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Farag HI, Murphy BA, Templeman JR, Hanlon C, Joshua J, Koch TG, Niel L, Shoveller AK, Bedecarrats GY, Ellison A, Wilcockson D, Martino TA. One Health: Circadian Medicine Benefits Both Non-human Animals and Humans Alike. J Biol Rhythms 2024; 39:237-269. [PMID: 38379166 PMCID: PMC11141112 DOI: 10.1177/07487304241228021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Circadian biology's impact on human physical health and its role in disease development and progression is widely recognized. The forefront of circadian rhythm research now focuses on translational applications to clinical medicine, aiming to enhance disease diagnosis, prognosis, and treatment responses. However, the field of circadian medicine has predominantly concentrated on human healthcare, neglecting its potential for transformative applications in veterinary medicine, thereby overlooking opportunities to improve non-human animal health and welfare. This review consists of three main sections. The first section focuses on the translational potential of circadian medicine into current industry practices of agricultural animals, with a particular emphasis on horses, broiler chickens, and laying hens. The second section delves into the potential applications of circadian medicine in small animal veterinary care, primarily focusing on our companion animals, namely dogs and cats. The final section explores emerging frontiers in circadian medicine, encompassing aquaculture, veterinary hospital care, and non-human animal welfare and concludes with the integration of One Health principles. In summary, circadian medicine represents a highly promising field of medicine that holds the potential to significantly enhance the clinical care and overall health of all animals, extending its impact beyond human healthcare.
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Affiliation(s)
- Hesham I. Farag
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
- Centre for Cardiovascular Investigations, University of Guelph, Guelph, ON, Canada
| | - Barbara A. Murphy
- School of Agriculture and Food Science, University College, Dublin, Ireland
| | - James R. Templeman
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Charlene Hanlon
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
- Department of Poultry Science, Auburn University, Auburn, Alabama, USA
| | - Jessica Joshua
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Thomas G. Koch
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - Lee Niel
- Department of Pathobiology, University of Guelph, Guelph, ON, Canada
| | - Anna K. Shoveller
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | | | - Amy Ellison
- School of Natural Sciences, Bangor University, Bangor, UK
| | - David Wilcockson
- Department of Life Sciences, Aberystwyth University, Aberystwyth, UK
| | - Tami A. Martino
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
- Centre for Cardiovascular Investigations, University of Guelph, Guelph, ON, Canada
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2
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Bussi IL, Ben-Hamo M, Salazar Leon LE, Casiraghi LP, Zhang VY, Neitz AF, Lee J, Takahashi JS, Kim JJ, de la Iglesia HO. The circadian molecular clock in the suprachiasmatic nucleus is necessary but not sufficient for fear entrainment. Proc Natl Acad Sci U S A 2024; 121:e2316841121. [PMID: 38502706 PMCID: PMC10990155 DOI: 10.1073/pnas.2316841121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 02/22/2024] [Indexed: 03/21/2024] Open
Abstract
We show that nocturnal aversive stimuli presented to mice while they are eating and drinking outside of their safe nest can entrain circadian behaviors, leading to a shift toward daytime activity. We also show that the canonical molecular circadian clock is necessary for fear entrainment and that an intact molecular clockwork in the suprachiasmatic nucleus, the site of the central circadian pacemaker, is necessary but not sufficient to sustain fear entrainment of circadian rhythms. Our results demonstrate that entrainment of a circadian clock by cyclic fearful stimuli can lead to severely mistimed circadian behavior that persists even after the aversive stimulus is removed. Together, our findings support the interpretation that circadian and sleep symptoms associated with fear and anxiety disorders are, in part, the output of a fear-entrained clock, and provide a mechanistic insight into this clock.
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Affiliation(s)
- Ivana L. Bussi
- Department of Biology, University of Washington, Seattle, WA98195-1800
| | - Miriam Ben-Hamo
- Department of Biology, University of Washington, Seattle, WA98195-1800
| | | | | | - Victor Y. Zhang
- Department of Biology, University of Washington, Seattle, WA98195-1800
| | - Alexandra F. Neitz
- Department of Biology, University of Washington, Seattle, WA98195-1800
- Molecular & Cellular Biology Graduate Program, University of Washington, Seattle, WA98195-7275
| | - Jeffrey Lee
- Department of Biology, University of Washington, Seattle, WA98195-1800
| | - Joseph S. Takahashi
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX75390-9111
- HHMI, Chevy Chase, MD 20815
| | - Jeansok J. Kim
- Department of Psychology, University of Washington, Seattle, WA98195-1525
| | - Horacio O. de la Iglesia
- Department of Biology, University of Washington, Seattle, WA98195-1800
- Molecular & Cellular Biology Graduate Program, University of Washington, Seattle, WA98195-7275
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3
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Bussi IL, Ben-Hamo M, Leon LES, Casiraghi LP, Zhang VY, Neitz AF, Lee J, Takahashi JS, Kim JJ, de la Iglesia HO. The circadian molecular clock in the suprachiasmatic nucleus is necessary but not sufficient for fear entrainment in the mouse. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.26.546624. [PMID: 37425771 PMCID: PMC10327100 DOI: 10.1101/2023.06.26.546624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Nocturnal aversive stimuli presented to mice during eating and drinking outside of their safe nest can entrain circadian behaviors, leading to a shift toward daytime activity. We show that the canonical molecular circadian clock is necessary for fear entrainment and that an intact molecular clockwork in the suprachiasmatic nucleus (SCN), the site of the central circadian pacemaker, is necessary but not sufficient to sustain fear entrainment of circadian rhythms. Our results demonstrate that entrainment of a circadian clock by cyclic fearful stimuli can lead to severely mistimed circadian behavior that persists even after the aversive stimulus is removed. Together, our results support the interpretation that circadian and sleep symptoms associated with fear and anxiety disorders may represent the output of a fear-entrained clock. One-Sentence Summary Cyclic fearful stimuli can entrain circadian rhythms in mice, and the molecular clock within the central circadian pacemaker is necessary but not sufficient for fear-entrainment.
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Duhart JM, Inami S, Koh K. Many faces of sleep regulation: beyond the time of day and prior wake time. FEBS J 2023; 290:931-950. [PMID: 34908236 PMCID: PMC9198110 DOI: 10.1111/febs.16320] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/07/2021] [Accepted: 12/14/2021] [Indexed: 12/19/2022]
Abstract
The two-process model of sleep regulation posits two main processes regulating sleep: the circadian process controlled by the circadian clock and the homeostatic process that depends on the history of sleep and wakefulness. The model has provided a dominant conceptual framework for sleep research since its publication ~ 40 years ago. The time of day and prior wake time are the primary factors affecting the circadian and homeostatic processes, respectively. However, it is critical to consider other factors influencing sleep. Since sleep is incompatible with other behaviors, it is affected by the need for essential behaviors such as eating, foraging, mating, caring for offspring, and avoiding predators. Sleep is also affected by sensory inputs, sickness, increased need for memory consolidation after learning, and other factors. Here, we review multiple factors influencing sleep and discuss recent insights into the mechanisms balancing competing needs.
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Affiliation(s)
- José Manuel Duhart
- Department of Neuroscience, Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia PA
- These authors contributed equally
- Present address: Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Sho Inami
- Department of Neuroscience, Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia PA
- These authors contributed equally
| | - Kyunghee Koh
- Department of Neuroscience, Farber Institute for Neurosciences, Thomas Jefferson University, Philadelphia PA
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5
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Salazar Leon LE, Sillitoe RV. Potential Interactions Between Cerebellar Dysfunction and Sleep Disturbances in Dystonia. DYSTONIA 2022; 1. [PMID: 37065094 PMCID: PMC10099477 DOI: 10.3389/dyst.2022.10691] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Dystonia is the third most common movement disorder. It causes debilitating twisting postures that are accompanied by repetitive and sometimes intermittent co- or over-contractions of agonist and antagonist muscles. Historically diagnosed as a basal ganglia disorder, dystonia is increasingly considered a network disorder involving various brain regions including the cerebellum. In certain etiologies of dystonia, aberrant motor activity is generated in the cerebellum and the abnormal signals then propagate through a “dystonia circuit” that includes the thalamus, basal ganglia, and cerebral cortex. Importantly, it has been reported that non-motor defects can accompany the motor symptoms; while their severity is not always correlated, it is hypothesized that common pathways may nevertheless be disrupted. In particular, circadian dysfunction and disordered sleep are common non-motor patient complaints in dystonia. Given recent evidence suggesting that the cerebellum contains a circadian oscillator, displays sleep-stage-specific neuronal activity, and sends robust long-range projections to several subcortical regions involved in circadian rhythm regulation, disordered sleep in dystonia may result from cerebellum-mediated dysfunction of the dystonia circuit. Here, we review the evidence linking dystonia, cerebellar network dysfunction, and cerebellar involvement in sleep. Together, these ideas may form the basis for the development of improved pharmacological and surgical interventions that could take advantage of cerebellar circuitry to restore normal motor function as well as non-motor (sleep) behaviors in dystonia.
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Affiliation(s)
- Luis E. Salazar Leon
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Roy V. Sillitoe
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
- Development, Disease Models & Therapeutics Graduate Program, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, 77030, USA
- Address correspondence to: Dr. Roy V. Sillitoe, Tel: 832-824-8913, Fax: 832-825-1251,
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Baker PM, Mathis V, Lecourtier L, Simmons SC, Nugent FS, Hill S, Mizumori SJY. Lateral Habenula Beyond Avoidance: Roles in Stress, Memory, and Decision-Making With Implications for Psychiatric Disorders. Front Syst Neurosci 2022; 16:826475. [PMID: 35308564 PMCID: PMC8930415 DOI: 10.3389/fnsys.2022.826475] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/10/2022] [Indexed: 01/02/2023] Open
Abstract
In this Perspective review, we highlight some of the less explored aspects of lateral habenula (LHb) function in contextual memory, sleep, and behavioral flexibility. We provide evidence that LHb is well-situated to integrate different internal state and multimodal sensory information from memory-, stress-, motivational-, and reward-related circuits essential for both survival and decision making. We further discuss the impact of early life stress (ELS) on LHb function as an example of stress-induced hyperactivity and dysregulation of neuromodulatory systems within the LHb that promote anhedonia and motivational deficits following ELS. We acknowledge that recent technological advancements in manipulation and recording of neural circuits in simplified and well-controlled behavioral paradigms have been invaluable in our understanding of the critical role of LHb in motivation and emotional regulation as well as the involvement of LHb dysfunction in stress-induced psychopathology. However, we also argue that the use of ethologically-relevant behaviors with consideration of complex aspects of decision-making is warranted for future studies of LHb contributions in a wide range of psychiatric illnesses. We conclude this Perspective with some of the outstanding issues for the field to consider where a multi-systems approach is needed to investigate the complex nature of LHb circuitry interactions with environmental stimuli that predisposes psychiatric disorders.
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Affiliation(s)
- Phillip M. Baker
- Department of Psychology, Seattle Pacific University, Seattle, WA, United States
- *Correspondence: Phillip M. Baker,
| | - Victor Mathis
- CNRS UPR 3212, Institut des Neurosciences Cellulaires et Intégratives, Center National de la Recherche Scientifique, University of Strasbourg, Strasbourg, France
| | - Lucas Lecourtier
- CNRS, Laboratoire de Neurosciences Cognitives et Adaptatives (LNCA), UMR 7364, Université de Strasbourg, Strasbourg, France
- Lucas Lecourtier,
| | - Sarah C. Simmons
- Department of Pharmacology and Molecular Therapeutics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Fereshteh S. Nugent
- Department of Pharmacology and Molecular Therapeutics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Fereshteh S. Nugent,
| | - Sierra Hill
- Department of Psychology, Seattle Pacific University, Seattle, WA, United States
| | - Sheri J. Y. Mizumori
- Department of Psychology, University of Washington, Seattle, WA, United States
- Sheri J. Y. Mizumori,
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7
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Brochu MP, Aubin-Horth N. Shedding light on the circadian clock of the threespine stickleback. J Exp Biol 2021; 224:jeb242970. [PMID: 34854903 PMCID: PMC8729910 DOI: 10.1242/jeb.242970] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 11/24/2021] [Indexed: 11/20/2022]
Abstract
The circadian clock is an internal timekeeping system shared by most organisms, and knowledge about its functional importance and evolution in natural environments is still needed. Here, we investigated the circadian clock of wild-caught threespine sticklebacks (Gasterosteus aculeatus) at the behavioural and molecular levels. Although their behaviour, ecology and evolution are well studied, information on their circadian rhythms are scarce. We quantified the daily locomotor activity rhythm under a light:dark cycle (LD) and under constant darkness (DD). Under LD, all fish exhibited significant daily rhythmicity, while under DD, only 18% of individuals remained rhythmic. This interindividual variation suggests that the circadian clock controls activity only in certain individuals. Moreover, under LD, some fish were almost exclusively nocturnal, while others were active around the clock. Furthermore, the most nocturnal fish were also the least active. These results suggest that light masks activity (i.e. suppresses activity without entraining the internal clock) more strongly in some individuals than others. Finally, we quantified the expression of five clock genes in the brain of sticklebacks under DD using qPCR. We did not detect circadian rhythmicity, which could indicate either that the clock molecular oscillator is highly light-dependent, or that there was an oscillation but that we were unable to detect it. Overall, our study suggests that a strong circadian control on behavioural rhythms may not necessarily be advantageous in a natural population of sticklebacks and that the daily phase of activity varies greatly between individuals because of a differential masking effect of light.
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Affiliation(s)
| | - Nadia Aubin-Horth
- Département de Biologie and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC G1V 0A6, Canada
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8
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Scheidwasser N, Faggella M, Kozlova E, Sandi C. Commentary: The Risky Closed Economy: A Holistic, Longitudinal Approach to Studying Fear and Anxiety in Rodents. Front Behav Neurosci 2021; 15:664941. [PMID: 33841112 PMCID: PMC8026869 DOI: 10.3389/fnbeh.2021.664941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 03/03/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
| | | | | | - Carmen Sandi
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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9
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Schuessler BP, Zambetti PR, Fukuoka KM, Kim EJ, Kim JJ. The Risky Closed Economy: A Holistic, Longitudinal Approach to Studying Fear and Anxiety in Rodents. Front Behav Neurosci 2020; 14:594568. [PMID: 33192372 PMCID: PMC7645110 DOI: 10.3389/fnbeh.2020.594568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/26/2020] [Indexed: 01/04/2023] Open
Abstract
Basic research of fear and anxiety in rodents has historically utilized a limited set of behavioral paradigms, for example, Pavlovian (classical) fear conditioning, the elevated plus-maze, or inhibitory (passive) avoidance. These traditional paradigms measure a limited selection of variables over a short duration, providing only a "snapshot" of fear and anxiety-related behavior. Overreliance on these paradigms and such behavioral snapshots ultimately lead to a narrow understanding of these complex motivational states. Here, we elaborate on the closed economy; a seldom-used paradigm that has been modified to comprehensively study fear and anxiety-related behavior and neurocircuitry in rodents. In this modified "Risky Closed Economy (RCE)" paradigm, animals live nearly uninterrupted in behavioral chambers where the need to acquire food and water and avoid threat is integrated into the task. Briefly, animals are free to acquire all of their food and water in a designated foraging zone. An unsignaled, unpredictable threat (footshock) is introduced into the foraging zone after a baseline activity and consumption period to model the risk of predation, which is then removed for a final extinction assessment. This longitudinal design, wherein data from a multitude of variables are collected automatically and continuously for 23 h/day over several weeks to months, affords a more holistic understanding of the effects of fear and anxiety on day-to-day behavior. Also, we discuss its general benefits relevant to other topics in neuroscience research, its limitations, and present data demonstrating for the first time The Risky Closed Economy's viability in mice.
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Affiliation(s)
- Bryan P. Schuessler
- Department of Psychology, University of Washington, Seattle, WA, United States
| | - Peter R. Zambetti
- Department of Psychology, University of Washington, Seattle, WA, United States
| | - Kisho M. Fukuoka
- Department of Psychology, University of Washington, Seattle, WA, United States
| | - Eun Joo Kim
- Department of Psychology, University of Washington, Seattle, WA, United States
| | - Jeansok J. Kim
- Department of Psychology, University of Washington, Seattle, WA, United States
- Program in Neuroscience, University of Washington, Seattle, WA, United States
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10
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Rittenhouse JL, Robart AR, Watts HE. Variation in chronotype is associated with migratory timing in a songbird. Biol Lett 2019; 15:20190453. [PMID: 31455169 DOI: 10.1098/rsbl.2019.0453] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Like many organisms, birds exhibit daily (circadian) and seasonal biological rhythms, and within populations both daily and seasonal timing often vary among individuals. Because photoperiod interacts with the circadian rhythms of many organisms to induce seasonal changes in behaviour and physiology, it is hypothesized that differences in daily timing, called chronotypes, underpin differences among individuals in the timing of seasonal events. For seasonal events stimulated by increasing daylength, this hypothesis predicts a positive relationship between the timing of daily and seasonal activities of individuals, with advanced chronotypes expressing events earlier in the year. The few previous tests of this hypothesis have focused on seasonal reproductive timing in birds. However, the hypothesis predicts that this relationship should extend to other photoinduced seasonal events. Therefore, we tested whether variation in chronotype was associated with variation in spring migratory timing in a captive songbird model, the pine siskin (Spinus pinus). We found that pine siskins expressing migratory restlessness exhibited repeatable chronotypes in their timing of nocturnal activity. Further, chronotype was significantly associated with the onset date of migratory behaviour, consistent with the hypothesized relationship between chronotype and seasonal timing.
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Affiliation(s)
| | - Ashley R Robart
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Heather E Watts
- School of Biological Sciences, Washington State University, Pullman, WA, USA.,Center for Reproductive Biology, Washington State University, Pullman, WA, USA
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11
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Paul JR, Davis JA, Goode LK, Becker BK, Fusilier A, Meador-Woodruff A, Gamble KL. Circadian regulation of membrane physiology in neural oscillators throughout the brain. Eur J Neurosci 2019; 51:109-138. [PMID: 30633846 DOI: 10.1111/ejn.14343] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 12/19/2018] [Accepted: 12/21/2018] [Indexed: 12/21/2022]
Abstract
Twenty-four-hour rhythmicity in physiology and behavior are driven by changes in neurophysiological activity that vary across the light-dark and rest-activity cycle. Although this neural code is most prominent in neurons of the primary circadian pacemaker in the suprachiasmatic nucleus (SCN) of the hypothalamus, there are many other regions in the brain where region-specific function and behavioral rhythmicity may be encoded by changes in electrical properties of those neurons. In this review, we explore the existing evidence for molecular clocks and/or neurophysiological rhythms (i.e., 24 hr) in brain regions outside the SCN. In addition, we highlight the brain regions that are ripe for future investigation into the critical role of circadian rhythmicity for local oscillators. For example, the cerebellum expresses rhythmicity in over 2,000 gene transcripts, and yet we know very little about how circadian regulation drives 24-hr changes in the neural coding responsible for motor coordination. Finally, we conclude with a discussion of how our understanding of circadian regulation of electrical properties may yield insight into disease mechanisms which may lead to novel chronotherapeutic strategies in the future.
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Affiliation(s)
- Jodi R Paul
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jennifer A Davis
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Lacy K Goode
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Bryan K Becker
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Allison Fusilier
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Aidan Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Karen L Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
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12
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Hassell JE, Nguyen KT, Gates CA, Lowry CA. The Impact of Stressor Exposure and Glucocorticoids on Anxiety and Fear. Curr Top Behav Neurosci 2019; 43:271-321. [PMID: 30357573 DOI: 10.1007/7854_2018_63] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Anxiety disorders and trauma- and stressor-related disorders, such as posttraumatic stress disorder (PTSD), are common and are associated with significant economic and social burdens. Although trauma and stressor exposure are recognized as a risk factors for development of anxiety disorders and trauma or stressor exposure is recognized as essential for diagnosis of PTSD, the mechanisms through which trauma and stressor exposure lead to these disorders are not well characterized. An improved understanding of the mechanisms through which trauma or stressor exposure leads to development and persistence of anxiety disorders or PTSD may result in novel therapeutic approaches for the treatment of these disorders. Here, we review the current state-of-the-art theories, with respect to mechanisms through which stressor exposure leads to acute or chronic exaggeration of avoidance or anxiety-like defensive behavioral responses and fear, endophenotypes in both anxiety disorders and trauma- and stressor-related psychiatric disorders. In this chapter, we will explore physiological responses and neural circuits involved in the development of acute and chronic exaggeration of anxiety-like defensive behavioral responses and fear states, focusing on the role of the hypothalamic-pituitary-adrenal (HPA) axis and glucocorticoid hormones.
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Affiliation(s)
- J E Hassell
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - K T Nguyen
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA
| | - C A Gates
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA
| | - C A Lowry
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA.
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA.
- Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
- Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
- Veterans Health Administration, Rocky Mountain Mental Illness Research Education and Clinical Center, Denver Veterans Affairs Medical Center (VAMC), Denver, CO, USA.
- Military and Veteran Microbiome Consortium for Research and Education (MVM-CoRE), Denver, CO, USA.
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13
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Coordination between Prefrontal Cortex Clock Gene Expression and Corticosterone Contributes to Enhanced Conditioned Fear Extinction Recall. eNeuro 2018; 5:eN-NWR-0455-18. [PMID: 30627637 PMCID: PMC6325539 DOI: 10.1523/eneuro.0455-18.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 12/19/2022] Open
Abstract
Post-traumatic stress disorder (PTSD) is associated with impaired conditioned fear extinction learning, a ventromedial prefrontal cortex (vmPFC)-dependent process. PTSD is also associated with dysregulation of vmPFC, circadian, and glucocorticoid hormone function. Rats have rhythmic clock gene expression in the vmPFC that requires appropriate diurnal circulatory patterns of corticosterone (CORT), suggesting the presence of CORT-entrained intrinsic circadian clock function within the PFC. We examined the role of vmPFC clock gene expression and its interaction with CORT profiles in regulation of auditory conditioned fear extinction learning. Extinction learning and recall were examined in male rats trained and tested either in the night (active phase) or in the day (inactive phase). Using a viral vector strategy, Per1 and Per2 clock gene expression were selectively knocked down within the vmPFC. Circulating CORT profiles were manipulated via adrenalectomy (ADX) ± diurnal and acute CORT replacement. Rats trained and tested during the night exhibited superior conditioned fear extinction recall that was absent in rats that had knock-down of vmPFC clock gene expression. Similarly, the superior nighttime extinction recall was absent in ADX rats, but restored in ADX rats given a combination of a diurnal pattern of CORT and acute elevation of CORT during the postextinction training consolidation period. Thus, conditioned fear extinction learning is regulated in a diurnal fashion that requires normal vmPFC clock gene expression and a combination of circadian and training-associated CORT. Strategic manipulation of these factors may enhance the therapeutic outcome of conditioned fear extinction related treatments in the clinical setting.
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Abstract
Life threatening situations as urgent as defending against a predator precludes the use of slow trial and error strategies. Natural selection has led to the evolution of a behavioral system that has 3 critical elements. 1) When it is activated it limits the behaviors available to the organism to a set of prewired responses that have proven over phylogeny to be effective at defense. 2) A rapid learning system, called Pavlovian fear conditioning, that has the ability to immediately identify threats and promote prewired defensive behaviors. 3) That learning system has the ability to integrate several informational dimensions to determine threat imminence and this allows the organism to match the most effective defensive behavior to the current situation. The adaptive significance of conscious experiential states is also considered.
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Affiliation(s)
- Michael S Fanselow
- Staglin Center for Brain and Behavioral Health, Department of Psychology, Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA 90095 USA
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15
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van der Veen DR, Riede SJ, Heideman PD, Hau M, van der Vinne V, Hut RA. Flexible clock systems: adjusting the temporal programme. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0254. [PMID: 28993498 DOI: 10.1098/rstb.2016.0254] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/24/2017] [Indexed: 12/20/2022] Open
Abstract
Under natural conditions, many aspects of the abiotic and biotic environment vary with time of day, season or even era, while these conditions are typically kept constant in laboratory settings. The timing information contained within the environment serves as critical timing cues for the internal biological timing system, but how this system drives daily rhythms in behaviour and physiology may also depend on the internal state of the animal. The disparity between timing of these cues in natural and laboratory conditions can result in substantial differences in the scheduling of behaviour and physiology under these conditions. In nature, temporal coordination of biological processes is critical to maximize fitness because they optimize the balance between reproduction, foraging and predation risk. Here we focus on the role of peripheral circadian clocks, and the rhythms that they drive, in enabling adaptive phenotypes. We discuss how reproduction, endocrine activity and metabolism interact with peripheral clocks, and outline the complex phenotypes arising from changes in this system. We conclude that peripheral timing is critical to adaptive plasticity of circadian organization in the field, and that we must abandon standard laboratory conditions to understand the mechanisms that underlie this plasticity which maximizes fitness under natural conditions.This article is part of the themed issue 'Wild clocks: integrating chronobiology and ecology to understand timekeeping in free-living animals'.
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Affiliation(s)
- Daan R van der Veen
- School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Sjaak J Riede
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Paul D Heideman
- Department of Biology, College of William and Mary, Williamsburg, VA, USA
| | - Michaela Hau
- Max-Planck-Institute for Ornithology, Seewiesen, Germany and University of Konstanz, Konstanz, Germany
| | - Vincent van der Vinne
- Neurobiology Department, University of Massachusetts Medical School, Worcester, MA, USA
| | - Roelof A Hut
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
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16
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Kronfeld-Schor N, Visser ME, Salis L, van Gils JA. Chronobiology of interspecific interactions in a changing world. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0248. [PMID: 28993492 DOI: 10.1098/rstb.2016.0248] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2017] [Indexed: 01/10/2023] Open
Abstract
Animals should time activities, such as foraging, migration and reproduction, as well as seasonal physiological adaptation, in a way that maximizes fitness. The fitness outcome of such activities depends largely on their interspecific interactions; the temporal overlap with other species determines when they should be active in order to maximize their encounters with food and to minimize their encounters with predators, competitors and parasites. To cope with the constantly changing, but predictable structure of the environment, organisms have evolved internal biological clocks, which are synchronized mainly by light, the most predictable and reliable environmental cue (but which can be masked by other variables), which enable them to anticipate and prepare for predicted changes in the timing of the species they interact with, on top of responding to them directly. Here, we review examples where the internal timing system is used to predict interspecific interactions, and how these interactions affect the internal timing system and activity patterns. We then ask how plastic these mechanisms are, how this plasticity differs between and within species and how this variability in plasticity affects interspecific interactions in a changing world, in which light, the major synchronizer of the biological clock, is no longer a reliable cue owing to the rapidly changing climate, the use of artificial light and urbanization.This article is part of the themed issue 'Wild clocks: integrating chronobiology and ecology to understand timekeeping in free-living animals'.
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Affiliation(s)
| | - Marcel E Visser
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), PO 50, Wageningen 6700 AB, The Netherlands
| | - Lucia Salis
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), PO 50, Wageningen 6700 AB, The Netherlands
| | - Jan A van Gils
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University, PO Box 59, Den Burg 1790 AB, The Netherlands
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17
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Helm B, Visser ME, Schwartz W, Kronfeld-Schor N, Gerkema M, Piersma T, Bloch G. Two sides of a coin: ecological and chronobiological perspectives of timing in the wild. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160246. [PMID: 28993490 PMCID: PMC5647273 DOI: 10.1098/rstb.2016.0246] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2017] [Indexed: 12/19/2022] Open
Abstract
Most processes within organisms, and most interactions between organisms and their environment, have distinct time profiles. The temporal coordination of such processes is crucial across levels of biological organization, but disciplines differ widely in their approaches to study timing. Such differences are accentuated between ecologists, who are centrally concerned with a holistic view of an organism in relation to its external environment, and chronobiologists, who emphasize internal timekeeping within an organism and the mechanisms of its adjustment to the environment. We argue that ecological and chronobiological perspectives are complementary, and that studies at the intersection will enable both fields to jointly overcome obstacles that currently hinder progress. However, to achieve this integration, we first have to cross some conceptual barriers, clarifying prohibitively inaccessible terminologies. We critically assess main assumptions and concepts in either field, as well as their common interests. Both approaches intersect in their need to understand the extent and regulation of temporal plasticity, and in the concept of 'chronotype', i.e. the characteristic temporal properties of individuals which are the targets of natural and sexual selection. We then highlight promising developments, point out open questions, acknowledge difficulties and propose directions for further integration of ecological and chronobiological perspectives through Wild Clock research.This article is part of the themed issue 'Wild Clocks: integrating chronobiology and ecology to understand timekeeping in free-living animals'.
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Affiliation(s)
- Barbara Helm
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Graham Kerr Building, Glasgow G128QQ, UK
| | - Marcel E Visser
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), PO 50, 6700 AB Wageningen, The Netherlands
| | - William Schwartz
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA, USA
| | | | - Menno Gerkema
- Chronobiology, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands
| | - Theunis Piersma
- NIOZ Royal Netherlands Institute for Sea Research, Department of Coastal Systems and Utrecht University, 1790 AB Den Burg, Texel, The Netherlands
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands
| | - Guy Bloch
- Department of Ecology, Evolution, and Behavior, The A. Silberman Institute of Life Sciences, Hebrew University, Jerusalem 91904, Israel
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18
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Scheduled feeding restores memory and modulates c-Fos expression in the suprachiasmatic nucleus and septohippocampal complex. Sci Rep 2017; 7:6755. [PMID: 28754901 PMCID: PMC5533780 DOI: 10.1038/s41598-017-06963-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 06/22/2017] [Indexed: 11/09/2022] Open
Abstract
Disruptions in circadian timing impair spatial memory in humans and rodents. Circadian-arrhythmic Siberian hamsters (Phodopus sungorus) exhibit substantial deficits in spatial working memory as assessed by a spontaneous alternation (SA) task. The present study found that daily scheduled feeding rescued spatial memory deficits in these arrhythmic animals. Improvements in memory persisted for at least 3 weeks after the arrhythmic hamsters were switched back to ad libitum feeding. During ad libitum feeding, locomotor activity resumed its arrhythmic state, but performance on the SA task varied across the day with a peak in daily performance that corresponded to the previous daily window of food anticipation. At the end of scheduled feeding, c-Fos brain mapping revealed differential gene expression in entrained versus arrhythmic hamsters in the suprachiasmatic nucleus (SCN) that paralleled changes in the medial septum and hippocampus, but not in other neural structures. These data show that scheduled feeding can improve cognitive performance when SCN timing has been compromised, possibly by coordinating activity in the SCN and septohippocampal pathway.
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Circadian Rhythms in Fear Conditioning: An Overview of Behavioral, Brain System, and Molecular Interactions. Neural Plast 2017; 2017:3750307. [PMID: 28698810 PMCID: PMC5494081 DOI: 10.1155/2017/3750307] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/28/2017] [Accepted: 05/14/2017] [Indexed: 12/17/2022] Open
Abstract
The formation of fear memories is a powerful and highly evolutionary conserved mechanism that serves the behavioral adaptation to environmental threats. Accordingly, classical fear conditioning paradigms have been employed to investigate fundamental molecular processes of memory formation. Evidence suggests that a circadian regulation mechanism allows for a timestamping of such fear memories and controlling memory salience during both their acquisition and their modification after retrieval. These mechanisms include an expression of molecular clocks in neurons of the amygdala, hippocampus, and medial prefrontal cortex and their tight interaction with the intracellular signaling pathways that mediate neural plasticity and information storage. The cellular activities are coordinated across different brain regions and neural circuits through the release of glucocorticoids and neuromodulators such as acetylcholine, which integrate circadian and memory-related activation. Disturbance of this interplay by circadian phase shifts or traumatic experience appears to be an important factor in the development of stress-related psychopathology, considering these circadian components are of critical importance for optimizing therapeutic approaches to these disorders.
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Riede SJ, van der Vinne V, Hut RA. The flexible clock: predictive and reactive homeostasis, energy balance and the circadian regulation of sleep–wake timing. J Exp Biol 2017; 220:738-749. [DOI: 10.1242/jeb.130757] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
ABSTRACT
The Darwinian fitness of mammals living in a rhythmic environment depends on endogenous daily (circadian) rhythms in behavior and physiology. Here, we discuss the mechanisms underlying the circadian regulation of physiology and behavior in mammals. We also review recent efforts to understand circadian flexibility, such as how the phase of activity and rest is altered depending on the encountered environment. We explain why shifting activity to the day is an adaptive strategy to cope with energetic challenges and show how this can reduce thermoregulatory costs. A framework is provided to make predictions about the optimal timing of activity and rest of non-model species for a wide range of habitats. This Review illustrates how the timing of daily rhythms is reciprocally linked to energy homeostasis, and it highlights the importance of this link in understanding daily rhythms in physiology and behavior.
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Affiliation(s)
- Sjaak J. Riede
- Groningen Institute for Evolutionary Life Sciences, Chronobiology Unit, University of Groningen, Groningen 9747AG, The Netherlands
| | - Vincent van der Vinne
- Groningen Institute for Evolutionary Life Sciences, Chronobiology Unit, University of Groningen, Groningen 9747AG, The Netherlands
| | - Roelof A. Hut
- Groningen Institute for Evolutionary Life Sciences, Chronobiology Unit, University of Groningen, Groningen 9747AG, The Netherlands
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21
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Pellman BA, Schuessler BP, Tellakat M, Kim JJ. Sexually Dimorphic Risk Mitigation Strategies in Rats. eNeuro 2017; 4:ENEURO.0288-16.2017. [PMID: 28197550 PMCID: PMC5292597 DOI: 10.1523/eneuro.0288-16.2017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 01/18/2017] [Accepted: 01/20/2017] [Indexed: 01/02/2023] Open
Abstract
The scientific understanding of fear and anxiety-in both normal and pathological forms-is presently limited by a predominance of studies that use male animals and Pavlovian fear conditioning-centered paradigms that restrict and assess specific behaviors (e.g., freezing) over brief sampling periods and overlook the broader contributions of the spatiotemporal context to an animal's behavioral responses to threats. Here, we use a risky "closed economy" system, in which the need to acquire food and water and the need to avoid threats are simultaneously integrated into the lives of rats, to examine sex differences in mitigating threat risk while foraging. Rats lived for an extended period (∼2 months) in enlarged chambers that consisted of a safe, bedded nest and a risky foraging area where footshocks could be delivered unpredictably. We observed that male and female rats used different strategies for responding to the threat of footshock. Whereas male rats increased the size of meals consumed to reduce the overall time spent foraging, female rats sacrificed their metabolic needs in order to avoid shocks. Ovarian hormone fluctuations were shown to exert slight but reliable rhythmic effects on risky decision-making in gonadally intact female rats. However, this did not produce significant differences in approach-avoidance trade-offs between ovariectomized and intact female groups, suggesting that male-female sex differences are not due to the activational effects of gonadal hormones but, rather, are likely to be organized during early development.
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Affiliation(s)
- Blake A. Pellman
- Department of Psychology, University of Washington, Seattle, Washington 98195-1525
| | - Bryan P. Schuessler
- Department of Psychology, University of Washington, Seattle, Washington 98195-1525
| | - Mohini Tellakat
- Department of Psychology, University of Texas at Austin, Austin, Texas 78712
| | - Jeansok J. Kim
- Department of Psychology, University of Washington, Seattle, Washington 98195-1525
- Program in Neuroscience, University of Washington, Seattle, Washington 98195-1525
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22
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Olivo D, Caba M, Gonzalez-Lima F, Rodríguez-Landa JF, Corona-Morales AA. Metabolic activation of amygdala, lateral septum and accumbens circuits during food anticipatory behavior. Behav Brain Res 2016; 316:261-270. [PMID: 27618763 DOI: 10.1016/j.bbr.2016.09.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 08/25/2016] [Accepted: 09/06/2016] [Indexed: 10/21/2022]
Abstract
When food is restricted to a brief fixed period every day, animals show an increase in temperature, corticosterone concentration and locomotor activity for 2-3h before feeding time, termed food anticipatory activity. Mechanisms and neuroanatomical circuits responsible for food anticipatory activity remain unclear, and may involve both oscillators and networks related to temporal conditioning. Rabbit pups are nursed once-a-day so they represent a natural model of circadian food anticipatory activity. Food anticipatory behavior in pups may be associated with neural circuits that temporally anticipate feeding, while the nursing event may produce consummatory effects. Therefore, we used New Zealand white rabbit pups entrained to circadian feeding to investigate the hypothesis that structures related to reward expectation and conditioned emotional responses would show a metabolic rhythm anticipatory of the nursing event, different from that shown by structures related to reward delivery. Quantitative cytochrome oxidase histochemistry was used to measure regional brain metabolic activity at eight different times during the day. We found that neural metabolism peaked before nursing, during food anticipatory behavior, in nuclei of the extended amygdala (basolateral, medial and central nuclei, bed nucleus of the stria terminalis), lateral septum and accumbens core. After pups were fed, however, maximal metabolic activity was expressed in the accumbens shell, caudate, putamen and cortical amygdala. Neural and behavioral activation persisted when animals were fasted by two cycles, at the time of expected nursing. These findings suggest that metabolic activation of amygdala-septal-accumbens circuits involved in temporal conditioning may contribute to food anticipatory activity.
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Affiliation(s)
- Diana Olivo
- Programa de Doctorado en Ciencias Biomédicas, Universidad Veracruzana, Xalapa, Veracruz 91190, Mexico.
| | - Mario Caba
- Centro de Investigaciones Biomédicas, Universidad Veracruzana, Xalapa, Veracruz 91190, Mexico.
| | - Francisco Gonzalez-Lima
- Department of Psychology and Institute for Neuroscience, The University of Texas at Austin, Austin, TX 78712, USA.
| | - Juan F Rodríguez-Landa
- Laboratorio de Neurofarmacología, Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz 91190, Mexico.
| | - Aleph A Corona-Morales
- Laboratorio de Investigación Genómica y Fisiológica, Facultad de Nutrición, Médicos y odontólogos s/n, Col. Unidad del Bosque, 91010, Universidad Veracruzana, Xalapa, Veracruz, Mexico.
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23
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Pellman BA, Kim JJ. What Can Ethobehavioral Studies Tell Us about the Brain's Fear System? Trends Neurosci 2016; 39:420-431. [PMID: 27130660 PMCID: PMC4884474 DOI: 10.1016/j.tins.2016.04.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 04/01/2016] [Accepted: 04/04/2016] [Indexed: 11/19/2022]
Abstract
Foraging-associated predation risk is a natural problem all prey must face. Fear evolved due to its protective functions, guiding and shaping behaviors that help animals adapt to various ecological challenges. Despite the breadth of risky situations in nature that demand diversity in fear behaviors, contemporary neurobiological models of fear stem largely from Pavlovian fear conditioning studies that focus on how a particular cue becomes capable of eliciting learned fear responses, thus oversimplifying the brain's fear system. Here we review fear from functional, mechanistic, and phylogenetic perspectives where environmental threats cause animals to alter their foraging strategies in terms of spatial and temporal navigation, and discuss whether the inferences we draw from fear conditioning studies operate in the natural world.
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Affiliation(s)
- Blake A Pellman
- Department of Psychology, University of Washington, Seattle, WA 98195-1525, USA
| | - Jeansok J Kim
- Department of Psychology, University of Washington, Seattle, WA 98195-1525, USA; Program in Neuroscience, University of Washington, Seattle, WA 98195-1525, USA.
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