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Ventura S, Duncan S, Ainge JA. Increased flexibility of CA3 memory representations following environmental enrichment. Curr Biol 2024; 34:2011-2019.e7. [PMID: 38636511 DOI: 10.1016/j.cub.2024.03.054] [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: 11/17/2023] [Revised: 02/16/2024] [Accepted: 03/25/2024] [Indexed: 04/20/2024]
Abstract
Environmental enrichment (EE) improves memory, particularly the ability to discriminate similar past experiences.1,2,3,4,5,6 The hippocampus supports this ability via pattern separation, the encoding of similar events using dissimilar memory representations.7 This is carried out in the dentate gyrus (DG) and CA3 subfields.8,9,10,11,12 Upregulation of adult neurogenesis in the DG improves memory through enhanced pattern separation.1,2,3,4,5,6,11,13,14,15,16 Adult-born granule cells (abGCs) in DG are suggested to contribute to pattern separation by driving inhibition in regions such as CA3,13,14,15,16,17,18 leading to sparser, nonoverlapping representations of similar events (although a role for abGCs in driving excitation in the hippocampus has also been reported16). Place cells in the hippocampus contribute to pattern separation by remapping to spatial and contextual alterations to the environment.19,20,21,22,23,24,25,26,27 How spatial responses in CA3 are affected by EE and input from increased numbers of abGCs in DG is, however, unknown. Here, we investigate the neural mechanisms facilitating improved memory following EE using associative recognition memory tasks that model the automatic and integrative nature of episodic memory. We find that EE-dependent improvements in difficult discriminations are related to increased neurogenesis and sparser memory representations across the hippocampus. Additionally, we report for the first time that EE changes how CA3 place cells discriminate similar contexts. CA3 place cells of enriched rats show greater spatial tuning, increased firing rates, and enhanced remapping to contextual changes. These findings point to more precise and flexible CA3 memory representations in enriched rats, which provides a putative mechanism for EE-dependent improvements in fine memory discrimination.
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Affiliation(s)
- Silvia Ventura
- School of Psychology & Neuroscience, University of St. Andrews, St. Mary's Quad, South Street, St. Andrews, Fife, Scotland KY16 9JP, UK
| | - Stephen Duncan
- School of Psychology & Neuroscience, University of St. Andrews, St. Mary's Quad, South Street, St. Andrews, Fife, Scotland KY16 9JP, UK; School of Psychological & Brain Sciences, Indiana University, 1101 E 10th Street, Bloomington, IN 47405, USA
| | - James A Ainge
- School of Psychology & Neuroscience, University of St. Andrews, St. Mary's Quad, South Street, St. Andrews, Fife, Scotland KY16 9JP, UK.
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2
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Chang WL, Hen R. Adult Neurogenesis, Context Encoding, and Pattern Separation: A Pathway for Treating Overgeneralization. ADVANCES IN NEUROBIOLOGY 2024; 38:163-193. [PMID: 39008016 DOI: 10.1007/978-3-031-62983-9_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
In mammals, the subgranular zone of the dentate gyrus is one of two brain regions (with the subventricular zone of the olfactory bulb) that continues to generate new neurons throughout adulthood, a phenomenon known as adult hippocampal neurogenesis (AHN) (Eriksson et al., Nat Med 4:1313-1317, 1998; García-Verdugo et al., J Neurobiol 36:234-248, 1998). The integration of these new neurons into the dentate gyrus (DG) has implications for memory encoding, with unique firing and wiring properties of immature neurons that affect how the hippocampal network encodes and stores attributes of memory. In this chapter, we will describe the process of AHN and properties of adult-born cells as they integrate into the hippocampal circuit and mature. Then, we will discuss some methodological considerations before we review evidence for the role of AHN in two major processes supporting memory that are performed by the DG. First, we will discuss encoding of contextual information for episodic memories and how this is facilitated by AHN. Second, will discuss pattern separation, a major role of the DG that reduces interference for the formation of new memories. Finally, we will review clinical and translational considerations, suggesting that stimulation of AHN may help decrease overgeneralization-a common endophenotype of mood, anxiety, trauma-related, and age-related disorders.
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Affiliation(s)
- Wei-Li Chang
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY, USA
- Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY, USA
| | - Rene Hen
- Departments of Psychiatry and Neuroscience, Columbia University, New York, NY, USA.
- Division of Systems Neuroscience, New York State Psychiatric Institute, New York, NY, USA.
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Funabashi D, Tsuchida R, Matsui T, Kita I, Nishijima T. Enlarged housing space and increased spatial complexity enhance hippocampal neurogenesis but do not increase physical activity in mice. Front Sports Act Living 2023; 5:1203260. [PMID: 37822972 PMCID: PMC10562532 DOI: 10.3389/fspor.2023.1203260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 09/13/2023] [Indexed: 10/13/2023] Open
Abstract
Introduction Environmental enrichment (EE) improves various health outcomes, such as hippocampal neurogenesis, in rodents, which is thought to be caused, in part, by increased physical activity. However, the specific effect of each enrichment component, such as enlarged housing spaces and increased spatial complexity with a variety of objects, on physical activity remains unclear because of methodological limitations in measuring physical activity. We aimed to examine whether enlarged housing spaces and increased spatial complexity increase physical activity in mice using a body-implantable actimeter. Methods Adult male C57BL/6J mice were assigned to either standard housing or EE groups. The housing environment in the EE mice was gradually enriched by enlarging the housing space and the placement of a variety of objects. Physical activity was measured using a body-implanted actimeter. Hippocampal neurogenesis was immunohistochemically examined. Results Enlarged housing spaces and the placement of a variety of objects did not increase physical activity in mice. In contrast, hippocampal neurogenesis was enhanced in the EE mice, suggesting that environmental interventions successfully provided enriched housing conditions for these mice. Conclusions These results indicate that enlarged housing spaces and increased spatial complexity do not increase physical activity in mice. Furthermore, we found that EE enhanced hippocampal neurogenesis without increasing activity volume. Besides the current understanding that increasing the amount of physical activity is key to improving hippocampal function, our result suggests that the environment in which physical activity takes place is also a crucial contextual factor in determining the impact of physical activity on hippocampal function.
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Affiliation(s)
- Daisuke Funabashi
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
- Exercise Biochemistry & Sport Neurobiology Division, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ryuki Tsuchida
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Takashi Matsui
- Exercise Biochemistry & Sport Neurobiology Division, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ichiro Kita
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Takeshi Nishijima
- Department of Health Promotion Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
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Stephen TKL, Cofresi LA, Quiroz E, Owusu-Ansah K, Ibrahim Y, Qualls E, Marshall J, Li W, Shetti A, Bonds JA, Minshall RD, Cologna SM, Lazarov O. Caveolin-1 Autonomously Regulates Hippocampal Neurogenesis Via Mitochondrial Dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.23.558792. [PMID: 37790360 PMCID: PMC10542167 DOI: 10.1101/2023.09.23.558792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
The mechanisms underlying adult hippocampal neurogenesis (AHN) are not fully understood. AHN plays instrumental roles in learning and memory. Understanding the signals that regulate AHN has implications for brain function and therapy. Here we show that Caveolin-1 (Cav-1), a protein that is highly enriched in endothelial cells and the principal component of caveolae, autonomously regulates AHN. Conditional deletion of Cav-1 in adult neural progenitor cells (nestin +) led to increased neurogenesis and enhanced performance of mice in contextual discrimination. Proteomic analysis revealed that Cav-1 plays a role in mitochondrial pathways in neural progenitor cells. Importantly, Cav-1 was localized to the mitochondria in neural progenitor cells and modulated mitochondrial fission-fusion, a critical process in neurogenesis. These results suggest that Cav-1 is a novel regulator of AHN and underscore the impact of AHN on cognition.
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Affiliation(s)
- Terilyn K. L. Stephen
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Luis Aponte Cofresi
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Elvis Quiroz
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Kofi Owusu-Ansah
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Yomna Ibrahim
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Ellis Qualls
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Jeffery Marshall
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Wenping Li
- Department of Chemistry, University of Illinois at Chicago, IL, USA
| | - Aashutosh Shetti
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Jacqueline A Bonds
- Departmet of Anesthesiology, University of California San Diego, CA, USA
| | - Richard D. Minshall
- Deparment of Pharmacology and Regenerative Medicine, University of Illinois at Chicago, IL,USA
- Department of Anesthesiology, University of Illinois at Chicago, IL USA
| | | | - Orly Lazarov
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
- Lead Contact
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5
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Grigoryan GA. The systemic effects of the enriched environment on the conditioned fear reaction. Front Behav Neurosci 2023; 17:1227575. [PMID: 37674611 PMCID: PMC10477375 DOI: 10.3389/fnbeh.2023.1227575] [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: 05/23/2023] [Accepted: 08/07/2023] [Indexed: 09/08/2023] Open
Abstract
In this review, a hypothesis is proposed to explain the beneficial effect of an enriched environment (EE) on the conditioned fear reaction (CFR) from the perspective of a functional system of behavioral control. According to the hypothesis, the EE affects all behavioral act components, including the processing of sensory information, memory, motivational and reinforcing systems, and motor activities, which weakens the CFR. Animals raised in the EE have effects that are comparable to those of context (CTX) and CS pre-exposures at latent inhibition. An abundance of stimuli in the EE and constant contact with them provide the formation of CS-noUS and CTX-noUS connections that later, during CFR learning, slow down and diminish fear. The EE also contributes to faster processing of information and habituation to it. As a result, many stimuli in the context lose their significance, and subjects simply ignore them. And finally, the EE affects the motivational and reinforcing brain mechanisms, induces an impairment of search activity, and worsens memory consolidation, which leads to a reduction of CFR.
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Affiliation(s)
- Grigory A. Grigoryan
- The Laboratory of Conditioned Reflexes and Physiology of Emotions, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
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6
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Reggente N. VR for Cognition and Memory. Curr Top Behav Neurosci 2023; 65:189-232. [PMID: 37440126 DOI: 10.1007/7854_2023_425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
This chapter will provide a review of research into human cognition through the lens of VR-based paradigms for studying memory. Emphasis is placed on why VR increases the ecological validity of memory research and the implications of such enhancements.
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Affiliation(s)
- Nicco Reggente
- Institute for Advanced Consciousness Studies, Santa Monica, CA, USA.
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7
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Culig L, Chu X, Bohr VA. Neurogenesis in aging and age-related neurodegenerative diseases. Ageing Res Rev 2022; 78:101636. [PMID: 35490966 PMCID: PMC9168971 DOI: 10.1016/j.arr.2022.101636] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 04/14/2022] [Accepted: 04/25/2022] [Indexed: 12/11/2022]
Abstract
Adult neurogenesis, the process by which neurons are generated in certain areas of the adult brain, declines in an age-dependent manner and is one potential target for extending cognitive healthspan. Aging is a major risk factor for neurodegenerative diseases and, as lifespans are increasing, these health challenges are becoming more prevalent. An age-associated loss in neural stem cell number and/or activity could cause this decline in brain function, so interventions that reverse aging in stem cells might increase the human cognitive healthspan. In this review, we describe the involvement of adult neurogenesis in neurodegenerative diseases and address the molecular mechanistic aspects of neurogenesis that involve some of the key aggregation-prone proteins in the brain (i.e., tau, Aβ, α-synuclein, …). We summarize the research pertaining to interventions that increase neurogenesis and regulate known targets in aging research, such as mTOR and sirtuins. Lastly, we share our outlook on restoring the levels of neurogenesis to physiological levels in elderly individuals and those with neurodegeneration. We suggest that modulating neurogenesis represents a potential target for interventions that could help in the fight against neurodegeneration and cognitive decline.
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Affiliation(s)
- Luka Culig
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Xixia Chu
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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8
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Cai J, Che X, Xu T, Luo Y, Yin M, Lu X, Wu C, Yang J. Repeated oxytocin treatment during abstinence inhibited context- or restraint stress-induced reinstatement of methamphetamine-conditioned place preference and promoted adult hippocampal neurogenesis in mice. Exp Neurol 2021; 347:113907. [PMID: 34715133 DOI: 10.1016/j.expneurol.2021.113907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/06/2021] [Accepted: 10/23/2021] [Indexed: 12/28/2022]
Abstract
Propensity to relapse, even after long-term abstinence, is a crucial feature of methamphetamine (METH) abuse. We and other laboratories have reported that acute treatment of oxytocin (OXT), a hormone and neuropeptide, could inhibit reinstatement of METH seeking in animal studies. However, the effects of repeated OXT treatment on METH reinstatement as well as underlying mechanisms are still unclear. In the present study, the effects of repeated OXT treatment during abstinence on context- or restraint stress-induced reinstatement were investigated using the mice conditioned place preference (CPP) paradigm. After three intermittent injections of METH (2 mg/kg, i.p.) to induce CPP, mice received a daily bilateral intra-hippocampus injection of OXT (0.625, 1.25 or 2.5 μg) for 8 consecutive days before the context- or restraint stress-induced reinstatement test. Meanwhile, adult hippocampal neurogenesis (AHN) level was detected using immunostaining. To further clarify the role of AHN underlying OXT's effects on METH-CPP reinstatement, temozolomide (TMZ, 25 mg/kg, i.p.) was employed to deplete AHN prior to OXT treatment. The data showed that repeated OXT treatment (1.25 and 2.5 μg, intra-hippocampus) significantly inhibited both context- and restraint stress-induced METH-CPP reinstatement and concomitantly promoted AHN in a dose-dependent manner. Notably, TMZ pre-treatment markedly abolished all the above-mentioned effects of OXT, suggesting that AHN was closely involved in OXT's inhibition on reinstatement induced by both triggers. Taken together, the present study indicated that repeated OXT treatment during abstinence could inhibit both context- and restraint stress-induced METH-CPP reinstatement possibly by promoting AHN in mice, which provided a better understanding for OXT's beneficial effects on METH addiction.
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Affiliation(s)
- Jialing Cai
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Xiaohang Che
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Tianyu Xu
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Yuanchao Luo
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Meixue Yin
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Xianda Lu
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Chunfu Wu
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China
| | - Jingyu Yang
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China.
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9
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Grigoryan GA. Molecular-Cellular Mechanisms of Plastic Restructuring Produced by an Enriched Environment. Effects on Learning and Memory. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421030041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Therapeutically viable generation of neurons with antisense oligonucleotide suppression of PTB. Nat Neurosci 2021; 24:1089-1099. [PMID: 34083786 PMCID: PMC8338913 DOI: 10.1038/s41593-021-00864-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 04/29/2021] [Indexed: 02/07/2023]
Abstract
Methods to enhance adult neurogenesis by reprogramming glial cells into neurons enable production of new neurons in the adult nervous system. Development of therapeutically viable approaches to induce new neurons is now required to bring this concept to clinical application. Here, we successfully generate new neurons in the cortex and dentate gyrus of the aged adult mouse brain by transiently suppressing polypyrimidine tract binding protein 1 using an antisense oligonucleotide delivered by a single injection into cerebral spinal fluid. Radial glial-like cells and other GFAP-expressing cells convert into new neurons that, over a 2-month period, acquire mature neuronal character in a process mimicking normal neuronal maturation. The new neurons functionally integrate into endogenous circuits and modify mouse behavior. Thus, generation of new neurons in the dentate gyrus of the aging brain can be achieved with a therapeutically feasible approach, thereby opening prospects for production of neurons to replace those lost to neurodegenerative disease.
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11
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Totty MS, Warren N, Huddleston I, Ramanathan KR, Ressler RL, Oleksiak CR, Maren S. Behavioral and brain mechanisms mediating conditioned flight behavior in rats. Sci Rep 2021; 11:8215. [PMID: 33859260 PMCID: PMC8050069 DOI: 10.1038/s41598-021-87559-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/31/2021] [Indexed: 11/09/2022] Open
Abstract
Environmental contexts can inform animals of potential threats, though it is currently unknown how context biases the selection of defensive behavior. Here we investigated context-dependent flight responses with a Pavlovian serial-compound stimulus (SCS) paradigm that evokes freeze-to-flight transitions. Similar to previous work in mice, we show that male and female rats display context-dependent flight-like behavior in the SCS paradigm. Flight behavior was dependent on contextual fear insofar as it was only evoked in a shock-associated context and was reduced in the conditioning context after context extinction. Flight behavior was only expressed to white noise regardless of temporal order within the compound. Nonetheless, rats that received unpaired SCS trials did not show flight-like behavior to the SCS, indicating it is associative. Finally, we show that pharmacological inactivation of two brain regions critical to the expression of contextual fear, the central nucleus of the amygdala (CeA) and bed nucleus of the stria terminalis (BNST), attenuates both contextual fear and flight responses. All of these effects were similar in male and female rats. This work demonstrates that contextual fear can summate with cued and innate fear to drive a high fear state and transition from post-encounter to circa-strike defensive modes.
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Affiliation(s)
- Michael S Totty
- Department of Psychological and Brain Sciences and Institute for Neuroscience, Texas A&M University, 301 Old Main Dr., College Station, TX, 77843-3474, USA
| | - Naomi Warren
- Department of Psychological and Brain Sciences and Institute for Neuroscience, Texas A&M University, 301 Old Main Dr., College Station, TX, 77843-3474, USA
| | - Isabella Huddleston
- Department of Psychological and Brain Sciences and Institute for Neuroscience, Texas A&M University, 301 Old Main Dr., College Station, TX, 77843-3474, USA
| | - Karthik R Ramanathan
- Department of Psychological and Brain Sciences and Institute for Neuroscience, Texas A&M University, 301 Old Main Dr., College Station, TX, 77843-3474, USA
| | - Reed L Ressler
- Department of Psychological and Brain Sciences and Institute for Neuroscience, Texas A&M University, 301 Old Main Dr., College Station, TX, 77843-3474, USA
| | - Cecily R Oleksiak
- Department of Psychological and Brain Sciences and Institute for Neuroscience, Texas A&M University, 301 Old Main Dr., College Station, TX, 77843-3474, USA
| | - Stephen Maren
- Department of Psychological and Brain Sciences and Institute for Neuroscience, Texas A&M University, 301 Old Main Dr., College Station, TX, 77843-3474, USA.
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12
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Lunardi P, Mansk LMZ, Jaimes LF, Pereira GS. On the novel mechanisms for social memory and the emerging role of neurogenesis. Brain Res Bull 2021; 171:56-66. [PMID: 33753208 DOI: 10.1016/j.brainresbull.2021.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/24/2021] [Accepted: 03/08/2021] [Indexed: 01/25/2023]
Abstract
Social memory (SM) is a key element in social cognition and it encompasses the neural representation of conspecifics, an essential information to guide behavior in a social context. Here we evaluate classical and cutting-edge studies on neurobiology of SM, using as a guiding principle behavioral tasks performed in adult rodents. Our review highlights the relevance of the hippocampus, especially the CA2 region, as a neural substrate for SM and suggest that neural ensembles in the olfactory bulb may also encode SM traces. Compared to other hippocampus-dependent memories, much remains to be done to describe the neurobiological foundations of SM. Nonetheless, we argue that special attention should be paid to neurogenesis. Finally, we pinpoint the remaining open question on whether the hippocampal adult neurogenesis acts through pattern separation to permit the discrimination of highly similar stimuli during behavior.
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Affiliation(s)
- Paula Lunardi
- Núcleo de Neurociências, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Lara M Z Mansk
- Núcleo de Neurociências, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Laura F Jaimes
- Núcleo de Neurociências, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Grace S Pereira
- Núcleo de Neurociências, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
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13
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Gustus K, Li L, Newville J, Cunningham LA. Functional and Structural Correlates of Impaired Enrichment-Mediated Adult Hippocampal Neurogenesis in a Mouse Model of Prenatal Alcohol Exposure. Brain Plast 2020; 6:67-82. [PMID: 33680847 PMCID: PMC7902980 DOI: 10.3233/bpl-200112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Background: Fetal alcohol spectrum disorders (FASDs) are associated with a wide range of cognitive deficiencies. Objective: We previously
found that gestational exposure to moderate levels of alcohol in mice throughout the 1st-2nd human trimester-equivalents
for brain development results in profound impairment of the hippocampal neurogenic response to enriched environment
(EE) in adulthood, without altering baseline neurogenesis rate under standard housing (SH). However, the functional and
structural consequences of impaired EE-mediated neurogenesis in the context of prenatal alcohol exposure (PAE) have
not been determined. Results: Here, we demonstrate that PAE-EE mice display impaired performance on a neurogenesis-dependent
pattern discrimination task, broadened behavioral activation of the dentate gyrus, as assessed by expression of the immediate
early gene, c-Fos, and impaired dendritic branching of adult-generated dentate granule cells (aDGCs). Conclusions: These studies further underscore the impact of moderate gestational alcohol exposure on adult hippocampal plasticity and support adult hippocampal neurogenesis as a potential therapeutic target to remediate certain neurological outcomes in FASD.
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Affiliation(s)
- Kymberly Gustus
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Lu Li
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Jessie Newville
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Lee Anna Cunningham
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, USA
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14
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Desplats P, Gutierrez AM, Antonelli MC, Frasch MG. Microglial memory of early life stress and inflammation: Susceptibility to neurodegeneration in adulthood. Neurosci Biobehav Rev 2020; 117:232-242. [PMID: 31703966 PMCID: PMC7198341 DOI: 10.1016/j.neubiorev.2019.10.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 09/15/2019] [Accepted: 10/20/2019] [Indexed: 02/08/2023]
Abstract
We review evidence supporting the role of early life programming in the susceptibility for adult neurodegenerative diseases while highlighting questions and proposing avenues for future research to advance our understanding of this fundamental process. The key elements of this phenomenon are chronic stress, neuroinflammation triggering microglial polarization, microglial memory and their connection to neurodegeneration. We review the mediating mechanisms which may function as early biomarkers of increased susceptibility for neurodegeneration. Can we devise novel early life modifying interventions to steer developmental trajectories to their optimum?
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Affiliation(s)
- Paula Desplats
- Department of Neurosciences, University of California San Diego, CA, USA; Department of Pathology, University of California San Diego, CA, USA
| | - Ashley M Gutierrez
- Department of Neurosciences, University of California San Diego, CA, USA
| | - Marta C Antonelli
- Instituto de Biología Celular y Neurociencia "Prof. Eduardo De Robertis", Facultad de Medicina, Universidad de Buenos Aires, Argentina; Department of Obstetrics and Gynecology, Klinikum rechts der Isar, Technical University of Munich, Germany
| | - Martin G Frasch
- Department of Obstetrics and Gynecology, University of Washington, Seattle, WA, USA; Center on Human Development and Disability, University of Washington, Seattle, WA, USA.
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15
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Wu A, Yu B, Chen Q, Matthews GA, Lu C, Campbell E, Tye KM, Komiyama T. Context-dependent plasticity of adult-born neurons regulated by cortical feedback. SCIENCE ADVANCES 2020; 6:6/42/eabc8319. [PMID: 33067236 PMCID: PMC7567600 DOI: 10.1126/sciadv.abc8319] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 09/02/2020] [Indexed: 05/26/2023]
Abstract
In a complex and dynamic environment, the brain flexibly adjusts its circuits to preferentially process behaviorally relevant information. Here, we investigated how the olfactory bulb copes with this demand by examining the plasticity of adult-born granule cells (abGCs). We found that learning of olfactory discrimination elevates odor responses of young abGCs and increases their apical dendritic spines. This plasticity did not occur in abGCs during passive odor experience nor in resident granule cells (rGCs) during learning. Furthermore, we found that feedback projections from the piriform cortex show elevated activity during learning, and activating piriform feedback elicited stronger excitatory postsynaptic currents in abGCs than rGCs. Inactivation of piriform feedback blocked abGC plasticity during learning, and activation of piriform feedback during passive experience induced learning-like plasticity of abGCs. Our work describes a neural circuit mechanism that uses adult neurogenesis to update a sensory circuit to flexibly adapt to new behavioral demands.
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Affiliation(s)
- An Wu
- Neurobiology Section, and Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA.
- Department of Neurosciences, and Halıcıoğlu Data Science Institute, University of California San Diego, La Jolla, CA 92093, USA
| | - Bin Yu
- Neurobiology Section, and Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA
- Department of Neurosciences, and Halıcıoğlu Data Science Institute, University of California San Diego, La Jolla, CA 92093, USA
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92093, USA
| | - Qiyu Chen
- Neurobiology Section, and Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA
- Department of Neurosciences, and Halıcıoğlu Data Science Institute, University of California San Diego, La Jolla, CA 92093, USA
| | | | - Chen Lu
- Neurobiology Section, and Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA
- Department of Neurosciences, and Halıcıoğlu Data Science Institute, University of California San Diego, La Jolla, CA 92093, USA
| | - Evan Campbell
- Neurobiology Section, and Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA
| | - Kay M Tye
- Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Takaki Komiyama
- Neurobiology Section, and Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA.
- Department of Neurosciences, and Halıcıoğlu Data Science Institute, University of California San Diego, La Jolla, CA 92093, USA
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Zocher S, Schilling S, Grzyb AN, Adusumilli VS, Bogado Lopes J, Günther S, Overall RW, Winter Y, Kempermann G. Early-life environmental enrichment generates persistent individualized behavior in mice. SCIENCE ADVANCES 2020; 6:eabb1478. [PMID: 32923634 PMCID: PMC7449688 DOI: 10.1126/sciadv.abb1478] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 07/10/2020] [Indexed: 06/11/2023]
Abstract
Individuals differ in their response to environmental stimuli, but the stability of individualized behaviors and their associated changes in brain plasticity are poorly understood. We developed a novel model of enriched environment to longitudinally monitor 40 inbred mice exploring 35 connected cages over periods of 3 to 6 months. We show that behavioral individuality that emerged during the first 3 months of environmental enrichment persisted when mice were withdrawn from the enriched environment for 3 additional months. Behavioral trajectories were associated with stable interindividual differences in adult hippocampal neurogenesis and persistent epigenetic effects on neuronal plasticity genes in the hippocampus. Using genome-wide DNA methylation sequencing, we show that one-third of the DNA methylation changes were maintained after withdrawal from the enriched environment. Our results suggest that, even under conditions that control genetic background and shared environment, early-life experiences result in lasting individualized changes in behavior, brain plasticity, and epigenetics.
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Affiliation(s)
- Sara Zocher
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Tatzberg 41, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Susan Schilling
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Tatzberg 41, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Anna N. Grzyb
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Tatzberg 41, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Vijay S. Adusumilli
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Tatzberg 41, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Jadna Bogado Lopes
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Tatzberg 41, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Sandra Günther
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Tatzberg 41, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - Rupert W. Overall
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Tatzberg 41, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
| | - York Winter
- Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany
| | - Gerd Kempermann
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Tatzberg 41, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany
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17
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Clemenson GD, Stark SM, Rutledge SM, Stark CEL. Enriching hippocampal memory function in older adults through video games. Behav Brain Res 2020; 390:112667. [PMID: 32439346 PMCID: PMC7286064 DOI: 10.1016/j.bbr.2020.112667] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/21/2020] [Accepted: 04/21/2020] [Indexed: 01/17/2023]
Abstract
Healthy aging is accompanied by a steady cognitive decline with clear losses in memory. Animal studies have consistently demonstrated that simply modifying an animal's living environment (known as environmental enrichment) can have a positive influence on age-related cognitive decline in the hippocampus. Previously, we showed that playing immersive 3D video games can improve hippocampal-based memory in young healthy adults, suggesting that the exploration of the large open worlds of modern-day video games may act as proxy for environmental enrichment in humans. Here, we replicated our previous video game study in healthy older adults, showing that playing video games for four weeks can improve hippocampal-based memory in a population that is already experiencing age-related decline in memory. Furthermore, we showed that the improvements last for up to four weeks past the intervention, highlighting the potential of video games as intervention for age-related cognitive decline.
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Affiliation(s)
- Gregory D Clemenson
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA, 92697, United States
| | - Shauna M Stark
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA, 92697, United States
| | - Samantha M Rutledge
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA, 92697, United States
| | - Craig E L Stark
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA, 92697, United States.
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Kolarik BS, Stark SM, Stark CEL. Enriching Hippocampal Memory Function in Older Adults Through Real-World Exploration. Front Aging Neurosci 2020; 12:158. [PMID: 32581768 PMCID: PMC7286388 DOI: 10.3389/fnagi.2020.00158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 05/08/2020] [Indexed: 12/20/2022] Open
Abstract
Age-related structural and functional changes in the hippocampus can have a severe impact on hippocampal-dependent memory performance. Here, we tested the hypothesis that a real-world spatial exploration and learning intervention would improve hippocampal-dependent memory performance in healthy older adults. We developed a scavenger hunt task that participants performed over the course of a 4-week behavioral intervention period. Following this intervention, participants’ lure discrimination index (LDI) on the Mnemonic Similarity Task was significantly higher than it was at baseline and greater than that of a No-Contact Control Group, while traditional recognition scores remained relatively unchanged. These results point to the viability of a spatial exploration intervention for improving hippocampal-dependent memory in older adults.
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Affiliation(s)
- Branden S Kolarik
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Shauna M Stark
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Craig E L Stark
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
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19
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Clemenson GD, Henningfield CM, Stark CEL. Improving Hippocampal Memory Through the Experience of a Rich Minecraft Environment. Front Behav Neurosci 2019; 13:57. [PMID: 30949036 PMCID: PMC6437107 DOI: 10.3389/fnbeh.2019.00057] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/06/2019] [Indexed: 12/15/2022] Open
Abstract
It is well known that the brain changes in response to the surrounding environment. The hippocampus has been shown to be particularly susceptible to environmental enrichment, with effects ranging from the generation of new hippocampal neurons and synapses to an increased expression of neurotrophic factors. While many of these changes in the hippocampus are well documented in animals, our understanding of how environmental enrichment can apply to humans is more ambiguous. In animals, spatial exploration has been shown to be a clear way to elicit the effects of environmental enrichment and considering the role of the hippocampus in spatial navigation, which has been shown in both animal models and humans, it suggests a viable avenue for translation of environmental enrichment to humans. Here, we test the hypothesis that the spatial exploration of a virtual video game environment, can impact the hippocampus and lead to an improvement in hippocampal-dependent memory. Using the video game Minecraft, we tested four groups of participants, each playing on custom servers and focusing on different aspects of Minecraft to test the effects of both building and exploration over the course of 2 weeks. We found an improvement in hippocampus-associated memory from pre-test to post-test and that the degree of improvement was tied to both the amount of exploration of the Minecraft world and the complexity of the structures built within Minecraft. Thus, the number of enrichment participants engaged in while playing Minecraft was directly correlated with improvements in hippocampal-dependent memory outside of the game.
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Affiliation(s)
- Gregory D Clemenson
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Caden M Henningfield
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Craig E L Stark
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
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20
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The role of adult hippocampal neurogenesis in brain health and disease. Mol Psychiatry 2019; 24:67-87. [PMID: 29679070 PMCID: PMC6195869 DOI: 10.1038/s41380-018-0036-2] [Citation(s) in RCA: 396] [Impact Index Per Article: 79.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 01/15/2018] [Accepted: 01/31/2018] [Indexed: 12/18/2022]
Abstract
Adult neurogenesis in the dentate gyrus of the hippocampus is highly regulated by a number of environmental and cell-intrinsic factors to adapt to environmental changes. Accumulating evidence suggests that adult-born neurons may play distinct physiological roles in hippocampus-dependent functions, such as memory encoding and mood regulation. In addition, several brain diseases, such as neurological diseases and mood disorders, have deleterious effects on adult hippocampal neurogenesis, and some symptoms of those diseases can be partially explained by the dysregulation of adult hippocampal neurogenesis. Here we review a possible link between the physiological functions of adult-born neurons and their roles in pathological conditions.
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21
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Llorens-Martín M. Exercising New Neurons to Vanquish Alzheimer Disease. Brain Plast 2018; 4:111-126. [PMID: 30564550 PMCID: PMC6296267 DOI: 10.3233/bpl-180065] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2018] [Indexed: 02/07/2023] Open
Abstract
Alzheimer disease (AD) is the most common type of dementia in individuals over 65 years of age. The neuropathological hallmarks of the condition are Tau neurofibrillary tangles and Amyloid-β senile plaques. Moreover, certain susceptible regions of the brain experience a generalized lack of neural plasticity and marked synaptic alterations during the progression of this as yet incurable disease. One of these regions, the hippocampus, is characterized by the continuous addition of new neurons throughout life. This phenomenon, named adult hippocampal neurogenesis (AHN), provides a potentially endless source of new synaptic elements that increase the complexity and plasticity of the hippocampal circuitry. Numerous lines of evidence show that physical activity and environmental enrichment (EE) are among the most potent positive regulators of AHN. Given that neural plasticity is markedly decreased in many neurodegenerative diseases, the therapeutic potential of making certain lifestyle changes, such as increasing physical activity, is being recognised in several non-pharmacologic strategies seeking to slow down or prevent the progression of these diseases. This review article summarizes current evidence supporting the putative therapeutic potential of EE and physical exercise to increase AHN and hippocampal plasticity both under physiological and pathological circumstances, with a special emphasis on neurodegenerative diseases and AD.
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Affiliation(s)
- María Llorens-Martín
- Department of Molecular Neuropathology, Centro de Biología Molecular “Severo Ochoa”, CBMSO, CSIC-UAM, Madrid, Spain
- Center for Networked Biomedical Research on Neurodegenerative Diseases CIBERNED, Madrid, Spain
- Department of Molecular Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
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22
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Schroyens N, Bender CL, Alfei JM, Molina VA, Luyten L, Beckers T. Post-weaning housing conditions influence freezing during contextual fear conditioning in adult rats. Behav Brain Res 2018; 359:172-180. [PMID: 30391556 PMCID: PMC6314464 DOI: 10.1016/j.bbr.2018.10.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 10/30/2018] [Accepted: 10/30/2018] [Indexed: 01/14/2023]
Abstract
The present study aimed to investigate the influence of housing conditions on contextual fear memory malleability. Male Wistar rats were housed in enriched, standard, or impoverished conditions after weaning and remained in these conditions throughout the entire experiment. After six weeks into those housing conditions, all animals underwent a 3-day protocol including contextual fear conditioning (day 1), memory reactivation followed by systemic administration of midazolam or vehicle (day 2), and a retention test (day 3). Percentage freezing was used as a behavioral measure of contextual fear. There was no evidence for an effect of housing conditions on the sensitivity of contextual fear memory to amnestic effects of post-reactivation midazolam administration, and no indication for amnestic effects of post-reactivation midazolam overall (including in the standard group). The inability to replicate previous demonstrations of post-reactivation amnesia using the same protocol underscores the subtle nature of post-reactivation pharmacological memory interference. Notably, impoverished housing resulted in a decrease in contextual freezing during contextual fear conditioning, reactivation and retention testing, compared to enriched and standard housing conditions. This observation warrants caution when interpreting the results from experiments regarding effects of housing on fear memory processes, particularly when freezing is used as a measure of fear.
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Affiliation(s)
- Natalie Schroyens
- Centre for the Psychology of Learning and Experimental Psychopathology, Department of Psychology, KU Leuven, Tiensestraat 102 bus 3712, 3000 Leuven, Belgium.
| | - Crhistian Luis Bender
- Instituto de Farmacología Experimental de Córdoba-CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
| | - Joaquín Matias Alfei
- Centre for the Psychology of Learning and Experimental Psychopathology, Department of Psychology, KU Leuven, Tiensestraat 102 bus 3712, 3000 Leuven, Belgium.
| | - Victor Alejandro Molina
- Instituto de Farmacología Experimental de Córdoba-CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
| | - Laura Luyten
- Centre for the Psychology of Learning and Experimental Psychopathology, Department of Psychology, KU Leuven, Tiensestraat 102 bus 3712, 3000 Leuven, Belgium.
| | - Tom Beckers
- Centre for the Psychology of Learning and Experimental Psychopathology, Department of Psychology, KU Leuven, Tiensestraat 102 bus 3712, 3000 Leuven, Belgium; Leuven Brain Institute, 3000 Leuven, Belgium.
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23
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Körholz JC, Zocher S, Grzyb AN, Morisse B, Poetzsch A, Ehret F, Schmied C, Kempermann G. Selective increases in inter-individual variability in response to environmental enrichment in female mice. eLife 2018; 7:e35690. [PMID: 30362941 PMCID: PMC6203437 DOI: 10.7554/elife.35690] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 09/14/2018] [Indexed: 11/17/2022] Open
Abstract
One manifestation of individualization is a progressively differential response of individuals to the non-shared components of the same environment. Individualization has practical implications in the clinical setting, where subtle differences between patients are often decisive for the success of an intervention, yet there has been no suitable animal model to study its underlying biological mechanisms. Here we show that enriched environment (ENR) can serve as a model of brain individualization. We kept 40 isogenic female C57BL/6JRj mice for 3 months in ENR and compared these mice to an equally sized group of standard-housed control animals, looking at the effects on a wide range of phenotypes in terms of both means and variances. Although ENR influenced multiple parameters and restructured correlation patterns between them, it only increased differences among individuals in traits related to brain and behavior (adult hippocampal neurogenesis, motor cortex thickness, open field and object exploration), in agreement with the hypothesis of a specific activity-dependent development of brain individuality.
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Affiliation(s)
- Julia C Körholz
- German Center for Neurodegenerative Diseases (DZNE) DresdenDresdenGermany
- CRTD – Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Sara Zocher
- German Center for Neurodegenerative Diseases (DZNE) DresdenDresdenGermany
- CRTD – Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Anna N Grzyb
- German Center for Neurodegenerative Diseases (DZNE) DresdenDresdenGermany
- CRTD – Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Benjamin Morisse
- German Center for Neurodegenerative Diseases (DZNE) DresdenDresdenGermany
- CRTD – Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Alexandra Poetzsch
- German Center for Neurodegenerative Diseases (DZNE) DresdenDresdenGermany
- CRTD – Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Fanny Ehret
- German Center for Neurodegenerative Diseases (DZNE) DresdenDresdenGermany
- CRTD – Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Christopher Schmied
- German Center for Neurodegenerative Diseases (DZNE) DresdenDresdenGermany
- CRTD – Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Gerd Kempermann
- German Center for Neurodegenerative Diseases (DZNE) DresdenDresdenGermany
- CRTD – Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
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24
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Impact of high sucrose diets on the discrimination of spatial and object memories with overlapping features. Physiol Behav 2018; 192:127-133. [DOI: 10.1016/j.physbeh.2018.02.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 02/13/2018] [Accepted: 02/14/2018] [Indexed: 01/06/2023]
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25
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How Do Microtubule Dynamics Relate to the Hallmarks of Learning and Memory? J Neurosci 2018; 36:5911-3. [PMID: 27251613 DOI: 10.1523/jneurosci.0920-16.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 04/26/2016] [Indexed: 11/21/2022] Open
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26
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Donley MP, Rosen JB. Novelty and fear conditioning induced gene expression in high and low states of anxiety. Learn Mem 2017; 24:449-461. [PMID: 28814471 PMCID: PMC5580523 DOI: 10.1101/lm.044289.116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 05/08/2017] [Indexed: 11/25/2022]
Abstract
Emotional states influence how stimuli are interpreted. High anxiety states in humans lead to more negative, threatening interpretations of novel information, typically accompanied by activation of the amygdala. We developed a handling protocol that induces long-lasting high and low anxiety-like states in rats to explore the role of state anxiety on brain activation during exposure to a novel environment and fear conditioning. In situ hybridization of the inducible transcription factor Egr-1 found increased gene expression in the lateral nucleus of the amygdala (LA) following exposure to a novel environment and contextual fear conditioning in high anxiety-like rats. In contrast, low state anxiety-like rats did not generate Egr-1 increases in LA when placed in a novel chamber. Egr-1 expression was also examined in the dorsal hippocampus and prefrontal cortex. In CA1 of the hippocampus and medial prefrontal cortex (mPFC), Egr-1 expression increased in response to novel context exposure and fear conditioning, independent of state anxiety level. Furthermore, in mPFC, Egr-1 in low anxiety-like rats was increased more with fear conditioning than novel exposure. The current series of experiments show that brain areas involved in fear and anxiety-like states do not respond uniformly to novelty during high and low states of anxiety.
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Affiliation(s)
- Melanie P Donley
- Department of Psychological and Brain Sciences, University of Delaware, Newark, Delaware 19716, USA
| | - Jeffrey B Rosen
- Department of Psychological and Brain Sciences, University of Delaware, Newark, Delaware 19716, USA
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Birkel L. Decreased use of spatial pattern separation in contemporary lifestyles may contribute to hippocampal atrophy and diminish mental health. Med Hypotheses 2017; 107:55-63. [DOI: 10.1016/j.mehy.2017.07.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 07/14/2017] [Indexed: 10/19/2022]
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28
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Yu T, Tensaouti Y, Bagha ZM, Davidson R, Kim A, Kernie SG. Adult newborn neurons interfere with fear discrimination in a protocol-dependent manner. Brain Behav 2017; 7:e00796. [PMID: 28948089 PMCID: PMC5607558 DOI: 10.1002/brb3.796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 06/27/2017] [Accepted: 07/02/2017] [Indexed: 12/25/2022] Open
Abstract
INTRODUCTION Significant enhancement of neurogenesis is known to occur in response to a variety of brain insults such as traumatic brain injury. Previous studies have demonstrated that injury-induced newborn neurons are required for hippocampus-dependent spatial learning and memory tasks like the Morris water maze, but not in contextual fear conditioning that requires both the hippocampus and amygdala. Recently, the dentate gyrus, where adult hippocampal neurogenesis occurs, has been implicated in processing information to form specific memory under specific environmental stimuli in a process known as pattern separation. METHODS To test whether injury-induced newborn neurons facilitate pattern separation, hippocampus-dependent contextual fear discrimination was performed using delta-HSV-TK transgenic mice, which can temporally inhibit injury-induced neurogenesis under the control of ganciclovir. RESULTS We observed that impaired neurogenesis enhanced the ability to distinguish aversive from naïve environments. In addition, this occurs most significantly following injury, but only in a context-dependent manner whereby the sequence of introducing the naïve environment from the aversive one affected the performance differentially. CONCLUSIONS Temporal impairment of both baseline and injury-induced adult neurogenesis enhances performance in fear discrimination in a context-dependent manner.
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Affiliation(s)
- Tzong‐Shiue Yu
- Department of PediatricsColumbia University College of Physicians and SurgeonsNew YorkNYUSA
| | - Yacine Tensaouti
- Department of PediatricsColumbia University College of Physicians and SurgeonsNew YorkNYUSA
| | - Zohaib M. Bagha
- Department of PediatricsColumbia University College of Physicians and SurgeonsNew YorkNYUSA
| | - Rina Davidson
- Department of PediatricsColumbia University College of Physicians and SurgeonsNew YorkNYUSA
| | - Ahleum Kim
- Department of PediatricsColumbia University College of Physicians and SurgeonsNew YorkNYUSA
| | - Steven G. Kernie
- Department of PediatricsColumbia University College of Physicians and SurgeonsNew YorkNYUSA
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29
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Gonçalves JT, Schafer ST, Gage FH. Adult Neurogenesis in the Hippocampus: From Stem Cells to Behavior. Cell 2017; 167:897-914. [PMID: 27814520 DOI: 10.1016/j.cell.2016.10.021] [Citation(s) in RCA: 750] [Impact Index Per Article: 107.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 10/11/2016] [Accepted: 10/12/2016] [Indexed: 02/08/2023]
Abstract
The dentate gyrus of the mammalian hippocampus continuously generates new neurons during adulthood. These adult-born neurons become functionally active and are thought to contribute to learning and memory, especially during their maturation phase, when they have extraordinary plasticity. In this Review, we discuss the molecular machinery involved in the generation of new neurons from a pool of adult neural stem cells and their integration into functional hippocampal circuits. We also summarize the potential functions of these newborn neurons in the adult brain, their contribution to behavior, and their relevance to disease.
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Affiliation(s)
- J Tiago Gonçalves
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Simon T Schafer
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Fred H Gage
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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Bertapelle C, Polese G, Di Cosmo A. Enriched Environment Increases PCNA and PARP1 Levels in Octopus vulgaris Central Nervous System: First Evidence of Adult Neurogenesis in Lophotrochozoa. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2017; 328:347-359. [PMID: 28251828 DOI: 10.1002/jez.b.22735] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 01/25/2017] [Accepted: 01/30/2017] [Indexed: 11/09/2022]
Abstract
Organisms showing a complex and centralized nervous system, such as teleosts, amphibians, reptiles, birds and mammals, and among invertebrates, crustaceans and insects, can adjust their behavior according to the environmental challenges. Proliferation, differentiation, migration, and axonal and dendritic development of newborn neurons take place in brain areas where structural plasticity, involved in learning, memory, and sensory stimuli integration, occurs. Octopus vulgaris has a complex and centralized nervous system, located between the eyes, with a hierarchical organization. It is considered the most "intelligent" invertebrate for its advanced cognitive capabilities, as learning and memory, and its sophisticated behaviors. The experimental data obtained by immunohistochemistry and western blot assay using proliferating cell nuclear antigen and poli (ADP-ribose) polymerase 1 as marker of cell proliferation and synaptogenesis, respectively, reviled cell proliferation in areas of brain involved in learning, memory, and sensory stimuli integration. Furthermore, we showed how enriched environmental conditions affect adult neurogenesis.
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Affiliation(s)
- Carla Bertapelle
- Department of Biology, University of Napoli Federico II, Naples, NA, Italy
| | - Gianluca Polese
- Department of Biology, University of Napoli Federico II, Naples, NA, Italy
| | - Anna Di Cosmo
- Department of Biology, University of Napoli Federico II, Naples, NA, Italy
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Zeleznikow-Johnston A, Burrows EL, Renoir T, Hannan AJ. Environmental enrichment enhances cognitive flexibility in C57BL/6 mice on a touchscreen reversal learning task. Neuropharmacology 2017; 117:219-226. [PMID: 28196627 DOI: 10.1016/j.neuropharm.2017.02.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/13/2017] [Accepted: 02/09/2017] [Indexed: 01/12/2023]
Abstract
Environmental enrichment (EE) is any positive modification of the 'standard housing' (SH) conditions in which laboratory animals are typically held, usually involving increased opportunity for cognitive stimulation and physical activity. EE has been reported to enhance baseline performance of wild-type animals on traditional cognitive behavioural tasks. Recently, touchscreen operant testing chambers have emerged as a way of performing rodent cognitive assays, providing greater reproducibility, translatability and automatability. Cognitive tests in touchscreen chambers are performed over numerous trials and thus experimenters have the power to detect subtle enhancements in performance. We used touchscreens to analyse the effects of EE on reversal learning, visual discrimination and hippocampal-dependent spatial pattern separation and working memory. We hypothesized that EE would enhance the performance of mice on cognitive touchscreen tasks. Our hypothesis was partially supported in that EE induced enhancements in cognitive flexibility as observed in visual discrimination and reversal learning improvements. However, no other significant effects of EE on cognitive performance were observed. EE decreased the activity level of mice in the touchscreen chambers, which may influence the enrichment level of the animals. Although we did not see enhancements on all hypothesized parameters, our testing paradigm is capable of detecting EE-induced improved cognitive flexibility in mice, which has implications for both understanding the mechanisms of EE and improving screening of putative cognitive-enhancing therapeutics.
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Affiliation(s)
- Ariel Zeleznikow-Johnston
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3010, Australia
| | - Emma L Burrows
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3010, Australia
| | - Thibault Renoir
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3010, Australia
| | - Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3010, Australia; Department of Anatomy and Neuroscience, University of Melbourne, Parkville, VIC 3010, Australia.
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Cortez I, Bulavin DV, Wu P, McGrath EL, Cunningham KA, Wakamiya M, Papaconstantinou J, Dineley KT. Aged dominant negative p38α MAPK mice are resistant to age-dependent decline in adult-neurogenesis and context discrimination fear conditioning. Behav Brain Res 2016; 322:212-222. [PMID: 27765672 DOI: 10.1016/j.bbr.2016.10.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 10/10/2016] [Accepted: 10/12/2016] [Indexed: 01/13/2023]
Abstract
A major aspect of mammalian aging is the decline in functional competence of many self-renewing cell types, including adult-born neuronal precursors. Since age-related senescence of self-renewal occurs simultaneously with chronic up-regulation of the p38MAPKalpha (p38α) signaling pathway, we used the dominant negative mouse model for attenuated p38α activity (DN-p38αAF/+) in which Thr180 and Tyr182 are mutated (T→A/Y→F) to prevent phosphorylation activation (DN-p38αAF/+) and kinase activity. As a result, aged DN-p38αAF/+ mice are resistant to age-dependent decline in proliferation and regeneration of several peripheral tissue progenitors when compared to wild-type littermates. Aging is the major risk factor for non-inherited forms of Alzheimer's disease (AD); environmental and genetic risk factors that accelerate the senescence phenotype are thought to contribute to an individual's relative risk. In the present study, we evaluated aged DN-p38αAF/+ and wildtype littermates in a series of behavioral paradigms to test if p38α mutant mice exhibit altered baseline abnormalities in neurological reflexes, locomotion, anxiety-like behavior, and age-dependent cognitive decline. While aged DN-p38αAF/+ and wildtype littermates appear equal in all tested baseline neurological and behavioral parameters, DN-p38αAF/+ exhibit superior context discrimination fear conditioning. Context discrimination is a cognitive task that is supported by proliferation and differentiation of adult-born neurons in the dentate gyrus of the hippocampus. Consistent with enhanced context discrimination in aged DN-p38αAF/+, we discovered enhanced production of adult-born neurons in the dentate gyrus of DN-p38αAF/+ mice compared to wildtype littermates. Our findings support the notion that p38α inhibition has therapeutic utility in aging diseases that affect cognition, such as AD.
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Affiliation(s)
- IbDanelo Cortez
- Department of Neurology, University of Texas Medical Branch at Galveston, Galveston TX, USA; Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston, Galveston TX, USA; Center for Addiction Research, University of Texas Medical Branch at Galveston, Galveston TX, USA.
| | - Dmitry V Bulavin
- Institute for Research on Cancer and Ageing of Nice, INSERM, University of Nice, France
| | - Ping Wu
- Department of Neuroscience & Cell Biology, University of Texas Medical Branch at Galveston, Galveston TX, USA
| | - Erica L McGrath
- Department of Neuroscience & Cell Biology, University of Texas Medical Branch at Galveston, Galveston TX, USA
| | - Kathryn A Cunningham
- Department of Pharmacology and Toxicology, University of Texas Medical Branch at Galveston, Galveston TX, USA; Center for Addiction Research, University of Texas Medical Branch at Galveston, Galveston TX, USA
| | - Maki Wakamiya
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston TX, USA; Transgenic Mouse Core Facility, University of Texas Medical Branch at Galveston, Galveston TX, USA
| | - John Papaconstantinou
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston TX, USA
| | - Kelly T Dineley
- Department of Neurology, University of Texas Medical Branch at Galveston, Galveston TX, USA; Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch at Galveston, Galveston TX, USA; Center for Addiction Research, University of Texas Medical Branch at Galveston, Galveston TX, USA
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Sanders J, Mayford M. Chronic fluoxetine dissociates contextual from auditory fear memory. Neurosci Lett 2016; 632:152-6. [PMID: 27592057 DOI: 10.1016/j.neulet.2016.08.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/18/2016] [Accepted: 08/30/2016] [Indexed: 11/30/2022]
Abstract
Fluoxetine is a medication used to treat Major Depressive Disorder and other psychiatric conditions. These experiments studied the effects of chronic fluoxetine treatment on the contextual versus auditory fear memory of mice. We found that chronic fluoxetine treatment of adult mice impaired their contextual fear memory, but spared auditory fear memory. Hippocampal perineuronal nets, which are involved in contextual fear memory plasticity, were unaltered by fluoxetine treatment. These data point to a selective inability to form contextual fear memory as a result of fluoxetine treatment, and they suggest that a blunting of hippocampal-mediated aversive memory may be a therapeutic action for this medication.
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Affiliation(s)
- Jeff Sanders
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0603, United States.
| | - Mark Mayford
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0603, United States
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Abstract
UNLABELLED The positive effects of environmental enrichment and their neural bases have been studied extensively in the rodent (van Praag et al., 2000). For example, simply modifying an animal's living environment to promote sensory stimulation can lead to (but is not limited to) enhancements in hippocampal cognition and neuroplasticity and can alleviate hippocampal cognitive deficits associated with neurodegenerative diseases and aging. We are interested in whether these manipulations that successfully enhance cognition (or mitigate cognitive decline) have similar influences on humans. Although there are many "enriching" aspects to daily life, we are constantly adapting to new experiences and situations within our own environment on a daily basis. Here, we hypothesize that the exploration of the vast and visually stimulating virtual environments within video games is a human correlate of environmental enrichment. We show that video gamers who specifically favor complex 3D video games performed better on a demanding recognition memory task that assesses participants' ability to discriminate highly similar lure items from repeated items. In addition, after 2 weeks of training on the 3D video game Super Mario 3D World, naive video gamers showed improved mnemonic discrimination ability and improvements on a virtual water maze task. Two control conditions (passive and training in a 2D game, Angry Birds), showed no such improvements. Furthermore, individual performance in both hippocampal-associated behaviors correlated with performance in Super Mario but not Angry Birds, suggesting that how individuals explored the virtual environment may influence hippocampal behavior. SIGNIFICANCE STATEMENT The hippocampus has long been associated with episodic memory and is commonly thought to rely on neuroplasticity to adapt to the ever-changing environment. In animals, it is well understood that exposing animals to a more stimulating environment, known as environmental enrichment, can stimulate neuroplasticity and improve hippocampal function and performance on hippocampally mediated memory tasks. Here, we suggest that the exploration of vast and visually stimulating environments within modern-day video games can act as a human correlate of environmental enrichment. Training naive video gamers in a rich 3D, but not 2D, video game, resulted in a significant improvement in hippocampus-associated cognition using several behavioral measures. Our results suggest that modern day video games may provide meaningful stimulation to the human hippocampus.
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Meyers EA, Gobeske KT, Bond AM, Jarrett JC, Peng CY, Kessler JA. Increased bone morphogenetic protein signaling contributes to age-related declines in neurogenesis and cognition. Neurobiol Aging 2015; 38:164-175. [PMID: 26827654 DOI: 10.1016/j.neurobiolaging.2015.10.035] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 10/25/2015] [Accepted: 10/30/2015] [Indexed: 12/12/2022]
Abstract
Aging is associated with decreased neurogenesis in the hippocampus and diminished hippocampus-dependent cognitive functions. Expression of bone morphogenetic protein 4 (BMP4) increases with age by more than 10-fold in the mouse dentate gyrus while levels of the BMP inhibitor, noggin, decrease. This results in a profound 30-fold increase in phosphorylated-SMAD1/5/8, the effector of canonical BMP signaling. Just as observed in mice, a profound increase in expression of BMP4 is observed in the dentate gyrus of humans with no known cognitive abnormalities. Inhibition of BMP signaling either by overexpression of noggin or transgenic manipulation not only increases neurogenesis in aging mice, but remarkably, is associated with a rescue of cognitive deficits to levels comparable to young mice. Additive benefits are observed when combining inhibition of BMP signaling and environmental enrichment. These findings indicate that increased BMP signaling contributes significantly to impairments in neurogenesis and to cognitive decline associated with aging, and identify this pathway as a potential druggable target for reversing age-related changes in cognition.
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Affiliation(s)
- Emily A Meyers
- Department of Neurology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA.
| | - Kevin T Gobeske
- Department of Neurology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA
| | - Allison M Bond
- Department of Neurology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA
| | - Jennifer C Jarrett
- Department of Neurology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA
| | - Chian-Yu Peng
- Department of Neurology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA
| | - John A Kessler
- Department of Neurology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA
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Johnston ST, Shtrahman M, Parylak S, Gonçalves JT, Gage FH. Paradox of pattern separation and adult neurogenesis: A dual role for new neurons balancing memory resolution and robustness. Neurobiol Learn Mem 2015; 129:60-8. [PMID: 26549627 DOI: 10.1016/j.nlm.2015.10.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 10/22/2015] [Accepted: 10/27/2015] [Indexed: 01/31/2023]
Abstract
Hippocampal adult neurogenesis is thought to subserve pattern separation, the process by which similar patterns of neuronal inputs are transformed into distinct neuronal representations, permitting the discrimination of highly similar stimuli in hippocampus-dependent tasks. However, the mechanism by which immature adult-born dentate granule neurons cells (abDGCs) perform this function remains unknown. Two theories of abDGC function, one by which abDGCs modulate and sparsify activity in the dentate gyrus and one by which abDGCs act as autonomous coding units, are generally suggested to be mutually exclusive. This review suggests that these two mechanisms work in tandem to dynamically regulate memory resolution while avoiding memory interference and maintaining memory robustness.
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Affiliation(s)
- Stephen T Johnston
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, United States
| | - Matthew Shtrahman
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, United States
| | - Sarah Parylak
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, United States
| | - J Tiago Gonçalves
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, United States
| | - Fred H Gage
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037, United States.
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Wu MV, Luna VM, Hen R. Running rescues a fear-based contextual discrimination deficit in aged mice. Front Syst Neurosci 2015; 9:114. [PMID: 26321926 PMCID: PMC4531235 DOI: 10.3389/fnsys.2015.00114] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/28/2015] [Indexed: 01/02/2023] Open
Abstract
Normal aging and exercise exert extensive, often opposing, effects on the dentate gyrus (DG) of the hippocampus altering volume, synaptic function, and behaviors. The DG is especially important for behaviors requiring pattern separation—a cognitive process that enables animals to differentiate between highly similar contextual experiences. To determine how age and exercise modulate pattern separation in an aversive setting, young, aged, and aged mice provided with a running wheel were assayed on a fear-based contextual discrimination task. Aged mice showed a profound impairment in contextual discrimination compared to young animals. Voluntary exercise rescued this deficit to such an extent that behavioral pattern separation of aged-run mice was now similar to young animals. Running also resulted in a significant increase in the number of immature neurons with tertiary dendrites in aged mice. Despite this, neurogenesis levels in aged-run mice were still considerably lower than in young animals. Thus, mechanisms other than DG neurogenesis likely play significant roles in improving behavioral pattern separation elicited by exercise in aged animals.
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Affiliation(s)
- Melody V Wu
- Department of Psychiatry, Columbia University New York, NY, USA ; Division of Integrative Neuroscience, New York State Psychiatric Institute New York, NY, USA
| | - Victor M Luna
- Department of Psychiatry, Columbia University New York, NY, USA ; Division of Integrative Neuroscience, New York State Psychiatric Institute New York, NY, USA
| | - René Hen
- Department of Psychiatry, Columbia University New York, NY, USA ; Division of Integrative Neuroscience, New York State Psychiatric Institute New York, NY, USA ; Departments of Neuroscience and Pharmacology, Columbia University New York, NY, USA
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38
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Sun MK, Nelson TJ, Alkon DL. Towards universal therapeutics for memory disorders. Trends Pharmacol Sci 2015; 36:384-94. [DOI: 10.1016/j.tips.2015.04.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 12/22/2022]
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Arias N, Méndez M, Arias JL. The importance of the context in the hippocampus and brain related areas throughout the performance of a fear conditioning task. Hippocampus 2015; 25:1242-9. [PMID: 25675878 DOI: 10.1002/hipo.22430] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2015] [Indexed: 11/10/2022]
Abstract
The importance context has been broadly studied in the management of phobias and in the drug addiction literature. The way in which changes to a context influence behavior after the simple acquisition of a passive avoidance task remains unclear. The hippocampus has long been implicated in the contextual and spatial processing required for contextual fear, but its role in encoding the aversive component of a contextual fear memory is still inconclusive. Our work tries to elucidate whether a change in context, represented as differences in the load of the stimuli, is critical for learning about the context-shock association and whether this manipulation of the context could be linked to any change in metabolic brain activity requirements. For this purpose, we used an avoidance conditioning task. Animals were divided into three different experimental conditions. In one group, acquisition was performed in an enriched stimuli environment and retention was performed in a typically lit chamber (the PA-ACQ-CONTX group). In another group, acquisition was performed in the typically lit chamber and retention was undertaken in the highly enriched chamber (the PA-RET-CONTX group). Finally, for the control group, PA-CN-CONTX, acquisition, and retention were performed in the enriched stimuli environment. Our results showed that the PA-ACQ-CONTX group had longer escape latencies and poorer retention than the PA-RET-CONTX and PA-CN-CONTX groups after 24 h of acquisition under contextual changes. To study metabolic brain activity, histochemical labelling of cytochrome c-oxidase (CO) was performed. CO results suggested a neural circuit including the hippocampus, amygdala, thalamus, parahippocampal cortices, and mammillary nuclei that is involved in the learning and memory processes that enable context-dependent behavior. These results highlight how dysfunction in this network may be involved in the contextualization of fear associations that underlie several forms of psychopathology, including post-traumatic stress disorder, schizophrenia, and substance abuse disorders.
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Affiliation(s)
- Natalia Arias
- Laboratorio De Neurociencias, Departamento De Psicología, Universidad De Oviedo, Oviedo, Spain.,INEUROPA, Instituto De Neurociencias Del Principado De Asturias, Spain
| | - Marta Méndez
- Laboratorio De Neurociencias, Departamento De Psicología, Universidad De Oviedo, Oviedo, Spain.,INEUROPA, Instituto De Neurociencias Del Principado De Asturias, Spain
| | - Jorge L Arias
- Laboratorio De Neurociencias, Departamento De Psicología, Universidad De Oviedo, Oviedo, Spain.,INEUROPA, Instituto De Neurociencias Del Principado De Asturias, Spain
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