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Amelchenko EM, Bezriadnov DV, Chekhov OA, Ivanova AA, Kedrov AV, Anokhin KV, Lazutkin AA, Enikolopov G. Cognitive Flexibility Is Selectively Impaired by Radiation and Is Associated with Differential Recruitment of Adult-Born Neurons. J Neurosci 2023; 43:6061-6083. [PMID: 37532464 PMCID: PMC10451007 DOI: 10.1523/jneurosci.0161-22.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 06/17/2023] [Accepted: 06/23/2023] [Indexed: 08/04/2023] Open
Abstract
Exposure to elevated doses of ionizing radiation, such as those in therapeutic procedures, catastrophic accidents, or space exploration, increases the risk of cognitive dysfunction. The full range of radiation-induced cognitive deficits is unknown, partly because commonly used tests may be insufficiently sensitive or may not be adequately tuned for assessing the fine behavioral features affected by radiation. Here, we asked whether γ-radiation might affect learning, memory, and the overall ability to adapt behavior to cope with a challenging environment (cognitive/behavioral flexibility). We developed a new behavioral assay, the context discrimination Morris water maze (cdMWM) task, which is hippocampus-dependent and requires the integration of various contextual cues and the adjustment of search strategies. We exposed male mice to 1 or 5 Gy of γ rays and, at different time points after irradiation, trained them consecutively in spatial MWM, reversal MWM, and cdMWM tasks, and assessed their learning, navigational search strategies, and memory. Mice exposed to 5 Gy performed successfully in the spatial and reversal MWM tasks; however, in the cdMWM task 6 or 8 weeks (but not 3 weeks) after irradiation, they demonstrated transient learning deficit, decreased use of efficient spatially precise search strategies during learning, and, 6 weeks after irradiation, memory deficit. We also observed impaired neurogenesis after irradiation and selective activation of 12-week-old newborn neurons by specific components of cdMWM training paradigm. Thus, our new behavioral paradigm reveals the effects of γ-radiation on cognitive flexibility and indicates an extended timeframe for the functional maturation of new hippocampal neurons.SIGNIFICANCE STATEMENT Exposure to radiation can affect cognitive performance and cognitive flexibility - the ability to adapt to changed circumstances and demands. The full range of consequences of irradiation on cognitive flexibility is unknown, partly because of a lack of suitable models. Here, we developed a new behavioral task requiring mice to combine various types of cues and strategies to find a correct solution. We show that animals exposed to γ-radiation, despite being able to successfully solve standard problems, show delayed learning, deficient memory, and diminished use of efficient navigation patterns in circumstances requiring adjustments of previously used search strategies. This new task could be applied in other settings for assessing the cognitive changes induced by aging, trauma, or disease.
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Affiliation(s)
- Evgeny M Amelchenko
- Center for Developmental Genetics
- Department of Anesthesiology, Stony Brook University, Stony Brook, New York 11794
| | - Dmitri V Bezriadnov
- P.K. Anokhin Research Institute of Normal Physiology, Moscow, 125315, Russian Federation
| | - Olga A Chekhov
- Center for Developmental Genetics
- Department of Anesthesiology, Stony Brook University, Stony Brook, New York 11794
| | - Anna A Ivanova
- Institute of Higher Nervous Activity and Neurophysiology RAS, Moscow, 117485, Russian Federation
- Institute for Advanced Brain Studies, Lomonosov Moscow State University, Moscow, 119234, Russian Federation
| | - Alexander V Kedrov
- P.K. Anokhin Research Institute of Normal Physiology, Moscow, 125315, Russian Federation
| | - Konstantin V Anokhin
- P.K. Anokhin Research Institute of Normal Physiology, Moscow, 125315, Russian Federation
- Institute for Advanced Brain Studies, Lomonosov Moscow State University, Moscow, 119234, Russian Federation
| | - Alexander A Lazutkin
- Center for Developmental Genetics
- Department of Anesthesiology, Stony Brook University, Stony Brook, New York 11794
- Institute of Higher Nervous Activity and Neurophysiology RAS, Moscow, 117485, Russian Federation
| | - Grigori Enikolopov
- Center for Developmental Genetics
- Department of Anesthesiology, Stony Brook University, Stony Brook, New York 11794
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2
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Amelchenko EM, Bezriadnov DV, Chekhov OA, Anokhin KV, Lazutkin AA, Enikolopov G. Age-related decline in cognitive flexibility is associated with the levels of hippocampal neurogenesis. Front Neurosci 2023; 17:1232670. [PMID: 37645372 PMCID: PMC10461065 DOI: 10.3389/fnins.2023.1232670] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/28/2023] [Indexed: 08/31/2023] Open
Abstract
Aging is associated with impairments in learning, memory, and cognitive flexibility, as well as a gradual decline in hippocampal neurogenesis. We investigated the performance of 6-and 14-month-old mice (considered mature adult and late middle age, respectively) in learning and memory tasks based on the Morris water maze (MWM) and determined their levels of preceding and current neurogenesis. While both age groups successfully performed in the spatial version of MWM (sMWM), the older mice were less efficient compared to the younger mice when presented with modified versions of the MWM that required a reassessment of the previously acquired experience. This was detected in the reversal version of MWM (rMWM) and was particularly evident in the context discrimination MWM (cdMWM), a novel task that required integrating various distal cues, local cues, and altered contexts and adjusting previously used search strategies. Older mice were impaired in several metrics that characterize rMWM and cdMWM, however, they showed improvement and narrowed the performance gap with the younger mice after additional training. Furthermore, we analyzed the adult-born mature and immature neurons in the hippocampal dentate gyrus and found a significant correlation between neurogenesis levels in individual mice and their performance in the tasks demanding cognitive flexibility. These results provide a detailed description of the age-related changes in learning and memory and underscore the importance of hippocampal neurogenesis in supporting cognitive flexibility.
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Affiliation(s)
- Evgeny M. Amelchenko
- Center for Developmental Genetics, Stony Brook, NY, United States
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States
| | | | - Olga A. Chekhov
- Center for Developmental Genetics, Stony Brook, NY, United States
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States
| | - Konstantin V. Anokhin
- P.K. Anokhin Research Institute of Normal Physiology RAS, Moscow, Russia
- Institute for Advanced Brain Studies, Lomonosov Moscow State University, Moscow, Russia
| | - Alexander A. Lazutkin
- Center for Developmental Genetics, Stony Brook, NY, United States
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States
- Institute of Higher Nervous Activity and Neurophysiology RAS, Moscow, Russia
| | - Grigori Enikolopov
- Center for Developmental Genetics, Stony Brook, NY, United States
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States
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Lods M, Mortessagne P, Pacary E, Terral G, Farrugia F, Mazier W, Masachs N, Charrier V, Cota D, Ferreira G, Abrous DN, Tronel S. Chemogenetic stimulation of adult neurogenesis, and not neonatal neurogenesis, is sufficient to improve long-term memory accuracy. Prog Neurobiol 2022; 219:102364. [DOI: 10.1016/j.pneurobio.2022.102364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 09/21/2022] [Accepted: 10/06/2022] [Indexed: 12/05/2022]
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Sex Differences in the Spatial Behavior Functions of Adult-Born Neurons in Rats. eNeuro 2022; 9:ENEURO.0054-22.2022. [PMID: 35473765 PMCID: PMC9116935 DOI: 10.1523/eneuro.0054-22.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/13/2022] [Accepted: 04/15/2022] [Indexed: 01/04/2023] Open
Abstract
Adult neurogenesis modifies hippocampal circuits and behavior, but removing newborn neurons does not consistently alter spatial processing, a core function of the hippocampus. Additionally, little is known about sex differences in neurogenesis since few studies have compared males and females. Since adult-born neurons regulate the stress response, we hypothesized that spatial functions may be more prominent under aversive conditions and may differ between males and females given sex differences in stress responding. We therefore trained intact and neurogenesis-deficient rats in the spatial water maze at temperatures that vary in their degree of aversiveness. In the standard water maze, ablating neurogenesis did not alter spatial learning in either sex. However, in cold water, ablating neurogenesis had divergent sex-dependent effects: relative to intact rats, male neurogenesis-deficient rats were slower to escape the maze and female neurogenesis-deficient rats were faster. Neurogenesis promoted temperature-related changes in search strategy in females, but it promoted search strategy stability in males. Females displayed greater recruitment (Fos expression) of the dorsal hippocampus than males, particularly in cold water. However, blocking neurogenesis did not alter Fos expression in either sex. Finally, morphologic analyses revealed greater experience-dependent plasticity in males. Adult-born neurons in males and females had similar morphology at baseline but training increased spine density and reduced presynaptic terminal size, specifically in males. Collectively, these findings indicate that adult-born neurons contribute to spatial learning in stressful conditions and they provide new evidence for sex differences in their behavioral functions.
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OTHMAN MZ, HASSAN Z, CHE HAS AT. Morris water maze: a versatile and pertinent tool for assessing spatial learning and memory. Exp Anim 2022; 71:264-280. [PMID: 35314563 PMCID: PMC9388345 DOI: 10.1538/expanim.21-0120] [Citation(s) in RCA: 73] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Since its development about 40 years ago (1981–2021), Morris water maze has turned into a very popular tool for assessing spatial learning and memory. Its many advantages have ensured its
pertinence to date. These include its effectiveness in evaluating hippocampal-dependent learning and memory, exemption from motivational differences across diverse experimental
manipulations, reliability in various cross-species studies, and adaptability to many experimental conditions with various test protocols. Nonetheless, throughout its establishment, several
experimental and analysis loopholes have galvanized researchers to assess ways in which it could be improved and adapted to fill this gap. Therefore, in this review, we briefly summarize
these developments since the early years of its establishment through to the most recent advancements in computerized analysis, offering more comprehensive analysis paradigms. In addition,
we discuss the adaptability of the Morris water maze across different test versions and analysis paradigms, providing suggestions with regard to the best paradigms for particular
experimental conditions. Hence, the proper selection of the experimental protocols, analysis paradigms, and consideration of the assay’s limitations should be carefully considered. Given
that appropriate measures are taken, with various adaptations made, the Morris water maze will likely remain a relevant tool to assess the mechanisms of spatial learning and memory.
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Hippocampal neurogenesis promotes preference for future rewards. Mol Psychiatry 2021; 26:6317-6335. [PMID: 34021262 DOI: 10.1038/s41380-021-01165-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/29/2021] [Accepted: 05/06/2021] [Indexed: 02/04/2023]
Abstract
Adult hippocampal neurogenesis has been implicated in a number of disorders where reward processing is disrupted but whether new neurons regulate specific aspects of reward-related decision making remains unclear. Given the role of the hippocampus in future-oriented cognition, here we tested whether adult neurogenesis regulates preference for future, advantageous rewards in a delay discounting paradigm for rats. Indeed, blocking neurogenesis caused a profound aversion for delayed rewards, and biased choice behavior toward immediately available, but smaller, rewards. Consistent with a role for the ventral hippocampus in impulsive decision making and future-thinking, neurogenesis-deficient animals displayed reduced activity in the ventral hippocampus. In intact animals, delay-based decision making restructured dendrites and spines in adult-born neurons and specifically activated adult-born neurons in the ventral dentate gyrus, relative to dorsal activation in rats that chose between immediately-available rewards. Putative developmentally-born cells, located in the superficial granule cell layer, did not display task-specific activity. These findings identify a novel and specific role for neurogenesis in decisions about future rewards, thereby implicating newborn neurons in disorders where short-sighted gains are preferred at the expense of long-term health.
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Domínguez-Rivas E, Ávila-Muñoz E, Schwarzacher SW, Zepeda A. Adult hippocampal neurogenesis in the context of lipopolysaccharide-induced neuroinflammation: A molecular, cellular and behavioral review. Brain Behav Immun 2021; 97:286-302. [PMID: 34174334 DOI: 10.1016/j.bbi.2021.06.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 06/17/2021] [Accepted: 06/19/2021] [Indexed: 12/17/2022] Open
Abstract
The continuous generation of new neurons occurs in at least two well-defined niches in the adult rodent brain. One of these areas is the subgranular zone of the dentate gyrus (DG) in the hippocampus. While the DG is associated with contextual and spatial learning and memory, hippocampal neurogenesis is necessary for pattern separation. Hippocampal neurogenesis begins with the activation of neural stem cells and culminates with the maturation and functional integration of a portion of the newly generated glutamatergic neurons into the hippocampal circuits. The neurogenic process is continuously modulated by intrinsic factors, one of which is neuroinflammation. The administration of lipopolysaccharide (LPS) has been widely used as a model of neuroinflammation and has yielded a body of evidence for unveiling the detrimental impact of inflammation upon the neurogenic process. This work aims to provide a comprehensive overview of the current knowledge on the effects of the systemic and central administration of LPS upon the different stages of neurogenesis and discuss their effects at the molecular, cellular, and behavioral levels.
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Affiliation(s)
- Eduardo Domínguez-Rivas
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Evangelina Ávila-Muñoz
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Stephan W Schwarzacher
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Angélica Zepeda
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico; Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, Frankfurt am Main, Germany.
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8
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Nawarawong NN, Nickell CG, Hopkins DM, Pauly JR, Nixon K. Functional Activation of Newborn Neurons Following Alcohol-Induced Reactive Neurogenesis. Brain Sci 2021; 11:499. [PMID: 33921189 PMCID: PMC8071556 DOI: 10.3390/brainsci11040499] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/10/2021] [Accepted: 04/11/2021] [Indexed: 02/07/2023] Open
Abstract
Abstinence after alcohol dependence leads to structural and functional recovery in many regions of the brain, especially the hippocampus. Significant increases in neural stem cell (NSC) proliferation and subsequent "reactive neurogenesis" coincides with structural recovery in hippocampal dentate gyrus (DG). However, whether these reactively born neurons are integrated appropriately into neural circuits remains unknown. Therefore, adult male rats were exposed to a binge model of alcohol dependence. On day 7 of abstinence, the peak of reactive NSC proliferation, rats were injected with bromodeoxyuridine (BrdU) to label dividing cells. After six weeks, rats underwent Morris Water Maze (MWM) training then were sacrificed ninety minutes after the final training session. Using fluorescent immunohistochemistry for c-Fos (neuronal activation), BrdU, and Neuronal Nuclei (NeuN), we investigated whether neurons born during reactive neurogenesis were incorporated into a newly learned MWM neuronal ensemble. Prior alcohol exposure increased the number of BrdU+ cells and newborn neurons (BrdU+/NeuN+ cells) in the DG versus controls. However, prior ethanol exposure had no significant impact on MWM-induced c-Fos expression. Despite increased BrdU+ neurons, no difference in the number of activated newborn neurons (BrdU+/c-Fos+/NeuN+) was observed. These data suggest that neurons born during alcohol-induced reactive neurogenesis are functionally integrated into hippocampal circuitry.
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Affiliation(s)
| | - Chelsea G. Nickell
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA; (C.G.N.); (D.M.H.); (J.R.P.)
| | - Deann M. Hopkins
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA; (C.G.N.); (D.M.H.); (J.R.P.)
| | - James R. Pauly
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA; (C.G.N.); (D.M.H.); (J.R.P.)
| | - Kimberly Nixon
- College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, USA;
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA; (C.G.N.); (D.M.H.); (J.R.P.)
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9
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Loss of α7 nicotinic acetylcholine receptors in GABAergic neurons causes sex-dependent decreases in radial glia-like cell quantity and impairments in cognitive and social behavior. Brain Struct Funct 2021; 226:365-379. [PMID: 33398432 DOI: 10.1007/s00429-020-02179-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 11/10/2020] [Indexed: 12/25/2022]
Abstract
The dentate gyrus (DG) is a unique brain structure in that neurons can be generated postnatally and integrated within existing circuitry throughout life. The maturation process of these newly generated neurons (granule cells) is modulated by nicotinic acetylcholine receptors (nAChRs) through a variety of mechanisms such as neural stem pool proliferation, cell survival, signal modulation, and dendritic integration. Disrupted nAChR signaling has been implicated in neuropsychiatric and neurodegenerative disorders, potentially via alterations in DG neurogenesis. GABAergic interneurons are known to express nAChRs, predominantly the α7 subtype, and have been shown to shape development, integration, and circuit reorganization of DG granule cells. Therefore, we examined histological and behavioral effects of knocking out α7 nAChRs in GABAergic neurons. Deletion of α7 nAChRs resulted in a reduction of radial glia-like cells within the subgranular zone of the DG and a concomitant trend towards decreased immature neurons, specifically in male mice, as well as sex-dependent changes in several behaviors, including social recognition and spatial learning. Overall, these findings suggest α7 nAChRs expressed in GABAergic neurons play an important role in regulating the adult neural stem cell pool and behavior in a sex-dependent manner. This provides important insight into the mechanisms by which cholinergic dysfunction contributes to the cognitive and behavioral changes associated with neurodevelopmental and neurodegenerative disorders.
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10
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Sippel D, Schwabedal J, Snyder JC, Oyanedel CN, Bernas SN, Garthe A, Tröndle A, Storch A, Kempermann G, Brandt MD. Disruption of NREM sleep and sleep-related spatial memory consolidation in mice lacking adult hippocampal neurogenesis. Sci Rep 2020; 10:16467. [PMID: 33020501 PMCID: PMC7536189 DOI: 10.1038/s41598-020-72362-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/31/2020] [Indexed: 12/25/2022] Open
Abstract
Cellular plasticity at the structural level and sleep at the behavioural level are both essential for memory formation. The link between the two is not well understood. A functional connection between adult neurogenesis and hippocampus-dependent memory consolidation during NREM sleep has been hypothesized but not experimentally shown. Here, we present evidence that during a three-day learning session in the Morris water maze task a genetic knockout model of adult neurogenesis (Cyclin D2-/-) showed changes in sleep macro- and microstructure. Sleep EEG analyses revealed a lower total sleep time and NREM fraction in Cyclin D2-/- mice as well as an impairment of sleep specific neuronal oscillations that are associated with memory consolidation. Better performance in the memory task was associated with specific sleep parameters in wild-type, but not in Cyclin D2-/- mice. In wild-type animals the number of proliferating cells correlated with the amount of NREM sleep. The lack of adult neurogenesis led to changes in sleep architecture and oscillations that represent the dialog between hippocampus and neocortex during sleep. We suggest that adult neurogenesis-as a key event of hippocampal plasticity-might play an important role for sleep-dependent memory consolidation and modulates learning-induced changes of sleep macro- and microstructure.
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Affiliation(s)
- D Sippel
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, 72076, Tübingen, Germany.,Department of Psychiatry and Psychotherapy, University Hospital Tübingen, 72076, Tübingen, Germany
| | - J Schwabedal
- Max Planck Institute for the Physics of Complex Systems, 01187, Dresden, Germany
| | - J C Snyder
- Department of Neurology, University Hospital, Technische Universität Dresden, 01307, Dresden, Germany
| | - C N Oyanedel
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, 72076, Tübingen, Germany
| | - S N Bernas
- Center for Regenerative Therapies TU Dresden, 01307, Dresden, Germany
| | - A Garthe
- German Center for Neurodegenerative Diseases (DZNE) Dresden, 01307, Dresden, Germany
| | - A Tröndle
- Department of Neurology, University Hospital, Technische Universität Dresden, 01307, Dresden, Germany.,Center for Regenerative Therapies TU Dresden, 01307, Dresden, Germany
| | - A Storch
- German Center for Neurodegenerative Diseases (DZNE) Rostock, 18147, Rostock, Germany.,Department of Neurology, University of Rostock, 18147, Rostock, Germany
| | - G Kempermann
- German Center for Neurodegenerative Diseases (DZNE) Dresden, 01307, Dresden, Germany.,Center for Regenerative Therapies TU Dresden, 01307, Dresden, Germany
| | - M D Brandt
- Department of Neurology, University Hospital, Technische Universität Dresden, 01307, Dresden, Germany. .,German Center for Neurodegenerative Diseases (DZNE) Dresden, 01307, Dresden, Germany.
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11
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Snyder JS, Drew MR. Functional neurogenesis over the years. Behav Brain Res 2020; 382:112470. [PMID: 31917241 PMCID: PMC7769695 DOI: 10.1016/j.bbr.2020.112470] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 01/03/2020] [Indexed: 01/01/2023]
Abstract
There has been interest in the function of adult neurogenesis since its discovery, by Joseph Altman, nearly 60 years ago. While controversy curtailed follow up studies, in the 1990s a second wave of research validated many of Altman's original claims and revealed that factors such as stress and environmental stimulation altered the production of new neurons in the hippocampus. However, only with the advent of tools for manipulating neurogenesis did it become possible to perform causal tests of the function of newborn neurons. Here, we identify approximately 100 studies in which adult neurogenesis was manipulated to study its function. A majority of these studies demonstrate functions for adult neurogenesis in classic hippocampal behaviors such as context learning and spatial memory, as well as emotional behaviors related to stress, anxiety and depression. However, a closer look reveals a number of other, arguably understudied, functions in decision making, temporal association memory, and addiction. In this special issue, we present 16 new studies and review articles that continue to address and clarify the function of adult neurogenesis in behaviors as diverse as memory formation, consolidation and forgetting, pattern separation and discrimination behaviors, addiction, and attention. Reviews of stem cell dynamics and regenerative properties provide insights into the mechanisms by which neurogenesis may be controlled to offset age- and disease-related brain injury. Finally, translation-oriented reviews identify next steps for minimizing the gap between discoveries made in animals and applications for human health. The articles in this issue synthesize and extend what we have learned in the last half century of functional neurogenesis research and identify themes that will define its future.
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Affiliation(s)
- 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.
| | - Michael R Drew
- Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
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12
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Cooke MB, O'Leary TP, Harris P, Ma R, Brown RE, Snyder JS. Pathfinder: open source software for analyzing spatial navigation search strategies. F1000Res 2019; 8:1521. [PMID: 32025289 PMCID: PMC6974928 DOI: 10.12688/f1000research.20352.2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/10/2020] [Indexed: 01/04/2023] Open
Abstract
Spatial navigation is a universal behavior that varies depending on goals, experience and available sensory stimuli. Spatial navigational tasks are routinely used to study learning, memory and goal-directed behavior, in both animals and humans. One popular paradigm for testing spatial memory is the Morris water maze, where subjects learn the location of a hidden platform that offers escape from a pool of water. Researchers typically express learning as a function of the latency to escape, though this reveals little about the underlying navigational strategies. Recently, a number of studies have begun to classify water maze search strategies in order to clarify the precise spatial and mnemonic functions of different brain regions, and to identify which aspects of spatial memory are disrupted in disease models. However, despite their usefulness, strategy analyses have not been widely adopted due to the lack of software to automate analyses. To address this need we developed Pathfinder, an open source application for analyzing spatial navigation behaviors. In a representative dataset, we show that Pathfinder effectively characterizes the development of highly-specific spatial search strategies as male and female mice learn a standard spatial water maze. Pathfinder can read data files from commercially- and freely-available software packages, is optimized for classifying search strategies in water maze paradigms, and can also be used to analyze 2D navigation by other species, and in other tasks, as long as timestamped xy coordinates are available. Pathfinder is simple to use, can automatically determine pool and platform geometry, generates heat maps, analyzes navigation with respect to multiple goal locations, and can be updated to accommodate future developments in spatial behavioral analyses. Given these features, Pathfinder may be a useful tool for studying how navigational strategies are regulated by the environment, depend on specific neural circuits, and are altered by pathology.
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Affiliation(s)
- Matthew B Cooke
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
| | - Timothy P O'Leary
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
| | - Phelan Harris
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
| | - Ricky Ma
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
| | - Richard E Brown
- Psychology and Neuroscience Department, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Jason S Snyder
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
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13
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Cooke MB, O'Leary TP, Harris P, Ma R, Brown RE, Snyder JS. Pathfinder: open source software for analyzing spatial navigation search strategies. F1000Res 2019; 8:1521. [PMID: 32025289 DOI: 10.12688/f1000research.20352.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/21/2019] [Indexed: 01/24/2023] Open
Abstract
Spatial navigation is a universal behavior that varies depending on goals, experience and available sensory stimuli. Spatial navigational tasks are routinely used to study learning, memory and goal-directed behavior, in both animals and humans. One popular paradigm for testing spatial memory is the Morris water maze, where subjects learn the location of a hidden platform that offers escape from a pool of water. Researchers typically express learning as a function of the latency to escape, though this reveals little about the underlying navigational strategies. Recently, a number of studies have begun to classify water maze search strategies in order to clarify the precise spatial and mnemonic functions of different brain regions, and to identify which aspects of spatial memory are disrupted in disease models. However, despite their usefulness, strategy analyses have not been widely adopted due to the lack of software to automate analyses. To address this need we developed Pathfinder, an open source application for analyzing spatial navigation behaviors. In a representative dataset, we show that Pathfinder effectively characterizes the development of highly-specific spatial search strategies as male and female mice learn a standard spatial water maze. Pathfinder can read data files from commercially- and freely-available software packages, is optimized for classifying search strategies in water maze paradigms, and can also be used to analyze 2D navigation by other species, and in other tasks, as long as timestamped xy coordinates are available. Pathfinder is simple to use, can automatically determine pool and platform geometry, generates heat maps, analyzes navigation with respect to multiple goal locations, and can be updated to accommodate future developments in spatial behavioral analyses. Given these features, Pathfinder may be a useful tool for studying how navigational strategies are regulated by the environment, depend on specific neural circuits, and are altered by pathology.
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Affiliation(s)
- Matthew B Cooke
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
| | - Timothy P O'Leary
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
| | - Phelan Harris
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
| | - Ricky Ma
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
| | - Richard E Brown
- Psychology and Neuroscience Department, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Jason S Snyder
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancovuer, British Columbia, V6T 1Z3, Canada
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