s)
- André A Fenton
- Center for Neural Science, New York University, New York, NY, USA.
- Neuroscience Institute at the NYU Langone Medical Center, New York, NY, USA.
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2
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Mazzara C, Migliore M. A realistic computational model for the formation of a Place Cell. Sci Rep 2023; 13:21763. [PMID: 38066014 PMCID: PMC10709575 DOI: 10.1038/s41598-023-48183-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Hippocampal Place Cells (PCs) are pyramidal neurons showing spatially localized firing when an animal gets into a specific area within an environment. Because of their obvious and clear relation with specific cognitive functions, Place Cells operations and modulations are intensely studied experimentally. However, although a lot of data have been gathered since their discovery, the cellular processes that interplay to turn a hippocampal pyramidal neuron into a Place Cell are still not completely understood. Here, we used a morphologically and biophysically detailed computational model of a CA1 pyramidal neuron to show how, and under which conditions, it can turn into a neuron coding for a specific cue location, through the self-organization of its synaptic inputs in response to external signals targeting different dendritic layers. Our results show that the model is consistent with experimental findings demonstrating PCs stability within the same spatial context over different trajectories, environment rotations, and place field remapping to adapt to changes in the environment. To date, this is the only biophysically and morphologically accurate cellular model of PCs formation, which can be directly used in physiologically accurate microcircuits and large-scale model networks to study cognitive functions and dysfunctions at cellular level.
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Affiliation(s)
- Camille Mazzara
- Department of Promoting Health, Maternal-Infant. Excellence and Internal and Specialized Medicine (PROMISE) G. D'Alessandro, University of Palermo, Palermo, Italy
- Institute of Biophysics, National Research Council, Palermo, Italy
| | - Michele Migliore
- Institute of Biophysics, National Research Council, Palermo, Italy.
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3
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Baeuchl C, Glöckner F, Koch C, Petzold J, Schuck NW, Smolka MN, Li SC. Dopamine differentially modulates medial temporal lobe activity and behavior during spatial navigation in young and older adults. Neuroimage 2023; 273:120099. [PMID: 37037380 DOI: 10.1016/j.neuroimage.2023.120099] [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: 09/15/2022] [Revised: 01/13/2023] [Accepted: 04/07/2023] [Indexed: 04/12/2023] Open
Abstract
Aging is associated with changes in spatial navigation behavior. In addition to an overall performance decline, older adults tend to rely more on proximal location cue information than on environmental boundary information during spatial navigation compared to young adults. The fact that older adults are more susceptible to errors during spatial navigation might be partly attributed to deficient dopaminergic modulation of hippocampal and striatal functioning. Hence, elevating dopamine levels might differentially modulate spatial navigation and memory performance in young and older adults. In this work, we administered levodopa (L-DOPA) in a double-blind within-subject, placebo-controlled design and recorded functional neuroimaging while young and older adults performed a 3D spatial navigation task in which boundary geometry or the position of a location cue were systematically manipulated. An age by intervention interaction on the neural level revealed an upregulation of brain responses in older adults and a downregulation of responses in young adults within the medial temporal lobe (including hippocampus and parahippocampus) and brainstem, during memory retrieval. Behaviorally, L-DOPA had no effect on older adults' overall memory performance; however, older adults whose spatial memory improved under L-DOPA also showed a shift towards more boundary processing under L-DOPA. In young adults, L-DOPA induced a decline in spatial memory performance in task-naïve participants. These results are consistent with the inverted-U-shaped hypothesis of dopamine signaling and cognitive function and suggest that increasing dopamine availability improves hippocampus-dependent place learning in some older adults.
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Affiliation(s)
- Christian Baeuchl
- Faculty of Psychology, Technische Universität Dresden, Dresden, Germany.
| | - Franka Glöckner
- Faculty of Psychology, Technische Universität Dresden, Dresden, Germany
| | - Christoph Koch
- Max Planck Research Group NeuroCode, Max Planck Institute for Human Development, Berlin, Germany; International Max Planck Research School on the Life Course (LIFE), Max Planck Institute for Human Development, Berlin, Germany; Max Planck UCL Centre for Computational Psychiatry and Aging Research, Berlin, Germany
| | - Johannes Petzold
- Department of Psychiatry, Technische Universität Dresden, Dresden, Germany
| | - Nicolas W Schuck
- Max Planck Research Group NeuroCode, Max Planck Institute for Human Development, Berlin, Germany; Max Planck UCL Centre for Computational Psychiatry and Aging Research, Berlin, Germany; Institute of Psychology, Universität Hamburg, Hamburg, German
| | - Michael N Smolka
- Department of Psychiatry, Technische Universität Dresden, Dresden, Germany
| | - Shu-Chen Li
- Faculty of Psychology, Technische Universität Dresden, Dresden, Germany; Centre for Tactile Internet with Human-in-the-Loop, Technische Universität Dresden, Dresden, Germany
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4
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Animal-to-Animal Variability in Partial Hippocampal Remapping in Repeated Environments. J Neurosci 2022; 42:5268-5280. [PMID: 35641190 PMCID: PMC9236289 DOI: 10.1523/jneurosci.3221-20.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/11/2022] [Accepted: 05/10/2022] [Indexed: 12/31/2022] Open
Abstract
Hippocampal place cells form a map of the environment of an animal. Changes in the hippocampal map can be brought about in a number of ways, including changes to the environment, task, internal state of the subject, and the passage of time. These changes in the hippocampal map have been called remapping. In this study, we examine remapping during repeated exposure to the same environment. Different animals can have different remapping responses to the same changes. This variability across animals in remapping behavior is not well understood. In this work, we analyzed electrophysiological recordings from the CA3 region of the hippocampus performed by Alme et al. (2014), in which five male rats were exposed to 11 different environments, including a variety of repetitions of those environments. To compare the hippocampal maps between two experiences, we computed average rate map correlation coefficients. We found changes in the hippocampal maps between different sessions in the same environment. These changes consisted of partial remapping, a form of remapping in which some place cells maintain their place fields, whereas other place cells remap their place fields. Each animal exhibited partial remapping differently. We discovered that the heterogeneity in hippocampal representational changes across animals is structured; individual animals had consistently different levels of partial remapping across a range of independent comparisons. Our findings highlight that partial hippocampal remapping between repeated environments depends on animal-specific factors.SIGNIFICANCE STATEMENT Context identification is a difficult problem. Animals are not provided with objective context identity labels, so they must infer which experiences come from which contexts. Different animals may have different strategies for performing this inference. We find that different animals have stereotypically different extents of partial hippocampal remapping, a neural correlate of subjective assessment of context identity.
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Pittaras E, Hamelin H, Granon S. Inter-Individual Differences in Cognitive Tasks: Focusing on the Shaping of Decision-Making Strategies. Front Behav Neurosci 2022; 16:818746. [PMID: 35431831 PMCID: PMC9007591 DOI: 10.3389/fnbeh.2022.818746] [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: 11/19/2021] [Accepted: 01/24/2022] [Indexed: 11/13/2022] Open
Abstract
In this paper, we review recent (published and novel) data showing inter-individual variation in decision-making strategies established by mice in a gambling task (MGT for Mouse Gambling Task). It may look intriguing, at first, that congenic animals develop divergent behaviors. However, using large groups of mice, we show that individualities emerge in the MGT, with about 30% of healthy mice displaying risk-averse choices while about 20-25% of mice make risk-prone choices. These strategies are accompanied by different brain network mobilization and individual levels of regional -prefrontal and striatal- monoamines. We further illustrate three ecological ways that influence drastically cognitive strategies in healthy adult mice: sleep deprivation, sucrose or artificial sweetener exposure, and regular exposure to stimulating environments. Questioning how to unmask individual strategies, what are their neural/neurochemical bases and whether we can shape or reshape them with different environmental manipulations is of great value, first to understand how the brain may build flexible decisions, and second to study behavioral plasticity, in healthy adult, as well as in developing brains. The latter may open new avenues for the identification of vulnerability traits to adverse events, before the emergence of mental pathologies.
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Affiliation(s)
- Elsa Pittaras
- Heller Laboratory, Department of Biology, Stanford University, Stanford, CA, United States
| | - Héloïse Hamelin
- Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Saclay, France
| | - Sylvie Granon
- Institut des Neurosciences Paris-Saclay, CNRS UMR 9197, Saclay, France
- *Correspondence: Sylvie Granon,
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6
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Dvorak D, Chung A, Park EH, Fenton AA. Dentate spikes and external control of hippocampal function. Cell Rep 2021; 36:109497. [PMID: 34348165 PMCID: PMC8369486 DOI: 10.1016/j.celrep.2021.109497] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 06/04/2021] [Accepted: 07/14/2021] [Indexed: 11/11/2022] Open
Abstract
Mouse hippocampus CA1 place-cell discharge typically encodes current location, but during slow gamma dominance (SGdom), when SG oscillations (30-50 Hz) dominate mid-frequency gamma oscillations (70-90 Hz) in CA1 local field potentials, CA1 discharge switches to represent distant recollected locations. We report that dentate spike type 2 (DSM) events initiated by medial entorhinal cortex II (MECII)→ dentate gyrus (DG) inputs promote SGdom and change excitation-inhibition coordinated discharge in DG, CA3, and CA1, whereas type 1 (DSL) events initiated by lateral entorhinal cortex II (LECII)→DG inputs do not. Just before SGdom, LECII-originating SG oscillations in DG and CA3-originating SG oscillations in CA1 phase and frequency synchronize at the DSM peak when discharge within DG and CA3 increases to promote excitation-inhibition cofiring within and across the DG→CA3→CA1 pathway. This optimizes discharge for the 5-10 ms DG-to-CA1 neuro-transmission that SGdom initiates. DSM properties identify extrahippocampal control of SGdom and a cortico-hippocampal mechanism that switches between memory-related modes of information processing.
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Affiliation(s)
- Dino Dvorak
- Center for Neural Science, New York University, New York, NY 10003, USA
| | - Ain Chung
- Center for Neural Science, New York University, New York, NY 10003, USA
| | - Eun Hye Park
- Center for Neural Science, New York University, New York, NY 10003, USA
| | - André Antonio Fenton
- Center for Neural Science, New York University, New York, NY 10003, USA; Neuroscience Institute at the NYU Langone Medical Center, New York, NY 10003, USA.
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7
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Frost BE, Martin SK, Cafalchio M, Islam MN, Aggleton JP, O'Mara SM. Anterior Thalamic Inputs Are Required for Subiculum Spatial Coding, with Associated Consequences for Hippocampal Spatial Memory. J Neurosci 2021; 41:6511-6525. [PMID: 34131030 PMCID: PMC8318085 DOI: 10.1523/jneurosci.2868-20.2021] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 03/24/2021] [Accepted: 03/28/2021] [Indexed: 11/21/2022] Open
Abstract
Just as hippocampal lesions are principally responsible for "temporal lobe" amnesia, lesions affecting the anterior thalamic nuclei seem principally responsible for a similar loss of memory, "diencephalic" amnesia. Compared with the former, the causes of diencephalic amnesia have remained elusive. A potential clue comes from how the two sites are interconnected, as within the hippocampal formation, only the subiculum has direct, reciprocal connections with the anterior thalamic nuclei. We found that both permanent and reversible anterior thalamic nuclei lesions in male rats cause a cessation of subicular spatial signaling, reduce spatial memory performance to chance, but leave hippocampal CA1 place cells largely unaffected. We suggest that a core element of diencephalic amnesia stems from the information loss in hippocampal output regions following anterior thalamic pathology.SIGNIFICANCE STATEMENT At present, we know little about interactions between temporal lobe and diencephalic memory systems. Here, we focused on the subiculum, as the sole hippocampal formation region directly interconnected with the anterior thalamic nuclei. We combined reversible and permanent lesions of the anterior thalamic nuclei, electrophysiological recordings of the subiculum, and behavioral analyses. Our results were striking and clear: following permanent thalamic lesions, the diverse spatial signals normally found in the subiculum (including place cells, grid cells, and head-direction cells) all disappeared. Anterior thalamic lesions had no discernible impact on hippocampal CA1 place fields. Thus, spatial firing activity within the subiculum requires anterior thalamic function, as does successful spatial memory performance. Our findings provide a key missing part of the much bigger puzzle concerning why anterior thalamic damage is so catastrophic for spatial memory in rodents and episodic memory in humans.
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Affiliation(s)
- Bethany E Frost
- School of Psychology and Institute of Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Sean K Martin
- School of Psychology and Institute of Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Matheus Cafalchio
- School of Psychology and Institute of Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Md Nurul Islam
- School of Psychology and Institute of Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - John P Aggleton
- School of Psychology, Cardiff University, Cardiff, CF10 3AS, United Kingdom
| | - Shane M O'Mara
- School of Psychology and Institute of Neuroscience, Trinity College Dublin, Dublin, D02 PN40, Ireland
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Sheintuch L, Geva N, Baumer H, Rechavi Y, Rubin A, Ziv Y. Multiple Maps of the Same Spatial Context Can Stably Coexist in the Mouse Hippocampus. Curr Biol 2020; 30:1467-1476.e6. [PMID: 32220328 DOI: 10.1016/j.cub.2020.02.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/15/2020] [Accepted: 02/07/2020] [Indexed: 11/29/2022]
Abstract
Hippocampal place cells selectively fire when an animal traverses a particular location and are considered a neural substrate of spatial memory. Place cells were shown to change their activity patterns (remap) across different spatial contexts but to maintain their spatial tuning in a fixed familiar context. Here, we show that mouse hippocampal neurons can globally remap, forming multiple distinct representations (maps) of the same familiar environment, without any apparent changes in sensory input or behavior. Alternations between maps occurred only across separate visits to the environment, implying switching between distinct stable attractors in the hippocampal network. Importantly, the different maps were spatially informative and persistent over weeks, demonstrating that they can be reliably stored and retrieved from long-term memory. Taken together, our results suggest that a memory of a given spatial context could be associated with multiple distinct neuronal representations, rather than just one.
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Affiliation(s)
- Liron Sheintuch
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Nitzan Geva
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Hadas Baumer
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yoav Rechavi
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alon Rubin
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Yaniv Ziv
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel.
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9
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Tudela R, Muñoz-Moreno E, Sala-Llonch R, López-Gil X, Soria G. Resting State Networks in the TgF344-AD Rat Model of Alzheimer's Disease Are Altered From Early Stages. Front Aging Neurosci 2019; 11:213. [PMID: 31440158 PMCID: PMC6694297 DOI: 10.3389/fnagi.2019.00213] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 07/26/2019] [Indexed: 12/12/2022] Open
Abstract
A better and non-invasive characterization of the preclinical phases of Alzheimer's disease (AD) is important to advance its diagnosis and obtain more effective benefits from potential treatments. The TgF344-AD rat model has been well characterized and shows molecular, behavioral and brain connectivity alterations that resemble the silent period of the pathology. Our aim was to longitudinally investigate functional brain connectivity in established resting-state networks (RSNs) obtained by independent component analysis (ICA) in a cohort of TgF344-AD and control rats every 3 months, from 5 to 18 months of age, to cover different stages of the disease. Before each acquisition, working memory performance was evaluated by the delayed non match-to-sample (DNMS) task. Differences in the temporal evolution were observed between groups in the amplitude and shape of the somatosensorial and sensorimotor networks but not in the whole default mode network (DMN). Subsequent high dimensional ICA analysis showed early alterations in the anterior DMN subnetwork activity of TgF344-AD rats compared to controls. Performance of DNMS task was positively correlated with somatosensorial network at 5 months of age in the wild-type (WT) animals but not in the Tg-F344 rats. At different time points, DMN showed negative correlation with cognitive performance in the control group while in the transgenic group the correlation was positive. In addition, behavioral differences observed at 5 months of age correlated with alterations in the posterior DMN subnetwork. We have demonstrated that functional connectivity using ICA represents a useful biomarker also in animal models of AD such as the TgF344AD rats, as it allows the identification of alterations associated with the progression of the disease, detecting differences in specific networks even at very early stages.
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Affiliation(s)
- Raúl Tudela
- Consorcio Centro de Investigación Biomédica en Red (CIBER) de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Group of Biomedical Imaging, University of Barcelona, Barcelona, Spain
| | - Emma Muñoz-Moreno
- Experimental 7T MRI Unit, Institut d’Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
| | - Roser Sala-Llonch
- Department of Biomedicine, Faculty of Medicine, University of Barcelona, Barcelona, Spain
| | - Xavier López-Gil
- Experimental 7T MRI Unit, Institut d’Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
| | - Guadalupe Soria
- Consorcio Centro de Investigación Biomédica en Red (CIBER) de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Group of Biomedical Imaging, University of Barcelona, Barcelona, Spain
- Experimental 7T MRI Unit, Institut d’Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain
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10
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Pennartz CMA, Farisco M, Evers K. Indicators and Criteria of Consciousness in Animals and Intelligent Machines: An Inside-Out Approach. Front Syst Neurosci 2019; 13:25. [PMID: 31379521 PMCID: PMC6660257 DOI: 10.3389/fnsys.2019.00025] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 06/24/2019] [Indexed: 01/02/2023] Open
Abstract
In today's society, it becomes increasingly important to assess which non-human and non-verbal beings possess consciousness. This review article aims to delineate criteria for consciousness especially in animals, while also taking into account intelligent artifacts. First, we circumscribe what we mean with "consciousness" and describe key features of subjective experience: qualitative richness, situatedness, intentionality and interpretation, integration and the combination of dynamic and stabilizing properties. We argue that consciousness has a biological function, which is to present the subject with a multimodal, situational survey of the surrounding world and body, subserving complex decision-making and goal-directed behavior. This survey reflects the brain's capacity for internal modeling of external events underlying changes in sensory state. Next, we follow an inside-out approach: how can the features of conscious experience, correlating to mechanisms inside the brain, be logically coupled to externally observable ("outside") properties? Instead of proposing criteria that would each define a "hard" threshold for consciousness, we outline six indicators: (i) goal-directed behavior and model-based learning; (ii) anatomic and physiological substrates for generating integrative multimodal representations; (iii) psychometrics and meta-cognition; (iv) episodic memory; (v) susceptibility to illusions and multistable perception; and (vi) specific visuospatial behaviors. Rather than emphasizing a particular indicator as being decisive, we propose that the consistency amongst these indicators can serve to assess consciousness in particular species. The integration of scores on the various indicators yields an overall, graded criterion for consciousness, somewhat comparable to the Glasgow Coma Scale for unresponsive patients. When considering theoretically derived measures of consciousness, it is argued that their validity should not be assessed on the basis of a single quantifiable measure, but requires cross-examination across multiple pieces of evidence, including the indicators proposed here. Current intelligent machines, including deep learning neural networks (DLNNs) and agile robots, are not indicated to be conscious yet. Instead of assessing machine consciousness by a brief Turing-type of test, evidence for it may gradually accumulate when we study machines ethologically and across time, considering multiple behaviors that require flexibility, improvisation, spontaneous problem-solving and the situational conspectus typically associated with conscious experience.
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Affiliation(s)
- Cyriel M. A. Pennartz
- Department of Cognitive and Systems Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
- Research Priority Area, Brain and Cognition, University of Amsterdam, Amsterdam, Netherlands
| | - Michele Farisco
- Centre for Research Ethics and Bioethics, Uppsala University, Uppsala, Sweden
- Biogem, Biology and Molecular Genetics Institute, Ariano Irpino, Italy
| | - Kathinka Evers
- Centre for Research Ethics and Bioethics, Uppsala University, Uppsala, Sweden
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11
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Li AWY, King J. Spatial memory and navigation in ageing: A systematic review of MRI and fMRI studies in healthy participants. Neurosci Biobehav Rev 2019; 103:33-49. [PMID: 31129234 DOI: 10.1016/j.neubiorev.2019.05.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 05/02/2019] [Accepted: 05/08/2019] [Indexed: 01/04/2023]
Abstract
AIM Spatial deficits are widely observed in normal ageing and early Alzheimer's disease. This review systematically examined neuroimaging evidence for structural and functional differences in the hippocampus (HC) associated with non-pathological age-related changes in allocentric spatial abilities. METHODS Databases were searched to identify peer-reviewed studies on allocentric spatial processing in normal ageing including MRI or fMRI data. 15 eligible studies were reviewed after applying exclusion criteria and quality assessment. RESULTS There was a marked deficit in allocentric spatial processing and trend towards egocentric strategies in older adults when compared to young controls or across the lifespan, associated in the majority of studies with HC volumetric changes, metabolic or microstructural indicators, and underactivity. A few studies reported no significant correlations. CONCLUSION Findings confirm literature supporting an age-related allocentric spatial processing deficit and a shift towards egocentric strategies. A majority of studies implicated HC atrophy, microstructural/metabolic alterations or functional changes in age-related allocentric spatial impairment. More sensitive imaging techniques and ecologically valid spatial tasks are needed to detect subtle changes in the HC and brain's navigational network.
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Affiliation(s)
- Adrienne W Y Li
- Department of Clinical, Educational and Health Psychology, University College London, Gower Street, London WC1E 6BT, United Kingdom.
| | - John King
- Department of Clinical, Educational and Health Psychology, University College London, Gower Street, London WC1E 6BT, United Kingdom
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12
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Mamad O, Agayby B, Stumpp L, Reilly RB, Tsanov M. Extrafield Activity Shifts the Place Field Center of Mass to Encode Aversive Experience. eNeuro 2019; 6:ENEURO.0423-17.2019. [PMID: 30923741 PMCID: PMC6437659 DOI: 10.1523/eneuro.0423-17.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 12/21/2018] [Accepted: 01/14/2019] [Indexed: 11/21/2022] Open
Abstract
Hippocampal place cells are known to have a key role in encoding spatial information. Aversive stimuli, such as predator odor, evoke place field remapping and a change in preferred firing locations. However, it remains unclear how place cells use positive or negative experiences to remap. We investigated whether CA1 place cells, recorded from behaving rats, remap randomly or whether their reconfiguration depends on the perceived location of the aversive stimulus. Exposure to trimethylthiazoline (TMT; an innately aversive odor), increased the amplitude of hippocampal β oscillations in the two arms of the maze in which TMT exposure occurred. We found that a population of place cells with fields located outside the TMT arms increased their activity (extrafield spiking) in the TMT arms during the aversive episodes. Moreover, in the subsequent post-TMT recording, these cells exhibited a significant shift in their center of mass (COM) towards the TMT arms. The induction of extrafield plasticity was mediated by the basolateral amygdala complex (BLA). Photostimulation of the BLA triggered aversive behavior, synchronized hippocampal local field oscillations, and increased the extrafield spiking of the hippocampal place cells for the first 100 ms after light delivery. Optogenetic BLA activation triggered an increase in extrafield spiking activity that was correlated with the degree of place field plasticity. Furthermore, BLA-mediated increase of the extrafield activity predicts the degree of subsequent field plasticity. Our findings demonstrate that that the remapping of hippocampal place cells during aversive episodes is not random but it depends on the location of the aversive stimulus.
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Affiliation(s)
- Omar Mamad
- Trinity College Institute of Neuroscience
- School of Psychology
| | - Beshoy Agayby
- Trinity College Institute of Neuroscience
- Trinity Centre for Bioengineering
- School of Engineering
| | - Lars Stumpp
- Trinity College Institute of Neuroscience
- Trinity Centre for Bioengineering
- School of Engineering
| | - Richard B. Reilly
- Trinity College Institute of Neuroscience
- Trinity Centre for Bioengineering
- School of Engineering
- School of Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Marian Tsanov
- Trinity College Institute of Neuroscience
- School of Psychology
- School of Medicine, Trinity College Dublin, Dublin 2, Ireland
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13
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Babichev A, Morozov D, Dabaghian Y. Robust spatial memory maps encoded by networks with transient connections. PLoS Comput Biol 2018; 14:e1006433. [PMID: 30226836 PMCID: PMC6161922 DOI: 10.1371/journal.pcbi.1006433] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 09/28/2018] [Accepted: 08/15/2018] [Indexed: 11/25/2022] Open
Abstract
The spiking activity of principal cells in mammalian hippocampus encodes an internalized neuronal representation of the ambient space—a cognitive map. Once learned, such a map enables the animal to navigate a given environment for a long period. However, the neuronal substrate that produces this map is transient: the synaptic connections in the hippocampus and in the downstream neuronal networks never cease to form and to deteriorate at a rapid rate. How can the brain maintain a robust, reliable representation of space using a network that constantly changes its architecture? We address this question using a computational framework that allows evaluating the effect produced by the decaying connections between simulated hippocampal neurons on the properties of the cognitive map. Using novel Algebraic Topology techniques, we demonstrate that emergence of stable cognitive maps produced by networks with transient architectures is a generic phenomenon. The model also points out that deterioration of the cognitive map caused by weakening or lost connections between neurons may be compensated by simulating the neuronal activity. Lastly, the model explicates the importance of the complementary learning systems for processing spatial information at different levels of spatiotemporal granularity. The reliability of our memories is nothing short of remarkable. Synaptic connections between neurons appear and disappear at a rapid rate, and the resulting networks constantly change their architecture due to various forms of neural plasticity. How can the brain develop a reliable representation of the world, learn and retain memories despite, or perhaps due to, such complex dynamics? Below we address these questions by modeling mechanisms of spatial learning in the hippocampal network, using novel algebraic topology methods. We demonstrate that although the functional units of the hippocampal network—the place cell assemblies—are unstable structures that may appear and disappear, the spatial memory map produced by a sufficiently large population of such assemblies robustly captures the topological structure of the environment.
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Affiliation(s)
- Andrey Babichev
- Department of Computational and Applied Mathematics, Rice University, Houston, Texas, United States of America
| | - Dmitriy Morozov
- Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Berkeley Institute for Data Science, University of California - Berkeley, Berkeley, California, United States of America
| | - Yuri Dabaghian
- Department of Neurology, The University of Texas McGovern Medical School, Houston, Texas, United States of America
- * E-mail:
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Barlow S, Fahey B, Smith KJ, Passecker J, Della-Chiesa A, Hok V, Day JS, Callaghan CK, O’Mara SM. Deficits in temporal order memory induced by interferon-alpha (IFN-α) treatment are rescued by aerobic exercise. Brain Res Bull 2018; 140:212-219. [DOI: 10.1016/j.brainresbull.2018.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/10/2018] [Accepted: 05/15/2018] [Indexed: 01/18/2023]
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15
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Normal CA1 Place Fields but Discoordinated Network Discharge in a Fmr1-Null Mouse Model of Fragile X Syndrome. Neuron 2018; 97:684-697.e4. [PMID: 29358017 DOI: 10.1016/j.neuron.2017.12.043] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 10/06/2017] [Accepted: 12/27/2017] [Indexed: 11/21/2022]
Abstract
Silence of FMR1 causes loss of fragile X mental retardation protein (FMRP) and dysregulated translation at synapses, resulting in the intellectual disability and autistic symptoms of fragile X syndrome (FXS). Synaptic dysfunction hypotheses for how intellectual disabilities like cognitive inflexibility arise in FXS predict impaired neural coding in the absence of FMRP. We tested the prediction by comparing hippocampus place cells in wild-type and FXS-model mice. Experience-driven CA1 synaptic function and synaptic plasticity changes are excessive in Fmr1-null mice, but CA1 place fields are normal. However, Fmr1-null discharge relationships to local field potential oscillations are abnormally weak, stereotyped, and homogeneous; also, discharge coordination within Fmr1-null place cell networks is weaker and less reliable than wild-type. Rather than disruption of single-cell neural codes, these findings point to invariant tuning of single-cell responses and inadequate discharge coordination within neural ensembles as a pathophysiological basis of cognitive inflexibility in FXS. VIDEO ABSTRACT.
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Cholvin T, Hok V, Giorgi L, Chaillan FA, Poucet B. Ventral Midline Thalamus Is Necessary for Hippocampal Place Field Stability and Cell Firing Modulation. J Neurosci 2018; 38:158-172. [PMID: 29133436 PMCID: PMC6705806 DOI: 10.1523/jneurosci.2039-17.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/12/2017] [Accepted: 11/07/2017] [Indexed: 12/21/2022] Open
Abstract
The reuniens (Re) and rhomboid (Rh) nuclei of the ventral midline thalamus are reciprocally connected with the hippocampus (Hip) and the medial prefrontal cortex (mPFC). Growing evidence suggests that these nuclei might play a crucial role in cognitive processes requiring Hip-mPFC interactions, including spatial navigation. Here, we tested the effect of ReRh lesions on the firing properties and spatial activity of dorsal hippocampal CA1 place cells as male rats explored a familiar or a novel environment. We found no change in the spatial characteristics of CA1 place cells in the familiar environment following ReRh lesions. Contrariwise, spatial coherence was decreased during the first session in a novel environment. We then investigated field stability of place cells recorded across 5 d both in the familiar and in a novel environment presented in a predefined sequence. While the remapping capacity of the place cells was not affected by the lesion, our results clearly demonstrated a disruption of the CA1 cellular representation of both environments in ReRh rats. More specifically, we found ReRh lesions to produce (1) a pronounced and long-lasting decrease of place field stability and (2) a strong alteration of overdispersion (i.e., firing variability). Thus, in ReRh rats, exploration of a novel environment appears to interfere with the representation of the familiar one, leading to decreased field stability in both environments. The present study shows the involvement of ReRh nuclei in the long-term spatial stability of CA1 place fields.SIGNIFICANCE STATEMENT Growing evidence suggest that the ventral midline thalamic nuclei (reuniens and rhomboid) might play a substantial role in various cognitive tasks including spatial memory. In the present article, we show that the lesions of these nuclei impair the spatial representations encoded by CA1 place cells of both familiar and novel environments. First, reduced variability of place cell firing appears to indicate an impairment of attentional processes. Second, impaired stability of place cell representations could explain the long-term memory deficits observed in previous behavioral studies.
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Affiliation(s)
- Thibault Cholvin
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
| | - Vincent Hok
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
| | - Lisa Giorgi
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
| | - Franck A Chaillan
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
| | - Bruno Poucet
- Laboratoire de Neurosciences Cognitives and
- Federation 3C, CNRS, Aix Marseille University, 13331 Marseille, France
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17
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Lester AW, Moffat SD, Wiener JM, Barnes CA, Wolbers T. The Aging Navigational System. Neuron 2017; 95:1019-1035. [PMID: 28858613 PMCID: PMC5659315 DOI: 10.1016/j.neuron.2017.06.037] [Citation(s) in RCA: 207] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/20/2017] [Accepted: 06/22/2017] [Indexed: 12/17/2022]
Abstract
The discovery of neuronal systems dedicated to computing spatial information, composed of functionally distinct cell types such as place and grid cells, combined with an extensive body of human-based behavioral and neuroimaging research has provided us with a detailed understanding of the brain's navigation circuit. In this review, we discuss emerging evidence from rodents, non-human primates, and humans that demonstrates how cognitive aging affects the navigational computations supported by these systems. Critically, we show 1) that navigational deficits cannot solely be explained by general deficits in learning and memory, 2) that there is no uniform decline across different navigational computations, and 3) that navigational deficits might be sensitive markers for impending pathological decline. Following an introduction to the mechanisms underlying spatial navigation and how they relate to general processes of learning and memory, the review discusses how aging affects the perception and integration of spatial information, the creation and storage of memory traces for spatial information, and the use of spatial information during navigational behavior. The closing section highlights the clinical potential of behavioral and neural markers of spatial navigation, with a particular emphasis on neurodegenerative disorders.
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Affiliation(s)
- Adam W Lester
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, USA; Division of Neural Systems, Memory and Aging, University of Arizona, Tucson, AZ 85721, USA
| | - Scott D Moffat
- School of Psychology, Georgia Institute of Technology, Atlanta, GA 30332 USA
| | - Jan M Wiener
- Department of Psychology, Ageing and Dementia Institute, Bournemouth University, Poole BH12 5BB, UK
| | - Carol A Barnes
- Evelyn F. McKnight Brain Institute, University of Arizona, Tucson, AZ 85721, USA; Division of Neural Systems, Memory and Aging, University of Arizona, Tucson, AZ 85721, USA; Departments of Psychology, Neurology, and Neuroscience, University of Arizona, Tucson, AZ 85721, USA
| | - Thomas Wolbers
- German Center for Neurodegenerative Diseases (DZNE), Aging and Cognition Research Group, 39120 Magdeburg, Germany; Center for Behavioral Brain Sciences (CBBS), 39118 Magdeburg, Germany.
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18
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Chen X, McNamara TP, Kelly JW, Wolbers T. Cue combination in human spatial navigation. Cogn Psychol 2017; 95:105-144. [PMID: 28478330 DOI: 10.1016/j.cogpsych.2017.04.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 04/09/2017] [Accepted: 04/12/2017] [Indexed: 11/28/2022]
Abstract
This project investigated the ways in which visual cues and bodily cues from self-motion are combined in spatial navigation. Participants completed a homing task in an immersive virtual environment. In Experiments 1A and 1B, the reliability of visual cues and self-motion cues was manipulated independently and within-participants. Results showed that participants weighted visual cues and self-motion cues based on their relative reliability and integrated these two cue types optimally or near-optimally according to Bayesian principles under most conditions. In Experiment 2, the stability of visual cues was manipulated across trials. Results indicated that cue instability affected cue weights indirectly by influencing cue reliability. Experiment 3 was designed to mislead participants about cue reliability by providing distorted feedback on the accuracy of their performance. Participants received feedback that their performance with visual cues was better and that their performance with self-motion cues was worse than it actually was or received the inverse feedback. Positive feedback on the accuracy of performance with a given cue improved the relative precision of performance with that cue. Bayesian principles still held for the most part. Experiment 4 examined the relations among the variability of performance, rated confidence in performance, cue weights, and spatial abilities. Participants took part in the homing task over two days and rated confidence in their performance after every trial. Cue relative confidence and cue relative reliability had unique contributions to observed cue weights. The variability of performance was less stable than rated confidence over time. Participants with higher mental rotation scores performed relatively better with self-motion cues than visual cues. Across all four experiments, consistent correlations were found between observed weights assigned to cues and relative reliability of cues, demonstrating that the cue-weighting process followed Bayesian principles. Results also pointed to the important role of subjective evaluation of performance in the cue-weighting process and led to a new conceptualization of cue reliability in human spatial navigation.
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Affiliation(s)
- Xiaoli Chen
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.
| | | | | | - Thomas Wolbers
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
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Integrating Spatial Working Memory and Remote Memory: Interactions between the Medial Prefrontal Cortex and Hippocampus. Brain Sci 2017; 7:brainsci7040043. [PMID: 28420200 PMCID: PMC5406700 DOI: 10.3390/brainsci7040043] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/11/2017] [Accepted: 04/14/2017] [Indexed: 12/22/2022] Open
Abstract
In recent years, two separate research streams have focused on information sharing between the medial prefrontal cortex (mPFC) and hippocampus (HC). Research into spatial working memory has shown that successful execution of many types of behaviors requires synchronous activity in the theta range between the mPFC and HC, whereas studies of memory consolidation have shown that shifts in area dependency may be temporally modulated. While the nature of information that is being communicated is still unclear, spatial working memory and remote memory recall is reliant on interactions between these two areas. This review will present recent evidence that shows that these two processes are not as separate as they first appeared. We will also present a novel conceptualization of the nature of the medial prefrontal representation and how this might help explain this area’s role in spatial working memory and remote memory recall.
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20
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Hok V, Poucet B, Duvelle É, Save É, Sargolini F. Spatial cognition in mice and rats: similarities and differences in brain and behavior. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2016; 7:406-421. [PMID: 27582415 DOI: 10.1002/wcs.1411] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 07/07/2016] [Accepted: 07/19/2016] [Indexed: 01/05/2023]
Abstract
The increasing use of mice models in cognitive tasks that were originally designed for rats raises crucial questions about cross-species comparison in the study of spatial cognition. The present review focuses on the major neuroethological differences existing between mice and rats, with particular attention given to the neurophysiological basis of space coding. While little difference is found in the basic properties of space representation in these two species, it appears that the stability of this representation changes more drastically over time in mice than in rats. We consider several hypotheses dealing with attentional, perceptual, and genetic aspects and offer some directions for future research that might help in deciphering hippocampal function in learning and memory processes. WIREs Cogn Sci 2016, 7:406-421. doi: 10.1002/wcs.1411 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Vincent Hok
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University, Marseille, France.,Fédération 3C, CNRS and Aix-Marseille University, Marseille, France
| | - Bruno Poucet
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University, Marseille, France. , .,Fédération 3C, CNRS and Aix-Marseille University, Marseille, France. ,
| | - Éléonore Duvelle
- Faculty of Brain Sciences, UCL Psychology and Language Sciences, London, UK
| | - Étienne Save
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University, Marseille, France.,Fédération 3C, CNRS and Aix-Marseille University, Marseille, France
| | - Francesca Sargolini
- Laboratory of Cognitive Neuroscience, CNRS and Aix-Marseille University, Marseille, France.,Fédération 3C, CNRS and Aix-Marseille University, Marseille, France.,Institut Universitaire de France, Paris, France
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21
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Jankowski MM, O'Mara SM. Dynamics of place, boundary and object encoding in rat anterior claustrum. Front Behav Neurosci 2015; 9:250. [PMID: 26557060 PMCID: PMC4617374 DOI: 10.3389/fnbeh.2015.00250] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/28/2015] [Indexed: 11/13/2022] Open
Abstract
Discrete populations of brain cells signal differing types of spatial information. These "spatial cells" are largely confined to a closely-connected network of sites. We describe here, for the first time, cells in the anterior claustrum of the freely-moving rat encoding place, boundary and object information. This novel claustral spatial signal potentially directly modulates a wide variety of anterior cortical regions. We hypothesize that one of the functions of the claustrum is to provide information about body position, boundaries and landmark information, enabling dynamic control of behavior.
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Affiliation(s)
| | - Shane M O'Mara
- Institute of Neuroscience, Trinity College Dublin, Ireland
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22
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Jankowski MM, Passecker J, Islam MN, Vann S, Erichsen JT, Aggleton JP, O'Mara SM. Evidence for spatially-responsive neurons in the rostral thalamus. Front Behav Neurosci 2015; 9:256. [PMID: 26528150 PMCID: PMC4602090 DOI: 10.3389/fnbeh.2015.00256] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 09/07/2015] [Indexed: 12/30/2022] Open
Abstract
Damage involving the anterior thalamic and adjacent rostral thalamic nuclei may result in a severe anterograde amnesia, similar to the amnesia resulting from damage to the hippocampal formation. Little is known, however, about the information represented in these nuclei. To redress this deficit, we recorded units in three rostral thalamic nuclei in freely-moving rats [the parataenial nucleus (PT), the anteromedial nucleus (AM) and nucleus reuniens NRe]. We found units in these nuclei possessing previously unsuspected spatial properties. The various cell types show clear similarities to place cells, head direction cells, and perimeter/border cells described in hippocampal and parahippocampal regions. Based on their connectivity, it had been predicted that the anterior thalamic nuclei process information with high spatial and temporal resolution while the midline nuclei have more diffuse roles in attention and arousal. Our current findings strongly support the first prediction but directly challenge or substantially moderate the second prediction. The rostral thalamic spatial cells described here may reflect direct hippocampal/parahippocampal inputs, a striking finding of itself, given the relative lack of place cells in other sites receiving direct hippocampal formation inputs. Alternatively, they may provide elemental thalamic spatial inputs to assist hippocampal spatial computations. Finally, they could represent a parallel spatial system in the brain.
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Affiliation(s)
| | | | - Md Nurul Islam
- Institute of Neuroscience, Trinity College Dublin Dublin, Ireland
| | | | | | | | - Shane M O'Mara
- Institute of Neuroscience, Trinity College Dublin Dublin, Ireland
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23
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López-Avalos MD, Fernández-Llebrez Zayas R, Cifuentes M, De Andrés MV, Fernández-Llebrez Del Rey P, Grondona JM, Pérez-Martín M, Pedraza C. Mente Activa® Improves Impaired Spatial Memory in Aging Rats. J Nutr Health Aging 2015; 19:819-27. [PMID: 26412286 DOI: 10.1007/s12603-015-0546-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Aging is accompanied by a decline in several aspects of the cognitive function, having negative personal and socioeconomic impacts. Dietary supplements could be beneficial for preventing age-related cognitive decline. In this context, we examined whether the nutritional supplement Mente Activa® has beneficial effects on aging-related cognitive deficits without inducing side effects. METHODS Mente Activa® was administered to old rats (n= 30 treated rats and n= 30 control rats) during 5 months, and the Morris water maze was used to test the learning capacities of the animals. The first assessment was conducted before the nutritional intervention (age of 18-19 months), to determine the baseline of the performance of animals on this test, and the second assessment was performed at the end of the treatment (23-24 moths). In order to examine possible secondary effects of this nutritional supplement, plasma, heart anatomy and liver parameters were evaluated. RESULTS Our data indicate that supplemented rats showed less escape latency, distance swum, higher use of spatial search strategies, and crossed the former platform location with higher frequency than control rats. These effects were specific of the treatment, indicating that this nutritional supplement has a beneficial effect on spatial memory. On the other hand, the regular intake of Mente Activa® did not induce any negative effects in plasma parameters and heart size. CONCLUSIONS Aged rats under a sustained dietary intake of the nutritional supplement Mente Activa® displayed improved learning and memory abilities compared to the non-treated rats. These results suggest the therapeutic potential and safety of use of Mente Activa® for age-related cognitive deficits, particularly, in the onset of the first cognitive dysfunction symptoms.
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Affiliation(s)
- M D López-Avalos
- C. Pedraza, Dpto. Psicobiología y Metodología de las CC. Facultad de Psicología. Universidad de Málaga, Campus de Teatinos s/n., Málaga, 29071. Spain, Tel: +34 952 132 510; Fax: +34 952 134 142, E-mail:
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24
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Jones BJ, Pest SM, Vargas IM, Glisky EL, Fellous JM. Contextual reminders fail to trigger memory reconsolidation in aged rats and aged humans. Neurobiol Learn Mem 2015; 120:7-15. [PMID: 25698469 DOI: 10.1016/j.nlm.2015.02.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 01/16/2015] [Accepted: 02/02/2015] [Indexed: 11/29/2022]
Abstract
There is strong evidence that hippocampal memory returns to a labile state upon reactivation, initiating a reconsolidation process that restabilizes it and allows for its updating. Normal aging is associated with deficits in episodic memory processes. However, the effects of aging on memory reconsolidation and its neural substrate remain largely unknown, and an animal model is lacking. In this study we investigated the effects of aging on context-dependent reconsolidation using an episodic set-learning task in humans and an analogous set-learning spatial task in rats. In both tasks, young and older subjects learned a set of objects (humans) or feeder locations (rats; Set 1) in Context A on Day 1. On Day 2, a different set (Set 2) was learned in either Context A (Reminder condition) or Context B (No Reminder condition). On Day 3, subjects were instructed (humans) or cued (rats) to recall Set 1. Young rats and humans in the Reminder condition falsely recalled significantly more items from Set 2 than those in the No Reminder condition, suggesting that the reminder context triggered a reactivation of Set 1 on Day 2 and allowed the integration of Set 2 items into Set 1. In both species, older subjects displayed a different pattern of results than young subjects. In aged rats, there was no difference between conditions in the level of falsely recalled Set 2 items (intrusions). Older humans in the No Reminder condition made significantly more intrusions than those in the Reminder condition. Follow-up control experiments in aged rats suggested that intrusions in older animals reflected general interference, independent of context manipulations. We conclude that contextual reminders are not sufficient to trigger memory updating in aged rats or aged humans, unlike in younger individuals. Future studies using this animal model should further our understanding of the role of the hippocampus in memory maintenance and updating during normal aging.
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Affiliation(s)
- Bethany J Jones
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ 85721, United States
| | - Stacey M Pest
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ 85721, United States
| | - Iliana M Vargas
- Department of Psychology, Northwestern University, Evanston, IL 60208, United States
| | - Elizabeth L Glisky
- Department of Psychology, University of Arizona, Tucson, AZ 85721, United States
| | - Jean-Marc Fellous
- Department of Psychology, University of Arizona, Tucson, AZ 85721, United States; Program in Applied Mathematics, University of Arizona, Tucson, AZ 87521-0089, United States.
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25
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Abstract
Previous work shows that medial prefrontal cortex (mPFC) cells exhibit spatio-selective activity at a goal location when rats are trained in a goal-oriented navigation task. Damaging the ventral and intermediate hippocampal regions severely disrupts both mPFC goal firing and behavioral performance in the same task. Additionally, hippocampal place cells tend to develop a secondary place field at the goal location, suggesting that goal locations can be encoded by local changes in firing rate, within an otherwise stable spatial representation. Therefore, it has been suggested that the coordinated activity of a large fraction of hippocampal cells at the goal location may interact with the mPFC to compute accurate planning trajectories, relying on both precise location-specific firing of place cells and the coarse-coded, goal-trajectory planning function of the prefrontal cortex. To test this hypothesis, we inactivated the mPFC and recorded hippocampal place cell activity while animals were performing the navigation task. The results show that post-training inactivation of the prefrontal cortex does not affect behavioral performance, suggesting that this structure is no longer required when animals are overtrained. The goal-related activity of place cells was not affected at either single unit or local field potential level. Conversely, profound modifications of place cell firing variability (overdispersion) were observed after suppression of prefrontal input, suggesting a possible mechanism underlying behavioral flexibility.
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26
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Tracking the course of hippocampal representations during learning: when is the map required? J Neurosci 2013; 33:3094-106. [PMID: 23407964 DOI: 10.1523/jneurosci.1348-12.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Distinct ensembles of hippocampal cells can be active in numerous contexts, but specific "cognitive maps" tend to be retrieved on repeat visits to the same place. During aging, the reliability of map retrieval in CA1 networks is reduced; this provides a unique opportunity to investigate correlations between inconsistent activity patterns in circuits hypothesized to enable context encoding and hippocampus-dependent learning ability. Here, CA1 pyramidal cells were recorded in six young and six old rats, while memory for specific locations was probed using a place-dependent eyeblink conditioning task. Rats were conditioned twice daily for 31 days, during which a total of 8259 and 7042 cells were recorded from young and old rats, respectively. Spontaneous remapping, a change in location of the majority of place fields between two consecutive sessions in the same environment, was observed in two young rats and four old rats during this task, but only after at least 13 days of training. Under these conditions the altered network representation did not result in loss of spatial accuracy of the blink, and in fact those rats with the best place conditioning remapped the most, whereas those with the best memory in a spatial water maze task remapped the least. These results suggest that when the hippocampal representation for a particular context is weak or unstable, such as can occur in senescence, extra-hippocampal systems that mediate alternate learning strategies are more likely to dominate behavior.
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Callaghan CK, Hok V, Della-Chiesa A, Virley DJ, Upton N, O'Mara SM. Age-related declines in delayed non-match-to-sample performance (DNMS) are reversed by the novel 5HT6 receptor antagonist SB742457. Neuropharmacology 2012; 63:890-7. [DOI: 10.1016/j.neuropharm.2012.06.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 06/14/2012] [Accepted: 06/15/2012] [Indexed: 12/18/2022]
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