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Long P, Ma Q, Wang Z, Wang G, Jiang J, Gao L. Genetic patterning in hippocampus of rat undergoing impaired spatial memory induced by long-term heat stress. Heliyon 2024; 10:e37319. [PMID: 39296065 PMCID: PMC11408118 DOI: 10.1016/j.heliyon.2024.e37319] [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: 05/04/2024] [Revised: 08/31/2024] [Accepted: 09/01/2024] [Indexed: 09/21/2024] Open
Abstract
The organism's normal physiological function is greatly impacted in a febrile environment, leading to the manifestation of pathological conditions including elevated body temperature, dehydration, gastric bleeding, and spermatogenic dysfunction. Numerous lines of evidence indicate that heat stress significantly impacts the brain's structure and function. Previous studies have demonstrated that both animals and humans experience cognitive impairment as a result of exposure to high temperatures. However, there is a lack of research on the effects of prolonged exposure to high-temperature environments on learning and memory function, as well as the underlying molecular regulatory mechanisms. In this study, we examined the impact of long-term heat stress exposure on spatial memory function in rats and conducted transcriptome sequencing analysis of rat hippocampal tissues to identify the crucial molecular targets affected by prolonged heat stress exposure. It was found that the long-term heat stress impaired rats' spatial memory function due to the pathological damages and apoptosis of hippocampal neurons at the CA3 region, which is accompanied with the decrease of growth hormone level in peripheral blood. RNA sequencing analysis revealed the signaling pathways related to positive regulation of external stimulation response and innate immune response were dramatically affected by heat stress. Among the verified differentially expressed genes, the knockdown of Arhgap36 in neuronal cell line HT22 significantly enhances the cell apoptosis, suggesting the impaired spatial memory induced by long-term heat stress may at least partially be mediated by the dysregulation of Arhgap36 in hippocampal neurons. The uncovered relationship between molecular changes in the hippocampus and behavioral alterations induced by long-term heat stress may offer valuable insights for the development of therapeutic targets and protective drugs to enhance memory function in heat-exposed individuals.
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Affiliation(s)
- Peihua Long
- Department of Physiology, Naval Medical University, Shanghai, 200433, PR China
| | - Qunfei Ma
- Department of Physiology, Naval Medical University, Shanghai, 200433, PR China
| | - Zhe Wang
- Department of Physiology, Naval Medical University, Shanghai, 200433, PR China
| | - Guanqin Wang
- Department of Physiology, Naval Medical University, Shanghai, 200433, PR China
| | - Jianan Jiang
- Department of Physiology, Naval Medical University, Shanghai, 200433, PR China
| | - Lu Gao
- Department of Physiology, Naval Medical University, Shanghai, 200433, PR China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, 200120, PR China
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2
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Kveim VA, Salm L, Ulmer T, Lahr M, Kandler S, Imhof F, Donato F. Divergent recruitment of developmentally defined neuronal ensembles supports memory dynamics. Science 2024; 385:eadk0997. [PMID: 39146420 DOI: 10.1126/science.adk0997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 06/24/2024] [Indexed: 08/17/2024]
Abstract
Memories are dynamic constructs whose properties change with time and experience. The biological mechanisms underpinning these dynamics remain elusive, particularly concerning how shifts in the composition of memory-encoding neuronal ensembles influence the evolution of a memory over time. By targeting developmentally distinct subpopulations of principal neurons, we discovered that memory encoding resulted in the concurrent establishment of multiple memory traces in the mouse hippocampus. Two of these traces were instantiated in subpopulations of early- and late-born neurons and followed distinct reactivation trajectories after encoding. The divergent recruitment of these subpopulations underpinned gradual reorganization of memory ensembles and modulated memory persistence and plasticity across multiple learning episodes. Thus, our findings reveal profound and intricate relationships between ensemble dynamics and the progression of memories over time.
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Affiliation(s)
- Vilde A Kveim
- Biozentrum, Universität Basel, 4056 Basel, Switzerland
| | - Laurenz Salm
- Biozentrum, Universität Basel, 4056 Basel, Switzerland
| | - Talia Ulmer
- Biozentrum, Universität Basel, 4056 Basel, Switzerland
| | - Maria Lahr
- Biozentrum, Universität Basel, 4056 Basel, Switzerland
| | | | - Fabia Imhof
- Biozentrum, Universität Basel, 4056 Basel, Switzerland
| | - Flavio Donato
- Biozentrum, Universität Basel, 4056 Basel, Switzerland
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3
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Yasar TB, Gombkoto P, Vyssotski AL, Vavladeli AD, Lewis CM, Wu B, Meienberg L, Lundegardh V, Helmchen F, von der Behrens W, Yanik MF. Months-long tracking of neuronal ensembles spanning multiple brain areas with Ultra-Flexible Tentacle Electrodes. Nat Commun 2024; 15:4822. [PMID: 38844769 PMCID: PMC11156863 DOI: 10.1038/s41467-024-49226-9] [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: 12/13/2023] [Accepted: 05/24/2024] [Indexed: 06/09/2024] Open
Abstract
We introduce Ultra-Flexible Tentacle Electrodes (UFTEs), packing many independent fibers with the smallest possible footprint without limitation in recording depth using a combination of mechanical and chemical tethering for insertion. We demonstrate a scheme to implant UFTEs simultaneously into many brain areas at arbitrary locations without angle-of-insertion limitations, and a 512-channel wireless logger. Immunostaining reveals no detectable chronic tissue damage even after several months. Mean spike signal-to-noise ratios are 1.5-3x compared to the state-of-the-art, while the highest signal-to-noise ratios reach 89, and average cortical unit yields are ~1.75/channel. UFTEs can track the same neurons across sessions for at least 10 months (longest duration tested). We tracked inter- and intra-areal neuronal ensembles (neurons repeatedly co-activated within 25 ms) simultaneously from hippocampus, retrosplenial cortex, and medial prefrontal cortex in freely moving rodents. Average ensemble lifetimes were shorter than the durations over which we can track individual neurons. We identify two distinct classes of ensembles. Those tuned to sharp-wave ripples display the shortest lifetimes, and the ensemble members are mostly hippocampal. Yet, inter-areal ensembles with members from both hippocampus and cortex have weak tuning to sharp wave ripples, and some have unusual months-long lifetimes. Such inter-areal ensembles occasionally remain inactive for weeks before re-emerging.
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Affiliation(s)
- Tansel Baran Yasar
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Peter Gombkoto
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Alexei L Vyssotski
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Angeliki D Vavladeli
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Christopher M Lewis
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland
- Brain Research Institute, University of Zurich, Zurich, Switzerland
| | - Bifeng Wu
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Linus Meienberg
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland
| | - Valter Lundegardh
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland
| | - Fritjof Helmchen
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland
- Brain Research Institute, University of Zurich, Zurich, Switzerland
- University Research Priority Program (URPP), Adaptive Brain Circuits in Development and Learning, University of Zurich, Zurich, Switzerland
| | - Wolfger von der Behrens
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Mehmet Fatih Yanik
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Zurich, Switzerland.
- Neuroscience Center Zurich, University of Zurich & ETH Zurich, Zurich, Switzerland.
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4
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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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Miller TD, Kennard C, Gowland PA, Antoniades CA, Rosenthal CR. Differential effects of bilateral hippocampal CA3 damage on the implicit learning and recognition of complex event sequences. Cogn Neurosci 2024; 15:27-55. [PMID: 38384107 PMCID: PMC11147457 DOI: 10.1080/17588928.2024.2315818] [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: 09/12/2023] [Accepted: 01/25/2024] [Indexed: 02/23/2024]
Abstract
Learning regularities in the environment is a fundament of human cognition, which is supported by a network of brain regions that include the hippocampus. In two experiments, we assessed the effects of selective bilateral damage to human hippocampal subregion CA3, which was associated with autobiographical episodic amnesia extending ~50 years prior to the damage, on the ability to recognize complex, deterministic event sequences presented either in a spatial or a non-spatial configuration. In contrast to findings from related paradigms, modalities, and homologue species, hippocampal damage did not preclude recognition memory for an event sequence studied and tested at four spatial locations, whereas recognition memory for an event sequence presented at a single location was at chance. In two additional experiments, recognition memory for novel single-items was intact, whereas the ability to recognize novel single-items in a different location from that presented at study was at chance. The results are at variance with a general role of the hippocampus in the learning and recognition of complex event sequences based on non-adjacent spatial and temporal dependencies. We discuss the impact of the results on established theoretical accounts of the hippocampal contributions to implicit sequence learning and episodic memory.
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Affiliation(s)
- Thomas D. Miller
- Wellcome Centre for Human Neuroimaging, University College London, London, UK
- National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Christopher Kennard
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Penny A. Gowland
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | | | - Clive R. Rosenthal
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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