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Joyce MKP, Wang J, Barbas H. Subgenual and Hippocampal Pathways in Amygdala Are Set to Balance Affect and Context Processing. J Neurosci 2023; 43:3061-3080. [PMID: 36977583 PMCID: PMC10146557 DOI: 10.1523/jneurosci.2066-22.2023] [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: 11/05/2022] [Revised: 03/02/2023] [Accepted: 03/13/2023] [Indexed: 03/30/2023] Open
Abstract
The amygdala, hippocampus, and subgenual cortex area 25 (A25) are engaged in complex cognitive-emotional processes. Yet pathway interactions from hippocampus and A25 with postsynaptic sites in amygdala remain largely unknown. In rhesus monkeys of both sexes, we studied with neural tracers how pathways from A25 and hippocampus interface with excitatory and inhibitory microcircuits in amygdala at multiple scales. We found that both hippocampus and A25 innervate distinct as well as overlapping sites of the basolateral (BL) amygdalar nucleus. Unique hippocampal pathways heavily innervated the intrinsic paralaminar basolateral nucleus, which is associated with plasticity. In contrast, orbital A25 preferentially innervated another intrinsic network, the intercalated masses, an inhibitory reticulum that gates amygdalar autonomic output and inhibits fear-related behaviors. Finally, using high-resolution confocal and electron microscopy (EM), we found that among inhibitory postsynaptic targets in BL, both hippocampal and A25 pathways preferentially formed synapses with calretinin (CR) neurons, which are known for disinhibition and may enhance excitatory drive in the amygdala. Among other inhibitory postsynaptic sites, A25 pathways innervated the powerful parvalbumin (PV) neurons which may flexibly regulate the gain of neuronal assemblies in the BL that affect the internal state. In contrast, hippocampal pathways innervated calbindin (CB) inhibitory neurons, which modulate specific excitatory inputs for processing context and learning correct associations. Common and unique patterns of innervation in amygdala by hippocampus and A25 have implications for how complex cognitive and emotional processes may be selectively disrupted in psychiatric disorders.SIGNIFICANCE STATEMENT The hippocampus, subgenual A25, and amygdala are associated with learning, memory, and emotions. We found that A25 is poised to affect diverse amygdalar processes, from emotional expression to fear learning by innervating the basal complex and the intrinsic intercalated masses. Hippocampal pathways uniquely interacted with another intrinsic amygdalar nucleus which is associated with plasticity, suggesting flexible processing of signals in context for learning. In the basolateral (BL) amygdala, which has a role in fear learning, both hippocampal and A25 interacted preferentially with disinhibitory neurons, suggesting a boost in excitation. The two pathways diverged in innervating other classes of inhibitory neurons, suggesting circuit specificities that could become perturbed in psychiatric diseases.
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Affiliation(s)
- Mary Kate P Joyce
- Neural Systems Laboratory, Department of Health Sciences, Boston University, Boston, Massachusetts 022152
- Graduate Program in Neuroscience, Boston University and School of Medicine, Boston, Massachusetts 02118
| | - Jingyi Wang
- Neural Systems Laboratory, Department of Health Sciences, Boston University, Boston, Massachusetts 022152
| | - Helen Barbas
- Neural Systems Laboratory, Department of Health Sciences, Boston University, Boston, Massachusetts 022152
- Graduate Program in Neuroscience, Boston University and School of Medicine, Boston, Massachusetts 02118
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts 02118
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Radulovic J, Ivkovic S, Adzic M. From chronic stress and anxiety to neurodegeneration: Focus on neuromodulation of the axon initial segment. HANDBOOK OF CLINICAL NEUROLOGY 2022; 184:481-495. [PMID: 35034756 DOI: 10.1016/b978-0-12-819410-2.00025-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
To adapt to the sustained demands of chronic stress, discrete brain circuits undergo structural and functional changes often resulting in anxiety disorders. In some individuals, anxiety disorders precede the development of motor symptoms of Parkinson's disease (PD) caused by degeneration of neurons in the substantia nigra (SN). Here, we present a circuit framework for probing a causal link between chronic stress, anxiety, and PD, which postulates a central role of abnormal neuromodulation of the SN's axon initial segment by brainstem inputs. It is grounded in findings demonstrating that the earliest PD pathologies occur in the stress-responsive, emotion regulation network of the brainstem, which provides the SN with dense aminergic and cholinergic innervation. SN's axon initial segment (AIS) has unique features that support the sustained and bidirectional propagation of activity in response to synaptic inputs. It is therefore, especially sensitive to circuit-mediated stress-induced imbalance of neuromodulation, and thus a plausible initiating site of neurodegeneration. This could explain why, although secondary to pathophysiologies in other brainstem nuclei, SN degeneration is the most extensive. Consequently, the cardinal symptom of PD, severe motor deficits, arise from degeneration of the nigrostriatal pathway rather than other brainstem nuclei. Understanding when and how circuit dysfunctions underlying anxiety can progress to neurodegeneration, raises the prospect of timed interventions for reversing, or at least impeding, the early pathophysiologies that lead to PD and possibly other neurodegenerative disorders.
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Affiliation(s)
- Jelena Radulovic
- Department of Neuroscience, Albert Einstein Medical College, Bronx, NY, United States; Department of Psychiatry and Behavioral Sciences, Albert Einstein Medical College, Bronx, NY, United States.
| | - Sanja Ivkovic
- Department of Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Miroslav Adzic
- Department of Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
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Saha R, Kriebel M, Anunu R, Volkmer H, Richter-Levin G. Intra-amygdala metaplasticity modulation of fear extinction learning. Eur J Neurosci 2020; 55:2455-2463. [PMID: 33305403 DOI: 10.1111/ejn.15080] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/03/2020] [Accepted: 12/04/2020] [Indexed: 12/22/2022]
Abstract
The amygdala is a key brain region involved in emotional memory formation. It is also responsible for memory modulation in other brain areas. Under extreme conditions, amygdala modulation may lead to the generation of abnormal plasticity and trauma-related psychopathologies. However, the amygdala itself is a dynamic brain region, which is amenable to long-term plasticity and is affected by emotional experiences. These alterations may modify the way the amygdala modulates activity and plasticity in other related brain regions, which in turn may alter the animal's response to subsequent challenges in what could be termed as "Behavioral metaplasticity."Because of the reciprocal interactions between the amygdala and other emotion processing regions, such as the medial prefrontal cortex (mPFC) or the hippocampus, experience-induced intra-amygdala metaplasticity could lead to alterations in mPFC-dependent or hippocampus-dependent behaviors. While initiated by alterations within the basolateral amygdala (BLA), such alterations in other brain regions may come to be independent of BLA modulation, thus establishing what may be termed "Trans-regional metaplasticity." In this article, we review evidence supporting the notions of intra-BLA metaplasticity and how this may develop into "Trans-regional metaplasticity." Future research is needed to understand how such dynamic metaplastic alterations contribute to developing psychopathologies, and how this knowledge may be translated into promoting novel interventions in psychopathologies associated with fear, stress, and trauma.
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Affiliation(s)
- Rinki Saha
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Martin Kriebel
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Tübingen, Germany
| | - Rachel Anunu
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Hansjuergen Volkmer
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Tübingen, Germany
| | - Gal Richter-Levin
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel.,Department of Psychology, University of Haifa, Haifa, Israel.,The Integrated Brain and Behavior Research Center (IBBRC), University of Haifa, Haifa, Israel
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GABAergic Transmission in the Basolateral Amygdala Differentially Modulates Plasticity in the Dentate Gyrus and the CA1 Areas. Int J Mol Sci 2020; 21:ijms21113786. [PMID: 32471158 PMCID: PMC7312428 DOI: 10.3390/ijms21113786] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/22/2020] [Accepted: 05/25/2020] [Indexed: 11/17/2022] Open
Abstract
The term "metaplasticity" is used to describe changes in synaptic plasticity sensitivity following an electrical, biochemical, or behavioral priming stimulus. For example, priming the basolateral amygdala (BLA) enhances long-term potentiation (LTP) in the dentate gyrus (DG) but decreases LTP in the CA1. However, the mechanisms underlying these metaplastic effects are only partly understood. Here, we examined whether the mechanism underlying these effects of BLA priming involves intra-BLA GABAergic neurotransmission. Low doses of muscimol, a GABAA receptor (GABAAR) agonist, were microinfused into the rat BLA before or after BLA priming. Our findings show that BLA GABAAR activation via muscimol mimicked the previously reported effects of electrical BLA priming on LTP in the perforant path and the ventral hippocampal commissure-CA1 pathways, decreasing CA1 LTP and increasing DG LTP. Furthermore, muscimol application before or after tetanic stimulation of the ventral hippocampal commissure-CA1 pathways attenuated the BLA priming-induced decrease in CA1 LTP. In contrast, muscimol application after tetanic stimulation of the perforant path attenuated the BLA priming-induced increase in DG LTP. The data indicate that GABAAR activation mediates metaplastic effects of the BLA on plasticity in the CA1 and the DG, but that the same GABAAR activation induces an intra-BLA form of metaplasticity, which alters the way BLA priming may modulate plasticity in other brain regions. These results emphasize the need for developing a dynamic model of BLA modulation of plasticity, a model that may better capture processes underlying memory alterations associated with emotional arousing or stressful events.
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The basolateral amygdala orexin 1 and 2 receptors’ involvement in modulating spatial reference memory. Brain Res 2019; 1704:16-25. [DOI: 10.1016/j.brainres.2018.09.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 08/28/2018] [Accepted: 09/15/2018] [Indexed: 01/05/2023]
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Alpizar SA, Baker AL, Gulledge AT, Hoppa MB. Loss of Neurofascin-186 Disrupts Alignment of AnkyrinG Relative to Its Binding Partners in the Axon Initial Segment. Front Cell Neurosci 2019; 13:1. [PMID: 30723396 PMCID: PMC6349729 DOI: 10.3389/fncel.2019.00001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 01/07/2019] [Indexed: 12/14/2022] Open
Abstract
The axon initial segment (AIS) is a specialized region within the proximal portion of the axon that initiates action potentials thanks in large part to an enrichment of sodium channels. The scaffolding protein ankyrinG (AnkG) is essential for the recruitment of sodium channels as well as several other intracellular and extracellular proteins to the AIS. In the present study, we explore the role of the cell adhesion molecule (CAM) neurofascin-186 (NF-186) in arranging the individual molecular components of the AIS in cultured rat hippocampal neurons. Using a CRISPR depletion strategy to ablate NF expression, we found that the loss of NF selectively perturbed AnkG accumulation and its relative proximal distribution within the AIS. We found that the overexpression of sodium channels could restore AnkG accumulation, but not its altered distribution within the AIS without NF present. We go on to show that although the loss of NF altered AnkG distribution, sodium channel function within the AIS remained normal. Taken together, these results demonstrate that the regulation of AnkG and sodium channel accumulation within the AIS can occur independently of one another, potentially mediated by other binding partners such as NF.
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Affiliation(s)
- Scott A Alpizar
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
| | - Arielle L Baker
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, United States
| | - Allan T Gulledge
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, United States
| | - Michael B Hoppa
- Department of Biological Sciences, Dartmouth College, Hanover, NH, United States
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Babaev O, Piletti Chatain C, Krueger-Burg D. Inhibition in the amygdala anxiety circuitry. Exp Mol Med 2018; 50:1-16. [PMID: 29628509 PMCID: PMC5938054 DOI: 10.1038/s12276-018-0063-8] [Citation(s) in RCA: 172] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 01/09/2023] Open
Abstract
Inhibitory neurotransmission plays a key role in anxiety disorders, as evidenced by the anxiolytic effect of the benzodiazepine class of γ-aminobutyric acid (GABA) receptor agonists and the recent discovery of anxiety-associated variants in the molecular components of inhibitory synapses. Accordingly, substantial interest has focused on understanding how inhibitory neurons and synapses contribute to the circuitry underlying adaptive and pathological anxiety behaviors. A key element of the anxiety circuitry is the amygdala, which integrates information from cortical and thalamic sensory inputs to generate fear and anxiety-related behavioral outputs. Information processing within the amygdala is heavily dependent on inhibitory control, although the specific mechanisms by which amygdala GABAergic neurons and synapses regulate anxiety-related behaviors are only beginning to be uncovered. Here, we summarize the current state of knowledge and highlight open questions regarding the role of inhibition in the amygdala anxiety circuitry. We discuss the inhibitory neuron subtypes that contribute to the processing of anxiety information in the basolateral and central amygdala, as well as the molecular determinants, such as GABA receptors and synapse organizer proteins, that shape inhibitory synaptic transmission within the anxiety circuitry. Finally, we conclude with an overview of current and future approaches for converting this knowledge into successful treatment strategies for anxiety disorders.
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Affiliation(s)
- Olga Babaev
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str. 3, 37075, Göttingen, Germany
| | - Carolina Piletti Chatain
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str. 3, 37075, Göttingen, Germany
| | - Dilja Krueger-Burg
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str. 3, 37075, Göttingen, Germany.
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Saha R, Kriebel M, Volkmer H, Richter-Levin G, Albrecht A. Neurofascin Knock Down in the Basolateral Amygdala Mediates Resilience of Memory and Plasticity in the Dorsal Dentate Gyrus Under Stress. Mol Neurobiol 2018; 55:7317-7326. [DOI: 10.1007/s12035-018-0930-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 01/24/2018] [Indexed: 11/24/2022]
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