1
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Terstege DJ, Epp JR. PAW, a cost-effective and open-source alternative to commercial rodent running wheels. HardwareX 2024; 17:e00499. [PMID: 38204596 PMCID: PMC10776975 DOI: 10.1016/j.ohx.2023.e00499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/24/2023] [Accepted: 12/08/2023] [Indexed: 01/12/2024]
Abstract
Voluntary wheel running is a common measure of general activity in many rodent models across neuroscience and physiology. However, current commercial wheel monitoring systems can be cost-prohibitive to many investigators, with many of these systems requiring investments of thousands of dollars. In recent years, several open-source alternatives have been developed, and while these tools are much more cost effective than commercial system, they often lack the flexibility to be applied to a wide variety of projects. Here, we have developed PAW, a 3D Printable Arduino-based Wheel logger. PAW is wireless, fully self-contained, easy to assemble, and all components necessary for its production can be obtained for only $75 CAD. Furthermore, with its compact internal electronics, the 3D printed casing can be easily modified to be used with a wide variety of running wheel designs for a wide variety of rodent species. Data recorded with the PAW system shows circadian patterns of activity which is expected from mice and is consistent with results found in the literature. Altogether, PAW is a flexible, low-cost system that can be beneficial to a broad range of researchers who study rodent models.
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Affiliation(s)
- Dylan J. Terstege
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada
| | - Jonathan R. Epp
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada
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2
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Ramkumar R, Edge-Partington M, Terstege DJ, Adigun K, Ren Y, Khan NS, Rouhi N, Jamani NF, Tsutsui M, Epp JR, Sargin D. Long-Term Impact of Early Life Stress on Serotonin Connectivity. Biol Psychiatry 2024:S0006-3223(24)00073-8. [PMID: 38316332 DOI: 10.1016/j.biopsych.2024.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 01/04/2024] [Accepted: 01/19/2024] [Indexed: 02/07/2024]
Abstract
BACKGROUND Chronic childhood stress is a prominent risk factor for developing affective disorders, yet mechanisms underlying this association remain unclear. Maintenance of optimal serotonin (5-HT) levels during early postnatal development is critical for the maturation of brain circuits. Understanding the long-lasting effects of early life stress (ELS) on serotonin-modulated brain connectivity is crucial to develop treatments for affective disorders arising from childhood stress. METHODS Using a mouse model of chronic developmental stress, we determined the long-lasting consequences of ELS on 5-HT circuits and behavior in females and males. Using FosTRAP mice, we cross-correlated regional c-Fos density to determine brain-wide functional connectivity of the raphe nucleus. We next performed in vivo fiber photometry to establish ELS-induced deficits in 5-HT dynamics and optogenetics to stimulate 5-HT release to improve behavior. RESULTS Adult female and male mice exposed to ELS showed heightened anxiety-like behavior. ELS further enhanced susceptibility to acute stress by disrupting the brain-wide functional connectivity of the raphe nucleus and the activity of 5-HT neuron population, in conjunction with increased orbitofrontal cortex (OFC) activity and disrupted 5-HT release in medial OFC. Optogenetic stimulation of 5-HT terminals in the medial OFC elicited an anxiolytic effect in ELS mice in a sex-dependent manner. CONCLUSIONS These findings suggest a significant disruption in 5-HT-modulated brain connectivity in response to ELS, with implications for sex-dependent vulnerability. The anxiolytic effect of the raphe-medial OFC circuit stimulation has potential implications for developing targeted stimulation-based treatments for affective disorders that arise from early life adversities.
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Affiliation(s)
- Raksha Ramkumar
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Moriah Edge-Partington
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Dylan J Terstege
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Kabirat Adigun
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Yi Ren
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nazmus S Khan
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Nahid Rouhi
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Naila F Jamani
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Mio Tsutsui
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jonathan R Epp
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Derya Sargin
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.
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3
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Terstege DJ, Dawson M, Jamani NF, Tsutsui M, Epp JR, Sargin D. Protocol for the integration of fiber photometry and social behavior in rodent models. STAR Protoc 2023; 4:102689. [PMID: 37979176 PMCID: PMC10694594 DOI: 10.1016/j.xpro.2023.102689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 09/25/2023] [Accepted: 10/12/2023] [Indexed: 11/20/2023] Open
Abstract
Fiber photometry offers insight into cell-type-specific activity underlying social interactions. We provide a protocol for the integration of fiber photometry recordings into the analysis of social behavior in rodent models. This includes considerations during surgery, notes on synchronizing fiber photometry with behavioral recordings, advice on using multi-animal behavioral tracking software, and scripts for the analysis of fiber photometry recordings. For complete details on the use and execution of this protocol, please refer to Dawson et al. (2023).1.
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Affiliation(s)
- Dylan J Terstege
- Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada.
| | - Matthew Dawson
- Department of Psychology, University of Calgary, Calgary, AB T2N 1N4, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Naila F Jamani
- Department of Psychology, University of Calgary, Calgary, AB T2N 1N4, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Mio Tsutsui
- Department of Psychology, University of Calgary, Calgary, AB T2N 1N4, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Jonathan R Epp
- Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Derya Sargin
- Department of Psychology, University of Calgary, Calgary, AB T2N 1N4, Canada; Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 1N4, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 1N4, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 1N4, Canada.
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4
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Terstege DJ, Epp JR. Parvalbumin as a sex-specific target in Alzheimer's disease research - A mini-review. Neurosci Biobehav Rev 2023; 153:105370. [PMID: 37619647 DOI: 10.1016/j.neubiorev.2023.105370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/14/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia, and both the incidence of this disease and its associated cognitive decline disproportionally effect women. While the etiology of AD is unknown, recent work has demonstrated that the balance of excitatory and inhibitory activity across the brain may serve as a strong predictor of cognitive impairments in AD. Across the cortex, the most prominent source of inhibitory signalling is from a class of parvalbumin-expressing interneurons (PV+). In this mini-review, the impacts of sex- and age-related factors on the function of PV+ neurons are examined within the context of vulnerability to AD pathology. These primary factors of influence include changes in brain metabolism, circulating sex hormone levels, and inflammatory response. In addition to positing the increased vulnerability of PV+ neurons to dysfunction in AD, this mini-review highlights the critical importance of presenting sex stratified data in the study of AD.
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Affiliation(s)
- Dylan J Terstege
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada
| | - Jonathan R Epp
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.
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5
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Villa BR, Bhatt D, Wolff MD, Addo-Osafo K, Epp JR, Teskey GC. Repeated episodes of postictal hypoxia are a mechanism for interictal cognitive impairments. Sci Rep 2023; 13:15474. [PMID: 37726428 PMCID: PMC10509159 DOI: 10.1038/s41598-023-42741-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/14/2023] [Indexed: 09/21/2023] Open
Abstract
Comorbidities during the period between seizures present a significant challenge for individuals with epilepsy. Despite their clinical relevance, the pathophysiology of the interictal symptomatology is largely unknown. Postictal severe hypoxia (PIH) in those brain regions participating in the seizure has been indicated as a mechanism underlying several negative postictal manifestations. It is unknown how repeated episodes of PIH affect interictal symptoms in epilepsy. Using a rat model, we observed that repeated seizures consistently induced episodes of PIH that become increasingly severe with each seizure occurrence. Additionally, recurrent seizure activity led to decreased levels of oxygen in the hippocampus during the interictal period. However, these reductions were prevented when we repeatedly blocked PIH using either the COX-inhibitor acetaminophen or the L-type calcium channel antagonist nifedipine. Moreover, we found that interictal cognitive deficits caused by seizures were completely alleviated by repeated attenuation of PIH events. Lastly, mitochondrial dysfunction may contribute to the observed pathological outcomes during the interictal period. These findings provide evidence that seizure-induced hypoxia may play a crucial role in several aspects of epilepsy. Consequently, developing and implementing treatments that specifically target and prevent PIH could potentially offer significant benefits for individuals with refractory epilepsy.
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Affiliation(s)
- Bianca R Villa
- Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada.
- Department of Cell Biology and Anatomy, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada.
| | - Dhyey Bhatt
- Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
- Department of Cell Biology and Anatomy, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Marshal D Wolff
- Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
- Department of Cell Biology and Anatomy, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Kwaku Addo-Osafo
- Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
- Department of Cell Biology and Anatomy, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Jonathan R Epp
- Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
- Department of Cell Biology and Anatomy, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - G Campbell Teskey
- Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
- Department of Cell Biology and Anatomy, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
- Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
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6
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Dawson M, Terstege DJ, Jamani N, Tsutsui M, Pavlov D, Bugescu R, Epp JR, Leinninger GM, Sargin D. Hypocretin/orexin neurons encode social discrimination and exhibit a sex-dependent necessity for social interaction. Cell Rep 2023; 42:112815. [PMID: 37459234 DOI: 10.1016/j.celrep.2023.112815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 05/20/2023] [Accepted: 06/29/2023] [Indexed: 07/29/2023] Open
Abstract
The hypothalamus plays a crucial role in the modulation of social behavior by encoding internal states. The hypothalamic hypocretin/orexin neurons, initially identified as regulators of sleep and appetite, are important for emotional and motivated behaviors. However, their role in social behavior remains unclear. Using fiber photometry and behavioral analysis, we show here that hypocretin neurons differentially encode social discrimination based on the nature of social encounters. The optogenetic inhibition of hypocretin neuron activity or blocking of hcrt-1 receptors reduces the amount of time mice are engaged in social interaction in males but not in females. Reduced hcrt-1 receptor signaling during social interaction is associated with altered activity in the insular cortex and ventral tegmental area in males. Our data implicating hypocretin neurons as sexually dimorphic regulators within social networks have significant implications for the treatment of neuropsychiatric diseases with social dysfunction, particularly considering varying prevalence among sexes.
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Affiliation(s)
- Matthew Dawson
- Department of Psychology, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Dylan J Terstege
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada; Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Naila Jamani
- Department of Psychology, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Mio Tsutsui
- Department of Psychology, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Dmitrii Pavlov
- Department of Psychology, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Raluca Bugescu
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Jonathan R Epp
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada; Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Gina M Leinninger
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Derya Sargin
- Department of Psychology, University of Calgary, Calgary, AB, Canada; Department of Physiology & Pharmacology, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada.
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7
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Devine J, Kurki HK, Epp JR, Gonzalez PN, Claes P, Hallgrímsson B. Classifying high-dimensional phenotypes with ensemble learning. bioRxiv 2023:2023.05.29.542750. [PMID: 37398168 PMCID: PMC10312448 DOI: 10.1101/2023.05.29.542750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Classification is a fundamental task in biology used to assign members to a class. While linear discriminant functions have long been effective, advances in phenotypic data collection are yielding increasingly high-dimensional datasets with more classes, unequal class covariances, and non-linear distributions. Numerous studies have deployed machine learning techniques to classify such distributions, but they are often restricted to a particular organism, a limited set of algorithms, and/or a specific classification task. In addition, the utility of ensemble learning or the strategic combination of models has not been fully explored.We performed a meta-analysis of 33 algorithms across 20 datasets containing over 20,000 high-dimensional shape phenotypes using an ensemble learning framework. Both binary (e.g., sex, environment) and multi-class (e.g., species, genotype, population) classification tasks were considered. The ensemble workflow contains functions for preprocessing, training individual learners and ensembles, and model evaluation. We evaluated algorithm performance within and among datasets. Furthermore, we quantified the extent to which various dataset and phenotypic properties impact performance.We found that discriminant analysis variants and neural networks were the most accurate base learners on average. However, their performance varied substantially between datasets. Ensemble models achieved the highest performance on average, both within and among datasets, increasing average accuracy by up to 3% over the top base learner. Higher class R2 values, mean class shape distances, and between- vs. within-class variances were positively associated with performance, whereas higher class covariance distances were negatively associated. Class balance and total sample size were not predictive.Learning-based classification is a complex task driven by many hyperparameters. We demonstrate that selecting and optimizing an algorithm based on the results of another study is a flawed strategy. Ensemble models instead offer a flexible approach that is data agnostic and exceptionally accurate. By assessing the impact of various dataset and phenotypic properties on classification performance, we also offer potential explanations for variation in performance. Researchers interested in maximizing performance stand to benefit from the simplicity and effectiveness of our approach made accessible via the R package pheble.
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Affiliation(s)
- Jay Devine
- Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr NW, Calgary, AB T2N 4N1, CANADA
| | - Helen K. Kurki
- Department of Anthropology, University of Victoria, 3800 Finnerty Rd, Victoria, BC V8P 5C2, CANADA
| | - Jonathan R. Epp
- Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr NW, Calgary, AB T2N 4N1, CANADA
| | - Paula N. Gonzalez
- Institute for Studies in Neuroscience and Complex Systems (ENyS) CONICET, Universidad Nacional de La Plata, Av. Calchaquí 5402, Florencio Varela, Buenos Aires, ARGENTINA
| | - Peter Claes
- Department of Human Genetics, KU Leuven, 3000 Leuven, BELGIUM
- Department of Electrical Engineering, ESAT/PSI, KU Leuven, 3000 Leuven, BELGIUM
| | - Benedikt Hallgrímsson
- Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr NW, Calgary, AB T2N 4N1, CANADA
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8
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Ren Y, Savadlou A, Park S, Siska P, Epp JR, Sargin D. The impact of loneliness and social isolation on the development of cognitive decline and Alzheimer's Disease. Front Neuroendocrinol 2023; 69:101061. [PMID: 36758770 DOI: 10.1016/j.yfrne.2023.101061] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/19/2023] [Accepted: 02/03/2023] [Indexed: 02/09/2023]
Abstract
Alzheimer's Disease (AD) is the leading cause of dementia, observed at a higher incidence in women compared with men. Treatments aimed at improving pathology in AD remain ineffective to stop disease progression. This makes the detection of the early intervention strategies to reduce future disease risk extremely important. Isolation and loneliness have been identified among the major risk factors for AD. The increasing prevalence of both loneliness and AD emphasizes the urgent need to understand this association to inform treatment. Here we present a comprehensive review of both clinical and preclinical studies that investigated loneliness and social isolation as risk factors for AD. We discuss that understanding the mechanisms of how loneliness exacerbates cognitive impairment and AD with a focus on sex differences will shed the light for the underlying mechanisms regarding loneliness as a risk factor for AD and to develop effective prevention or treatment strategies.
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Affiliation(s)
- Yi Ren
- Department of Cell Biology and Anatomy, University of Calgary, Canada; Cumming School of Medicine, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Canada
| | - Aisouda Savadlou
- Department of Psychology, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Canada
| | - Soobin Park
- Department of Psychology, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Canada
| | - Paul Siska
- Department of Psychology, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Canada
| | - Jonathan R Epp
- Department of Cell Biology and Anatomy, University of Calgary, Canada; Cumming School of Medicine, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Canada
| | - Derya Sargin
- Department of Psychology, University of Calgary, Canada; Department of Physiology & Pharmacology, University of Calgary, Canada; Hotchkiss Brain Institute, University of Calgary, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Canada.
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9
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Terstege DJ, Epp JR. Network Neuroscience Untethered: Brain-Wide Immediate Early Gene Expression for the Analysis of Functional Connectivity in Freely Behaving Animals. Biology (Basel) 2022; 12:biology12010034. [PMID: 36671727 PMCID: PMC9855808 DOI: 10.3390/biology12010034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/19/2022] [Accepted: 12/23/2022] [Indexed: 12/28/2022]
Abstract
Studying how spatially discrete neuroanatomical regions across the brain interact is critical to advancing our understanding of the brain. Traditional neuroimaging techniques have led to many important discoveries about the nature of these interactions, termed functional connectivity. However, in animal models these traditional neuroimaging techniques have generally been limited to anesthetized or head-fixed setups or examination of small subsets of neuroanatomical regions. Using the brain-wide expression density of immediate early genes (IEG), we can assess brain-wide functional connectivity underlying a wide variety of behavioural tasks in freely behaving animal models. Here, we provide an overview of the necessary steps required to perform IEG-based analyses of functional connectivity. We also outline important considerations when designing such experiments and demonstrate the implications of these considerations using an IEG-based network dataset generated for the purpose of this review.
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10
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Moretti J, Terstege DJ, Poh EZ, Epp JR, Rodger J. Low intensity repetitive transcranial magnetic stimulation modulates brain-wide functional connectivity to promote anti-correlated c-Fos expression. Sci Rep 2022; 12:20571. [PMID: 36446821 PMCID: PMC9708643 DOI: 10.1038/s41598-022-24934-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/22/2022] [Indexed: 11/30/2022] Open
Abstract
Repetitive transcranial magnetic stimulation (rTMS) induces action potentials to induce plastic changes in the brain with increasing evidence for the therapeutic importance of brain-wide functional network effects of rTMS; however, the influence of sub-action potential threshold (low-intensity; LI-) rTMS on neuronal activity is largely unknown. We investigated whether LI-rTMS modulates neuronal activity and functional connectivity and also specifically assessed modulation of parvalbumin interneuron activity. We conducted a brain-wide analysis of c-Fos, a marker for neuronal activity, in mice that received LI-rTMS to visual cortex. Mice received single or multiple sessions of excitatory 10 Hz LI-rTMS with custom rodent coils or were sham controls. We assessed changes to c-Fos positive cell densities and c-Fos/parvalbumin co-expression. Peak c-Fos expression corresponded with activity during rTMS. We also assessed functional connectivity changes using brain-wide c-Fos-based network analysis. LI-rTMS modulated c-Fos expression in cortical and subcortical regions. c-Fos density changes were most prevalent with acute stimulation, however chronic stimulation decreased parvalbumin interneuron activity, most prominently in the amygdala and striatum. LI-rTMS also increased anti-correlated functional connectivity, with the most prominent effects also in the amygdala and striatum following chronic stimulation. LI-rTMS induces changes in c-Fos expression that suggest modulation of neuronal activity and functional connectivity throughout the brain. Our results suggest that LI-rTMS promotes anticorrelated functional connectivity, possibly due to decreased parvalbumin interneuron activation induced by chronic stimulation. These changes may underpin therapeutic rTMS effects, therefore modulation of subcortical activity supports rTMS for treatment of disorders involving subcortical dysregulation.
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Affiliation(s)
- Jessica Moretti
- School of Biological Sciences, The University of Western Australia, Perth, WA, Australia.
- Perron Institute for Neurological and Translational Science, Perth, WA, Australia.
| | - Dylan J Terstege
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Eugenia Z Poh
- School of Biological Sciences, The University of Western Australia, Perth, WA, Australia
- Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Jonathan R Epp
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Jennifer Rodger
- School of Biological Sciences, The University of Western Australia, Perth, WA, Australia.
- Perron Institute for Neurological and Translational Science, Perth, WA, Australia.
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11
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Terstege DJ, Durante IM, Epp JR. Brain-wide neuronal activation and functional connectivity are modulated by prior exposure to repetitive learning episodes. Front Behav Neurosci 2022; 16:907707. [PMID: 36160680 PMCID: PMC9501867 DOI: 10.3389/fnbeh.2022.907707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 08/23/2022] [Indexed: 11/26/2022] Open
Abstract
Memory storage and retrieval are shaped by past experiences. Prior learning and memory episodes have numerous impacts on brain structure from micro to macroscale. Previous experience with specific forms of learning increases the efficiency of future learning. It is less clear whether such practice effects on one type of memory might also have transferable effects to other forms of memory. Different forms of learning and memory rely on different brain-wide networks but there are many points of overlap in these networks. Enhanced structural or functional connectivity caused by one type of learning may be transferable to another type of learning due to overlap in underlying memory networks. Here, we investigated the impact of prior chronic spatial training on the task-specific functional connectivity related to subsequent contextual fear memory recall in mice. Our results show that mice exposed to prior spatial training exhibited decreased brain-wide activation compared to control mice during the retrieval of a context fear memory. With respect to functional connectivity, we observed changes in several network measures, notably an increase in global efficiency. Interestingly, we also observed an increase in network resilience based on simulated targeted node deletion. Overall, this study suggests that chronic learning has transferable effects on the functional connectivity networks of other types of learning and memory. The generalized enhancements in network efficiency and resilience suggest that learning itself may protect brain networks against deterioration.
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Cromar GL, Epp JR, Popovic A, Gu Y, Ha V, Walters BJ, St. Pierre J, Xiong X, Howland JG, Josselyn SA, Frankland PW, Parkinson J. Toxoplasma infection in male mice alters dopamine-sensitive behaviors and host gene expression patterns associated with neuropsychiatric disease. PLoS Negl Trop Dis 2022; 16:e0010600. [PMID: 35857765 PMCID: PMC9342775 DOI: 10.1371/journal.pntd.0010600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 08/01/2022] [Accepted: 06/21/2022] [Indexed: 11/18/2022] Open
Abstract
During chronic infection, the single celled parasite, Toxoplasma gondii, can migrate to the brain where it has been associated with altered dopamine function and the capacity to modulate host behavior, increasing risk of neurocognitive disorders. Here we explore alterations in dopamine-related behavior in a new mouse model based on stimulant (cocaine)-induced hyperactivity. In combination with cocaine, infection resulted in heightened sensorimotor deficits and impairment in prepulse inhibition response, which are commonly disrupted in neuropsychiatric conditions. To identify molecular pathways in the brain affected by chronic T. gondii infection, we investigated patterns of gene expression. As expected, infection was associated with an enrichment of genes associated with general immune response pathways, that otherwise limits statistical power to identify more informative pathways. To overcome this limitation and focus on pathways of neurological relevance, we developed a novel context enrichment approach that relies on a customized ontology. Applying this approach, we identified genes that exhibited unexpected patterns of expression arising from the combination of cocaine exposure and infection. These include sets of genes which exhibited dampened response to cocaine in infected mice, suggesting a possible mechanism for some observed behaviors and a neuroprotective effect that may be advantageous to parasite persistence. This model offers a powerful new approach to dissect the molecular pathways by which T. gondii infection contributes to neurocognitive disorders.
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Affiliation(s)
- Graham L. Cromar
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
| | - Jonathan R. Epp
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
| | - Ana Popovic
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
- Dept. of Biochemistry, University of Toronto, Toronto, Canada
| | - Yusing Gu
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
| | - Violet Ha
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
| | - Brandon J. Walters
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
| | - James St. Pierre
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
| | - Xuejian Xiong
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
| | - John G. Howland
- Dept. of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, Canada
| | - Sheena A. Josselyn
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
- Dept. of Physiology, University of Toronto, Toronto, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Canada
- Dept. of Psychology, University of Toronto, Toronto, Canada
| | - Paul W. Frankland
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
- Dept. of Physiology, University of Toronto, Toronto, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Canada
- Dept. of Psychology, University of Toronto, Toronto, Canada
- * E-mail: (PF); (JP)
| | - John Parkinson
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
- Dept. of Biochemistry, University of Toronto, Toronto, Canada
- Dept. of Molecular Genetics, University of Toronto, Toronto, Canada
- * E-mail: (PF); (JP)
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13
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Terstege DJ, Addo-Osafo K, Campbell Teskey G, Epp JR. New neurons in old brains: implications of age in the analysis of neurogenesis in post-mortem tissue. Mol Brain 2022; 15:38. [PMID: 35501905 PMCID: PMC9063342 DOI: 10.1186/s13041-022-00926-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 04/20/2022] [Indexed: 11/10/2022] Open
Abstract
Adult neurogenesis, the proliferation and integration of newly generated neurons, has been observed in the adult mammalian hippocampus of many species. Numerous studies have also found adult neurogenesis in the human hippocampus, but several recent high-profile studies have suggested that this process is considerably reduced in humans, occurring in children but not in adults. In comparison, rodent studies also show age-related decline but a greater degree of proliferation of new neurons in adult animals. These differences may represent biological species differences or could alternatively be explained by methodological differences in tissue handling and fixation. Here, we examine whether differences in the post-mortem interval between death and tissue fixation might impact subsequent detection of adult neurogenesis due to increased tissue degradation. Because there are fewer new neurons present in older subjects to begin with we hypothesized that, subject age might interact significantly with post-mortem interval in the detection of adult neurogenesis. We analyzed neurogenesis in the hippocampus of rats that were either perfusion-fixed or the brains extracted and immersion-fixed at various post-mortem intervals. We observed an interaction between animal age and the time delay between death and tissue fixation. While similar levels of neurogenesis were observed in young rats regardless of fixation, older rats had significantly fewer labeled neurons when fixation was not immediate. Furthermore, the morphological detail of the labeled neurons was significantly reduced in the delayed fixation conditions at all ages. This study highlights critical concerns that must be considered when using post-mortem tissue to quantify adult neurogenesis.
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Affiliation(s)
- Dylan J Terstege
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, HMRB 162, Health Sciences Centre, 3330 Hospital Drive NW, AB, T2N 4N1, Calgary, Canada
| | - Kwaku Addo-Osafo
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, HMRB 162, Health Sciences Centre, 3330 Hospital Drive NW, AB, T2N 4N1, Calgary, Canada
| | - G Campbell Teskey
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, HMRB 162, Health Sciences Centre, 3330 Hospital Drive NW, AB, T2N 4N1, Calgary, Canada
| | - Jonathan R Epp
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, HMRB 162, Health Sciences Centre, 3330 Hospital Drive NW, AB, T2N 4N1, Calgary, Canada.
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14
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Scott GA, Terstege DJ, Roebuck AJ, Gorzo KA, Vu AP, Howland JG, Epp JR. Adult neurogenesis mediates forgetting of multiple types of memory in the rat. Mol Brain 2021; 14:97. [PMID: 34174906 PMCID: PMC8236170 DOI: 10.1186/s13041-021-00808-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/08/2021] [Indexed: 11/30/2022] Open
Abstract
The formation and retention of hippocampus-dependent memories is impacted by neurogenesis, a process that involves the production of new neurons in the dentate gyrus of the hippocampus. Recent studies demonstrate that increasing neurogenesis after memory formation induces forgetting of previously acquired memories. Neurogenesis-induced forgetting was originally demonstrated in mice, but a recent report suggests that the same effect may be absent in rats. Although a general species difference is possible, other potential explanations for these incongruent findings are that memories which are more strongly reinforced become resilient to forgetting or that perhaps only certain types of memories are affected. Here, we investigated whether neurogenesis-induced forgetting occurs in rats using several hippocampus-dependent tasks including contextual fear conditioning (CFC), the Morris Water Task (MWT), and touchscreen paired associates learning (PAL). Neurogenesis was increased following training using voluntary exercise for 4 weeks before recall of the previous memory was assessed. We show that voluntary running causes forgetting of context fear memories in a neurogenesis-dependent manner, and that neurogenesis-induced forgetting is present in rats across behavioral tasks despite differences in complexity or reliance on spatial, context, or object memories. In addition, we asked whether stronger memories are less susceptible to forgetting by varying the strength of training. Even with a very strong training protocol in the CFC task, we still observed enhanced forgetting related to increased neurogenesis. These results suggest that forgetting due to neurogenesis is a conserved mechanism that aids in the clearance of memories.
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Affiliation(s)
- Gavin A Scott
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, HMRB 162, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Dylan J Terstege
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, HMRB 162, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Andrew J Roebuck
- Yukon University, 500 University Drive, Whitehorse, YT, Y1A 5K4, Canada
| | - Kelsea A Gorzo
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, HMRB 162, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Alex P Vu
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, HMRB 162, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - John G Howland
- Department of Anatomy, Physiology, and Pharmacology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, S7N 5E5, Canada
| | - Jonathan R Epp
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Cumming School of Medicine, HMRB 162, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada.
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15
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Scott GA, Terstege DJ, Vu AP, Law S, Evans A, Epp JR. Disrupted Neurogenesis in Germ-Free Mice: Effects of Age and Sex. Front Cell Dev Biol 2020; 8:407. [PMID: 32548122 PMCID: PMC7272680 DOI: 10.3389/fcell.2020.00407] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 05/04/2020] [Indexed: 12/26/2022] Open
Abstract
The gut microbiome has profound effects on development and function of the nervous system. Recent evidence indicates that disruption of the gut microbiome leads to altered hippocampal neurogenesis. Here, we examined whether the effects of gut microbiome disruption on neurogenesis are age-dependent, given that both neurogenesis and the microbiome show age-related changes. Additionally, we examined memory induced functional connectivity of hippocampal networks. Control and germ-free mice at three different ages (4, 8, and 12 weeks) were trained in contextual fear-conditioning, then subsequently tested the following day. Hippocampal neurogenesis, quantified via BrdU and doublecortin, exhibited age-dependent changes relative to controls, with the established age-dependent decrease in neurogenesis being delayed in germ-free mice. Moreover, we found sex-dependent effects of germ-free status on neurogenesis, with 4 week old male germ-free mice having decreased neurogenesis and 8 week old female germ-free mice having increased neurogenesis. To assess systems-level consequences of disrupted neurogenesis, we assessed functional connectivity of hippocampal networks by inducing c-Fos expression with contextual memory retrieval and applying a previously described network analysis. Our results indicate impaired connectivity of the dentate gyrus in germ-free mice in a pattern highly correlated with adult neurogenesis. In control but not germ-free mice, functional connectivity became more refined with age, indicating that age dependent network refinement is disrupted in germ-free mice. Overall, the results show that disruption of the gut microbiome affects hippocampal neurogenesis in an age- and sex-dependent manner and that these changes are also related to changes in the dentate gyrus functional network.
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Affiliation(s)
- Gavin A Scott
- Cumming School of Medicine, Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
| | - Dylan J Terstege
- Cumming School of Medicine, Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
| | - Alex P Vu
- Cumming School of Medicine, Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
| | - Sampson Law
- Cumming School of Medicine, Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
| | - Alexandria Evans
- Cumming School of Medicine, Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
| | - Jonathan R Epp
- Cumming School of Medicine, Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
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16
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Kramer EE, Steadman PE, Epp JR, Frankland PW, Josselyn SA. Assessing Individual Neuronal Activity Across the Intact Brain: Using Hybridization Chain Reaction (HCR) to DetectArcmRNA Localized to the Nucleus in Volumes of Cleared Brain Tissue. ACTA ACUST UNITED AC 2018; 84:e49. [DOI: 10.1002/cpns.49] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Emily E. Kramer
- Program in Neurosciences and Mental Health, Hospital for Sick Children; Toronto Ontario Canada
- Institute of Medical Sciences, University of Toronto; Toronto Ontario Canada
| | - Patrick E. Steadman
- Program in Neurosciences and Mental Health, Hospital for Sick Children; Toronto Ontario Canada
- Institute of Medical Sciences, University of Toronto; Toronto Ontario Canada
| | - Jonathan R. Epp
- Program in Neurosciences and Mental Health, Hospital for Sick Children; Toronto Ontario Canada
- Department of Cell Biology and Anatomy, University of Calgary; Calgary Alberta Canada
- Current address: Hotchkiss Brain Institute, Cumming School of Medicine; Calgary Alberta Canada
| | - Paul W. Frankland
- Program in Neurosciences and Mental Health, Hospital for Sick Children; Toronto Ontario Canada
- Institute of Medical Sciences, University of Toronto; Toronto Ontario Canada
- Department of Psychology, University of Toronto; Toronto Ontario Canada
- Department of Physiology, University of Toronto; Toronto Ontario Canada
- Brain, Mind & Consciousness Program, Canadian Institute for Advanced Research; Toronto Ontario Canada. Child & Brain Development Program, Canadian Institute for Advanced Research; Toronto Ontario Canada
| | - Sheena A. Josselyn
- Program in Neurosciences and Mental Health, Hospital for Sick Children; Toronto Ontario Canada
- Institute of Medical Sciences, University of Toronto; Toronto Ontario Canada
- Department of Psychology, University of Toronto; Toronto Ontario Canada
- Department of Physiology, University of Toronto; Toronto Ontario Canada
- Brain, Mind & Consciousness Program, Canadian Institute for Advanced Research; Toronto Ontario Canada. Child & Brain Development Program, Canadian Institute for Advanced Research; Toronto Ontario Canada
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17
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Abstract
As adult-generated neurons integrate into hippocampal circuits, they compete with mature neurons for inputs from the entorhinal cortex. By reducing spines on mature granule cells, McAvoy et al. (2016) find that new neurons integrate more efficiently, and this facilitates learning.
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Affiliation(s)
- Jonathan R Epp
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Paul W Frankland
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Psychology, University of Toronto, Toronto, ON M5S 3G3, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada.
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18
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Epp JR, Silva Mera R, Köhler S, Josselyn SA, Frankland PW. Neurogenesis-mediated forgetting minimizes proactive interference. Nat Commun 2016; 7:10838. [PMID: 26917323 PMCID: PMC4773435 DOI: 10.1038/ncomms10838] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 01/26/2016] [Indexed: 12/30/2022] Open
Abstract
Established memories may interfere with the encoding of new memories, particularly when existing and new memories overlap in content. By manipulating levels of hippocampal neurogenesis, here we show that neurogenesis regulates this form of proactive interference. Increasing hippocampal neurogenesis weakens existing memories and, in doing so, facilitates the encoding of new, conflicting (but not non-conflicting) information in mice. Conversely, decreasing neurogenesis stabilizes existing memories, and impedes the encoding of new, conflicting information. These results suggest that reduced proactive interference is an adaptive benefit of neurogenesis-induced forgetting. New neurons are continuously produced throughout adulthood in the hippocampus. Here the authors provide evidence that adult hippocampal neurogenesis weakens existing memories, and facilitates the encoding of new, confliction information in mice.
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Affiliation(s)
- Jonathan R Epp
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | - Rudy Silva Mera
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
| | - Stefan Köhler
- Department of Psychology, Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada N6A 5B7.,Baycrest Centre, Rotman Research Institute, Toronto, Ontario, Canada M6A 2E1
| | - Sheena A Josselyn
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.,Department of Psychology, University of Toronto, Toronto, Ontario, Canada M5S 3GM.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Paul W Frankland
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.,Department of Psychology, University of Toronto, Toronto, Ontario, Canada M5S 3GM.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada M5S 1A8
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19
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Pederson BA, Turnbull J, Epp JR, Weaver SA, Zhao X, Pencea N, Roach PJ, Frankland PW, Ackerley CA, Minassian BA. Inhibiting glycogen synthesis prevents Lafora disease in a mouse model. Ann Neurol 2014; 74:297-300. [PMID: 23913475 DOI: 10.1002/ana.23899] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/05/2013] [Accepted: 03/15/2013] [Indexed: 11/10/2022]
Abstract
Lafora disease (LD) is a fatal progressive myoclonus epilepsy characterized neuropathologically by aggregates of abnormally structured glycogen and proteins (Lafora bodies [LBs]), and neurodegeneration. Whether LBs could be prevented by inhibiting glycogen synthesis and whether they are pathogenic remain uncertain. We genetically eliminated brain glycogen synthesis in LD mice. This resulted in long-term prevention of LB formation, neurodegeneration, and seizure susceptibility. This study establishes that glycogen synthesis is requisite for LB formation and that LBs are pathogenic. It opens a therapeutic window for potential treatments in LD with known and future small molecule inhibitors of glycogen synthesis.
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20
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Turnbull J, Epp JR, Goldsmith D, Zhao X, Pencea N, Wang P, Frankland PW, Ackerley CA, Minassian BA. PTG protein depletion rescues malin-deficient Lafora disease in mouse. Ann Neurol 2014; 75:442-6. [PMID: 24419970 DOI: 10.1002/ana.24104] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 01/06/2014] [Accepted: 01/06/2014] [Indexed: 11/11/2022]
Abstract
Ubiquitin ligases regulate quantities and activities of target proteins, often pleiotropically. The malin ubiquitin E3 ligase is reported to regulate autophagy, the misfolded protein response, microRNA silencing, Wnt signaling, neuronatin-mediated endoplasmic reticulum stress, and the laforin glycogen phosphatase. Malin deficiency causes Lafora disease, pathologically characterized by neurodegeneration and accumulations of malformed glycogen (Lafora bodies). We show that reducing glycogen production in malin-deficient mice by genetically removing PTG, a glycogen synthesis activator protein, nearly completely eliminates Lafora bodies and rescues the neurodegeneration, myoclonus, seizure susceptibility, and behavioral abnormality. Glycogen synthesis downregulation is a potential therapy for the fatal adolescence onset epilepsy Lafora disease.
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Affiliation(s)
- Julie Turnbull
- Program in Genetics and Genome Biology, University of Toronto, Toronto, Ontario, Canada
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21
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Epp JR, Beasley CL, Galea LAM. Increased hippocampal neurogenesis and p21 expression in depression: dependent on antidepressants, sex, age, and antipsychotic exposure. Neuropsychopharmacology 2013; 38:2297-306. [PMID: 23778854 PMCID: PMC3773682 DOI: 10.1038/npp.2013.132] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 05/14/2013] [Accepted: 05/15/2013] [Indexed: 12/15/2022]
Abstract
The mammalian hippocampus continues to generate new neurons throughout life. The function of adult-generated neurons remains controversial, but adult neurogenesis in the hippocampus is related to depression. Studies show that neurogenesis in the hippocampus is regulated by antidepressants in both humans and rodents, but no studies have examined the effects of age, sex, or antipsychotic exposure on the relationship between depression, antidepressant exposure, and hippocampal neurogenesis in humans. Hippocampal sections were obtained from the Stanley Medical Research Institute and were immunohistochemically labeled for the immature neuron marker doublecortin and the cell cycle arrest marker p21. We compared the number of cells in the granule cell layer and subgranular zone that expressed these proteins in brains from control subjects (n=12), patients with major depressive disorder (MDD) without psychotic symptoms (n=12), and patients with MDD and psychotic symptoms (n=12). We show here that the density of doublecortin/NeuN expression was increased in MDD patients compared with controls and MDD patients with psychosis, with the effect greater in women. Further, we show that older depressed patients without psychosis had higher levels of p21/NeuN expression and that depressed individuals prescribed antidepressants had higher levels of p21/NeuN expression, but only in older women. We show for the first time that changes in neurogenesis due to prescribed antidepressants or depression are dependent on age, sex, and the presence of antipsychotics or psychotic symptoms.
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Affiliation(s)
- Jonathan R Epp
- Program in Neuroscience, Department of Psychology, Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Clare L Beasley
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Liisa AM Galea
- Program in Neuroscience, Department of Psychology, Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada,Program in Neuroscience, Department of Psychology, Centre for Brain Health, University of British Columbia, 2136 West Mall, Vancouver, BC V6T 1Z4, Canada, Tel: +604 822 6536, Fax: +604 822 6923, E-mail:
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22
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Chow C, Epp JR, Lieblich SE, Barha CK, Galea LAM. Sex differences in neurogenesis and activation of new neurons in response to spatial learning and memory. Psychoneuroendocrinology 2013; 38:1236-50. [PMID: 23219473 DOI: 10.1016/j.psyneuen.2012.11.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2012] [Revised: 10/30/2012] [Accepted: 11/07/2012] [Indexed: 11/29/2022]
Abstract
Adult hippocampal neurogenesis is often associated with hippocampus-dependent learning and memory. Throughout a new neuron's development, it is differentially sensitive to factors that can influence its survival and functionality. Previous research shows that spatial training that occurred 6-10 days after an injection of the DNA synthesis marker, bromodeoxyuridine (BrdU), increased cell survival in male rats. Because sex differences in spatial cognition and hippocampal neurogenesis have been reported, it is unclear whether spatial training would influence hippocampal neurogenesis in the same way in males and females. Therefore, this study examined sex differences in hippocampal neurogenesis following training in a spatial task. Male and female rats were trained in the spatial or cued version of the Morris water maze 6-10 days after one injection of BrdU (200mg/kg). Twenty days following BrdU injection, all animals were given a probe trial and perfused. Males performed better in the spatial, but not cue, task than females. Spatial training increased BrdU-labeled cells relative to cue training only in males, but both males and females showed greater activation of new cells (BrdU co-labeled with immediate early gene product zif268) after spatial training compared to cue training. Furthermore, performance during spatial training was positively correlated with cell activation in females but not males. This study shows that while spatial training differentially regulates hippocampal neurogenesis in males and females, the activity of new neurons in response to spatial memory retrieval is similar. These findings highlight the importance of sex on neural plasticity and cognition.
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Affiliation(s)
- Carmen Chow
- Program in Neuroscience, Department of Psychology, Brain Research Centre, University of British Columbia, Vancouver, BC, Canada
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23
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Niibori Y, Yu TS, Epp JR, Akers KG, Josselyn SA, Frankland PW. Suppression of adult neurogenesis impairs population coding of similar contexts in hippocampal CA3 region. Nat Commun 2013; 3:1253. [PMID: 23212382 PMCID: PMC4931925 DOI: 10.1038/ncomms2261] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 11/06/2012] [Indexed: 12/19/2022] Open
Abstract
Different places may share common features, but are coded by distinct populations of CA3 neurons in the hippocampus. Here we show that chemical or genetic suppression of adult neurogenesis in the hippocampus impairs this population-based coding of similar (but not dissimilar) contexts. These data provide a neural basis for impaired spatial discrimination following ablation of adult neurogenesis, and support the proposal that adult neurogenesis regulates the efficiency of a pattern separation process in the hippocampus.
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Affiliation(s)
- Yosuke Niibori
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
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24
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Abstract
The structure of the mammalian hippocampus continues to be modified throughout life by continuous addition of neurons in the dentate gyrus. Although the existence of adult neurogenesis is now widely accepted the function that adult generated granule cells play is a topic of intense debate. Many studies have argued that adult generated neurons, due to unique physiological characteristics, play a unique role in hippocampus-dependent learning and memory. However, it is not currently clear whether this is the case or what specific capability adult generated neurons may confer that developmentally generated neurons do not. These questions have been addressed in numerous ways, from examining the effects of increasing or decreasing neurogenesis to computational modeling. One particular area of research has examined the effects of hippocampus dependent learning on proliferation, survival, integration and activation of immature neurons in response to memory retrieval. Within this subfield there remains a range of data showing that hippocampus dependent learning may increase, decrease or alternatively may not alter these components of neurogenesis in the hippocampus. Determining how and when hippocampus-dependent learning alters adult neurogenesis will help to further clarify the role of adult generated neurons. There are many variables (such as age of immature neurons, species, strain, sex, stress, task difficulty, and type of learning) as well as numerous methodological differences (such as marker type, quantification techniques, apparatus size etc.) that could all be crucial for a clear understanding of the interaction between learning and neurogenesis. Here, we review these findings and discuss the different conditions under which hippocampus-dependent learning impacts adult neurogenesis in the dentate gyrus.
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Affiliation(s)
- Jonathan R. Epp
- *Correspondence: Jonathan R. Epp, Neurosciences and Mental Health, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada. e-mail: ;
| | | | - Liisa A. M. Galea
- Department of Psychology, Program in Neuroscience, Brain Research Centre, University of British ColumbiaVancouver, BC, Canada
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Epp JR, Haack AK, Galea LAM. Activation and survival of immature neurons in the dentate gyrus with spatial memory is dependent on time of exposure to spatial learning and age of cells at examination. Neurobiol Learn Mem 2011; 95:316-25. [PMID: 21216298 DOI: 10.1016/j.nlm.2011.01.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 12/02/2010] [Accepted: 01/03/2011] [Indexed: 11/27/2022]
Abstract
Neurogenesis continues to occur throughout life in the dentate gyrus of the hippocampus and may be related to hippocampus-dependent learning. We have recently reported that there is an enhancement of neurogenesis in the hippocampus only when BrdU is administered 6 days prior to starting spatial training but not when training started either 1 day or 11 days following BrdU administration. In that study, all rats were perfused on day 16 after BrdU injection in order to compare cells of the same age (i.e. 16 day old cells) and thus the survival time after learning was different between groups. This study was designed to address whether the amount of time that passed following training could also contribute to the effects of spatial learning on hippocampal neurogenesis and whether there was differential new neuron activation in response to spatial learning that depended on the age of new cells at the time of spatial learning. Here we tested whether a survival period of 5 days following spatial learning at either 1-5, 6-10 or 11-15 days following BrdU administration would alter cell survival and/or activation of new neurons. Our results indicate that 5 days after training in the Morris water task cell survival is unaltered by training on days 1-5, increased by training at days 6-10 and decreased when training occurs on days 11-15. Furthermore spatial learners trained on days 6-10 or 11-15 show greater activation of new neurons compared to cue-trained rats during a probe trial 5 days after training. In addition, rats trained on the spatial task on days 11-15 had a greater number of activated new neurons compared to rats trained on the spatial task on days 6-10. These results suggest there is a gradual removal of older BrdU-labeled new neurons following spatial learning perhaps due to a competitive interaction with a population of younger BrdU-labeled new neurons.
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Affiliation(s)
- Jonathan R Epp
- Department of Psychology, Graduate Program in Neuroscience, Brain Research Centre, University of British Columbia, Vancouver, BC, Canada
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Abstract
Adult neurogenesis continues throughout life in the mammalian hippocampus. The precise function of the adult generated neurons remains uncertain although there is growing evidence that they are involved in hippocampus-dependent learning and memory. Training rats on a hidden platform version of the Morris water task has been shown to increase or decrease the survival of newly produced cells in the dentate gyrus (DG) compared to training on a visible platform version. Here we investigated whether the difficulty of the task is related to the degree or direction of the change in neurogenesis. We trained rats on either a visible platform version of the Morris water task or one of three different hidden platform paradigms: four training trials per session version, two training trials per session, and reduced-cue (a version in which the majority of the distal cues were removed from the room). BrdU was administered 6 days prior to training and rats were perfused 24 h after the last training session. As expected, training on the four trial hidden platform version increased cell survival compared to training on the visible platform version. However, training on the more difficult reduced-cue hidden platform version resulted in a decrease in cell survival. Rats that received fewer trials per session did not differ in terms of cell survival in comparison to rats trained on the visible platform version. These findings demonstrate that altering the difficulty of the spatial task has an impact on the corresponding change in cell survival. The lack of obvious distal cues likely changed the strategy used by the rats to determine the location of the platform and resulted in a decrease, instead of an increase in cell survival in the hippocampus. In conclusion, different types of hippocampus-dependent learning can differentially impact cell survival.
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Affiliation(s)
- Jonathan R Epp
- Department of Psychology, Graduate Program in Neuroscience, Brain Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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Rummel J, Epp JR, Galea LAM. Estradiol does not influence strategy choice but place strategy choice is associated with increased cell proliferation in the hippocampus of female rats. Horm Behav 2010; 58:582-90. [PMID: 20688068 DOI: 10.1016/j.yhbeh.2010.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 07/24/2010] [Accepted: 07/26/2010] [Indexed: 01/09/2023]
Abstract
Adult neurogenesis occurs in the hippocampus of most mammals. While the function of adult hippocampal neurogenesis is not known, there is a relationship between neurogenesis and hippocampus-dependent learning and memory. Ovarian hormones can influence learning and memory and strategy choice. In competitive memory tasks, higher levels of estradiol shift female rats towards the use of the place strategy. Previous studies using a cue-competition paradigm find that 36% of male rats will use a hippocampus-dependent place strategy and place strategy users had lower levels of cell proliferation in the hippocampus. Here, we used the same paradigm to test whether endogenous or exogenous ovarian hormones influence strategy choice in the cue-competition paradigm and whether cell proliferation was related to strategy choice. We tested ovariectomized estradiol-treated (10 microg of estradiol benzoate) or sham-operated female rats on alternating blocks of hippocampus-dependent and hippocampus-independent versions of the Morris water task. Rats were then given a probe session with the platform visible and in a novel location. Preferred strategy was classified as place strategy (hippocampus-dependent) if they swam to the old platform location or cue strategy (hippocampus-independent) if they swam to the visible platform. All groups showed a preference for the cue strategy. However, proestrous rats were more likely to be place strategy users than rats not in proestrus. Female place strategy users had increased cell proliferation in the dentate gyrus compared to cue strategy users. Our study suggests that 78% of female rats chose the cue strategy instead of the place strategy. In summary the present results suggest that estradiol does not shift strategy use in this paradigm and that cell proliferation is related to strategy use with greater cell proliferation seen in place strategy users in female rats.
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Affiliation(s)
- Julia Rummel
- Department of Psychology, Graduate Program in Neuroscience, Brain Research Centre, University of British Columbia, 2136 West Mall, Vancouver, BC, Canada
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Epp JR, Galea LAM. Hippocampus-dependent strategy choice predicts low levels of cell proliferation in the dentate gyrus. Neurobiol Learn Mem 2009; 91:437-46. [PMID: 19185612 DOI: 10.1016/j.nlm.2009.01.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 12/16/2008] [Accepted: 01/09/2009] [Indexed: 11/17/2022]
Abstract
Neurogenesis continues to occur throughout life in the mammalian hippocampus. Previous research has suggested that the production of new neurons in the hippocampus during adulthood may be related to hippocampus-dependent learning and memory. However, the exact relationship between adult neurogenesis and learning and memory remains unclear. Here we investigated whether learning strategy selection is related to cell proliferation or to survival of new neurons in the hippocampus of adult male rats. We trained rats on alternating blocks of hippocampus-dependent (hidden platform) and hippocampus-independent (visible platform) versions of the Morris water task with the platform always in the same position. Following training, rats were given a probe session during which the platform was visible and in a novel location. Preferred strategy was determined by observing the initial swim path. Rats were classified as place strategy (hippocampus-dependent) users if they swam to the old platform location. Cue strategy (hippocampus-independent) users were classified as those rats that swam initially to the visible platform. Our results indicate that rats that preferentially used a place strategy had significantly lower cell proliferation than cue strategy users. However, there was no significant difference in cell survival or number of immature neurons between strategy user groups. These results suggest that low levels of cell proliferation in the dentate gyrus may be conducive or coincident with more efficient memory processing in the hippocampus.
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Affiliation(s)
- Jonathan R Epp
- Department of Psychology, Graduate Program in Neuroscience, Brain Research Centre, University of British Columbia, BC, Canada
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Mueller AD, Pollock MS, Lieblich SE, Epp JR, Galea LAM, Mistlberger RE. Sleep deprivation can inhibit adult hippocampal neurogenesis independent of adrenal stress hormones. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1693-703. [DOI: 10.1152/ajpregu.00858.2007] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Sleep deprivation (SD) can suppress cell proliferation in the hippocampal dentate gyrus of adult male rodents, suggesting that sleep may contribute to hippocampal functions by promoting neurogenesis. However, suppression of cell proliferation in rats by the platform-over-water SD method has been attributed to elevated corticosterone (Cort), a potent inhibitor of cell proliferation and nonspecific correlate of this procedure. We report here results that do not support this conclusion. Intact and adrenalectomized (ADX) male rats were subjected to a 96-h SD using multiple- and single-platform methods. New cells were identified by immunoreactivity for 5-bromo-2′-deoxyuridine (BrdU) or Ki67 and new neurons by immunoreactivity for BrdU and doublecortin. EEG recordings confirmed a 95% deprivation of rapid eye movement (REM) sleep and a 40% decrease of non-REM sleep. Cell proliferation in the dentate gyrus was suppressed by up to 50% in sleep-deprived rats relative to apparatus control or home cage control rats. This effect was also observed in ADX rats receiving continuous low-dose Cort replacement via subcutaneous minipumps but not in ADX rats receiving Cort replacement via drinking water. In these latter rats, Cort intake via water was reduced by 60% during SD; upregulation of cell proliferation by reduced Cort intake may obscure inhibitory effects of sleep loss on cell proliferation. SD had no effect on the percentage of new cells expressing a neuronal phenotype. These results demonstrate that the Cort replacement method is critical for detecting an effect of SD on cell proliferation and support a significant role for sleep in adult neurogenesis.
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Galea LAM, Uban KA, Epp JR, Brummelte S, Barha CK, Wilson WL, Lieblich SE, Pawluski JL. Endocrine regulation of cognition and neuroplasticity: Our pursuit to unveil the complex interaction between hormones, the brain, and behaviour. ACTA ACUST UNITED AC 2008; 62:247-60. [DOI: 10.1037/a0014501] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Epp JR, Spritzer MD, Galea LAM. Hippocampus-dependent learning promotes survival of new neurons in the dentate gyrus at a specific time during cell maturation. Neuroscience 2007; 149:273-85. [PMID: 17900815 DOI: 10.1016/j.neuroscience.2007.07.046] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 07/26/2007] [Accepted: 07/27/2007] [Indexed: 01/16/2023]
Abstract
Adult neurogenesis in the hippocampus continues throughout life and may play an important role in hippocampus-dependent learning and memory. Previous research has been equivocal, demonstrating that spatial learning may enhance, decrease or not significantly affect the survival of new neurons. A potential cause of these varying results may be differences in when bromodeoxyuridine (BrdU) was administered relative to spatial training. We examined whether the time elapsed between BrdU administration and spatial learning would alter the survival of the labeled cells. We injected rats with BrdU once on day 0 and then trained in the standard place version of the Morris water task on days 1-5, 6-10 or 11-15 after BrdU injection. We found an enhancement of neurogenesis in the hippocampus only when BrdU was administered 6 days prior to the beginning of spatial training. There was no significant change in hippocampal neurogenesis for groups that started training either 1 or 11 days following BrdU administration. This suggests that a critical period exists in the development of new neurons during which time their survival may be altered by activation of the hippocampus. Furthermore, when dividing rats into poor versus good learners based on overall performance using a median split, only poor place learners and not good place learners exhibit increased hippocampal neurogenesis compared with cue learning, collapsed across time of training. These findings provide further evidence of a link between learning and adult neurogenesis.
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Affiliation(s)
- J R Epp
- Department of Psychology, Graduate Program in Neuroscience, Brain Research Centre, University of British Columbia, 2136 West Mall, Vancouver, British Columbia, Canada, V6T 1Z4
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Spanswick SC, Epp JR, Keith JR, Sutherland RJ. Adrenalectomy-induced granule cell degeneration in the hippocampus causes spatial memory deficits that are not reversed by chronic treatment with corticosterone or fluoxetine. Hippocampus 2007; 17:137-46. [PMID: 17183555 DOI: 10.1002/hipo.20252] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Long-term adrenalectomy (ADX) causes a nearly complete and selective loss of granule cells in the dentate gyrus (DG) of the hippocampus. Previously, learning and memory deficits have been observed following ADX-induced granule cell degeneration for tasks that require the hippocampus. Our objective here was to determine whether corticosterone (CORT) replacement and treatment with the neurogenic compound fluoxetine could reverse behavioral deficits after ADX. We trained ADX and control rats in a moving, hidden platform version of the Morris water task before chronic administration (6 weeks) of CORT and either fluoxetine or vehicle. After treatment, all rats were retested in the Morris water task. Brains were labeled for the endogenous neurogenic markers Ki67 and doublecortin. Here we provide evidence that neurogenesis persists at a normal rate in the hippocampus after long-term ADX. After 8 weeks of CORT and fluoxetine administration, ADX-fluoxetine rats did not differ significantly compared to ADX-vehicle rats receiving CORT or compared to control rats in the number of Ki67 or doublecortin labeled cells. ADX-fluoxetine rats also did not significantly differ from ADX-vehicle rats in regards to granule cell layer thickness. Our results indicate that long-term ADX is associated with impaired spatial ability in the Morris water task and that neither chronic treatment with CORT, nor with CORT and fluoxetine are capable of altering the Morris water task deficit.
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Affiliation(s)
- Simon C Spanswick
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
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