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Hegedüs P, Király B, Schlingloff D, Lyakhova V, Velencei A, Szabó Í, Mayer MI, Zelenak Z, Nyiri G, Hangya B. Parvalbumin-expressing basal forebrain neurons mediate learning from negative experience. Nat Commun 2024; 15:4768. [PMID: 38849336 PMCID: PMC11161511 DOI: 10.1038/s41467-024-48755-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 05/11/2024] [Indexed: 06/09/2024] Open
Abstract
Parvalbumin (PV)-expressing GABAergic neurons of the basal forebrain (BFPVNs) were proposed to serve as a rapid and transient arousal system, yet their exact role in awake behaviors remains unclear. We performed bulk calcium measurements and electrophysiology with optogenetic tagging from the horizontal limb of the diagonal band of Broca (HDB) while male mice were performing an associative learning task. BFPVNs responded with a distinctive, phasic activation to punishment, but showed slower and delayed responses to reward and outcome-predicting stimuli. Optogenetic inhibition during punishment impaired the formation of cue-outcome associations, suggesting a causal role of BFPVNs in associative learning. BFPVNs received strong inputs from the hypothalamus, the septal complex and the median raphe region, while they synapsed on diverse cell types in key limbic structures, where they broadcasted information about aversive stimuli. We propose that the arousing effect of BFPVNs is recruited by aversive stimuli to serve crucial associative learning functions.
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Affiliation(s)
- Panna Hegedüs
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, H-1085, Budapest, Hungary
| | - Bálint Király
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
| | - Dániel Schlingloff
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
| | - Victoria Lyakhova
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
- János Szentágothai Doctoral School of Neurosciences, Semmelweis University, H-1085, Budapest, Hungary
| | - Anna Velencei
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
| | - Írisz Szabó
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
| | - Márton I Mayer
- Laboratory of Cerebral Cortex Research, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
| | - Zsofia Zelenak
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
| | - Gábor Nyiri
- Laboratory of Cerebral Cortex Research, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary
| | - Balázs Hangya
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, H-1083, Budapest, Hungary.
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McDonald AJ. Functional neuroanatomy of basal forebrain projections to the basolateral amygdala: Transmitters, receptors, and neuronal subpopulations. J Neurosci Res 2024; 102:e25318. [PMID: 38491847 PMCID: PMC10948038 DOI: 10.1002/jnr.25318] [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: 09/26/2023] [Revised: 01/20/2024] [Accepted: 02/23/2024] [Indexed: 03/18/2024]
Abstract
The projections of the basal forebrain (BF) to the hippocampus and neocortex have been extensively studied and shown to be important for higher cognitive functions, including attention, learning, and memory. Much less is known about the BF projections to the basolateral nuclear complex of the amygdala (BNC), although the cholinergic innervation of this region by the BF is actually far more robust than that of cortical areas. This review will focus on light and electron microscopic tract-tracing and immunohistochemical (IHC) studies, many of which were published in the last decade, that have analyzed the relationship of BF inputs and their receptors to specific neuronal subtypes in the BNC in order to better understand the anatomical substrates of BF-BNC circuitry. The results indicate that BF inputs to the BNC mainly target the basolateral nucleus of the BNC (BL) and arise from cholinergic, GABAergic, and perhaps glutamatergic BF neurons. Cholinergic inputs mainly target dendrites and spines of pyramidal neurons (PNs) that express muscarinic receptors (MRs). MRs are also expressed by cholinergic axons, as well as cortical and thalamic axons that synapse with PN dendrites and spines. BF GABAergic axons to the BL also express MRs and mainly target BL interneurons that contain parvalbumin. It is suggested that BF-BL circuitry could be very important for generating rhythmic oscillations known to be critical for emotional learning. BF cholinergic inputs to the BNC might also contribute to memory formation by activating M1 receptors located on PN dendritic shafts and spines that also express NMDA receptors.
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Affiliation(s)
- Alexander Joseph McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina, USA
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3
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Kimchi EY, Burgos-Robles A, Matthews GA, Chakoma T, Patarino M, Weddington JC, Siciliano C, Yang W, Foutch S, Simons R, Fong MF, Jing M, Li Y, Polley DB, Tye KM. Reward contingency gates selective cholinergic suppression of amygdala neurons. eLife 2024; 12:RP89093. [PMID: 38376907 PMCID: PMC10942609 DOI: 10.7554/elife.89093] [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: 02/21/2024] Open
Abstract
Basal forebrain cholinergic neurons modulate how organisms process and respond to environmental stimuli through impacts on arousal, attention, and memory. It is unknown, however, whether basal forebrain cholinergic neurons are directly involved in conditioned behavior, independent of secondary roles in the processing of external stimuli. Using fluorescent imaging, we found that cholinergic neurons are active during behavioral responding for a reward - even prior to reward delivery and in the absence of discrete stimuli. Photostimulation of basal forebrain cholinergic neurons, or their terminals in the basolateral amygdala (BLA), selectively promoted conditioned responding (licking), but not unconditioned behavior nor innate motor outputs. In vivo electrophysiological recordings during cholinergic photostimulation revealed reward-contingency-dependent suppression of BLA neural activity, but not prefrontal cortex. Finally, ex vivo experiments demonstrated that photostimulation of cholinergic terminals suppressed BLA projection neuron activity via monosynaptic muscarinic receptor signaling, while also facilitating firing in BLA GABAergic interneurons. Taken together, we show that the neural and behavioral effects of basal forebrain cholinergic activation are modulated by reward contingency in a target-specific manner.
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Affiliation(s)
- Eyal Y Kimchi
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Neurology, Northwestern UniversityChicagoUnited States
| | - Anthony Burgos-Robles
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
- The Department of Neuroscience, Developmental, and Regenerative Biology, Neuroscience Institute & Brain Health Consortium, University of Texas at San AntonioSan AntonioUnited States
| | - Gillian A Matthews
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Tatenda Chakoma
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Makenzie Patarino
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Javier C Weddington
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Cody Siciliano
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
- Vanderbilt Center for Addiction Research, Department of Pharmacology, Vanderbilt UniversityNashvilleUnited States
| | - Wannan Yang
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Shaun Foutch
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Renee Simons
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Ming-fai Fong
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
- Coulter Department of Biomedical Engineering, Georgia Tech & Emory UniversityAtlantaUnited States
| | - Miao Jing
- Chinese Institute for Brain ResearchBeijingChina
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences; PKUIDG/McGovern Institute for Brain Research; Peking-Tsinghua Center for Life SciencesBeijingChina
| | - Daniel B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and EarBostonUnited States
- Department of Otolaryngology – Head and Neck Surgery, Harvard Medical SchoolBostonUnited States
| | - Kay M Tye
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
- HHMI Investigator, Member of the Kavli Institute for Brain and Mind, and Wylie Vale Professor at the Salk Institute for Biological StudiesLa JollaUnited States
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Akmese C, Sevinc C, Halim S, Unal G. Differential role of GABAergic and cholinergic ventral pallidal neurons in behavioral despair, conditioned fear memory and active coping. Prog Neuropsychopharmacol Biol Psychiatry 2023; 125:110760. [PMID: 37031946 DOI: 10.1016/j.pnpbp.2023.110760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/24/2023] [Accepted: 04/06/2023] [Indexed: 04/11/2023]
Abstract
The ventral pallidum (VP), a major component of the reward circuit, is well-associated with appetitive behaviors. Recent evidence suggests that this basal forebrain nucleus may have an overarching role in affective processing, including behavioral responses to aversive stimuli. We investigated this by utilizing selective immunotoxin lesions and a series of behavioral tests in adult male Wistar rats. We made bilateral GAT1-Saporin, 192-IgG-Saporin or PBS (vehicle) injections into the VP to respectively eliminate GABAergic and cholinergic neurons, and tested the animals in the forced swim test (FST), open field test (OFT), elevated plus maze (EPM), Morris water maze (MWM) and cued fear conditioning. Both GAT1-Saporin and 192-IgG-Saporin injections reduced behavioral despair without altering general locomotor activity. During the acquisition phase of cued fear conditioning, this antidepressant effect was accompanied by reduced freezing and increased darting in the 192-IgG-Saporin group, and increased jumping in the GAT1-Saporin group. In the extinction phase, cholinergic lesions impaired fear memory irrespective of the context, while GABAergic lesions reduced memory durability only during the early phases of extinction in a novel context. In line with this, selective cholinergic, but not GABAergic, lesions impaired spatial memory in the MWM. We observed no consistent effect in anxiety-like behavior assessed in the OFT and EPM. These findings indicate that both the GABAergic and cholinergic neuronal groups of the VP may contribute to emotion regulation through modulation of behavioral despair and acquired fear by suppressing active coping and promoting species-specific passive behaviors.
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Affiliation(s)
- Cemal Akmese
- Behavioral Neuroscience Laboratory, Department of Psychology, Boğaziçi University, 34342 Istanbul, Turkey
| | - Cem Sevinc
- Behavioral Neuroscience Laboratory, Department of Psychology, Boğaziçi University, 34342 Istanbul, Turkey
| | - Sahar Halim
- Behavioral Neuroscience Laboratory, Department of Psychology, Boğaziçi University, 34342 Istanbul, Turkey
| | - Gunes Unal
- Behavioral Neuroscience Laboratory, Department of Psychology, Boğaziçi University, 34342 Istanbul, Turkey.
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Chronic Intermittent Ethanol Exposure Dysregulates Nucleus Basalis Magnocellularis Afferents in the Basolateral Amygdala. eNeuro 2022; 9:ENEURO.0164-22.2022. [PMID: 36280288 PMCID: PMC9668348 DOI: 10.1523/eneuro.0164-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/22/2022] [Accepted: 08/25/2022] [Indexed: 12/24/2022] Open
Abstract
Nucleus basalis magnocellularis (NBM) cholinergic projections to the basolateral amygdala (BLA) regulate the acquisition and consolidation of fear-like and anxiety-like behaviors. However, it is unclear whether the alterations in the NBM-BLA circuit promote negative affect during ethanol withdrawal (WD). Therefore, we performed ex vivo whole-cell patch-clamp electrophysiology in both the NBM and the BLA of male Sprague Dawley rats following 10 d of chronic intermittent ethanol (CIE) exposure and 24 h of WD. We found that CIE exposure and withdrawal enhanced the neuronal excitability of NBM putative "cholinergic" neurons. We subsequently used optogenetics to directly manipulate NBM terminal activity within the BLA and measure cholinergic modulation of glutamatergic afferents and BLA pyramidal neurons. Our findings indicate that CIE and withdrawal upregulate NBM cholinergic facilitation of glutamate release via activation of presynaptic nicotinic acetylcholine receptors (AChRs). Ethanol withdrawal-induced increases in NBM terminal activity also enhance BLA pyramidal neuron firing. Collectively, our results provide a novel characterization of the NBM-BLA circuit and suggest that CIE-dependent modifications to NBM afferents enhance BLA pyramidal neuron activity during ethanol withdrawal.
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Hájos N. Interneuron Types and Their Circuits in the Basolateral Amygdala. Front Neural Circuits 2021; 15:687257. [PMID: 34177472 PMCID: PMC8222668 DOI: 10.3389/fncir.2021.687257] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/11/2021] [Indexed: 11/29/2022] Open
Abstract
The basolateral amygdala (BLA) is a cortical structure based on its cell types, connectivity features, and developmental characteristics. This part of the amygdala is considered to be the main entry site of processed and multisensory information delivered via cortical and thalamic afferents. Although GABAergic inhibitory cells in the BLA comprise only 20% of the entire neuronal population, they provide essential control over proper network operation. Previous studies have uncovered that GABAergic cells in the basolateral amygdala are as diverse as those present in other cortical regions, including the hippocampus and neocortex. To understand the role of inhibitory cells in various amygdala functions, we need to reveal the connectivity and input-output features of the different types of GABAergic cells. Here, I review the recent achievements in uncovering the diversity of GABAergic cells in the basolateral amygdala with a specific focus on the microcircuit organization of these inhibitory cells.
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Affiliation(s)
- Norbert Hájos
- Laboratory of Network Neurophysiology, ELRN Institute of Experimental Medicine, Budapest, Hungary
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Bostanciklioğlu M. Unexpected awakenings in severe dementia from case reports to laboratory. Alzheimers Dement 2020; 17:125-136. [PMID: 33064369 DOI: 10.1002/alz.12162] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/17/2020] [Accepted: 07/07/2020] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Case report notions of unexpected memory retrieval in patients with severe dementia near to death are starting to alter the central "irreversible" paradigm of dementia and locate dementia as a problem of memory retrieval, not consolidation. We suggest that the most likely central tenet of this paradoxical memory retrieval is the fluctuation of neuromodulators projecting from the brain stem to the medial prefrontal cortex and the hippocampus. The neuromodulation-centric explanation of this phenomenon aims to open the "irreversible" paradigm of dementia up for discussion and suggest a plausible treatment strategy by questioning how the devastating process of death fluctuates memory performance in severe dementia. BACKGROUND Supporting demented patients, who are mostly unresponsive, without making demands or asking a question and regarding them as valuable human beings unexpectedly improve their memory performance around the time of death. NEW LUCIDITY HYPOTHESIS Around the time of death, neurological signs (hyper-arousal and -attention) of demented people point out that neurotransmitter discharges are dramatically changed. Relatively resistant neuromodulator circuits to neurodegeneration can maintain optimal levels of arousal and attention for memory processing. In this way, unexpected episodes of lucidity can be triggered. Also, corticotropin-releasing peptides might increase mental clarity by increasing the excitability of the neuromodulator circuits. The science of memory retrieval is more complicated and nuanced than retrieval observations in case reports, but the rapid development of new techniques holds promise for future understanding of lucidity in severe dementia. MAJOR CHALLENGE FOR THE MODEL There is no an animal or human model to test this hypothesis; however, the similarities between neurological signs (instantaneous cognitive fluctuations) of delirium and paradoxical lucidity could provide a unique window to understand neural events of terminal lucidity on a modified animal model of delirium. Likewise, similarities between unexpected consciousness signs of terminal lucidity and lucid dreaming suggest that lucid dreaming episodes might be considered a human model for terminal lucidity research.
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Böhm E, Brunert D, Rothermel M. Input dependent modulation of olfactory bulb activity by HDB GABAergic projections. Sci Rep 2020; 10:10696. [PMID: 32612119 PMCID: PMC7329849 DOI: 10.1038/s41598-020-67276-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/27/2020] [Indexed: 12/16/2022] Open
Abstract
Basal forebrain modulation of central circuits is associated with active sensation, attention, and learning. While cholinergic modulations have been studied extensively the effect of non-cholinergic basal forebrain subpopulations on sensory processing remains largely unclear. Here, we directly compare optogenetic manipulation effects of two major basal forebrain subpopulations on principal neuron activity in an early sensory processing area, i.e. mitral/tufted cells (MTCs) in the olfactory bulb. In contrast to cholinergic projections, which consistently increased MTC firing, activation of GABAergic fibers from basal forebrain to the olfactory bulb leads to differential modulation effects: while spontaneous MTC activity is mainly inhibited, odor-evoked firing is predominantly enhanced. Moreover, sniff-triggered averages revealed an enhancement of maximal sniff evoked firing amplitude and an inhibition of firing rates outside the maximal sniff phase. These findings demonstrate that GABAergic neuromodulation affects MTC firing in a bimodal, sensory-input dependent way, suggesting that GABAergic basal forebrain modulation could be an important factor in attention mediated filtering of sensory information to the brain.
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Affiliation(s)
- Erik Böhm
- Department of Chemosensation, AG Neuromodulation, Institute for Biology II, RWTH Aachen University, Aachen, 52074, Germany
| | - Daniela Brunert
- Department of Chemosensation, AG Neuromodulation, Institute for Biology II, RWTH Aachen University, Aachen, 52074, Germany
| | - Markus Rothermel
- Department of Chemosensation, AG Neuromodulation, Institute for Biology II, RWTH Aachen University, Aachen, 52074, Germany.
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Hanson E, Swanson J, Arenkiel BR. GABAergic Input From the Basal Forebrain Promotes the Survival of Adult-Born Neurons in the Mouse Olfactory Bulb. Front Neural Circuits 2020; 14:17. [PMID: 32390805 PMCID: PMC7190813 DOI: 10.3389/fncir.2020.00017] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 03/31/2020] [Indexed: 12/15/2022] Open
Abstract
A unique feature of the olfactory system is the continuous generation and integration of new neurons throughout adulthood. Adult-born neuron survival and integration is dependent on activity and sensory experience, which is largely mediated by early synaptic inputs that adult-born neurons receive upon entering the olfactory bulb (OB). As in early postnatal development, the first synaptic inputs onto adult-born neurons are GABAergic. However, the specific sources of early synaptic GABA and the influence of specific inputs on adult-born neuron development are poorly understood. Here, we use retrograde and anterograde viral tracing to reveal robust GABAergic projections from the basal forebrain horizontal limb of the diagonal band of Broca (HDB) to the granule cell layer (GCL) and glomerular layer (GL) of the mouse OB. Whole-cell electrophysiological recordings indicate that these projections target interneurons in the GCL and GL, including adult-born granule cells (abGCs). Recordings from birth-dated abGCs reveal a developmental time course in which HDB GABAergic input onto abGCs emerges as the neurons first enter the OB, and strengthens throughout the critical period of abGC development. Finally, we show that removing GABAergic signaling from HDB neurons results in decreased abGC survival. Together these data show that GABAergic projections from the HDB synapse onto immature abGCs in the OB to promote their survival through the critical period, thus representing a source of long-range input modulating plasticity in the adult OB.
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Affiliation(s)
- Elizabeth Hanson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Jessica Swanson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Benjamin R. Arenkiel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Baylor College of Medicine, Houston, TX, United States
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McDonald AJ. Functional neuroanatomy of the basolateral amygdala: Neurons, neurotransmitters, and circuits. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2020; 26:1-38. [PMID: 34220399 PMCID: PMC8248694 DOI: 10.1016/b978-0-12-815134-1.00001-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Alexander J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
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11
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Beyeler A, Dabrowska J. Neuronal diversity of the amygdala and the bed nucleus of the stria terminalis. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2020; 26:63-100. [PMID: 32792868 DOI: 10.1016/b978-0-12-815134-1.00003-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Anna Beyeler
- Neurocentre Magendie, French National Institutes of Health (INSERM) unit 1215, Neurocampus of Bordeaux University, Bordeaux, France
| | - Joanna Dabrowska
- Center for the Neurobiology of Stress Resilience and Psychiatric Disorders, Discipline of Cellular and Molecular Pharmacology, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
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12
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Neuromodulation in circuits of aversive emotional learning. Nat Neurosci 2019; 22:1586-1597. [PMID: 31551602 DOI: 10.1038/s41593-019-0503-3] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/21/2019] [Indexed: 02/07/2023]
Abstract
Emotional learning and memory are functionally and dysfunctionally regulated by the neuromodulatory state of the brain. While the role of excitatory and inhibitory neural circuits mediating emotional learning and its control have been the focus of much research, we are only now beginning to understand the more diffuse role of neuromodulation in these processes. Recent experimental studies of the acetylcholine, noradrenaline and dopamine systems in fear learning and extinction of fear responding provide surprising answers to key questions in neuromodulation. One area of research has revealed how modular organization, coupled with context-dependent coding modes, allows for flexible brain-wide or targeted neuromodulation. Other work has shown how these neuromodulators act in downstream targets to enhance signal-to-noise ratios and gain, as well as to bind distributed circuits through neuronal oscillations. These studies elucidate how different neuromodulatory systems regulate aversive emotional processing and reveal fundamental principles of neuromodulatory function.
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Social brain, social dysfunction and social withdrawal. Neurosci Biobehav Rev 2019; 97:10-33. [DOI: 10.1016/j.neubiorev.2018.09.012] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 05/31/2018] [Accepted: 09/17/2018] [Indexed: 01/07/2023]
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Krabbe S, Gründemann J, Lüthi A. Amygdala Inhibitory Circuits Regulate Associative Fear Conditioning. Biol Psychiatry 2018; 83:800-809. [PMID: 29174478 DOI: 10.1016/j.biopsych.2017.10.006] [Citation(s) in RCA: 162] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/28/2017] [Accepted: 10/04/2017] [Indexed: 11/16/2022]
Abstract
Associative memory formation is essential for an animal's survival by ensuring adaptive behavioral responses in an ever-changing environment. This is particularly important under conditions of immediate threats such as in fear learning. One of the key brain regions involved in associative fear learning is the amygdala. The basolateral amygdala is the main entry site for sensory information to the amygdala complex, and local plasticity in excitatory basolateral amygdala principal neurons is considered to be crucial for learning of conditioned fear responses. However, activity and plasticity of excitatory circuits are tightly controlled by local inhibitory interneurons in a spatially and temporally defined manner. In this review, we provide an updated view on how distinct interneuron subtypes in the basolateral amygdala contribute to the acquisition and extinction of conditioned fear memories.
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Affiliation(s)
- Sabine Krabbe
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jan Gründemann
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Andreas Lüthi
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland.
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Fajardo-Serrano A, Liu L, Mott DD, McDonald AJ. Evidence for M 2 muscarinic receptor modulation of axon terminals and dendrites in the rodent basolateral amygdala: An ultrastructural and electrophysiological analysis. Neuroscience 2017. [PMID: 28629847 DOI: 10.1016/j.neuroscience.2017.06.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The basolateral amygdala receives a very dense cholinergic innervation from the basal forebrain that is important for memory consolidation. Although behavioral studies have shown that both M1 and M2 muscarinic receptors are critical for these mnemonic functions, there have been very few neuroanatomical and electrophysiological investigations of the localization and function of different types of muscarinic receptors in the amygdala. In the present study we investigated the subcellular localization of M2 muscarinic receptors (M2Rs) in the anterior basolateral nucleus (BLa) of the mouse, including the localization of M2Rs in parvalbumin (PV) immunoreactive interneurons, using double-labeling immunoelectron microscopy. Little if any M2R-immunoreactivity (M2R-ir) was observed in neuronal somata, but the neuropil was densely labeled. Ultrastructural analysis using a pre-embedding immunogold-silver technique (IGS) demonstrated M2R-ir in dendritic shafts, spines, and axon terminals forming asymmetrical (excitatory) or symmetrical (mostly inhibitory) synapses. In addition, about one-quarter of PV+ axon terminals and half of PV+ dendrites, localized using immunoperoxidase, were M2R+ when observed in single thin sections. In all M2R+ neuropilar structures, including those that were PV+, about one-quarter to two-thirds of M2R+ immunoparticles were plasma-membrane-associated, depending on the structure. The expression of M2Rs in PV+ and PV-negative terminals forming symmetrical synapses indicates M2R modulation of inhibitory transmission. Electrophysiological studies in mouse and rat brain slices, including paired recordings from interneurons and pyramidal projection neurons, demonstrated M2R-mediated suppression of GABA release. These findings suggest cell-type-specific functions of M2Rs and shed light on organizing principles of cholinergic modulation in the BLa.
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Affiliation(s)
- Ana Fajardo-Serrano
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - Lei Liu
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - David D Mott
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - Alexander J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA.
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Saha R, Knapp S, Chakraborty D, Horovitz O, Albrecht A, Kriebel M, Kaphzan H, Ehrlich I, Volkmer H, Richter-Levin G. GABAergic Synapses at the Axon Initial Segment of Basolateral Amygdala Projection Neurons Modulate Fear Extinction. Neuropsychopharmacology 2017; 42:473-484. [PMID: 27634356 PMCID: PMC5399240 DOI: 10.1038/npp.2016.205] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 08/18/2016] [Accepted: 08/22/2016] [Indexed: 11/09/2022]
Abstract
Inhibitory synaptic transmission in the amygdala has a pivotal role in fear learning and its extinction. However, the local circuits formed by GABAergic inhibitory interneurons within the amygdala and their detailed function in shaping these behaviors are not well understood. Here we used lentiviral-mediated knockdown of the cell adhesion molecule neurofascin in the basolateral amygdala (BLA) to specifically remove inhibitory synapses at the axon initial segment (AIS) of BLA projection neurons. Quantitative analysis of GABAergic synapse markers and measurement of miniature inhibitory postsynaptic currents in BLA projection neurons after neurofascin knockdown ex vivo confirmed the loss of GABAergic input. We then studied the impact of this manipulation on anxiety-like behavior and auditory cued fear conditioning and its extinction as BLA related behavioral paradigms, as well as on long-term potentiation (LTP) in the ventral subiculum-BLA pathway in vivo. BLA knockdown of neurofascin impaired ventral subiculum-BLA-LTP. While this manipulation did not affect anxiety-like behavior and fear memory acquisition and consolidation, it specifically impaired extinction. Our findings indicate that modification of inhibitory synapses at the AIS of BLA projection neurons is sufficient to selectively impair extinction behavior. A better understanding of the role of distinct GABAergic synapses may provide novel and more specific targets for therapeutic interventions in extinction-based therapies.
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Affiliation(s)
- Rinki Saha
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Stephanie Knapp
- Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany,Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany,Graduate School for Neural and Behavioral Science, University of Tübingen, Tübingen, Germany
| | | | - Omer Horovitz
- Department of Psychology, University of Haifa, Haifa, Israel
| | - Anne Albrecht
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel,The Institute for the Study of Affective Neuroscience, University of Haifa, Haifa, Israel
| | - Martin Kriebel
- NMI Natural and Medical Sciences Institute, University of Tübingen, Reutlingen, Germany
| | - Hanoch Kaphzan
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Ingrid Ehrlich
- Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany,Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
| | - Hansjürgen Volkmer
- NMI Natural and Medical Sciences Institute, University of Tübingen, Reutlingen, Germany
| | - Gal Richter-Levin
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel,Department of Psychology, University of Haifa, Haifa, Israel,The Institute for the Study of Affective Neuroscience, University of Haifa, Haifa, Israel,Sagol Department of Neurobiology, University of Haifa, Abba Khoushy Avenue 199, Haifa 31905, Israel, Tel: +972 48240962, Fax: +972 48288578, E-mail:
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17
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Lucas EK, Jegarl AM, Morishita H, Clem RL. Multimodal and Site-Specific Plasticity of Amygdala Parvalbumin Interneurons after Fear Learning. Neuron 2016; 91:629-43. [PMID: 27427462 DOI: 10.1016/j.neuron.2016.06.032] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 05/12/2016] [Accepted: 06/15/2016] [Indexed: 01/02/2023]
Abstract
Stimulus processing in fear conditioning is constrained by parvalbumin interneurons (PV-INs) through inhibition of principal excitatory neurons. However, the contributions of PV-IN microcircuits to input gating and long-term plasticity in the fear system remain unknown. Here we interrogate synaptic connections between afferent pathways, PV-INs, and principal excitatory neurons in the basolateral amygdala. We find that subnuclei of this region are populated two functionally distinct PV-IN networks. PV-INs in the lateral (LA), but not the basal (BA), amygdala possess complex dendritic arborizations, receive potent excitatory drive, and mediate feedforward inhibition onto principal neurons. After fear conditioning, PV-INs exhibit nucleus- and target-selective plasticity, resulting in persistent reduction of their excitatory input and inhibitory output in LA but not BA. These data reveal previously overlooked specializations of amygdala PV-INs and indicate specific circuit mechanisms for inhibitory plasticity during the encoding of associative fear memories.
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Affiliation(s)
- Elizabeth K Lucas
- Fishberg Department of Neuroscience and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Anita M Jegarl
- Fishberg Department of Neuroscience and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Hirofumi Morishita
- Fishberg Department of Neuroscience and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Psychiatry and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Roger L Clem
- Fishberg Department of Neuroscience and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Psychiatry and the Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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18
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Malt EA, Juhasz K, Malt UF, Naumann T. A Role for the Transcription Factor Nk2 Homeobox 1 in Schizophrenia: Convergent Evidence from Animal and Human Studies. Front Behav Neurosci 2016; 10:59. [PMID: 27064909 PMCID: PMC4811959 DOI: 10.3389/fnbeh.2016.00059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/11/2016] [Indexed: 12/22/2022] Open
Abstract
Schizophrenia is a highly heritable disorder with diverse mental and somatic symptoms. The molecular mechanisms leading from genes to disease pathology in schizophrenia remain largely unknown. Genome-wide association studies (GWASs) have shown that common single-nucleotide polymorphisms associated with specific diseases are enriched in the recognition sequences of transcription factors that regulate physiological processes relevant to the disease. We have used a “bottom-up” approach and tracked a developmental trajectory from embryology to physiological processes and behavior and recognized that the transcription factor NK2 homeobox 1 (NKX2-1) possesses properties of particular interest for schizophrenia. NKX2-1 is selectively expressed from prenatal development to adulthood in the brain, thyroid gland, parathyroid gland, lungs, skin, and enteric ganglia, and has key functions at the interface of the brain, the endocrine-, and the immune system. In the developing brain, NKX2-1-expressing progenitor cells differentiate into distinct subclasses of forebrain GABAergic and cholinergic neurons, astrocytes, and oligodendrocytes. The transcription factor is highly expressed in mature limbic circuits related to context-dependent goal-directed patterns of behavior, social interaction and reproduction, fear responses, responses to light, and other homeostatic processes. It is essential for development and mature function of the thyroid gland and the respiratory system, and is involved in calcium metabolism and immune responses. NKX2-1 interacts with a number of genes identified as susceptibility genes for schizophrenia. We suggest that NKX2-1 may lie at the core of several dose dependent pathways that are dysregulated in schizophrenia. We correlate the symptoms seen in schizophrenia with the temporal and spatial activities of NKX2-1 in order to highlight promising future research areas.
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Affiliation(s)
- Eva A Malt
- Department of Adult Habilitation, Akershus University HospitalLørenskog, Norway; Institute of Clinical Medicine, Ahus Campus University of OsloOslo, Norway
| | - Katalin Juhasz
- Department of Adult Habilitation, Akershus University Hospital Lørenskog, Norway
| | - Ulrik F Malt
- Institute of Clinical Medicine, University of OsloOslo, Norway; Department of Research and Education, Institution of Oslo University HospitalOslo, Norway
| | - Thomas Naumann
- Centre of Anatomy, Institute of Cell Biology and Neurobiology, Charite Universitätsmedizin Berlin Berlin, Germany
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19
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Synaptic Targets of Medial Septal Projections in the Hippocampus and Extrahippocampal Cortices of the Mouse. J Neurosci 2016; 35:15812-26. [PMID: 26631464 DOI: 10.1523/jneurosci.2639-15.2015] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Temporal coordination of neuronal assemblies among cortical areas is essential for behavioral performance. GABAergic projections from the medial septum and diagonal band complex exclusively innervate GABAergic interneurons in the rat hippocampus, contributing to the coordination of neuronal activity, including the generation of theta oscillations. Much less is known about the synaptic target neurons outside the hippocampus. To reveal the contribution of synaptic circuits involving the medial septum of mice, we have identified postsynaptic cortical neurons in wild-type and parvalbumin-Cre knock-in mice. Anterograde axonal tracing from the septum revealed extensive innervation of the hippocampus as well as the subiculum, presubiculum, parasubiculum, the medial and lateral entorhinal cortices, and the retrosplenial cortex. In all examined cortical regions, many septal GABAergic boutons were in close apposition to somata or dendrites immunopositive for interneuron cell-type molecular markers, such as parvalbumin, calbindin, calretinin, N-terminal EF-hand calcium-binding protein 1, cholecystokinin, reelin, or a combination of these molecules. Electron microscopic observations revealed septal boutons forming axosomatic or axodendritic type II synapses. In the CA1 region of hippocampus, septal GABAergic projections exclusively targeted interneurons. In the retrosplenial cortex, 93% of identified postsynaptic targets belonged to interneurons and the rest to pyramidal cells. These results suggest that the GABAergic innervation from the medial septum and diagonal band complex contributes to temporal coordination of neuronal activity via several types of cortical GABAergic interneurons in both hippocampal and extrahippocampal cortices. Oscillatory septal neuronal firing at delta, theta, and gamma frequencies may phase interneuron activity.
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20
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McDonald AJ, Mott DD. Functional neuroanatomy of amygdalohippocampal interconnections and their role in learning and memory. J Neurosci Res 2016; 95:797-820. [PMID: 26876924 DOI: 10.1002/jnr.23709] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/01/2015] [Accepted: 12/14/2015] [Indexed: 01/31/2023]
Abstract
The amygdalar nuclear complex and hippocampal/parahippocampal region are key components of the limbic system that play a critical role in emotional learning and memory. This Review discusses what is currently known about the neuroanatomy and neurotransmitters involved in amygdalo-hippocampal interconnections, their functional roles in learning and memory, and their involvement in mnemonic dysfunctions associated with neuropsychiatric and neurological diseases. Tract tracing studies have shown that the interconnections between discrete amygdalar nuclei and distinct layers of individual hippocampal/parahippocampal regions are robust and complex. Although it is well established that glutamatergic pyramidal cells in the amygdala and hippocampal region are the major players mediating interconnections between these regions, recent studies suggest that long-range GABAergic projection neurons are also involved. Whereas neuroanatomical studies indicate that the amygdala only has direct interconnections with the ventral hippocampal region, electrophysiological studies and behavioral studies investigating fear conditioning and extinction, as well as amygdalar modulation of hippocampal-dependent mnemonic functions, suggest that the amygdala interacts with dorsal hippocampal regions via relays in the parahippocampal cortices. Possible pathways for these indirect interconnections, based on evidence from previous tract tracing studies, are discussed in this Review. Finally, memory disorders associated with dysfunction or damage to the amygdala, hippocampal region, and/or their interconnections are discussed in relation to Alzheimer's disease, posttraumatic stress disorder (PTSD), and temporal lobe epilepsy. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Alexander J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina
| | - David D Mott
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina
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21
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Catestatin and GABA(A)R related feeding habits rely on dopamine, ghrelin plus leptin neuroreceptor expression variations. Physiol Behav 2016; 157:225-30. [PMID: 26875516 DOI: 10.1016/j.physbeh.2016.02.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 01/20/2016] [Accepted: 02/09/2016] [Indexed: 12/31/2022]
Abstract
Catestatin (CST), an endogenously small sympathoinhibitory peptide is capable of interfering with the major cerebral neuroreceptor-blocking site, i.e. γ-aminobutyric acidA receptor (GABAAR) system especially in limbic brain areas that are involved with feeding behaviors. The GABAARergic-related effects seem to derive from its interaction with other molecular neuroreceptors such as dopaminergic, ghrelin and leptinergic. In this context, the present study aimed to investigate probable feeding responses (eating and drinking) induced by treatment with CST and the GABAAR antagonist bicucullin (BIC) alone or simultaneously (CST+BIC) in the Syrian hibernating hamster (Mesocricetus auratus) model. Hamsters that received these compounds via intracerebroventricular infusions displayed notable variations of feeding and drinking bouts. In particular, an anorexigenic response was evident following treatment with CST while BIC evoked a significant increase of eating and drinking behaviors. Surprisingly when both agents were given simultaneously, a predominating anorexigenic response was detected as shown by evident CST-dependent reduction of feeding bouts. Contextually such behaviors, especially those following the combined treatment were tightly correlated with the significantly increased cerebral dopamine receptor 1 (D1) plus reduced ghrelin receptor (GhsR) and leptin receptor (LepR) transcript levels. Overall, the anorexigenic effect of CST deriving from its tight interaction with GABAARs activity plus D1 and GhsR transcripts tends to propose these neuronal elements as pivotal factors responsible for feeding disorders.
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22
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Muller JF, Mascagni F, Zaric V, Mott DD, McDonald AJ. Localization of the M2 muscarinic cholinergic receptor in dendrites, cholinergic terminals, and noncholinergic terminals in the rat basolateral amygdala: An ultrastructural analysis. J Comp Neurol 2016; 524:2400-17. [PMID: 26779591 DOI: 10.1002/cne.23959] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/29/2015] [Accepted: 01/04/2016] [Indexed: 02/04/2023]
Abstract
Activation of M2 muscarinic receptors (M2Rs) in the rat anterior basolateral nucleus (BLa) is critical for the consolidation of memories of emotionally arousing events. The present investigation used immunocytochemistry at the electron microscopic level to determine which structures in the BLa express M2Rs. In addition, dual localization of M2R and the vesicular acetylcholine transporter protein (VAChT), a marker for cholinergic axons, was performed to determine whether M2R is an autoreceptor in cholinergic axons innervating the BLa. M2R immunoreactivity (M2R-ir) was absent from the perikarya of pyramidal neurons, with the exception of the Golgi complex, but was dense in the proximal dendrites and axon initial segments emanating from these neurons. Most perikarya of nonpyramidal neurons were also M2R-negative. About 95% of dendritic shafts and 60% of dendritic spines were M2 immunoreactive (M2R(+) ). Some M2R(+) dendrites had spines, suggesting that they belonged to pyramidal cells, whereas others had morphological features typical of nonpyramidal neurons. M2R-ir was also seen in axon terminals, most of which formed asymmetrical synapses. The main targets of M2R(+) terminals forming asymmetrical (putative excitatory) synapses were dendritic spines, most of which were M2R(+) . The main targets of M2R(+) terminals forming symmetrical (putative inhibitory or neuromodulatory) synapses were unlabeled perikarya and M2R(+) dendritic shafts. M2R-ir was also seen in VAChT(+) cholinergic terminals, indicating a possible autoreceptor role. These findings suggest that M2R-mediated mechanisms in the BLa are very complex, involving postsynaptic effects in dendrites as well as regulating release of glutamate, γ-aminobutyric acid, and acetylcholine from presynaptic axon terminals. J. Comp. Neurol. 524:2400-2417, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Jay F Muller
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina, 29208
| | - Franco Mascagni
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina, 29208
| | - Violeta Zaric
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina, 29208
| | - David D Mott
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina, 29208
| | - Alexander J McDonald
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina, 29208
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23
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Mongia S, Tripathi A, Mengual E. Arborization patterns of amygdalopetal axons from the rat ventral pallidum. Brain Struct Funct 2016; 221:4549-4573. [PMID: 26832919 DOI: 10.1007/s00429-016-1184-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 01/07/2016] [Indexed: 10/22/2022]
Abstract
We previously analyzed the arborization patterns of rat ventral pallidal (VP) axons that coursed caudally to innervate the thalamus and brainstem (Tripathi et al. in Brain Struct Funct 218:1133-1157, 2013). Here, we have reconstructed 16 previously undetected axons from the same tracer deposits that follow a more lateral trajectory. Virtually all 16 axons emanating from the different VP compartments collateralized in the extended amygdala system (EAS) and amygdaloid complex. The most frequent targets of axons from the lateral and medial (VPm) VP compartments were the rostral sublenticular extended amygdala, the extended amygdala (EA), the central nucleus of the amygdala and the posterior part of the basolateral amygdaloid nucleus. In contrast, axons from the rostral extension of the VP preferentially innervated the anterior amygdaloid area, the magnocellular preoptic nucleus, and the anterior part of the basomedial amygdaloid nucleus. We additionally found and reconstructed a single corticopetal axon arising from the VPm. The new results show that both direct and indirect projections from the basolateral complex and EAS to the ventral striatopallidal system are reciprocated by VP projections, and suggest that the systems can be activated simultaneously. The results additionally suggest that the amygdaloid complex and cortex are innervated separately from the VP. Finally, the combination of new and previous data indicate that approximately 84 % of VP axons (88/105) participate in basal ganglia circuits, 15 % (16/105) target the amygdaloid complex, and less than 1 % innervate the cortex.
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Affiliation(s)
- S Mongia
- Departamento de Anatomía, Facultad de Medicina, Universidad de Navarra, Ed. Los Castaños, C/. Irunlarrea 1, 31008, Pamplona, Navarra, Spain
| | - A Tripathi
- Center for Applied Medical Research (CIMA), Division of Neurosciences, Universidad de Navarra, Pamplona, Spain.,Department of Integrative Medical Biology, Umeå University, 90187, Umeå, Sweden
| | - E Mengual
- Center for Applied Medical Research (CIMA), Division of Neurosciences, Universidad de Navarra, Pamplona, Spain. .,Departamento de Anatomía, Facultad de Medicina, Universidad de Navarra, Ed. Los Castaños, C/. Irunlarrea 1, 31008, Pamplona, Navarra, Spain.
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24
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Prager EM, Bergstrom HC, Wynn GH, Braga MFM. The basolateral amygdala γ-aminobutyric acidergic system in health and disease. J Neurosci Res 2015; 94:548-67. [PMID: 26586374 DOI: 10.1002/jnr.23690] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 10/01/2015] [Accepted: 10/18/2015] [Indexed: 01/13/2023]
Abstract
The brain comprises an excitatory/inhibitory neuronal network that maintains a finely tuned balance of activity critical for normal functioning. Excitatory activity in the basolateral amygdala (BLA), a brain region that plays a central role in emotion and motivational processing, is tightly regulated by a relatively small population of γ-aminobutyric acid (GABA) inhibitory neurons. Disruption in GABAergic inhibition in the BLA can occur when there is a loss of local GABAergic interneurons, an alteration in GABAA receptor activation, or a dysregulation of mechanisms that modulate BLA GABAergic inhibition. Disruptions in GABAergic control of the BLA emerge during development, in aging populations, or after trauma, ultimately resulting in hyperexcitability. BLA hyperexcitability manifests behaviorally as an increase in anxiety, emotional dysregulation, or development of seizure activity. This Review discusses the anatomy, development, and physiology of the GABAergic system in the BLA and circuits that modulate GABAergic inhibition, including the dopaminergic, serotonergic, noradrenergic, and cholinergic systems. We highlight how alterations in various neurotransmitter receptors, including the acid-sensing ion channel 1a, cannabinoid receptor 1, and glutamate receptor subtypes, expressed on BLA interneurons, modulate GABAergic transmission and how defects of these systems affect inhibitory tonus within the BLA. Finally, we discuss alterations in the BLA GABAergic system in neurodevelopmental (autism/fragile X syndrome) and neurodegenerative (Alzheimer's disease) diseases and after the development of epilepsy, anxiety, and traumatic brain injury. A more complete understanding of the intrinsic excitatory/inhibitory circuit balance of the amygdala and how imbalances in inhibitory control contribute to excessive BLA excitability will guide the development of novel therapeutic approaches in neuropsychiatric diseases.
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Affiliation(s)
- Eric M Prager
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services, University of the Health Sciences, Bethesda, Maryland
| | | | - Gary H Wynn
- Center for the Study of Traumatic Stress, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services, University of the Health Sciences, Bethesda, Maryland.,Center for the Study of Traumatic Stress, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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25
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Letzkus J, Wolff S, Lüthi A. Disinhibition, a Circuit Mechanism for Associative Learning and Memory. Neuron 2015; 88:264-76. [PMID: 26494276 DOI: 10.1016/j.neuron.2015.09.024] [Citation(s) in RCA: 235] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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26
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Baribeau DA, Anagnostou E. Oxytocin and vasopressin: linking pituitary neuropeptides and their receptors to social neurocircuits. Front Neurosci 2015; 9:335. [PMID: 26441508 PMCID: PMC4585313 DOI: 10.3389/fnins.2015.00335] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/07/2015] [Indexed: 11/13/2022] Open
Abstract
Oxytocin and vasopressin are pituitary neuropeptides that have been shown to affect social processes in mammals. There is growing interest in these molecules and their receptors as potential precipitants of, and/or treatments for, social deficits in neurodevelopmental disorders, including autism spectrum disorder. Numerous behavioral-genetic studies suggest that there is an association between these peptides and individual social abilities; however, an explanatory model that links hormonal activity at the receptor level to complex human behavior remains elusive. The following review summarizes the known associations between the oxytocin and vasopressin neuropeptide systems and social neurocircuits in the brain. Following a micro- to macro- level trajectory, current literature on the synthesis and secretion of these peptides, and the structure, function and distribution of their respective receptors is first surveyed. Next, current models regarding the mechanism of action of these peptides on microcircuitry and other neurotransmitter systems are discussed. Functional neuroimaging evidence on the acute effects of exogenous administration of these peptides on brain activity is then reviewed. Overall, a model in which the local neuromodulatory effects of pituitary neuropeptides on brainstem and basal forebrain regions strengthen signaling within social neurocircuits proves appealing. However, these findings are derived from animal models; more research is needed to clarify the relevance of these mechanisms to human behavior and treatment of social deficits in neuropsychiatric disorders.
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Affiliation(s)
| | - Evdokia Anagnostou
- Autism Research Centre, Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital Toronto, ON, Canada
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27
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Zhang J, Muller JF, McDonald AJ. Mu opioid receptor localization in the basolateral amygdala: An ultrastructural analysis. Neuroscience 2015; 303:352-63. [PMID: 26164501 DOI: 10.1016/j.neuroscience.2015.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 06/30/2015] [Accepted: 07/01/2015] [Indexed: 10/23/2022]
Abstract
Receptor binding studies have shown that the density of mu opioid receptors (MORs) in the basolateral amygdala is among the highest in the brain. Activation of these receptors in the basolateral amygdala is critical for stress-induced analgesia, memory consolidation of aversive events, and stress adaptation. Despite the importance of MORs in these stress-related functions, little is known about the neural circuits that are modulated by amygdalar MORs. In the present investigation light and electron microscopy combined with immunohistochemistry was used to study the expression of MORs in the anterior basolateral nucleus (BLa). At the light microscopic level, light to moderate MOR-immunoreactivity (MOR-ir) was observed in a small number of cell bodies of nonpyramidal interneurons and in a small number of processes and puncta in the neuropil. At the electron microscopic level most MOR-ir was observed in dendritic shafts, dendritic spines, and axon terminals. MOR-ir was also observed in the Golgi apparatus of the cell bodies of pyramidal neurons (PNs) and interneurons. Some of the MOR-positive (MOR+) dendrites were spiny, suggesting that they belonged to PNs, while others received multiple asymmetrical synapses typical of interneurons. The great majority of MOR+ axon terminals (80%) that formed synapses made asymmetrical (excitatory) synapses; their main targets were spines, including some that were MOR+. The main targets of symmetrical (inhibitory and/or neuromodulatory) synapses were dendritic shafts, many of which were MOR+, but some of these terminals formed synapses with somata or spines. All of our observations were consistent with the few electrophysiological studies which have been performed on MOR activation in the basolateral amygdala. Collectively, these findings suggest that MORs may be important for filtering out weak excitatory inputs to PNs, allowing only strong inputs or synchronous inputs to influence pyramidal neuronal firing.
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Affiliation(s)
- J Zhang
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, United States
| | - J F Muller
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, United States
| | - A J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, United States.
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28
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Klenowski PM, Fogarty MJ, Belmer A, Noakes PG, Bellingham MC, Bartlett SE. Structural and functional characterization of dendritic arbors and GABAergic synaptic inputs on interneurons and principal cells in the rat basolateral amygdala. J Neurophysiol 2015; 114:942-57. [PMID: 26041829 DOI: 10.1152/jn.00824.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 06/02/2015] [Indexed: 11/22/2022] Open
Abstract
The basolateral amygdala (BLA) is a complex brain region associated with processing emotional states, such as fear, anxiety, and stress. Some aspects of these emotional states are driven by the network activity of synaptic connections, derived from both local circuitry and projections to the BLA from other regions. Although the synaptic physiology and general morphological characteristics are known for many individual cell types within the BLA, the combination of morphological, electrophysiological, and distribution of neurochemical GABAergic synapses in a three-dimensional neuronal arbor has not been reported for single neurons from this region. The aim of this study was to assess differences in morphological characteristics of BLA principal cells and interneurons, quantify the distribution of GABAergic neurochemical synapses within the entire neuronal arbor of each cell type, and determine whether GABAergic synaptic density correlates with electrophysiological recordings of inhibitory postsynaptic currents. We show that BLA principal neurons form complex dendritic arborizations, with proximal dendrites having fewer spines but higher densities of neurochemical GABAergic synapses compared with distal dendrites. Furthermore, we found that BLA interneurons exhibited reduced dendritic arbor lengths and spine densities but had significantly higher densities of putative GABAergic synapses compared with principal cells, which was correlated with an increased frequency of spontaneous inhibitory postsynaptic currents. The quantification of GABAergic connectivity, in combination with morphological and electrophysiological measurements of the BLA cell types, is the first step toward a greater understanding of how fear and stress lead to changes in morphology, local connectivity, and/or synaptic reorganization of the BLA.
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Affiliation(s)
- Paul M Klenowski
- Translational Research Institute and Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Matthew J Fogarty
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia; and
| | - Arnauld Belmer
- Translational Research Institute and Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Peter G Noakes
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia; and Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Mark C Bellingham
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia; and
| | - Selena E Bartlett
- Translational Research Institute and Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia;
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McDonald AJ, Zaric V. Extrinsic origins of the somatostatin and neuropeptide Y innervation of the rat basolateral amygdala. Neuroscience 2015; 294:82-100. [PMID: 25769940 DOI: 10.1016/j.neuroscience.2015.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 03/03/2015] [Accepted: 03/03/2015] [Indexed: 01/05/2023]
Abstract
The amygdalar basolateral nuclear complex (BLC) is a cortex-like structure that receives inputs from many cortical areas. It has long been assumed that cortico-amygdalar projections, as well as inter-areal intracortical connections, arise from cortical pyramidal cells. However, recent studies have shown that GABAergic long-range nonpyramidal neurons (LRNP neurons) in the cortex also contribute to inter-areal connections. The present study combined Fluorogold (FG) retrograde tract tracing with immunohistochemistry for cortical nonpyramidal neuronal markers to determine if cortical LRNP neurons project to the BLC in the rat. Injections of FG into the BLC produced widespread retrograde labeling in the cerebral hemispheres and diencephalon. Triple-labeling for FG, somatostatin (SOM), and neuropeptide Y (NPY) revealed a small number of FG+/SOM+/NPY+ neurons and FG+/SOM+/NPY- neurons in the lateral entorhinal area, amygdalopiriform transition area, and piriform cortex, but not in the prefrontal and insular cortices, or in the diencephalon. In addition, FG+/SOM+/NPY+ neurons were observed in the amygdalostriatal transition area and in a zone surrounding the intercalated nuclei. About half of the SOM+ neurons in the lateral entorhinal area labeled by FG were GABA+. FG+ neurons containing parvalbumin were only seen in the basal forebrain, and no FG+ neurons containing vasoactive intestinal peptide were observed in any brain region. Since LRNP neurons involved in corticocortical connections are critical for synchronous oscillations that allow temporal coordination between distant cortical regions, the LRNP neurons identified in this study may play a role in the synchronous oscillations of the BLC and hippocampal region that are involved in the retrieval of fear memories.
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Affiliation(s)
- A J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, United States.
| | - V Zaric
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, United States
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Merriman JD, Aouizerat BE, Cataldo JK, Dunn LB, Kober K, Langford DJ, West C, Cooper BA, Paul SM, Miaskowski C. Associations between catecholaminergic, GABAergic, and serotonergic genes and self-reported attentional function in oncology patients and their family caregivers. Eur J Oncol Nurs 2014; 19:251-9. [PMID: 25524657 DOI: 10.1016/j.ejon.2014.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Accepted: 11/19/2014] [Indexed: 11/28/2022]
Abstract
PURPOSE OF THE RESEARCH Evaluate for associations between variations in genes involved in catecholaminergic, gamma-aminobutyric acid (GABA)-ergic, and serotonergic mechanisms of neurotransmission and attentional function latent classes. PATIENTS AND METHODS This descriptive, longitudinal study was conducted at two radiation therapy departments. The sample included three latent classes of individuals with distinct trajectories of self-reported attentional function during radiation therapy, who were previously identified using growth mixture modeling among 167 oncology patients and 85 of their family caregivers. Multivariable models were used to evaluate for genotypic associations of neurotransmission genes with attentional function latent class membership, after controlling for covariates. RESULTS Variations in catecholaminergic (i.e., ADRA1D rs4815675, SLC6A3 rs37022), GABAergic (i.e., SLC6A1 rs2697138), and serotonergic (i.e., HTR2A rs2296972, rs9534496) neurotransmission genes were significant predictors of latent class membership in multivariable models. CONCLUSIONS Findings suggest that variations in genes that encode for three distinct but related neurotransmission systems are involved in alterations in attentional function. Knowledge of both phenotypic and genetic markers associated with alterations in attentional function can be used by clinicians to identify patients and family caregivers who are at higher risk for this symptom. Increased understanding of the genetic markers associated with alterations in attentional function may provide insights into the underlying mechanisms for this significant clinical problem.
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Affiliation(s)
- John D Merriman
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA.
| | - Bradley E Aouizerat
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA; Institute for Human Genetics, University of California, San Francisco, 513 Parnassus Avenue, Box 0794, San Francisco, CA 94143-0794, USA.
| | - Janine K Cataldo
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA.
| | - Laura B Dunn
- School of Medicine, University of California, San Francisco, 513 Parnassus Avenue, Box 0410, San Francisco, CA 94143-0410, USA.
| | - Kord Kober
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA.
| | - Dale J Langford
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA.
| | - Claudia West
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA.
| | - Bruce A Cooper
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA.
| | - Steven M Paul
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA.
| | - Christine Miaskowski
- School of Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, San Francisco, CA 94143-0610, USA.
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McKenna JT, Yang C, Franciosi S, Winston S, Abarr KK, Rigby MS, Yanagawa Y, McCarley RW, Brown RE. Distribution and intrinsic membrane properties of basal forebrain GABAergic and parvalbumin neurons in the mouse. J Comp Neurol 2013; 521:1225-50. [PMID: 23254904 DOI: 10.1002/cne.23290] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 10/31/2012] [Accepted: 12/12/2012] [Indexed: 12/14/2022]
Abstract
The basal forebrain (BF) strongly regulates cortical activation, sleep homeostasis, and attention. Many BF neurons involved in these processes are GABAergic, including a subpopulation of projection neurons containing the calcium-binding protein, parvalbumin (PV). However, technical difficulties in identification have prevented a precise mapping of the distribution of GABAergic and GABA/PV+ neurons in the mouse or a determination of their intrinsic membrane properties. Here we used mice expressing fluorescent proteins in GABAergic (GAD67-GFP knock-in mice) or PV+ neurons (PV-Tomato mice) to study these neurons. Immunohistochemical staining for GABA in GAD67-GFP mice confirmed that GFP selectively labeled BF GABAergic neurons. GFP+ neurons and fibers were distributed throughout the BF, with the highest density in the magnocellular preoptic area (MCPO). Immunohistochemistry for PV indicated that the majority of PV+ neurons in the BF were large (>20 μm) or medium-sized (15-20 μm) GFP+ neurons. Most medium and large-sized BF GFP+ neurons, including those retrogradely labeled from the neocortex, were fast-firing and spontaneously active in vitro. They exhibited prominent hyperpolarization-activated inward currents and subthreshold "spikelets," suggestive of electrical coupling. PV+ neurons recorded in PV-Tomato mice had similar properties but had significantly narrower action potentials and a higher maximal firing frequency. Another population of smaller GFP+ neurons had properties similar to striatal projection neurons. The fast firing and electrical coupling of BF GABA/PV+ neurons, together with their projections to cortical interneurons and the thalamic reticular nucleus, suggest a strong and synchronous control of the neocortical fast rhythms typical of wakefulness and REM sleep.
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Affiliation(s)
- James T McKenna
- Laboratory of Neuroscience, VA Boston Healthcare System and Harvard Medical School, Department of Psychiatry, Brockton, Massachusetts, 02301, USA
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Muller JF, Mascagni F, Zaric V, McDonald AJ. Muscarinic cholinergic receptor M1 in the rat basolateral amygdala: ultrastructural localization and synaptic relationships to cholinergic axons. J Comp Neurol 2013; 521:1743-59. [PMID: 23559406 DOI: 10.1002/cne.23254] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 09/20/2012] [Accepted: 10/25/2012] [Indexed: 02/02/2023]
Abstract
Muscarinic neurotransmission in the anterior basolateral amygdalar nucleus (BLa) mediated by the M1 receptor (M1R) is critical for memory consolidation. Although knowledge of the subcellular localization of M1R in the BLa would contribute to an understanding of cholinergic mechanisms involved in mnemonic function, there have been no ultrastructural studies of this receptor in the BLa. In the present investigation, immunocytochemistry at the electron microscopic level was used to determine which structures in the BLa express M1R. The innervation of these structures by cholinergic axons expressing the vesicular acetylcholine transporter (VAChT) was also studied. All perikarya of pyramidal neurons were labeled, and about 90% of dendritic shafts and 60% of dendritic spines were M1R+. Some dendrites had spines suggesting that they belonged to pyramidal cells, whereas others had morphological features typical of interneurons. M1R immunoreactivity (M1R-ir) was also seen in axon terminals, most of which formed asymmetrical synapses. The main targets of M1R+ terminals forming asymmetrical synapses were dendritic spines, most of which were M1R+. The main targets of M1R+ terminals forming symmetrical synapses were M1R+ perikarya and dendritic shafts. About three-quarters of VAChT+ cholinergic terminals formed synapses; the main postsynaptic targets were M1R+ dendritic shafts and spines. In some cases M1R-ir was seen near the postsynaptic membrane of these processes, but in other cases it was found outside of the active zone of VAChT+ synapses. These findings suggest that M1R mechanisms in the BLa are complex, involving postsynaptic effects as well as regulating release of neurotransmitters from presynaptic terminals.
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Affiliation(s)
- Jay F Muller
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina 29208, USA
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Waider J, Proft F, Langlhofer G, Asan E, Lesch KP, Gutknecht L. GABA concentration and GABAergic neuron populations in limbic areas are differentially altered by brain serotonin deficiency in Tph2 knockout mice. Histochem Cell Biol 2012; 139:267-81. [PMID: 23052836 DOI: 10.1007/s00418-012-1029-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2012] [Indexed: 12/21/2022]
Abstract
While tryptophan hydroxylase-2 (Tph2) null mutant (Tph2(-/-)) mice are completely deficient in brain serotonin (5-HT) synthesis, the formation of serotonergic neurons and pathfinding of their projections are not impaired. However, 5-HT deficiency, during development and in the adult, might affect morphological and functional parameters of other neural systems. To assess the influence of 5-HT deficiency on γ-amino butyric acid (GABA) systems, we carried out measurements of GABA concentrations in limbic brain regions of adult male wildtype (wt), heterozygous (Tph2(+/-)) and Tph2(-/-) mice. In addition, unbiased stereological estimation of GABAergic interneuron numbers and density was performed in subregions of amygdala and hippocampus. Amygdala and prefrontal cortex displayed significantly increased and decreased GABA concentrations, respectively, exclusively in Tph2(+/-) mice while no changes were detected between Tph2(-/-) and wt mice. In contrast, in the hippocampus, increased GABA concentrations were found in Tph2(-/-) mice. While total cell density in the anterior basolateral amygdala did not differ between genotypes, the number and density of the GABAergic interneurons were significantly decreased in Tph2(-/-) mice, with the group of parvalbumin (PV)-immunoreactive (ir) interneurons contributing somewhat less to the decrease than that of non-PV-ir GABAergic interneurons. Major morphological changes were also absent in the dorsal hippocampus, and only a trend toward reduced density of PV-ir cells was observed in the CA3 region of Tph2(-/-) mice. Our findings are the first to document that life-long reduction or complete lack of brain 5-HT transmission causes differential changes of GABA systems in limbic regions which are key players in emotional learning and memory processes. The changes likely reflect a combination of developmental alterations and functional adaptations of emotion circuits to balance the lack of 5-HT, and may underlie altered emotional behavior in 5-HT-deficient mice. Taken together, our findings provide further insight into the mechanisms how life-long 5-HT deficiency impacts the pathogenesis of anxiety- and fear-related disorders.
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Affiliation(s)
- Jonas Waider
- Laboratory of Translational Neuroscience, Division of Molecular Psychiatry, Department of Psychiatry, Psychosomatics, and Psychotherapy, University of Wuerzburg, Fuechsleinstrasse 15, 97080 Wuerzburg, Germany.
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McDonald AJ, Mascagni F, Zaric V. Subpopulations of somatostatin-immunoreactive non-pyramidal neurons in the amygdala and adjacent external capsule project to the basal forebrain: evidence for the existence of GABAergic projection neurons in the cortical nuclei and basolateral nuclear complex. Front Neural Circuits 2012; 6:46. [PMID: 22837739 PMCID: PMC3402756 DOI: 10.3389/fncir.2012.00046] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 07/06/2012] [Indexed: 11/13/2022] Open
Abstract
The hippocampus and amygdala are key structures of the limbic system whose connections include reciprocal interactions with the basal forebrain (BF). The hippocampus receives both cholinergic and GABAergic afferents from the medial septal area of the BF. Hippocampal projections back to the medial septal area arise from non-pyramidal GABAergic neurons that express somatostatin (SOM), calbindin (CB), and neuropeptide Y (NPY). Recent experiments in our lab have demonstrated that the basolateral amygdala, like the hippocampus, receives both cholinergic and GABAergic afferents from the BF. These projections arise from neurons in the substantia innominata (SI) and ventral pallidum (VP). It remained to be determined, however, whether the amygdala has projections back to the BF that arise from GABAergic non-pyramidal neurons. This question was investigated in the present study by combining Fluorogold (FG) retrograde tract tracing with immunohistochemistry for GABAergic non-pyramidal cell markers, including SOM, CB, NPY, parvalbumin, calretinin, and glutamic acid decarboxylase (GAD). FG injections into the BF produced a diffuse array of retrogradely labeled neurons in many nuclei of the amygdala. The great majority of amygdalar FG+ neurons did not express non-pyramidal cell markers. However, a subpopulation of non-pyramidal SOM+ neurons, termed “long-range non-pyramidal neurons” (LRNP neurons), in the external capsule, basolateral amygdala, and cortical and medial amygdalar nuclei were FG+. About one-third of the SOM+ LRNP neurons were CB+ or NPY+, and one-half were GAD+. It remains to be determined if these inhibitory amygdalar projections to the BF, like those from the hippocampus, are important for regulating synchronous oscillations in the amygdalar-BF network.
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Affiliation(s)
- Alexander J McDonald
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine Columbia, SC, USA
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Synaptic transmission changes in fear memory circuits underlie key features of an animal model of schizophrenia. Behav Brain Res 2012; 227:184-93. [DOI: 10.1016/j.bbr.2011.10.050] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 10/26/2011] [Accepted: 10/31/2011] [Indexed: 12/26/2022]
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