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Meyer HC, Fields A, Vannucci A, Gerhard DM, Bloom PA, Heleniak C, Opendak M, Sullivan R, Tottenham N, Callaghan BL, Lee FS. The Added Value of Crosstalk Between Developmental Circuit Neuroscience and Clinical Practice to Inform the Treatment of Adolescent Anxiety. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2023; 3:169-178. [PMID: 37124361 PMCID: PMC10140450 DOI: 10.1016/j.bpsgos.2022.02.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 02/01/2022] [Accepted: 02/07/2022] [Indexed: 01/04/2023] Open
Abstract
Significant advances have been made in recent years regarding the developmental trajectories of brain circuits and networks, revealing links between brain structure and function. Emerging evidence highlights the importance of developmental trajectories in determining early psychiatric outcomes. However, efforts to encourage crosstalk between basic developmental neuroscience and clinical practice are limited. Here, we focus on the potential advantage of considering features of neural circuit development when optimizing treatments for adolescent patient populations. Drawing on characteristics of adolescent neurodevelopment, we highlight two examples, safety cues and incentives, that leverage insights from neural circuit development and may have great promise for augmenting existing behavioral treatments for anxiety disorders during adolescence. This commentary seeks to serve as a framework to maximize the translational potential of basic research in developmental populations for strengthening psychiatric treatments. In turn, input from clinical practice including the identification of age-specific clinically relevant phenotypes will continue to guide future basic research in the same neural circuits to better reflect clinical practices. Encouraging reciprocal communication to bridge the gap between basic developmental neuroscience research and clinical implementation is an important step toward advancing both research and practice in this domain.
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Affiliation(s)
- Heidi C. Meyer
- Department of Psychiatry, Joan & Sanford I. Weill Medical College of Cornell University, New York, New York
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts
| | - Andrea Fields
- Department of Psychology, Columbia University, New York, New York
| | - Anna Vannucci
- Department of Psychology, Columbia University, New York, New York
| | - Danielle M. Gerhard
- Department of Psychiatry, Joan & Sanford I. Weill Medical College of Cornell University, New York, New York
| | - Paul A. Bloom
- Department of Psychology, Columbia University, New York, New York
| | | | - Maya Opendak
- Department of Child and Adolescent Psychiatry, NYU Grossman School of Medicine, New York, New York
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, Orangeburg, New York
- Department of Neuroscience, Kennedy Krieger Institute and Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Regina Sullivan
- Emotional Brain Institute, Nathan Kline Institute for Psychiatric Research, Orangeburg, New York
| | - Nim Tottenham
- Department of Psychology, Columbia University, New York, New York
| | - Bridget L. Callaghan
- Department of Psychology, University of California, Los Angeles, Los Angeles, California
| | - Francis S. Lee
- Department of Psychiatry, Joan & Sanford I. Weill Medical College of Cornell University, New York, New York
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2
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Mohr MA, Michael NS, DonCarlos LL, Sisk CL. Sex differences in proliferation and attrition of pubertally born cells in the rat posterior dorsal medial amygdala. Dev Cogn Neurosci 2022; 57:101141. [PMID: 35933923 PMCID: PMC9357828 DOI: 10.1016/j.dcn.2022.101141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 07/08/2022] [Accepted: 07/21/2022] [Indexed: 11/26/2022] Open
Abstract
The rodent posterodorsal medial amygdala (MePD) evaluates and assigns valence to social sensory stimuli. The perception of social stimuli evolves during puberty, when the focus of social interactions shifts from kin to peers. Using the cell birthdate marker bromo-deoxyuridine (BrdU), we previously discovered that more pubertally born cells are added to the rat MePD in males than females. Here we addressed several questions that remained unanswered by our previous work. First, to determine whether there are sex differences in cell proliferation within the MePD, we examined BrdU-immunoreactive (-ir) cells at 2 and 4 h following BrdU administration on postnatal day 30 (P30). The density of BrdU-ir cells was greater in males than in females, indicating greater proliferation in males. Proliferation was substantiated by double-label immunohistochemistry showing that MePD BrdU-ir cells colocalize proliferating cell nuclear antigen, but not the cell death marker Caspase3. We next studied longer time points (2-21 days) following BrdU administration on P30 and found that the rate of cell attrition is higher in males. Finally, triple-label immunohistochemistry of P30-born MePD cells revealed that some of these cells differentiate into neurons or astrocytes within three weeks of cell birth, with no discernable sex differences. The demonstration of pubertal neuro- and glio-genesis in the MePD of male and female rats adds a new dimension to developmental plasticity of the MePD that may contribute to pubertal changes in the perception of social stimuli in both sexes.
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Affiliation(s)
- Margaret A Mohr
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
| | | | - Lydia L DonCarlos
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
| | - Cheryl L Sisk
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA.
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Hanson JL, Nacewicz BM. Amygdala Allostasis and Early Life Adversity: Considering Excitotoxicity and Inescapability in the Sequelae of Stress. Front Hum Neurosci 2021; 15:624705. [PMID: 34140882 PMCID: PMC8203824 DOI: 10.3389/fnhum.2021.624705] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 04/23/2021] [Indexed: 12/19/2022] Open
Abstract
Early life adversity (ELA), such as child maltreatment or child poverty, engenders problems with emotional and behavioral regulation. In the quest to understand the neurobiological sequelae and mechanisms of risk, the amygdala has been of major focus. While the basic functions of this region make it a strong candidate for understanding the multiple mental health issues common after ELA, extant literature is marked by profound inconsistencies, with reports of larger, smaller, and no differences in regional volumes of this area. We believe integrative models of stress neurodevelopment, grounded in "allostatic load," will help resolve inconsistencies in the impact of ELA on the amygdala. In this review, we attempt to connect past research studies to new findings with animal models of cellular and neurotransmitter mediators of stress buffering to extreme fear generalization onto testable research and clinical concepts. Drawing on the greater impact of inescapability over unpredictability in animal models, we propose a mechanism by which ELA aggravates an exhaustive cycle of amygdala expansion and subsequent toxic-metabolic damage. We connect this neurobiological sequela to psychosocial mal/adaptation after ELA, bridging to behavioral studies of attachment, emotion processing, and social functioning. Lastly, we conclude this review by proposing a multitude of future directions in preclinical work and studies of humans that suffered ELA.
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Affiliation(s)
- Jamie L. Hanson
- Department of Psychology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Brendon M. Nacewicz
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, United States
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4
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Jurkowski MP, Bettio L, K. Woo E, Patten A, Yau SY, Gil-Mohapel J. Beyond the Hippocampus and the SVZ: Adult Neurogenesis Throughout the Brain. Front Cell Neurosci 2020; 14:576444. [PMID: 33132848 PMCID: PMC7550688 DOI: 10.3389/fncel.2020.576444] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/19/2020] [Indexed: 12/31/2022] Open
Abstract
Convincing evidence has repeatedly shown that new neurons are produced in the mammalian brain into adulthood. Adult neurogenesis has been best described in the hippocampus and the subventricular zone (SVZ), in which a series of distinct stages of neuronal development has been well characterized. However, more recently, new neurons have also been found in other brain regions of the adult mammalian brain, including the hypothalamus, striatum, substantia nigra, cortex, and amygdala. While some studies have suggested that these new neurons originate from endogenous stem cell pools located within these brain regions, others have shown the migration of neurons from the SVZ to these regions. Notably, it has been shown that the generation of new neurons in these brain regions is impacted by neurologic processes such as stroke/ischemia and neurodegenerative disorders. Furthermore, numerous factors such as neurotrophic support, pharmacologic interventions, environmental exposures, and stem cell therapy can modulate this endogenous process. While the presence and significance of adult neurogenesis in the human brain (and particularly outside of the classical neurogenic regions) is still an area of debate, this intrinsic neurogenic potential and its possible regulation through therapeutic measures present an exciting alternative for the treatment of several neurologic conditions. This review summarizes evidence in support of the classic and novel neurogenic zones present within the mammalian brain and discusses the functional significance of these new neurons as well as the factors that regulate their production. Finally, it also discusses the potential clinical applications of promoting neurogenesis outside of the classical neurogenic niches, particularly in the hypothalamus, cortex, striatum, substantia nigra, and amygdala.
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Affiliation(s)
- Michal P. Jurkowski
- Island Medical Program, University of British Columbia, Vancouver, BC, Canada
| | - Luis Bettio
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Emma K. Woo
- Island Medical Program, University of British Columbia, Vancouver, BC, Canada
| | - Anna Patten
- Centre for Interprofessional Clinical Simulation Learning (CICSL), Royal Jubilee Hospital, Victoria, BC, Canada
| | - Suk-Yu Yau
- Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Joana Gil-Mohapel
- Island Medical Program, University of British Columbia, Vancouver, BC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
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Gee DG, Bath KG, Johnson CM, Meyer HC, Murty VP, van den Bos W, Hartley CA. Neurocognitive Development of Motivated Behavior: Dynamic Changes across Childhood and Adolescence. J Neurosci 2018; 38:9433-9445. [PMID: 30381435 PMCID: PMC6209847 DOI: 10.1523/jneurosci.1674-18.2018] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 09/23/2018] [Accepted: 09/24/2018] [Indexed: 12/12/2022] Open
Abstract
The ability to anticipate and respond appropriately to the challenges and opportunities present in our environments is critical for adaptive behavior. Recent methodological innovations have led to substantial advances in our understanding of the neurocircuitry supporting such motivated behavior in adulthood. However, the neural circuits and cognitive processes that enable threat- and reward-motivated behavior undergo substantive changes over the course of development, and these changes are less well understood. In this article, we highlight recent research in human and animal models demonstrating how developmental changes in prefrontal-subcortical neural circuits give rise to corresponding changes in the processing of threats and rewards from infancy to adulthood. We discuss how these developmental trajectories are altered by experiential factors, such as early-life stress, and highlight the relevance of this research for understanding the developmental onset and treatment of psychiatric disorders characterized by dysregulation of motivated behavior.
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Affiliation(s)
- Dylan G Gee
- Department of Psychology, Yale University, New Haven, CT 06520,
| | - Kevin G Bath
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912
| | - Carolyn M Johnson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Heidi C Meyer
- Department of Psychiatry, Weill Cornell Medicine, New York, NY 10065
| | - Vishnu P Murty
- Department of Psychology, Temple University, Philadelphia, PA 19122
| | - Wouter van den Bos
- Department of Developmental Psychology, University of Amsterdam, Amsterdam, Netherlands, and
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6
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Lo Iacono L, Carola V. The impact of adolescent stress experiences on neurobiological development. Semin Cell Dev Biol 2018; 77:93-103. [DOI: 10.1016/j.semcdb.2017.09.040] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/18/2017] [Accepted: 09/29/2017] [Indexed: 01/23/2023]
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Limacher-Burrell A, Bhagwandin A, Maseko BC, Manger PR. Nuclear organization of the African elephant (Loxodonta africana) amygdaloid complex: an unusual mammalian amygdala. Brain Struct Funct 2017; 223:1191-1216. [PMID: 29098403 DOI: 10.1007/s00429-017-1555-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/24/2017] [Indexed: 11/25/2022]
Abstract
Here we describe the nuclear organization of the African elephant amygdaloid complex using Nissl, myelin, and a range of immunohistochemical stains. The African elephant is thought to exhibit many affect-laden and social-empathic behaviours; however, to date the amygdaloid complex, which is the generator of emotional states of the brain is yet to be fully explored in the elephants. For the most part, the amygdaloid complex of the African elephant is similar to that observed in other mammals in terms of the presence of nuclei and their topological relationships; however, we did observe several specific differences in amygdaloid organization. The elephant amygdala has undergone rotation in both the coronal and sagittal planes, seemingly associated with the expansion of the temporal lobe. Numerous scalloped cell clusters, termed glomeruli, forming the intermediate nuclei of the basal, accessory basal and central nuclear groups, were occupied by structures immunopositive to doublecortin. The nuclei typically associated with the accessory olfactory system (posterior cortical nucleus and medial nuclear complex) were absent from the elephant amygdala. The anterior cortical nucleus is very large and appears to be comprised of two subdivisions. The lateral nuclear complex is expanded and has two novel subdivisions. The amygdalohippocampal area appears relatively enlarged. The numerous shared and derived characters make the elephant amygdaloid complex very unusual and unique amongst mammals, but the derived characters appear to relate to observed elephant affect-laden behaviours.
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Affiliation(s)
- Aude'Marie Limacher-Burrell
- School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193, South Africa
| | - Adhil Bhagwandin
- School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193, South Africa
| | - Busisiwe C Maseko
- School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193, South Africa
| | - Paul R Manger
- School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193, South Africa.
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8
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Mohr MA, DonCarlos LL, Sisk CL. Inhibiting Production of New Brain Cells during Puberty or Adulthood Blunts the Hormonally Induced Surge of Luteinizing Hormone in Female Rats. eNeuro 2017; 4:ENEURO.0133-17.2017. [PMID: 29098175 PMCID: PMC5666323 DOI: 10.1523/eneuro.0133-17.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 10/09/2017] [Accepted: 10/16/2017] [Indexed: 01/15/2023] Open
Abstract
New cells are added during both puberty and adulthood to hypothalamic regions that govern reproduction, homeostasis, and social behaviors, yet the functions of these late-born cells remain elusive. Here, we pharmacologically inhibited cell proliferation in ventricular zones during puberty or in adulthood and determined subsequent effects on the hormone-induced surge of luteinizing hormone (LH) in female rats. Initial neuroanatomical analyses focused on verifying incorporation, activation, and pharmacological inhibition of pubertally or adult born cells in the anteroventral periventricular nucleus (AVPV) of the hypothalamus because of the essential role of the AVPV in triggering the preovulatory LH surge in females. We first showed that approximately half of the pubertally born AVPV cells are activated by estradiol plus progesterone (P) treatment, as demonstrated by Fos expression, and that approximately 10% of pubertally born AVPV cells express estrogen receptor alpha (ERα). Next, we found that mitotic inhibition through intracerebroventricular (ICV) administration of cytosine β-D-arabinofuranoside (AraC), whether during puberty or in adulthood, decreased the number of new cells added to the AVPV and the suprachiasmatic nucleus (SCN), and also blunted and delayed the hormone-induced LH surge. These studies do not prove, but are highly suggestive, that ongoing postnatal addition of new cells in periventricular brain regions, including the AVPV and SCN, may be important to the integrity of female reproduction.
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Affiliation(s)
- Margaret A. Mohr
- Neuroscience Program, Michigan State University, East Lansing, MI 48824
| | - Lydia L. DonCarlos
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153
| | - Cheryl L. Sisk
- Neuroscience Program, Michigan State University, East Lansing, MI 48824
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9
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Boulanger JJ, Messier C. Doublecortin in Oligodendrocyte Precursor Cells in the Adult Mouse Brain. Front Neurosci 2017; 11:143. [PMID: 28400715 PMCID: PMC5368229 DOI: 10.3389/fnins.2017.00143] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 03/07/2017] [Indexed: 12/21/2022] Open
Abstract
Key PointsOligodendrocyte precursor cells express doublecortin, a microtubule-associated protein. Oligodendrocyte precursor cells express doublecortin, but at a lower level of expression than in neuronal precursor. Doublecortin is not associated with a potential immature neuronal phenotype in Oligodendrocyte precursor cells.
Oligodendrocyte precursor cells (OPC) are glial cells that differentiate into myelinating oligodendrocytes during embryogenesis and early stages of post-natal life. OPCs continue to divide throughout adulthood and some eventually differentiate into oligodendrocytes in response to demyelinating lesions. There is growing evidence that OPCs are also involved in activity-driven de novo myelination of previously unmyelinated axons and myelin remodeling in adulthood. Considering these roles in the adult brain, OPCs are likely mobile cells that can migrate on some distances before they differentiate into myelinating oligodendrocytes. A number of studies have noted that OPCs express doublecortin (DCX), a microtubule-associated protein expressed in neural precursor cells and in migrating immature neurons. Here we describe the distribution of DCX in OPCs. We found that almost all OPCs express DCX, but the level of expression appears to be much lower than what is found in neural precursor. We found that DCX is downregulated when OPCs start expressing mature oligodendrocyte markers and is absent in myelinating oligodendrocytes. DCX does not appear to signal an immature neuronal phenotype in OPCs in the adult mouse brain. Rather, it could be involved either in cell migration, or as a marker of an immature oligodendroglial cell phenotype.
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Affiliation(s)
| | - Claude Messier
- School of Psychology, University of Ottawa Ottawa, ON, Canada
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10
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Age-dependent regulation of GABA transmission by kappa opioid receptors in the basolateral amygdala of Sprague-Dawley rats. Neuropharmacology 2017; 117:124-133. [PMID: 28163104 DOI: 10.1016/j.neuropharm.2017.01.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 01/26/2017] [Accepted: 01/29/2017] [Indexed: 12/17/2022]
Abstract
Anxiety disorders are one of the most common and debilitating mental illnesses worldwide. Growing evidence indicates an age-dependent rise in the incidence of anxiety disorders from adolescence through adulthood, suggestive of underlying neurodevelopmental mechanisms. Kappa opioid receptors (KORs) are known to contribute to the development and expression of anxiety; however, the functional role of KORs in the basolateral amygdala (BLA), a brain structure critical in mediating anxiety, particularly across ontogeny, are unknown. Using whole-cell patch-clamp electrophysiology in acute brain slices from adolescent (postnatal day (P) 30-45) and adult (P60+) male Sprague-Dawley rats, we found that the KOR agonist, U69593, increased the frequency of GABAA-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) in the adolescent BLA, without an effect in the adult BLA or on sIPSC amplitude at either age. The KOR effect was blocked by the KOR antagonist, nor-BNI, which alone did not alter GABA transmission at either age, and the effect of the KOR agonist was TTX-sensitive. Additionally, KOR activation did not alter glutamatergic transmission in the BLA at either age. In contrast, U69593 inhibited sIPSC frequency in the central amygdala (CeA) at both ages, without altering sIPSC amplitude. Western blot analysis of KOR expression indicated that KOR levels were not different between the two ages in either the BLA or CeA. This is the first study to provide compelling evidence for a novel and unique neuromodulatory switch in one of the primary brain regions involved in initiating and mediating anxiety that may contribute to the ontogenic rise in anxiety disorders.
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Hunt PS, Burk JA, Barnet RC. Adolescent transitions in reflexive and non-reflexive behavior: Review of fear conditioning and impulse control in rodent models. Neurosci Biobehav Rev 2016; 70:33-45. [PMID: 27339692 PMCID: PMC5074887 DOI: 10.1016/j.neubiorev.2016.06.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 06/03/2016] [Accepted: 06/18/2016] [Indexed: 01/11/2023]
Abstract
Adolescence is a time of critical brain changes that pave the way for adult learning processes. However, the extent to which learning in adolescence is best characterized as a transitional linear progression from childhood to adulthood, or represents a period that differs from earlier and later developmental stages, remains unclear. Here we examine behavioral literature on associative fear conditioning and complex choice behavior with rodent models. Many aspects of fear conditioning are intact by adolescence and do not differ from adult patterns. Sufficient evidence, however, suggests that adolescent learning cannot be characterized simply as an immature precursor to adulthood. Across different paradigms assessing choice behavior, literature suggests that adolescent animals typically display more impulsive patterns of responding compared to adults. The extent to which the development of basic conditioning processes serves as a scaffold for later adult decision making is an additional research area that is important for theory, but also has widespread applications for numerous psychological conditions.
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12
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Baker KD, Bisby MA, Richardson R. Impaired fear extinction in adolescent rodents: Behavioural and neural analyses. Neurosci Biobehav Rev 2016; 70:59-73. [PMID: 27235077 DOI: 10.1016/j.neubiorev.2016.05.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/06/2016] [Accepted: 05/21/2016] [Indexed: 01/01/2023]
Abstract
Despite adolescence being a developmental window of vulnerability, up until very recently there were surprisingly few studies on fear extinction during this period. Here we summarise the recent work in this area, focusing on the unique behavioural and neural characteristics of fear extinction in adolescent rodents, and humans where relevant. A prominent hypothesis posits that anxiety disorders peak during late childhood/adolescence due to the non-linear maturation of the fear inhibition neural circuitry. We discuss evidence that impaired extinction retention in adolescence is due to subregions of the medial prefrontal cortex and amygdala mediating fear inhibition being underactive while other subregions that mediate fear expression are overactive. We also review work on various interventions and surprising circumstances which enhance fear extinction in adolescence. This latter work revealed that the neural correlates of extinction in adolescence are different to that in younger and older animals even when extinction retention is not impaired. This growing body of work highlights that adolescence is a unique period of development for fear inhibition.
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Affiliation(s)
- Kathryn D Baker
- School of Psychology, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Madelyne A Bisby
- School of Psychology, UNSW Australia, Sydney, NSW 2052, Australia
| | - Rick Richardson
- School of Psychology, UNSW Australia, Sydney, NSW 2052, Australia
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13
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Holmes MM. Social regulation of adult neurogenesis: A comparative approach. Front Neuroendocrinol 2016; 41:59-70. [PMID: 26877107 DOI: 10.1016/j.yfrne.2016.02.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 02/07/2016] [Accepted: 02/09/2016] [Indexed: 01/25/2023]
Abstract
The social environment sculpts the mammalian brain throughout life. Adult neurogenesis, the birth of new neurons in the mature brain, can be up- or down-regulated by various social manipulations. These include social isolation, social conflict, social status, socio-sexual interactions, and parent/offspring interactions. However, socially-mediated changes in neuron production are often species-, sex-, and/or region-specific. In order to reconcile the variability of social effects on neurogenesis, we need to consider species-specific social adaptations and other contextual variables (e.g. age, social status, reproductive status, etc.) that shift the valence of social stimuli. Using a comparative approach to understand how adult-generated neurons in turn influence social behaviors will shed light on how adult neurogenesis contributes to survival and reproduction in diverse species.
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Affiliation(s)
- Melissa M Holmes
- Department of Psychology, University of Toronto, Canada; Department of Cell & Systems Biology, University of Toronto, Canada; Department of Ecology & Evolutionary Biology, University of Toronto, Canada.
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Proliferating cells in the adolescent rat amygdala: Characterization and response to stress. Neuroscience 2015; 311:105-17. [PMID: 26476262 DOI: 10.1016/j.neuroscience.2015.10.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/24/2015] [Accepted: 10/02/2015] [Indexed: 12/27/2022]
Abstract
The amygdala is a heterogeneous group of nuclei that plays a role in emotional and social learning. As such, there has been increased interest in its development in adolescent animals, a period in which emotional/social learning increases dramatically. While many mechanisms of amygdala development have been studied, the role of cell proliferation during adolescence has received less attention. Using bromodeoxyuridine (BrdU) injections in adolescent and adult rats, we previously found an almost fivefold increase in BrdU-positive cells in the amygdala of adolescents compared to adults. Approximately one third of BrdU-labeled cells in the amygdala contained the putative neural marker doublecortin (DCX), suggesting a potential for neurogenesis. To further investigate this possibility in adolescents, we examined the proliferative dynamics of DCX/BrdU-labeled cells. Surprisingly, DCX/BrdU-positive cells were found to comprise a stable subpopulation of BrdU-containing cells across survivals up to 56 days, and there was no evidence of neural maturation by 28 days after BrdU injection. Additionally, we found that approximately 50% of BrdU+ cells within the adolescent amygdala contain neural-glial antigen (NG2) and are therefore presumptive oligodendrocyte precursors (OPCs). We next characterized the response to a short-lived stressor (3-day repeated variable stress, RVS). The total BrdU-labeled cell number decreased by ∼30% by 13 days following RVS (10 days post-BrdU injection) as assessed by stereologic counting methods, but the DCX/BrdU-labeled subpopulation was relatively resistant to RVS effects. In contrast, NG2/BrdU-labeled cells were strongly influenced by RVS. We conclude that typical neurogenesis is not a feature of the adolescent amygdala. These findings point to several possibilities, including the possibility that DCX/BrdU cells are late-developing neural precursors, or a unique subtype of NG2 cell that is relatively resistant to stress. In contrast, many proliferating OPCs are significantly impacted by a short-lived stressor, suggesting consequences for myelination in the developing amygdala.
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15
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Asok A, Bernard K, Rosen JB, Dozier M, Roth TL. Infant-caregiver experiences alter telomere length in the brain. PLoS One 2014; 9:e101437. [PMID: 24983884 PMCID: PMC4077840 DOI: 10.1371/journal.pone.0101437] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 06/06/2014] [Indexed: 11/18/2022] Open
Abstract
Following adverse childhood experiences, high quality maternal care can protect against accelerated telomere shortening in peripheral cells. It is less clear, however, how telomere length in the brain is influenced by early caregiving experiences. Using rats, we investigated if quality of care (i.e., aversive or nurturing care outside of the homecage) during the first seven days of postnatal (PN) life affected telomere length in the adult brain (PN90) of male and female rats. At PN90, we found that nurturing care outside of the homecage was associated with longer telomeres in the medial prefrontal cortex relative to nurturing care inside the homecage (i.e., normal maternal care) and aversive care outside of the homecage. Further, pups exposed to aversive care outside of the homecage demonstrated longer telomeres in the amygdala relative to pups exposed to nurturing care inside the homecage. These effects were specific to females. No differences in telomere length between caregiving conditions were observed in the ventral hippocampus. Thus, positive and negative early-life experiences result in long-term, sex-specific changes of telomeres in the brain.
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Affiliation(s)
- Arun Asok
- University of Delaware, Department of Psychological and Brain Sciences, Newark, DE, United States of America
| | - Kristin Bernard
- Stony Brook University, Department of Psychology, Stony Brook, NY, United States of America
| | - Jeffrey B. Rosen
- University of Delaware, Department of Psychological and Brain Sciences, Newark, DE, United States of America
| | - Mary Dozier
- University of Delaware, Department of Psychological and Brain Sciences, Newark, DE, United States of America
| | - Tania L. Roth
- University of Delaware, Department of Psychological and Brain Sciences, Newark, DE, United States of America
- * E-mail:
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Yetnikoff L, Reichard RA, Schwartz ZM, Parsely KP, Zahm DS. Protracted maturation of forebrain afferent connections of the ventral tegmental area in the rat. J Comp Neurol 2014; 522:1031-47. [PMID: 23983069 PMCID: PMC4217282 DOI: 10.1002/cne.23459] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/30/2013] [Accepted: 08/14/2013] [Indexed: 01/21/2023]
Abstract
The mesocorticolimbic dopamine system has long attracted the interest of researchers concerned with the unique gamut of behavioral and mental health vulnerabilities associated with adolescence. Accordingly, the development of the mesocorticolimbic system has been studied extensively, but almost exclusively with regard to dopaminergic output, particularly in the nucleus accumbens and medial prefrontal cortex. To the contrary, the ontogeny of inputs to the ventral tegmental area (VTA), the source of mesocorticolimbic dopamine, has been neglected. This is not a trivial oversight, as the activity of VTA neurons, which reflects their capacity to transmit information about salient events, is sensitively modulated by inputs. Here, we assessed the development of VTA afferent connections using the β subunit of cholera toxin (Ctβ) as a retrograde axonal tracer in adolescent (postnatal day 39) and early adult (8-9-week-old) rats. After intra-VTA injections of Ctβ, adolescent and early adult animals exhibited qualitatively similar distributions of retrogradely labeled neurons in the sense that VTA-projecting neurons were present at all of the same rostrocaudal levels in all of the same structures in both age groups. However, quantitation of retrogradely labeled neurons revealed that adolescent brains, compared with early adult brains, had significantly fewer VTA-projecting neurons preferentially within an interconnected network of cortical and striatopallidal forebrain structures. These findings provide a novel perspective on the development of the mesocorticolimbic dopamine system and may have important implications for age-dependent specificity in the function of this system, particularly with regard to adolescent impulsivity and mental health vulnerabilities.
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Affiliation(s)
- Leora Yetnikoff
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Rhett A. Reichard
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Zachary M. Schwartz
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Kenneth P. Parsely
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Daniel S. Zahm
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63104
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