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Okada R, Ikegaya Y, Matsumoto N. Short-Term Preexposure to Novel Enriched Environment Augments Hippocampal Ripples in Urethane-Anesthetized Mice. Biol Pharm Bull 2024; 47:1021-1027. [PMID: 38797694 DOI: 10.1248/bpb.b24-00118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Learning and memory are affected by novel enriched environment, a condition where animals play and interact with a variety of toys and conspecifics. Exposure of animals to the novel enriched environments improves memory by altering neural plasticity during natural sleep, a process called memory consolidation. The hippocampus, a pivotal brain region for learning and memory, generates high-frequency oscillations called ripples during sleep, which is required for memory consolidation. Naturally occurring sleep shares characteristics in common with general anesthesia in terms of extracellular oscillations, guaranteeing anesthetized animals suitable to examine neural activity in a sleep-like state. However, it is poorly understood whether the preexposure of animals to the novel enriched environment modulates neural activity in the hippocampus under subsequent anesthesia. To ask this question, we allowed mice to freely explore the novel enriched environment or their standard environment, anesthetized them, and recorded local field potentials in the hippocampal CA1 area. We then compared the characteristics of hippocampal ripples between the two groups and found that the amplitude of ripples and the number of successive ripples were larger in the novel enriched environment group than in the standard environment group, suggesting that the afferent synaptic input from the CA3 area to the CA1 area was higher when the animals underwent the novel enriched environment. These results underscore the importance of prior experience that surpasses subsequent physical states from the neurophysiological point of view.
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Affiliation(s)
- Rio Okada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
- Institute for AI and Beyond, The University of Tokyo
- Center for Information and Neural Networks, National Institute of Information and Communications Technology
| | - Nobuyoshi Matsumoto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
- Institute for AI and Beyond, The University of Tokyo
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Çalışkan G, Demiray YE, Stork O. Comparison of three common inbred mouse strains reveals substantial differences in hippocampal GABAergic interneuron populations and in vitro network oscillations. Eur J Neurosci 2023; 58:3383-3401. [PMID: 37550182 DOI: 10.1111/ejn.16112] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 07/03/2023] [Accepted: 07/06/2023] [Indexed: 08/09/2023]
Abstract
A major challenge in neuroscience is to pinpoint neurobiological correlates of specific cognitive and neuropsychiatric traits. At the mesoscopic level, promising candidates for establishing such connections are brain oscillations that can be robustly recorded as local field potentials with varying frequencies in the hippocampus in vivo and in vitro. Inbred mouse strains show natural variation in hippocampal synaptic plasticity (e.g. long-term potentiation), a cellular correlate of learning and memory. However, their diversity in expression of different types of hippocampal network oscillations has not been fully explored. Here, we investigated hippocampal network oscillations in three widely used inbred mouse strains: C57BL/6J (B6J), C57BL/6NCrl (B6N) and 129S2/SvPasCrl (129) with the aim to identify common oscillatory characteristics in inbred mouse strains that show aberrant emotional/cognitive behaviour (B6N and 129) and compare them to "control" B6J strain. First, we detected higher gamma oscillation power in the hippocampal CA3 of both B6N and 129 strains. Second, higher incidence of hippocampal sharp wave-ripple (SPW-R) transients was evident in these strains. Third, we observed prominent differences in the densities of distinct interneuron types and CA3 associative network activity, which are indispensable for sustainment of mesoscopic network oscillations. Together, these results add further evidence to profound physiological differences among inbred mouse strains commonly used in neuroscience research.
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Affiliation(s)
- Gürsel Çalışkan
- Research Group "Synapto-Oscillopathies", Institute of Biology, Otto-von-Guericke-University, Magdeburg, Germany
- Department of Genetics and Molecular Neurobiology, Institute of Biology, Otto-von-Guericke-University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Yunus E Demiray
- Department of Genetics and Molecular Neurobiology, Institute of Biology, Otto-von-Guericke-University, Magdeburg, Germany
| | - Oliver Stork
- Department of Genetics and Molecular Neurobiology, Institute of Biology, Otto-von-Guericke-University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- Center for Intervention and Research on Adaptive and Maladaptive Brain Circuits Underlying MentalHealth (C-I-R-C), Jena-Magdeburg-Halle, Germany
- German Center for Mental Health (DZPG), Site Jena-Magdeburg-Halle, Jena-Magdeburg-Halle, Germany
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Mieske P, Hobbiesiefken U, Fischer-Tenhagen C, Heinl C, Hohlbaum K, Kahnau P, Meier J, Wilzopolski J, Butzke D, Rudeck J, Lewejohann L, Diederich K. Bored at home?—A systematic review on the effect of environmental enrichment on the welfare of laboratory rats and mice. Front Vet Sci 2022; 9:899219. [PMID: 36061113 PMCID: PMC9435384 DOI: 10.3389/fvets.2022.899219] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
Boredom is an emotional state that occurs when an individual has nothing to do, is not interested in the surrounding, and feels dreary and in a monotony. While this condition is usually defined for humans, it may very well describe the lives of many laboratory animals housed in small, barren cages. To make the cages less monotonous, environmental enrichment is often proposed. Although housing in a stimulating environment is still used predominantly as a luxury good and for treatment in preclinical research, enrichment is increasingly recognized to improve animal welfare. To gain insight into how stimulating environments influence the welfare of laboratory rodents, we conducted a systematic review of studies that analyzed the effect of enriched environment on behavioral parameters of animal well–being. Remarkably, a considerable number of these parameters can be associated with symptoms of boredom. Our findings show that a stimulating living environment is essential for the development of natural behavior and animal welfare of laboratory rats and mice alike, regardless of age and sex. Conversely, confinement and under-stimulation has potentially detrimental effects on the mental and physical health of laboratory rodents. We show that boredom in experimental animals is measurable and does not have to be accepted as inevitable.
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Affiliation(s)
- Paul Mieske
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Ute Hobbiesiefken
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Carola Fischer-Tenhagen
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Céline Heinl
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Katharina Hohlbaum
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Pia Kahnau
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Jennifer Meier
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Jenny Wilzopolski
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Daniel Butzke
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Juliane Rudeck
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Lars Lewejohann
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
- Institute of Animal Welfare, Animal Behavior and Laboratory Animal Science, Freie Universität Berlin, Berlin, Germany
| | - Kai Diederich
- German Center for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), Berlin, Germany
- *Correspondence: Kai Diederich
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