1
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Wang P, Huang Y, Sun B, Chen H, Ma Y, Liu Y, Yang T, Jin H, Qiao Y, Cao Y. Folic acid blocks ferroptosis induced by cerebral ischemia and reperfusion through regulating folate hydrolase transcriptional adaptive program. J Nutr Biochem 2024; 124:109528. [PMID: 37979712 DOI: 10.1016/j.jnutbio.2023.109528] [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: 02/25/2023] [Revised: 10/17/2023] [Accepted: 11/08/2023] [Indexed: 11/20/2023]
Abstract
Cerebral ischemia-reperfusion (I/R) injury is notably linked with folic acid (FA) deficiency. The aim of our investigation was to explore the effects and underlying mechanisms by which FA mitigates I/R, specifically through regulating the GCPII transcriptional adaptive program. Initially, we discovered that following cerebral I/R, levels of FA, methionine synthase (MTR), and methylenetetrahydrofolate reductase (MTHFR) were decreased, while GCPII expression was elevated. Secondly, administering FA could mitigate cognitive impairment and neuronal damage induced by I/R. Thirdly, the mechanism of FA supplementation involved suppressing the transcriptional factor Sp1, subsequently inhibiting GCPII transcription, reducing Glu content, obstructing cellular ferroptosis, and alleviating cerebral I/R injury. In summary, our data demonstrate that FA affords protection against cerebral I/R injury by inhibiting the GCPII transcriptional adaptive response. These findings unveil that targeting GCPII might be a viable therapeutic strategy for cerebral I/R.
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Affiliation(s)
- Peng Wang
- Department of Physiology, Harbin Medical University-Daqing, Daqing, Heilongjiang, China
| | - Yangyang Huang
- Department of Pediatrics, Daqing People's Hospital, Daqing, Heilongjiang, China
| | - Buxun Sun
- Department of Physiology, Harbin Medical University-Daqing, Daqing, Heilongjiang, China
| | - Hongpeng Chen
- Department of Physiology, Harbin Medical University-Daqing, Daqing, Heilongjiang, China
| | - YiFan Ma
- Department of Physiology, Harbin Medical University-Daqing, Daqing, Heilongjiang, China
| | - Yuhang Liu
- Department of Physiology, Harbin Medical University-Daqing, Daqing, Heilongjiang, China
| | - Tao Yang
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing, Heilongjiang, China
| | - Hongbo Jin
- Department of Physiology, Harbin Medical University, Harbin, Heilongjiang, China.
| | - Yuandong Qiao
- Department of Genetics, Harbin Medical University-Daqing, Daqing, Heilongjiang, China.
| | - Yongggang Cao
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing, Heilongjiang, China.
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2
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Rolls ET. Hippocampal spatial view cells for memory and navigation, and their underlying connectivity in humans. Hippocampus 2023; 33:533-572. [PMID: 36070199 PMCID: PMC10946493 DOI: 10.1002/hipo.23467] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 08/16/2022] [Accepted: 08/16/2022] [Indexed: 01/08/2023]
Abstract
Hippocampal and parahippocampal gyrus spatial view neurons in primates respond to the spatial location being looked at. The representation is allocentric, in that the responses are to locations "out there" in the world, and are relatively invariant with respect to retinal position, eye position, head direction, and the place where the individual is located. The underlying connectivity in humans is from ventromedial visual cortical regions to the parahippocampal scene area, leading to the theory that spatial view cells are formed by combinations of overlapping feature inputs self-organized based on their closeness in space. Thus, although spatial view cells represent "where" for episodic memory and navigation, they are formed by ventral visual stream feature inputs in the parahippocampal gyrus in what is the parahippocampal scene area. A second "where" driver of spatial view cells are parietal inputs, which it is proposed provide the idiothetic update for spatial view cells, used for memory recall and navigation when the spatial view details are obscured. Inferior temporal object "what" inputs and orbitofrontal cortex reward inputs connect to the human hippocampal system, and in macaques can be associated in the hippocampus with spatial view cell "where" representations to implement episodic memory. Hippocampal spatial view cells also provide a basis for navigation to a series of viewed landmarks, with the orbitofrontal cortex reward inputs to the hippocampus providing the goals for navigation, which can then be implemented by hippocampal connectivity in humans to parietal cortex regions involved in visuomotor actions in space. The presence of foveate vision and the highly developed temporal lobe for object and scene processing in primates including humans provide a basis for hippocampal spatial view cells to be key to understanding episodic memory in the primate and human hippocampus, and the roles of this system in primate including human navigation.
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Affiliation(s)
- Edmund T. Rolls
- Oxford Centre for Computational NeuroscienceOxfordUK
- Department of Computer ScienceUniversity of WarwickCoventryUK
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3
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McNaughton N, Vann SD. Construction of complex memories via parallel distributed cortical-subcortical iterative integration. Trends Neurosci 2022; 45:550-562. [PMID: 35599065 PMCID: PMC7612902 DOI: 10.1016/j.tins.2022.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/01/2022] [Accepted: 04/22/2022] [Indexed: 01/08/2023]
Abstract
The construction of complex engrams requires hippocampal-cortical interactions. These include both direct interactions and ones via often-overlooked subcortical loops. Here, we review the anatomical organization of a hierarchy of parallel 'Papez' loops through the hypothalamus that are homologous in mammals from rats to humans. These hypothalamic loops supplement direct hippocampal-cortical connections with iterative reprocessing paced by theta rhythmicity. We couple existing anatomy and lesion data with theory to propose that recirculation in these loops progressively enhances desired connections, while reducing interference from competing external goals and internal associations. This increases the signal-to-noise ratio in the distributed engrams (neocortical and cerebellar) necessary for complex learning and memory. The hypothalamic nodes provide key motivational input for engram enhancement during consolidation.
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Affiliation(s)
- Neil McNaughton
- Department of Psychology and Brain Health Research Centre, University of Otago, POB56, Dunedin, New Zealand.
| | - Seralynne D Vann
- School of Psychology, Cardiff University, Park Place, Cardiff, CF10 3AT, UK.
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4
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Robertson EM. Memory leaks: information shared across memory systems. Trends Cogn Sci 2022; 26:544-554. [DOI: 10.1016/j.tics.2022.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 10/18/2022]
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5
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Gao JQ, Wang P, Yan JW, Ba LN, Shi PL, Wu HM, Guan XY, Cao YG, Sun HL, Mao XY. Shear Stress Rescued the Neuronal Impairment Induced by Global Cerebral Ischemia Reperfusion via Activating PECAM-1-eNOS-NO Pathway. Front Cell Dev Biol 2021; 8:631286. [PMID: 33553171 PMCID: PMC7859356 DOI: 10.3389/fcell.2020.631286] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 12/30/2020] [Indexed: 12/17/2022] Open
Abstract
Microvessel hypoperfusion following ischemic stress resulted in a decreased shear stress of brain microvascular endothelial cells (BMECs) and contributed to abnormal expression of PECAM-1 after global cerebral ischemia/reperfusion (I/R) injury. Here, we identified novel pathophysiologic and rehabilitative procedures specific to shear stress in microvascular endothelial cells in response to global cerebral I/R injury. We found that the decrease in cerebral blood flow of gerbils after global cerebral I/R injury reduces shear stress, and the abnormal change in shear stress leads to microvascular endothelial cell and neuron damage. Nevertheless, suitable high levels of shear stress contribute to rescuing the dysfunction and malformation of BMECs via regulating the PECAM-1-eNOS-NO pathway to enhance nitric oxide release, decrease the expression of caspase-3 to reduce apoptosis, and improve the shear-adaptability of endothelial cells, thereby playing a protective role in the gerbil brain.
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Affiliation(s)
- Jing-Quan Gao
- Department of Nursing, Harbin Medical University-Daqing, Daqing, China
| | - Peng Wang
- Department of Physiology, Harbin Medical University-Daqing, Daqing, China
| | - Jun-Wei Yan
- Department of Vascular Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Li-Na Ba
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing, China
| | - Pi-Long Shi
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing, China
| | - Hong-Mei Wu
- Department of Nursing, Harbin Medical University-Daqing, Daqing, China
| | - Xue-Ying Guan
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing, China
| | - Yong-Gang Cao
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing, China
| | - Hong-Li Sun
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing, China
| | - Xiao-Yuan Mao
- Institute of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha, China.,Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha, China
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6
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Different patterns of recollection for matched real-world and laboratory-based episodes in younger and older adults. Cognition 2020; 202:104309. [DOI: 10.1016/j.cognition.2020.104309] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 04/12/2020] [Accepted: 04/13/2020] [Indexed: 11/19/2022]
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7
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Schilder BM, Petry HM, Hof PR. Evolutionary shifts dramatically reorganized the human hippocampal complex. J Comp Neurol 2019; 528:3143-3170. [DOI: 10.1002/cne.24822] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 11/18/2019] [Accepted: 11/18/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Brian M. Schilder
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai New York New York
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai New York New York
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai New York New York
| | - Heywood M. Petry
- Department of Psychological and Brain Sciences, University of Louisville Louisville Kentucky
| | - Patrick R. Hof
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai New York New York
- Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai New York New York
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8
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Cahill SP, Martinovic A, Cole JD, Seib DR, Snyder JS. A combination of running and memantine increases neurogenesis and reduces activation of developmentally-born dentate granule neurons in rats. Behav Brain Res 2019; 372:112005. [PMID: 31167109 DOI: 10.1016/j.bbr.2019.112005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 05/16/2019] [Accepted: 05/31/2019] [Indexed: 11/19/2022]
Abstract
During hippocampal-dependent memory formation, sensory signals from the neocortex converge in the dentate gyrus. It is generally believed that the dentate gyrus decorrelates inputs in order to minimize interference between codes for similar experiences, often referred to as pattern separation. The proportion of dentate neurons that are activated by experience is therefore likely to impact how memories are stored and separated. Emerging evidence from mouse models suggests that adult-born neurons can both increase and decrease activity levels in the dentate gyrus. However, the conditions that determine the direction of this modulation, and whether it occurs in other species, remains unclear. Furthermore, since the dentate gyrus is composed of a heterogeneous population of cells that are born throughout life, newborn neurons may not modulate all cells equally. We aimed to investigate whether adult neurogenesis in rats regulates activity in dentate gyrus neurons that are born at the peak of early postnatal development. Adult neurogenesis was increased by subjecting rats to an alternating running and memantine treatment schedule, and it was decreased with a transgenic GFAP-TK rat model. Activity was measured by Fos expression in BrdU+ cells after rats explored a novel environment. Running+memantine treatment increased adult neurogenesis by only 17%, but completely blocked experience-dependent Fos expression. In contrast, GFAP-TK rats had a 68% reduction in adult neurogenesis but normal experience-dependent Fos expression. The inconsistent relationship between neurogenesis and Fos expression suggests that neurogenesis does not regulate DG activity during exploration of a novel environment. Nonetheless, running and memantine may benefit disorders where there is elevated activity in the dentate gyrus, such as anxiety and age-related memory impairments.
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Affiliation(s)
- Shaina P Cahill
- Department of Psychology, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada
| | - Angela Martinovic
- Department of Psychology, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada
| | - John Darby Cole
- Department of Psychology, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada
| | - Desiree R Seib
- Department of Psychology, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada
| | - Jason S Snyder
- Department of Psychology, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada.
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9
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Quillfeldt JA. Temporal Flexibility of Systems Consolidation and the Synaptic Occupancy/Reset Theory (SORT): Cues About the Nature of the Engram. Front Synaptic Neurosci 2019; 11:1. [PMID: 30814946 PMCID: PMC6381034 DOI: 10.3389/fnsyn.2019.00001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 01/14/2019] [Indexed: 11/24/2022] Open
Abstract
The ability to adapt to new situations involves behavioral changes expressed either from an innate repertoire, or by acquiring experience through memory consolidation mechanisms, by far a much richer and flexible source of adaptation. Memory formation consists of two interrelated processes that take place at different spatial and temporal scales, Synaptic Consolidation, local plastic changes in the recruited neurons, and Systems Consolidation, a process of gradual reorganization of the explicit/declarative memory trace between hippocampus and the neocortex. In this review, we summarize some converging experimental results from our lab that support a normal temporal framework of memory systems consolidation as measured both from the anatomical and the psychological points of view, and propose a hypothetical model that explains these findings while predicting other phenomena. Then, the same experimental design was repeated interposing additional tasks between the training and the remote test to verify for any interference: we found that (a) when the animals were subject to a succession of new learnings, systems consolidation was accelerated, with the disengagement of the hippocampus taking place before the natural time point of this functional switch, but (b) when a few reactivation sessions reexposed the animal to the training context without the shock, systems consolidation was delayed, with the hippocampus prolonging its involvement in retrieval. We hypothesize that new learning recruits from a fixed number of plastic synapses in the CA1 area to store the engram index, while reconsolidation lead to a different outcome, in which additional synapses are made available. The first situation implies the need of a reset mechanism in order to free synapses needed for further learning, and explains the acceleration observed under intense learning activity, while the delay might be explained by a different process, able to generate extra free synapses: depending on the cognitive demands, it deals either with a fixed or a variable pool of available synapses. The Synaptic Occupancy/Reset Theory (SORT) emerged as an explanation for the temporal flexibility of systems consolidation, to encompass the two different dynamics of explicit memories, as well as to bridge both synaptic and systems consolidation in one single mechanism.
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Affiliation(s)
- Jorge Alberto Quillfeldt
- Psychobiology and Neurocomputation Lab, Department of Biophysics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Neurosciences Graduate Program, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Department of Psychology, McGill University, Montreal, QC, Canada
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10
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Rolls ET, Wirth S. Spatial representations in the primate hippocampus, and their functions in memory and navigation. Prog Neurobiol 2018; 171:90-113. [DOI: 10.1016/j.pneurobio.2018.09.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 09/10/2018] [Accepted: 09/10/2018] [Indexed: 01/01/2023]
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11
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Abstract
Memories for events are thought to be represented in sparse, distributed neuronal ensembles (or engrams). In this article, we review how neurons are chosen to become part of a particular engram, via a process of neuronal allocation. Experiments in rodents indicate that eligible neurons compete for allocation to a given engram, with more excitable neurons winning this competition. Moreover, fluctuations in neuronal excitability determine how engrams interact, promoting either memory integration (via coallocation to overlapping engrams) or separation (via disallocation to nonoverlapping engrams). In parallel with rodent studies, recent findings in humans verify the importance of this memory integration process for linking memories that occur close in time or share related content. A deeper understanding of allocation promises to provide insights into the logic underlying how knowledge is normally organized in the brain and the disorders in which this process has gone awry.
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Affiliation(s)
- Sheena A Josselyn
- Department of Psychology, University of Toronto, Ontario M5S 3G3, Canada; ,
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
- Department of Physiology, University of Toronto, Ontario M5S 1A8, Canada
- Institute of Medical Sciences, University of Toronto, Ontario M5S 1A8, Canada
- Brain, Mind & Consciousness Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1M1, Canada
| | - Paul W Frankland
- Department of Psychology, University of Toronto, Ontario M5S 3G3, Canada; ,
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
- Department of Physiology, University of Toronto, Ontario M5S 1A8, Canada
- Institute of Medical Sciences, University of Toronto, Ontario M5S 1A8, Canada
- Child & Brain Development Program, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1M1, Canada
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12
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Virtual reality method to analyze visual recognition in mice. PLoS One 2018; 13:e0196563. [PMID: 29768429 PMCID: PMC5955493 DOI: 10.1371/journal.pone.0196563] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 04/16/2018] [Indexed: 12/15/2022] Open
Abstract
Behavioral tests have been extensively used to measure the visual function of mice. To determine how precisely mice perceive certain visual cues, it is necessary to have a quantifiable measurement of their behavioral responses. Recently, virtual reality tests have been utilized for a variety of purposes, from analyzing hippocampal cell functionality to identifying visual acuity. Despite the widespread use of these tests, the training requirement for the recognition of a variety of different visual targets, and the performance of the behavioral tests has not been thoroughly characterized. We have developed a virtual reality behavior testing approach that can essay a variety of different aspects of visual perception, including color/luminance and motion detection. When tested for the ability to detect a color/luminance target or a moving target, mice were able to discern the designated target after 9 days of continuous training. However, the quality of their performance is significantly affected by the complexity of the visual target, and their ability to navigate on a spherical treadmill. Importantly, mice retained memory of their visual recognition for at least three weeks after the end of their behavioral training.
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13
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Bermudez-Contreras E, Chekhov S, Sun J, Tarnowsky J, McNaughton BL, Mohajerani MH. High-performance, inexpensive setup for simultaneous multisite recording of electrophysiological signals and mesoscale voltage imaging in the mouse cortex. NEUROPHOTONICS 2018; 5:025005. [PMID: 29651448 PMCID: PMC5874445 DOI: 10.1117/1.nph.5.2.025005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 03/05/2018] [Indexed: 05/17/2023]
Abstract
Simultaneous recording of optical and electrophysiological signals from multiple cortical areas may provide crucial information to expand our understanding of cortical function. However, the insertion of multiple electrodes into the brain may compromise optical imaging by both restricting the field of view and interfering with the approaches used to stabilize the specimen. Existing methods that combine electrophysiological recording and optical imaging in vivo implement either multiple surface electrodes, silicon probes, or a single electrode for deeper recordings. To address such limitation, we built a microelectrode array (hyperdrive, patent US5928143 A) compatible with wide-field imaging that allows insertion of up to 12 probes into a large brain area (8 mm diameter). The hyperdrive is comprised of a circle of individual microdrives where probes are positioned at an angle leaving a large brain area unobstructed for wide-field imaging. Multiple tetrodes and voltage-sensitive dye imaging were used for acute simultaneous registration of spontaneous and evoked cortical activity in anesthetized mice. The electrophysiological signals were used to extract local field potential (LFP) traces, multiunit, and single-unit spiking activity. To demonstrate our approach, we compared LFP and VSD signals over multiple regions of the cortex and analyzed the relationship between single-unit and global cortical population activities. The study of the interactions between cortical activity at local and global scales, such as the one presented in this work, can help to expand our knowledge of brain function.
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Affiliation(s)
- Edgar Bermudez-Contreras
- University of Lethbridge, Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, Lethbridge, Alberta, Canada
| | - Sergey Chekhov
- University of Lethbridge, Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, Lethbridge, Alberta, Canada
| | - Jianjun Sun
- University of Lethbridge, Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, Lethbridge, Alberta, Canada
| | - Jennifer Tarnowsky
- University of Lethbridge, Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, Lethbridge, Alberta, Canada
| | - Bruce L. McNaughton
- University of Lethbridge, Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, Lethbridge, Alberta, Canada
- University of California at Irvine, Center for the Neurobiology of Learning and Memory, Department of Neurobiology and Behavior, Irvine, California, United States
- Address all correspondence to: Bruce L. McNaughton, E-mail: ; Majid H. Mohajerani, E-mail:
| | - Majid H. Mohajerani
- University of Lethbridge, Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, Lethbridge, Alberta, Canada
- Address all correspondence to: Bruce L. McNaughton, E-mail: ; Majid H. Mohajerani, E-mail:
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14
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Abstract
Neurocomputational models have long posited that episodic memories in the human hippocampus are represented by sparse, stimulus-specific neural codes. A concomitant proposal is that when sparse-distributed neural assemblies become active, they suppress the activity of competing neurons (neural sharpening). We investigated episodic memory coding in the hippocampus and amygdala by measuring single-neuron responses from 20 epilepsy patients (12 female) undergoing intracranial monitoring while they completed a continuous recognition memory task. In the left hippocampus, the distribution of single-neuron activity indicated that only a small fraction of neurons exhibited strong responding to a given repeated word and that each repeated word elicited strong responding in a different small fraction of neurons. This finding reflects sparse distributed coding. The remaining large fraction of neurons exhibited a concurrent reduction in firing rates relative to novel words. The observed pattern accords with longstanding predictions that have previously received scant support from single-cell recordings from human hippocampus.
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15
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Lewis SA, Negelspach DC, Kaladchibachi S, Cowen SL, Fernandez F. Spontaneous alternation: A potential gateway to spatial working memory in Drosophila. Neurobiol Learn Mem 2017; 142:230-235. [DOI: 10.1016/j.nlm.2017.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 05/17/2017] [Accepted: 05/21/2017] [Indexed: 10/19/2022]
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