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Palchaudhuri S, Osypenko D, Schneggenburger R. Fear Learning: An Evolving Picture for Plasticity at Synaptic Afferents to the Amygdala. Neuroscientist 2024; 30:87-104. [PMID: 35822657 DOI: 10.1177/10738584221108083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Unraveling the neuronal mechanisms of fear learning might allow neuroscientists to make links between a learned behavior and the underlying plasticity at specific synaptic connections. In fear learning, an innocuous sensory event such as a tone (called the conditioned stimulus, CS) acquires an emotional value when paired with an aversive outcome (unconditioned stimulus, US). Here, we review earlier studies that have shown that synaptic plasticity at thalamic and cortical afferents to the lateral amygdala (LA) is critical for the formation of auditory-cued fear memories. Despite the early progress, it has remained unclear whether there are separate synaptic inputs that carry US information to the LA to act as a teaching signal for plasticity at CS-coding synapses. Recent findings have begun to fill this gap by showing, first, that thalamic and cortical auditory afferents can also carry US information; second, that the release of neuromodulators contributes to US-driven teaching signals; and third, that synaptic plasticity additionally happens at connections up- and downstream of the LA. Together, a picture emerges in which coordinated synaptic plasticity in serial and parallel circuits enables the formation of a finely regulated fear memory.
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Affiliation(s)
- Shriya Palchaudhuri
- Laboratory of Synaptic Mechanisms, Brain Mind Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Denys Osypenko
- Laboratory of Synaptic Mechanisms, Brain Mind Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Ralf Schneggenburger
- Laboratory of Synaptic Mechanisms, Brain Mind Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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2
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Alkadhi KA. NMDA receptor-independent LTP in mammalian nervous system. Prog Neurobiol 2021; 200:101986. [PMID: 33400965 DOI: 10.1016/j.pneurobio.2020.101986] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 12/16/2020] [Accepted: 12/28/2020] [Indexed: 11/17/2022]
Abstract
Long-term potentiation (LTP) of synaptic transmission is a form of activity-dependent synaptic plasticity that exists at most synapses in the nervous system. In the central nervous system (CNS), LTP has been recorded at numerous synapses and is a prime candidate mechanism associating activity-dependent plasticity with learning and memory. LTP involves long-lasting increase in synaptic strength with various underlying mechanisms. In the CNS, the predominant type of LTP is believed to be dependent on activation of the ionotropic glutamate N-methyl-D-aspartate receptor (NMDAR), which is highly calcium-permeable. However, various forms of NMDAR-independent LTP have been identified in diverse areas of the nervous system. The NMDAR-independent LTP may require activation of glutamate metabotropic receptors (mGluR) or ionotropic receptors other than NMDAR such as nicotinic acetylcholine receptor (α7-nAChR), serotonin 5-HT3 receptor or calcium-permeable AMPA receptor (CP-AMPAR). In this review, NMDAR-independent LTP of various areas of the central and peripheral nervous systems are discussed.
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Affiliation(s)
- Karim A Alkadhi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX, 77204, USA.
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3
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Nikolenko VN, Oganesyan MV, Rizaeva NA, Kudryashova VA, Nikitina AT, Pavliv MP, Shchedrina MA, Giller DB, Bulygin KV, Sinelnikov MY. Amygdala: Neuroanatomical and Morphophysiological Features in Terms of Neurological and Neurodegenerative Diseases. Brain Sci 2020; 10:brainsci10080502. [PMID: 32751957 PMCID: PMC7465610 DOI: 10.3390/brainsci10080502] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 07/25/2020] [Accepted: 07/30/2020] [Indexed: 01/07/2023] Open
Abstract
The amygdala is one of the most discussed structures of the brain. Correlations between its level of activity, size, biochemical organization, and various pathologies are the subject of many studies, and can serve as a marker of existing or future disease. It is hypothesized that the amygdala is not just a structural unit, but includes many other regions in the brain. In this review, we present the updated neuroanatomical and physiological aspects of the amygdala, discussing its involvement in neurodegenerative and neurological diseases. The amygdala plays an important role in the processing of input signals and behavioral synthesis. Lesions in the amygdala have been shown to cause neurological disfunction of ranging severity. Abnormality in the amygdala leads to conditions such as depression, anxiety, autism, and also promotes biochemical and physiological imbalance. The amygdala collects pathological proteins, and this fact can be considered to play a big role in the progression and diagnosis of many degenerative diseases, such as Alzheimer’s disease, chronic traumatic encephalopathy, Lewy body diseases, and hippocampal sclerosis. The amygdala has shown to play a crucial role as a central communication system in the brain, therefore understanding its neuroanatomical and physiological features can open a channel for targeted therapy of neurodegenerative diseases.
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Affiliation(s)
- Vladimir N. Nikolenko
- Department of Human Anatomy, Sechenov University, 119991 Moscow, Russia; (V.N.N.); (M.V.O.); (N.A.R.); (V.A.K.); (D.B.G.); (K.V.B.)
- Department of Human Anatomy, Moscow State University, 119991 Moscow, Russia
| | - Marine V. Oganesyan
- Department of Human Anatomy, Sechenov University, 119991 Moscow, Russia; (V.N.N.); (M.V.O.); (N.A.R.); (V.A.K.); (D.B.G.); (K.V.B.)
| | - Negoriya A. Rizaeva
- Department of Human Anatomy, Sechenov University, 119991 Moscow, Russia; (V.N.N.); (M.V.O.); (N.A.R.); (V.A.K.); (D.B.G.); (K.V.B.)
| | - Valentina A. Kudryashova
- Department of Human Anatomy, Sechenov University, 119991 Moscow, Russia; (V.N.N.); (M.V.O.); (N.A.R.); (V.A.K.); (D.B.G.); (K.V.B.)
| | - Arina T. Nikitina
- International School “Medicine of Future”, Sechenov University, 119991 Moscow, Russia; (A.T.N.); (M.P.P.)
| | - Maria P. Pavliv
- International School “Medicine of Future”, Sechenov University, 119991 Moscow, Russia; (A.T.N.); (M.P.P.)
| | - Marina A. Shchedrina
- Institute for Regenerative Medicine, Sechenov University, 119991 Moscow, Russia;
| | - Dmitry B. Giller
- Department of Human Anatomy, Sechenov University, 119991 Moscow, Russia; (V.N.N.); (M.V.O.); (N.A.R.); (V.A.K.); (D.B.G.); (K.V.B.)
| | - Kirill V. Bulygin
- Department of Human Anatomy, Sechenov University, 119991 Moscow, Russia; (V.N.N.); (M.V.O.); (N.A.R.); (V.A.K.); (D.B.G.); (K.V.B.)
- Department of Human Anatomy, Moscow State University, 119991 Moscow, Russia
| | - Mikhail Y. Sinelnikov
- Institute for Regenerative Medicine, Sechenov University, 119991 Moscow, Russia;
- Correspondence: ; Tel.: +7-89199688587
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4
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Associative and plastic thalamic signaling to the lateral amygdala controls fear behavior. Nat Neurosci 2020; 23:625-637. [PMID: 32284608 DOI: 10.1038/s41593-020-0620-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 03/05/2020] [Indexed: 01/21/2023]
Abstract
Decades of research support the idea that associations between a conditioned stimulus (CS) and an unconditioned stimulus (US) are encoded in the lateral amygdala (LA) during fear learning. However, direct proof for the sources of CS and US information is lacking. Definitive evidence of the LA as the primary site for cue association is also missing. Here, we show that calretinin (Calr)-expressing neurons of the lateral thalamus (Calr+LT neurons) convey the association of fast CS (tone) and US (foot shock) signals upstream from the LA in mice. Calr+LT input shapes a short-latency sensory-evoked activation pattern of the amygdala via both feedforward excitation and inhibition. Optogenetic silencing of Calr+LT input to the LA prevents auditory fear conditioning. Notably, fear conditioning drives plasticity in Calr+LT neurons, which is required for appropriate cue and contextual fear memory retrieval. Collectively, our results demonstrate that Calr+LT neurons provide integrated CS-US representations to the LA that support the formation of aversive memories.
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Polepalli JS, Gooch H, Sah P. Diversity of interneurons in the lateral and basal amygdala. NPJ SCIENCE OF LEARNING 2020; 5:10. [PMID: 32802405 PMCID: PMC7400739 DOI: 10.1038/s41539-020-0071-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 05/29/2020] [Indexed: 05/06/2023]
Abstract
The basolateral amygdala (BLA) is a temporal lobe structure that contributes to a host of behaviors. In particular, it is a central player in learning about aversive events and thus assigning emotional valence to sensory events. It is a cortical-like structure and contains glutamatergic pyramidal neurons and GABAergic interneurons. It is divided into the lateral (LA) and basal (BA) nuclei that have distinct cell types and connections. Interneurons in the BLA are a heterogenous population, some of which have been implicated in specific functional roles. Here we use optogenetics and slice electrophysiology to investigate the innervation, postsynaptic receptor stoichiometry, and plasticity of excitatory inputs onto interneurons within the BLA. Interneurons were divided into six groups based on their discharge properties, each of which received input from the auditory thalamus (AT) and auditory cortex (AC). Auditory innervation was concentrated in the LA, and optogenetic stimulation evoked robust synaptic responses in nearly all interneurons, drove many cells to threshold, and evoked disynaptic inhibition in most interneurons. Auditory input to the BA was sparse, innervated fewer interneurons, and evoked smaller synaptic responses. Biophysically, the subunit composition and distribution of AMPAR and NMDAR also differed between the two nuclei, with fewer BA IN expressing calcium permeable AMPAR, and a higher proportion expressing GluN2B-containing NMDAR. Finally, unlike LA interneurons, LTP could not be induced in the BA. These findings show that interneurons in the LA and BA are physiologically distinct populations and suggest they may have differing roles during associative learning.
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Affiliation(s)
- Jai S. Polepalli
- Queensland Brain Institute, University of Queensland, St Lucia, QLD 4072 Australia
- Department of Anatomy, Yong Yoo Lin School of Medicine, National University of Singapore, Singapore, 117594 Singapore
| | - Helen Gooch
- Queensland Brain Institute, University of Queensland, St Lucia, QLD 4072 Australia
| | - Pankaj Sah
- Queensland Brain Institute, University of Queensland, St Lucia, QLD 4072 Australia
- Brain Research Centre and Department of Biology, Southern University of Science and Technology, Nanshan District, Shenzhen, Guangdong Province P.R. China
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6
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Johnson LR, Battle AR, Martinac B. Remembering Mechanosensitivity of NMDA Receptors. Front Cell Neurosci 2019; 13:533. [PMID: 31866826 PMCID: PMC6906178 DOI: 10.3389/fncel.2019.00533] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 11/18/2019] [Indexed: 12/14/2022] Open
Abstract
An increase in post-synaptic Ca2+ conductance through activation of the ionotropic N-methyl-D-aspartate receptor (NMDAR) and concomitant structural changes are essential for the initiation of long-term potentiation (LTP) and memory formation. Memories can be initiated by coincident events, as occurs in classical conditioning, where the NMDAR can act as a molecular coincidence detector. Binding of glutamate and glycine, together with depolarization of the postsynaptic cell membrane to remove the Mg2+ channel pore block, results in NMDAR opening for Ca2+ conductance. Accumulating evidence has implicated both force-from-lipids and protein tethering mechanisms for mechanosensory transduction in NMDAR, which has been demonstrated by both, membrane stretch and application of amphipathic molecules such as arachidonic acid (AA). The contribution of mechanosensitivity to memory formation and consolidation may be to increase activity of the NMDAR leading to facilitated memory formation. In this review we look back at the progress made toward understanding the physiological and pathological role of NMDA receptor channels in mechanobiology of the nervous system and consider these findings in like of their potential functional implications for memory formation. We examine recent studies identifying mechanisms of both NMDAR and other mechanosensitive channels and discuss functional implications including gain control of NMDA opening probability. Mechanobiology is a rapidly growing area of biology with many important implications for understanding form, function and pathology in the nervous system.
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Affiliation(s)
- Luke R Johnson
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia.,Division of Psychology, School of Medicine, University of Tasmania, Launceston, TAS, Australia.,Department of Psychiatry, Center for the Study of Traumatic Stress, Uniformed Services University of the Health Sciences, Bethesda, MD, United States.,School of Biomedical Sciences, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology, Brisbane, QLD, Australia
| | - Andrew R Battle
- School of Biomedical Sciences, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology, Brisbane, QLD, Australia.,Prince Charles Hospital Northside Clinical Unit, School of Clinical Medicine, The University of Queensland, Brisbane, QLD, Australia.,Translational Research Institute, Woolloongabba, QLD, Australia
| | - Boris Martinac
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia
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Abstract
The activity of neural circuits that underpin particular behaviours are one of the most interesting questions in neurobiology today. This understanding will not only lead to a detailed understanding of learning and memory formation, but also provides a platform for the development of novel therapeutic approaches to a range of neurological disorders that afflict humans. Among the different behavioural paradigms, Pavlovian fear conditioning and its extinction are two of the most extensively used to study acquisition, consolidation and retrieval of fear-related memories. The amygdala, medial prefrontal cortex (mPFC) and hippocampus are three regions with extensive bidirectional connections, and play key roles in fear processing. In this chapter, we summarise our current understanding of the structure and physiological role of these three regions in fear learning and extinction.
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Affiliation(s)
- Roger Marek
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Pankaj Sah
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
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Danielewicz J, Trenk A, Hess G. Imipramine ameliorates early life stress-induced alterations in synaptic plasticity in the rat lateral amygdala. Behav Brain Res 2016; 317:319-326. [PMID: 27693266 DOI: 10.1016/j.bbr.2016.09.065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 12/11/2022]
Abstract
Long-term potentiation (LTP) and long-term depression (LTD) are two opposite forms of synaptic plasticity at the cortical and thalamic inputs to the lateral amygdala (LA). It has been demonstrated that maternal separation (MS) of rat pups results in alterations in the potential for both pathways to undergo LTP and LTD in adolescence. Imipramine, a prototypic tricyclic antidepressant, has been shown to counteract some detrimental effects of MS on rat behavior, however it is not known whether MS-induced alterations in the potential for bidirectional synaptic plasticity in the LA could be reversed by imipramine treatment. To this end, rat pups were subjected to MS (3h/day) on postnatal days (PNDs) 1-21. On each of PNDs 29-42, male rats previously subjected to MS were injected subcutaneously with imipramine (10mg/kg). Field potentials were recorded ex vivo from slices containing the LA and saturating levels of LTP and LTD were induced. At the thalamic input to the LA, both the maximum LTP and the maximum LTD were reduced in rats subjected to MS when compared to control animals, confirming earlier results. However, these effects were no longer present in rats subjected to MS and later treated with imipramine. At the cortical input in slices prepared from MS-subjected rats, an impairment of the maximum LTP and an enhancement of the maximum LTD were observed. At the cortical input in rats subjected to MS and receiving imipramine treatment, the level of LTD was comparable to control but imipramine did not restore the potential for LTP at this input. These results demonstrate that imipramine fully reverses the effects of MS in the thalamo-amygdalar pathway, however, in the cortico-amygdalar pathway the reversal of the effects of MS by imipramine is partial.
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Affiliation(s)
| | | | - Grzegorz Hess
- Institute of Zoology, Jagiellonian University, Krakow, Poland; Institute of Pharmacology, Polish Academy of Sciences, 31-343 Krakow, Smetna street 12, Poland.
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9
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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: 104] [Impact Index Per Article: 11.6] [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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10
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Bosch D, Ehrlich I. Postnatal maturation of GABAergic modulation of sensory inputs onto lateral amygdala principal neurons. J Physiol 2015; 593:4387-409. [PMID: 26227545 DOI: 10.1113/jp270645] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/28/2015] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Throughout life, fear learning is indispensable for survival and neural plasticity in the lateral amygdala underlies this learning and storage of fear memories. During development, properties of fear learning continue to change into adulthood, but currently little is known about changes in amygdala circuits that enable these behavioural transitions. In recordings from neurons in lateral amygdala brain slices from infant up to adult mice, we show that spontaneous and evoked excitatory and inhibitory synaptic transmissions mature into adolescence. At this time, increased inhibitory activity and signalling has the ability to restrict the function of excitation by presynaptic modulation, and may thus enable precise stimulus associations to limit fear generalization from adolescence onward. Our results provide a basis for addressing plasticity mechanisms that underlie altered fear behaviour in young animals. ABSTRACT Convergent evidence suggests that plasticity in the lateral amygdala (LA) participates in acquisition and storage of fear memory. Sensory inputs from thalamic and cortical areas activate principal neurons and local GABAergic interneurons, which provide feed-forward inhibition that tightly controls LA activity and plasticity via pre- and postsynaptic GABAA and GABAB receptors. GABAergic control is also critical during fear expression, generalization and extinction in adult animals. During rodent development, properties of fear and extinction learning continue to change into early adulthood. Currently, few studies have assessed physiological changes in amygdala circuits that may enable these behavioural transitions. To obtain first insights, we investigated changes in spontaneous and sensory input-evoked inhibition onto LA principal neurons and then focused on GABAB receptor-mediated modulation of excitatory sensory inputs in infant, juvenile, adolescent and young adult mice. We found that spontaneous and sensory-evoked inhibition increased during development. Physiological changes were accompanied by changes in dendritic morphology. While GABAB heteroreceptors were functionally expressed on sensory afferents already early in development, they could only be physiologically recruited by sensory-evoked GABA release to mediate heterosynaptic inhibition from adolescence onward. Furthermore, we found GABAB -mediated tonic inhibition of sensory inputs by ambient GABA that also emerged in adolescence. The observed increase in GABAergic drive may be a substrate for providing modulatory GABA. Our data suggest that GABAB -mediated tonic and evoked presynaptic inhibition can suppress sensory input-driven excitation in the LA to enable precise stimulus associations and limit generalization of conditioned fear from adolescence onward.
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Affiliation(s)
- Daniel Bosch
- Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller-Str. 25, 72076, Tuebingen, Germany.,Werner Reichardt Centre for Integrative Neuroscience, University of Tuebingen, Otfried-Mueller-Str. 25, 72076, Tuebingen, Germany
| | - Ingrid Ehrlich
- Hertie Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller-Str. 25, 72076, Tuebingen, Germany.,Werner Reichardt Centre for Integrative Neuroscience, University of Tuebingen, Otfried-Mueller-Str. 25, 72076, Tuebingen, Germany
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11
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Mirante O, Brandalise F, Bohacek J, Mansuy IM. Distinct molecular components for thalamic- and cortical-dependent plasticity in the lateral amygdala. Front Mol Neurosci 2014; 7:62. [PMID: 25071439 PMCID: PMC4080466 DOI: 10.3389/fnmol.2014.00062] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/16/2014] [Indexed: 01/05/2023] Open
Abstract
N-methyl-D-aspartate receptor (NMDAR)-dependent long-term depression (LTD) in the lateral nucleus of the amygdala (LA) is a form of synaptic plasticity thought to be a cellular substrate for the extinction of fear memory. The LA receives converging inputs from the sensory thalamus and neocortex that are weakened following fear extinction. Combining field and patch-clamp electrophysiological recordings in mice, we show that paired-pulse low-frequency stimulation can induce a robust LTD at thalamic and cortical inputs to LA, and we identify different underlying molecular components at these pathways. We show that while LTD depends on NMDARs and activation of the protein phosphatases PP2B and PP1 at both pathways, it requires NR2B-containing NMDARs at the thalamic pathway, but NR2C/D-containing NMDARs at the cortical pathway. LTD appears to be induced post-synaptically at the thalamic input but presynaptically at the cortical input, since post-synaptic calcium chelation and NMDAR blockade prevent thalamic but not cortical LTD. These results highlight distinct molecular features of LTD in LA that may be relevant for traumatic memory and its erasure, and for pathologies such as post-traumatic stress disorder (PTSD).
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Affiliation(s)
- Osvaldo Mirante
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
| | - Federico Brandalise
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland
| | - Johannes Bohacek
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
| | - Isabelle M Mansuy
- Brain Research Institute, Medical Faculty, University Zürich Zürich, Switzerland ; Department of Health Science and Technology, Swiss Federal Institute of Technology Zürich, Switzerland
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12
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Gaier ED, Rodriguiz RM, Zhou J, Ralle M, Wetsel WC, Eipper BA, Mains RE. In vivo and in vitro analyses of amygdalar function reveal a role for copper. J Neurophysiol 2014; 111:1927-39. [PMID: 24554785 DOI: 10.1152/jn.00631.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mice with a single copy of the peptide amidating monooxygenase (Pam) gene (PAM(+/-)) are impaired in contextual and cued fear conditioning. These abnormalities coincide with deficient long-term potentiation (LTP) at excitatory thalamic afferent synapses onto pyramidal neurons in the lateral amygdala. Slice recordings from PAM(+/-) mice identified an increase in GABAergic tone (Gaier ED, Rodriguiz RM, Ma XM, Sivaramakrishnan S, Bousquet-Moore D, Wetsel WC, Eipper BA, Mains RE. J Neurosci 30: 13656-13669, 2010). Biochemical data indicate a tissue-specific deficit in Cu content in the amygdala; amygdalar expression of Atox-1 and Atp7a, essential for transport of Cu into the secretory pathway, is reduced in PAM(+/-) mice. When PAM(+/-) mice were fed a diet supplemented with Cu, the impairments in fear conditioning were reversed, and LTP was normalized in amygdala slice recordings. A role for endogenous Cu in amygdalar LTP was established by the inhibitory effect of a brief incubation of wild-type slices with bathocuproine disulfonate, a highly selective, cell-impermeant Cu chelator. Interestingly, bath-applied CuSO₄ had no effect on excitatory currents but reversibly potentiated the disynaptic inhibitory current. Bath-applied CuSO₄ was sufficient to potentiate wild-type amygdala afferent synapses. The ability of dietary Cu to affect signaling in pathways that govern fear-based behaviors supports an essential physiological role for Cu in amygdalar function at both the synaptic and behavioral levels. This work is relevant to neurological and psychiatric disorders in which disturbed Cu homeostasis could contribute to altered synaptic transmission, including Wilson's, Menkes, Alzheimer's, and prion-related diseases.
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Affiliation(s)
- E D Gaier
- Neuroscience Department, University of Connecticut Health Center, Farmington, Connecticut
| | - R M Rodriguiz
- Department of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina
| | - J Zhou
- Department of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina
| | - M Ralle
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon
| | - W C Wetsel
- Department of Psychiatry and Behavioral Sciences, Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina; Department of Neurobiology, Duke University Medical Center, Durham, North Carolina; and Department of Cell Biology, Duke University Medical Center, Durham, North Carolina
| | - B A Eipper
- Neuroscience Department, University of Connecticut Health Center, Farmington, Connecticut
| | - R E Mains
- Neuroscience Department, University of Connecticut Health Center, Farmington, Connecticut;
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13
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Danielewicz J, Hess G. Early life stress alters synaptic modification range in the rat lateral amygdala. Behav Brain Res 2014; 265:32-7. [PMID: 24556204 DOI: 10.1016/j.bbr.2014.02.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 02/06/2014] [Accepted: 02/10/2014] [Indexed: 02/06/2023]
Abstract
The influence of exposure to early adversity on emotional learning later in life remains poorly understood. Long-term potentiation (LTP) in the cortico-amygdalar and thalamo-amygdalar pathways has been postulated to provide a mechanism of synaptic modifications underlying fear learning and memory. These synapses also express homosynaptic long-term depression (LTD). Here we examined the effects of maternal separation stress on the extent of LTP and LTD which could be induced in the lateral amygdala (LA) of adolescent rats. Rat pups were subjected to maternal separation (MS, 3 h/day) on post-natal days 1-21. Field potentials were recorded ex vivo from slices containing the LA, which were prepared from adolescent males. Saturating levels of LTP and LTD were induced using repeated sequences of theta-burst stimulation and low frequency stimulation, respectively. An impairment of the maximum LTP and an enhancement of the maximum LTD were observed in the cortical input in slices prepared from MS-subjected rats. In the thalamic input, both the maximum LTP and the maximum LTD were reduced when compared to control animals. Thus, in the cortico-amygdalar pathway MS stress shifted the potential for bidirectional synaptic modification toward LTD but it shrank the synaptic modification range in the thalamo-amygdalar pathway.
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Affiliation(s)
| | - Grzegorz Hess
- Institute of Zoology, Jagiellonian University, Krakow, Poland; Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland.
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14
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Sears RM, Schiff HC, LeDoux JE. Molecular Mechanisms of Threat Learning in the Lateral Nucleus of the Amygdala. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 122:263-304. [DOI: 10.1016/b978-0-12-420170-5.00010-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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15
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Suvrathan A, Bennur S, Ghosh S, Tomar A, Anilkumar S, Chattarji S. Stress enhances fear by forming new synapses with greater capacity for long-term potentiation in the amygdala. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130151. [PMID: 24298153 DOI: 10.1098/rstb.2013.0151] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Prolonged and severe stress leads to cognitive deficits, but facilitates emotional behaviour. Little is known about the synaptic basis for this contrast. Here, we report that in rats subjected to chronic immobilization stress, long-term potentiation (LTP) and NMDA receptor (NMDAR)-mediated synaptic responses are enhanced in principal neurons of the lateral amygdala, a brain area involved in fear memory formation. This is accompanied by electrophysiological and morphological changes consistent with the formation of 'silent synapses', containing only NMDARs. In parallel, chronic stress also reduces synaptic inhibition. Together, these synaptic changes would enable amygdalar neurons to undergo further experience-dependent modifications, leading to stronger fear memories. Consistent with this prediction, stressed animals exhibit enhanced conditioned fear. Hence, stress may leave its mark in the amygdala by generating new synapses with greater capacity for plasticity, thereby creating an ideal neuronal substrate for affective disorders. These findings also highlight the unique features of stress-induced plasticity in the amygdala that are strikingly different from the stress-induced impairment of structure and function in the hippocampus.
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Affiliation(s)
- Aparna Suvrathan
- National Centre for Biological Sciences, Bangalore 560065, India
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16
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The basolateral amygdala is critical for learning about neutral stimuli in the presence of danger, and the perirhinal cortex is critical in the absence of danger. J Neurosci 2013; 33:13112-25. [PMID: 23926265 DOI: 10.1523/jneurosci.1998-13.2013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The perirhinal cortex (PRh) and basolateral amygdala (BLA) appear to mediate distinct aspects of learning and memory. Here, we used rats to investigate the involvement of the PRh and BLA in acquisition and extinction of associations between two different environmental stimuli (e.g., a tone and a light) in higher-order conditioning. When both stimuli were neutral, infusion of the GABAA, muscimol, or the NMDA receptor (NMDAR) antagonist ifenprodil into the PRh impaired associative formation. However, when one stimulus was neutral and the other was a learned danger signal, acquisition and extinction of the association between them was unaffected by manipulations targeting the PRh. Temporary inactivation of the BLA had the opposite effect: formation and extinction of an association between two stimuli was spared when both stimuli were neutral, but impaired when one stimulus was a learned danger signal. Subsequent experiments showed that the experience of fear per se shifts processing of an association between neutral stimuli from the PRh to the BLA. When training was conducted in a dangerous environment, formation and extinction of an association between neutral stimuli was impaired by BLA inactivation or NMDAR blockade in this region, but was unaffected by PRh inactivation. These double dissociations in the roles of the PRh and BLA in learning under different stimulus and environmental conditions imply that fear-induced activation of the amygdala changes how the brain processes sensory stimuli. Harmless stimuli are treated as potentially harmful, resulting in a shift from cortical to subcortical processing in the BLA.
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Papoutsi A, Kastellakis G, Psarrou M, Anastasakis S, Poirazi P. Coding and decoding with dendrites. ACTA ACUST UNITED AC 2013; 108:18-27. [PMID: 23727338 DOI: 10.1016/j.jphysparis.2013.05.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 03/26/2013] [Accepted: 05/21/2013] [Indexed: 01/19/2023]
Abstract
Since the discovery of complex, voltage dependent mechanisms in the dendrites of multiple neuron types, great effort has been devoted in search of a direct link between dendritic properties and specific neuronal functions. Over the last few years, new experimental techniques have allowed the visualization and probing of dendritic anatomy, plasticity and integrative schemes with unprecedented detail. This vast amount of information has caused a paradigm shift in the study of memory, one of the most important pursuits in Neuroscience, and calls for the development of novel theories and models that will unify the available data according to some basic principles. Traditional models of memory considered neural cells as the fundamental processing units in the brain. Recent studies however are proposing new theories in which memory is not only formed by modifying the synaptic connections between neurons, but also by modifications of intrinsic and anatomical dendritic properties as well as fine tuning of the wiring diagram. In this review paper we present previous studies along with recent findings from our group that support a key role of dendrites in information processing, including the encoding and decoding of new memories, both at the single cell and the network level.
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Affiliation(s)
- Athanasia Papoutsi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece; Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - George Kastellakis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece; Department of Biology, University of Crete, Heraklion, Crete, Greece
| | - Maria Psarrou
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece
| | - Stelios Anastasakis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece.
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18
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Marek R, Strobel C, Bredy TW, Sah P. The amygdala and medial prefrontal cortex: partners in the fear circuit. J Physiol 2013; 591:2381-91. [PMID: 23420655 DOI: 10.1113/jphysiol.2012.248575] [Citation(s) in RCA: 206] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Fear conditioning and fear extinction are Pavlovian conditioning paradigms extensively used to study the mechanisms that underlie learning and memory formation. The neural circuits that mediate this learning are evolutionarily conserved, and seen in virtually all species from flies to humans. In mammals, the amygdala and medial prefrontal cortex are two structures that play a key role in the acquisition, consolidation and retrieval of fear memory, as well extinction of fear. These two regions have extensive bidirectional connections, and in recent years, the neural circuits that mediate fear learning and fear extinction are beginning to be elucidated. In this review, we provide an overview of our current understanding of the neural architecture within the amygdala and medial prefrontal cortex. We describe how sensory information is processed in these two structures and the neural circuits between them thought to mediate different aspects of fear learning. Finally, we discuss how changes in circuits within these structures may mediate fear responses following fear conditioning and extinction.
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Affiliation(s)
- Roger Marek
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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19
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Delaney AJ, Power JM, Sah P. Ifenprodil reduces excitatory synaptic transmission by blocking presynaptic P/Q type calcium channels. J Neurophysiol 2012; 107:1571-5. [DOI: 10.1152/jn.01066.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ifenprodil is a selective blocker of NMDA receptors that are heterodimers composed of GluN1/GluN2B subunits. This pharmacological profile has been extensively used to test the role of GluN2B-containing NMDA receptors in learning and memory formation. However, ifenprodil has also been reported to have actions at a number of other receptors, including high voltage-activated calcium channels. Here we show that, in the basolateral amygdala, ifenprodil dose dependently blocks excitatory transmission to principal neurons by a presynaptic mechanism. This action of ifenprodil has an IC50 of ∼10 μM and is fully occluded by the P/Q type calcium channel blocker ω-agatoxin. We conclude that ifenprodil reduces synaptic transmission in the basolateral amygdala by partially blocking P-type voltage-dependent calcium channels.
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Affiliation(s)
- Andrew J. Delaney
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - John M. Power
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Pankaj Sah
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
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20
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Negrete-Díaz JV, Duque-Feria P, Andrade-Talavera Y, Carrión M, Flores G, Rodríguez-Moreno A. Kainate receptor-mediated depression of glutamatergic transmission involving protein kinase A in the lateral amygdala. J Neurochem 2012; 121:36-43. [PMID: 22251150 DOI: 10.1111/j.1471-4159.2012.07665.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Kainate receptors (KARs) have been described as modulators of synaptic transmission at different synapses. However, this role of KARs has not been well characterized in the amygdala. We have explored the effect of kainate receptor activation at the synapse established between fibers originating at medial geniculate nucleus and the principal cells in the lateral amygdala. We have observed an inhibition of evoked excitatory postsynaptic currents (eEPSCs) amplitude after a brief application of KARs agonists KA and ATPA. Paired-pulse recordings showed a clear pair pulse facilitation that was enhanced after KA or ATPA application. When postsynaptic cells were loaded with BAPTA, the depression of eEPSC amplitude observed after the perfusion of KAR agonists was not prevented. We have also observed that the inhibition of the eEPSCs by KARs agonists was prevented by protein kinase A but not by protein kinase C inhibitors. Taken together our results indicate that KARs present at this synapse are pre-synaptic and their activation mediate the inhibition of glutamate release through a mechanism that involves the activation of protein kinase A.
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Affiliation(s)
- José Vicente Negrete-Díaz
- Laboratorio de Neurociencia Celular y Plasticidad, Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, Sevilla, Spain
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21
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Effects of elevation of brain magnesium on fear conditioning, fear extinction, and synaptic plasticity in the infralimbic prefrontal cortex and lateral amygdala. J Neurosci 2011; 31:14871-81. [PMID: 22016520 DOI: 10.1523/jneurosci.3782-11.2011] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Anxiety disorders, such as phobias and posttraumatic stress disorder, are among the most common mental disorders. Cognitive therapy helps in treating these disorders; however, many cases relapse or resist the therapy, which justifies the search for cognitive enhancers that might augment the efficacy of cognitive therapy. Studies suggest that enhancement of plasticity in certain brain regions such as the prefrontal cortex (PFC) and/or hippocampus might enhance the efficacy of cognitive therapy. We found that elevation of brain magnesium, by a novel magnesium compound [magnesium-l-threonate (MgT)], enhances synaptic plasticity in the hippocampus and learning and memory in rats. Here, we show that MgT treatment enhances retention of the extinction of fear memory, without enhancing, impairing, or erasing the original fear memory. We then explored the molecular basis of the effects of MgT treatment on fear memory and extinction. In intact animals, elevation of brain magnesium increased NMDA receptors (NMDARs) signaling, BDNF expression, density of presynaptic puncta, and synaptic plasticity in the PFC but, interestingly, not in the basolateral amygdala. In vitro, elevation of extracellular magnesium concentration increased synaptic NMDAR current and plasticity in the infralimbic PFC, but not in the lateral amygdala, suggesting a difference in their sensitivity to elevation of brain magnesium. The current study suggests that elevation of brain magnesium might be a novel approach for enhancing synaptic plasticity in a regional-specific manner leading to enhancing the efficacy of extinction without enhancing or impairing fear memory formation.
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22
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Johnson LR, Hou M, Prager EM, Ledoux JE. Regulation of the Fear Network by Mediators of Stress: Norepinephrine Alters the Balance between Cortical and Subcortical Afferent Excitation of the Lateral Amygdala. Front Behav Neurosci 2011; 5:23. [PMID: 21647395 PMCID: PMC3102213 DOI: 10.3389/fnbeh.2011.00023] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 04/18/2011] [Indexed: 12/01/2022] Open
Abstract
Pavlovian auditory fear conditioning involves the integration of information about an acoustic conditioned stimulus (CS) and an aversive unconditioned stimulus in the lateral nucleus of the amygdala (LA). The auditory CS reaches the LA subcortically via a direct connection from the auditory thalamus and also from the auditory association cortex itself. How neural modulators, especially those activated during stress, such as norepinephrine (NE), regulate synaptic transmission and plasticity in this network is poorly understood. Here we show that NE inhibits synaptic transmission in both the subcortical and cortical input pathway but that sensory processing is biased toward the subcortical pathway. In addition binding of NE to β-adrenergic receptors further dissociates sensory processing in the LA. These findings suggest a network mechanism that shifts sensory balance toward the faster but more primitive subcortical input.
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Affiliation(s)
- Luke R Johnson
- Department of Psychiatry and Program in Neuroscience, Uniformed Services University Bethesda, MD, USA
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23
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Hillman BG, Gupta SC, Stairs DJ, Buonanno A, Dravid SM. Behavioral analysis of NR2C knockout mouse reveals deficit in acquisition of conditioned fear and working memory. Neurobiol Learn Mem 2011; 95:404-14. [PMID: 21295149 PMCID: PMC3432405 DOI: 10.1016/j.nlm.2011.01.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 12/30/2010] [Accepted: 01/21/2011] [Indexed: 12/21/2022]
Abstract
N-methyl-D-aspartate (NMDA) receptors play an important role in excitatory neurotransmission and mediate synaptic plasticity associated with learning and memory. NMDA receptors are composed of two NR1 and two NR2 subunits and the identity of the NR2 subunit confers unique electrophysiologic and pharmacologic properties to the receptor. The precise role of NR2C-containing receptors in vivo is poorly understood. We have performed a battery of behavioral tests on NR2C knockout/nβ-galactosidase knock-in mice and found no difference in spontaneous activity, basal anxiety, forced-swim immobility, novel object recognition, pain sensitivity and reference memory in comparison to wildtype counterparts. However, NR2C knockout mice were found to exhibit deficits in fear acquisition and working memory compared to wildtype mice. Deficit in fear acquisition correlated with lack of fear conditioning-induced plasticity at the thalamo-amygdala synapse. These findings suggest a unique role of NR2C-containing receptors in associative and executive learning representing a novel therapeutic target for deficits in cognition.
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Affiliation(s)
- Brandon G Hillman
- Department of Pharmacology, Creighton University, Omaha, NE 68178, USA
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24
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Riaza Bermudo-Soriano C, Perez-Rodriguez MM, Vaquero-Lorenzo C, Baca-Garcia E. New perspectives in glutamate and anxiety. Pharmacol Biochem Behav 2011; 100:752-74. [PMID: 21569789 DOI: 10.1016/j.pbb.2011.04.010] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 04/05/2011] [Accepted: 04/15/2011] [Indexed: 02/07/2023]
Abstract
Anxiety and stress-related disorders, namely posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), obsessive-compulsive disorder (ODC), social and specific phobias, and panic disorder, are a major public health issue. A growing body of evidence suggests that glutamatergic neurotransmission may be involved in the biological mechanisms underlying stress response and anxiety-related disorders. The glutamatergic system mediates the acquisition and extinction of fear-conditioning. Thus, new drugs targeting glutamatergic neurotransmission may be promising candidates for new pharmacological treatments. In particular, N-methyl-d-aspartate receptors (NMDAR) antagonists (AP5, AP7, CGP37849, CGP39551, LY235959, NPC17742, and MK-801), NMDAR partial agonists (DCS, ACPC), α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) antagonists (topiramate), and several allosteric modulators targeting metabotropic glutamate receptors (mGluRs) mGluR1, mGluR2/3, and mGluR5, have shown anxiolytic-like effects in several animal and human studies. Several studies have suggested that polyamines (agmatine, putrescine, spermidine, and spermine) may be involved in the neurobiological mechanisms underlying stress-response and anxiety-related disorders. This could mainly be attributed to their ability to modulate ionotropic glutamate receptors, especially NR2B subunits. The aim of this review is to establish that glutamate neurotransmission and polyaminergic system play a fundamental role in the onset of anxiety-related disorders. This may open the way for new drugs that may help to treat these conditions.
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25
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The NO-cGMP-PKG signaling pathway coordinately regulates ERK and ERK-driven gene expression at pre- and postsynaptic sites following LTP-inducing stimulation of thalamo-amygdala synapses. Neural Plast 2011; 2010:540940. [PMID: 21461354 PMCID: PMC3065048 DOI: 10.1155/2010/540940] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 11/26/2010] [Accepted: 12/08/2010] [Indexed: 02/07/2023] Open
Abstract
Long-term potentiation (LTP) at thalamic input synapses to the lateral nucleus of the amygdala (LA) has been proposed as a cellular mechanism of the formation of auditory fear memories. We have previously shown that signaling via ERK/MAPK in both the LA and the medial division of the medial geniculate nucleus/posterior intralaminar nucleus (MGm/PIN) is critical for LTP at thalamo-LA synapses. Here, we show that LTP-inducing stimulation of thalamo-LA inputs regulates the activation of ERK and the expression of ERK-driven immediate early genes (IEGs) in both the LA and MGm/PIN. Further, we show that pharmacological blockade of NMDAR-driven synaptic plasticity, NOS activation, or PKG signaling in the LA significantly impairs high-frequency stimulation-(HFS-) induced ERK activation and IEG expression in both regions, while blockade of extracellular NO signaling in the LA impairs HFS-induced ERK activation and IEG expression exclusively in the MGm/PIN. These findings suggest that NMDAR-driven synaptic plasticity and NO-cGMP-PKG signaling within the LA coordinately regulate ERK-driven gene expression in both the LA and the MGm/PIN following LTP induction at thalamo-LA synapses, and that synaptic plasticity in the LA promotes ERK-driven transcription in MGm/PIN neurons via NO-driven “retrograde signaling”.
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26
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Abstract
The lateral amygdala (LA) plays a key role in emotional learning and is the main site for sensory input into the amygdala. Within the LA, pyramidal neurons comprise the major cell population with plasticity of inputs to these neurons thought to underlie fear learning. Pyramidal neuron activity is tightly controlled by local interneurons, and GABAergic modulation strongly influences amygdala-dependent learning. Synaptic inputs to some interneurons in the LA can also undergo synaptic plasticity, but the identity of these cells and the mechanisms that underlie this plasticity are not known. Here we show that long-term potentiation (LTP) in LA interneurons is restricted to a specific type of interneuron that is defined by the lack of expression of synaptic NR2B subunits. We find that LTP is only present at cortical inputs to these cells and is initiated by calcium influx via calcium-permeable AMPA receptors. LTP is maintained by trafficking of GluR2-lacking AMPA receptors that require an interaction with SAP97 and the actin cytoskeleton. Our results define a novel population of interneurons in the LA that control principal neuron excitability by feed-forward inhibition of cortical origin. This selective enhanced inhibition may contribute to reducing the activity of principal neurons engaged during extinction of conditioned fear.
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27
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GluN2B subunits of the NMDA receptor contribute to the AMPA receptor internalization during long-term depression in the lateral amygdala of juvenile rats. Neuroscience 2010; 171:1102-8. [DOI: 10.1016/j.neuroscience.2010.09.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Revised: 09/03/2010] [Accepted: 09/22/2010] [Indexed: 11/19/2022]
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28
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Spampanato J, Polepalli J, Sah P. Interneurons in the basolateral amygdala. Neuropharmacology 2010; 60:765-73. [PMID: 21093462 DOI: 10.1016/j.neuropharm.2010.11.006] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 11/01/2010] [Accepted: 11/10/2010] [Indexed: 01/18/2023]
Abstract
The amygdala is a temporal lobe structure that is the center of emotion processing in the mammalian brain. Recent interest in the amygdala arises from its role in processing fear and the relationship of fear to human anxiety. The amygdaloid complex is divided into a number of subnuclei that have extensive intra and extra nuclear connections. In this review we discuss recent findings on the physiology and plasticity of inputs to interneurons in the basolateral amygdala, the primary input station. These interneurons are a heterogeneous group of cells that can be separated on immunohistochemical and electrophysiological grounds. Glutamatergic inputs to these interneurons form diverse types of excitatory synapses. This diversity is manifest in both the subunit composition of the underlying NMDA receptors as well as their ability to show plasticity. We discuss these differences and their relationship to fear learning. This article is part of a Special Issue entitled 'Synaptic Plasticity & Interneurons'.
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Affiliation(s)
- Jay Spampanato
- The Queensland Brain Institute, University of Queensland, QBI Building (79), St Lucia, QLD 4072, Australia.
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29
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Haploinsufficiency in peptidylglycine alpha-amidating monooxygenase leads to altered synaptic transmission in the amygdala and impaired emotional responses. J Neurosci 2010; 30:13656-69. [PMID: 20943906 DOI: 10.1523/jneurosci.2200-10.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The mammalian amygdala expresses various neuropeptides whose signaling has been implicated in emotionality. Many neuropeptides require amidation for full activation by peptidylglycine α-amidating monooxygenase (PAM), a transmembrane vesicular cuproenzyme and regulator of the secretory pathway. Mice heterozygous for the Pam gene (PAM(+/-)) exhibit physiological and behavioral abnormalities related to specific peptidergic pathways. In the present study, we evaluated emotionality and examined molecular and cellular responses that characterize neurophysiological differences in the PAM(+/-) amygdala. PAM(+/-) mice presented with anxiety-like behaviors in the zero maze that were alleviated by diazepam. PAM(+/-) animals were deficient in short- and long-term contextual and cued fear conditioning and required higher shock intensities to establish fear-potentiated startle than their wild-type littermates. Immunohistochemical analysis of the amygdala revealed PAM expression in pyramidal neurons and local interneurons that synthesize GABA. We performed whole-cell recordings of pyramidal neurons in the PAM(+/-) amygdala to elucidate neurophysiological correlates of the fear behavioral phenotypes. Consistent with these observations, thalamic afferent synapses in the PAM(+/-) lateral nucleus were deficient in long-term potentiation. This deficit was apparent in the absence and presence of the GABA(A) receptor antagonist picrotoxin and was abolished when both GABA(A) and GABA(B) receptors were blocked. Both evoked and spontaneous excitatory signals were enhanced in the PAM(+/-) lateral nucleus. Phasic GABAergic signaling was also augmented in the PAM(+/-) amygdala, and this difference comprised activity-independent and -dependent components. These physiological findings represent perturbations in the PAM(+/-) amygdala that may underlie the aberrant emotional responses in the intact animal.
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30
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Lazzaro SC, Hou M, Cunha C, LeDoux JE, Cain CK. Antagonism of lateral amygdala alpha1-adrenergic receptors facilitates fear conditioning and long-term potentiation. Learn Mem 2010; 17:489-93. [PMID: 20870745 DOI: 10.1101/lm.1918210] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Norepinephrine receptors have been studied in emotion, memory, and attention. However, the role of alpha1-adrenergic receptors in fear conditioning, a major model of emotional learning, is poorly understood. We examined the effect of terazosin, an alpha1-adrenergic receptor antagonist, on cued fear conditioning. Systemic or intra-lateral amygdala terazosin delivered before conditioning enhanced short- and long-term memory. Terazosin delivered after conditioning did not affect consolidation. In vitro, terazosin impaired lateral amygdala inhibitory postsynaptic currents leading to facilitation of excitatory postsynaptic currents and long-term potentiation. Since alpha1 blockers are prescribed for hypertension and post-traumatic stress disorder, these results may have important clinical implications.
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Affiliation(s)
- Stephanie C Lazzaro
- Center for Neural Science, New York University, New York, New York 10003, USA.
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31
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Homeostatic switch in hebbian plasticity and fear learning after sustained loss of Cav1.2 calcium channels. J Neurosci 2010; 30:8367-75. [PMID: 20573883 DOI: 10.1523/jneurosci.4164-08.2010] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ca(2+) influx through postsynaptic Ca(v)1.x L-type voltage-gated channels (LTCCs) is particularly effective in activating neuronal biochemical signaling pathways that might be involved in Hebbian synaptic plasticity (i.e., long-term potentiation and depression) and learning and memory. Here, we demonstrate that Ca(v)1.2 is the functionally relevant LTCC isoform in the thalamus-amygdala pathway of mice. We further show that acute pharmacological block of LTCCs abolishes Hebbian plasticity in the thalamus-amygdala pathway and impairs the acquisition of conditioned fear. On the other hand, chronic genetic loss of Ca(v)1.2 triggers a homeostatic change of the synapse, leading to a fundamental alteration of the mechanism of Hebbian plasticity by synaptic incorporation of Ca(2+)-permeable, GluA2-lacking AMPA receptors. Our results demonstrate for the first time the importance of the Ca(v)1.2 LTCC subtype in synaptic plasticity and fear memory acquisition.
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32
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Synaptic maturation at cortical projections to the lateral amygdala in a mouse model of Rett syndrome. PLoS One 2010; 5:e11399. [PMID: 20625482 PMCID: PMC2896423 DOI: 10.1371/journal.pone.0011399] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 06/10/2010] [Indexed: 12/14/2022] Open
Abstract
Rett syndrome (RTT) is a neuro-developmental disorder caused by loss of function of Mecp2 - methyl-CpG-binding protein 2 - an epigenetic factor controlling DNA transcription. In mice, removal of Mecp2 in the forebrain recapitulates most of behavioral deficits found in global Mecp2 deficient mice, including amygdala-related hyper-anxiety and lack of social interaction, pointing a role of Mecp2 in emotional learning. Yet very little is known about the establishment and maintenance of synaptic function in the adult amygdala and the role of Mecp2 in these processes. Here, we performed a longitudinal examination of synaptic properties at excitatory projections to principal cells of the lateral nucleus of the amygdala (LA) in Mecp2 mutant mice and their wild-type littermates. We first show that during animal life, Cortico-LA projections switch from a tonic to a phasic mode, whereas Thalamo-LA synapses are phasic at all ages. In parallel, we observed a specific elimination of Cortico-LA synapses and a decrease in their ability of generating presynaptic long term potentiation. In absence of Mecp2, both synaptic maturation and synaptic elimination were exaggerated albeit still specific to cortical projections. Surprisingly, associative LTP was unaffected at Mecp2 deficient synapses suggesting that synaptic maintenance rather than activity-dependent synaptic learning may be causal in RTT physiopathology. Finally, because the timing of synaptic evolution was preserved, we propose that some of the developmental effects of Mecp2 may be exerted within an endogenous program and restricted to synapses which maturate during animal life.
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Pape HC, Pare D. Plastic synaptic networks of the amygdala for the acquisition, expression, and extinction of conditioned fear. Physiol Rev 2010; 90:419-63. [PMID: 20393190 DOI: 10.1152/physrev.00037.2009] [Citation(s) in RCA: 751] [Impact Index Per Article: 53.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The last 10 years have witnessed a surge of interest for the mechanisms underlying the acquisition and extinction of classically conditioned fear responses. In part, this results from the realization that abnormalities in fear learning mechanisms likely participate in the development and/or maintenance of human anxiety disorders. The simplicity and robustness of this learning paradigm, coupled with the fact that the underlying circuitry is evolutionarily well conserved, make it an ideal model to study the basic biology of memory and identify genetic factors and neuronal systems that regulate the normal and pathological expressions of learned fear. Critical advances have been made in determining how modified neuronal functions upon fear acquisition become stabilized during fear memory consolidation and how these processes are controlled in the course of fear memory extinction. With these advances came the realization that activity in remote neuronal networks must be coordinated for these events to take place. In this paper, we review these mechanisms of coordinated network activity and the molecular cascades leading to enduring fear memory, and allowing for their extinction. We will focus on Pavlovian fear conditioning as a model and the amygdala as a key component for the acquisition and extinction of fear responses.
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Affiliation(s)
- Hans-Christian Pape
- Institute of Physiology, Westfaelische Wilhelms-University, Muenster, Germany; and Rutgers State University, Newark, New Jersey, USA.
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34
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Pan BX, Ito W, Morozov A. Divergence between thalamic and cortical inputs to lateral amygdala during juvenile-adult transition in mice. Biol Psychiatry 2009; 66:964-71. [PMID: 19699473 PMCID: PMC2787234 DOI: 10.1016/j.biopsych.2009.07.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 07/06/2009] [Accepted: 07/07/2009] [Indexed: 11/29/2022]
Abstract
BACKGROUND Adolescence is considered a critical time of life for emotional development in humans. During this period the amygdala, which regulates emotions, undergoes structural reorganization. Auditory fear conditioning, a form of amygdala-dependent emotional learning, occurs differently in juvenile and adult rodents. Because this learning is mediated by plastic changes in the thalamic and cortical inputs to lateral amygdala (LA), we investigated changes in synaptic properties of these inputs during juvenile-to-adult transition. METHODS Whole-cell patch clamp recording in amygdala slices from juvenile and young adult mice was conducted to investigate long-term potentiation and basal synaptic transmission in the thalamic and cortical inputs to LA. RESULTS We show that physiological differences develop between thalamic and cortical afferents to LA during the juvenile-to-adult transition. Although in juvenile mice the two pathways have similar properties, in young adult mice the thalamic pathway has reduced plasticity, increased number of quanta released by a single action potential, and decreased proportion of silent synapses. CONCLUSIONS Changes in thalamic but not cortical inputs to amygdala take place during late development and might contribute to differences in auditory fear conditioning between juveniles and adults.
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Affiliation(s)
- Bing-Xing Pan
- Unit on Behavioral Genetics, Laboratory of Molecular Pathophysiology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
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35
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Tsvetkov EA, Masalov IS, Vesselkin NP. Study of role of inhibitory interneurons in mechanisms of regulation of sensory synapses formed by thalamic and cortical inputs on pyramidal cells of the dorsolateral amygdala nucleus. J EVOL BIOCHEM PHYS+ 2009. [DOI: 10.1134/s0022093009040070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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36
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Muller T, Albrecht D, Gebhardt C. Both NR2A and NR2B subunits of the NMDA receptor are critical for long-term potentiation and long-term depression in the lateral amygdala of horizontal slices of adult mice. Learn Mem 2009; 16:395-405. [DOI: 10.1101/lm.1398709] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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37
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Judson MC, Bergman MY, Campbell DB, Eagleson KL, Levitt P. Dynamic gene and protein expression patterns of the autism-associated met receptor tyrosine kinase in the developing mouse forebrain. J Comp Neurol 2009; 513:511-31. [PMID: 19226509 DOI: 10.1002/cne.21969] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The establishment of appropriate neural circuitry depends on the coordination of multiple developmental events across space and time. These events include proliferation, migration, differentiation, and survival-all of which can be mediated by hepatocyte growth factor (HGF) signaling through the Met receptor tyrosine kinase. We previously found a functional promoter variant of the MET gene to be associated with autism spectrum disorder, suggesting that forebrain circuits governing social and emotional function may be especially vulnerable to developmental disruptions in HGF/Met signaling. However, little is known about the spatiotemporal distribution of Met expression in the forebrain during the development of such circuits. To advance our understanding of the neurodevelopmental influences of Met activation, we employed complementary Western blotting, in situ hybridization, and immunohistochemistry to comprehensively map Met transcript and protein expression throughout perinatal and postnatal development of the mouse forebrain. Our studies reveal complex and dynamic spatiotemporal patterns of expression during this period. Spatially, Met transcript is localized primarily to specific populations of projection neurons within the neocortex and in structures of the limbic system, including the amygdala, hippocampus, and septum. Met protein appears to be principally located in axon tracts. Temporally, peak expression of transcript and protein occurs during the second postnatal week. This period is characterized by extensive neurite outgrowth and synaptogenesis, supporting a role for the receptor in these processes. Collectively, these data suggest that Met signaling may be necessary for the appropriate wiring of forebrain circuits, with particular relevance to the social and emotional dimensions of behavior.
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Affiliation(s)
- Matthew C Judson
- Graduate Program in Neuroscience, Vanderbilt University Medical Center, Nashville, Tennessee 37203, USA
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38
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Smeal RM, Keefe KA, Wilcox KS. Differences in excitatory transmission between thalamic and cortical afferents to single spiny efferent neurons of rat dorsal striatum. Eur J Neurosci 2009; 28:2041-52. [PMID: 19046385 DOI: 10.1111/j.1460-9568.2008.06505.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The striatum is crucially involved in motor and cognitive function, and receives significant glutamate input from the cortex and thalamus. The corticostriatal pathway arises from diverse regions of the cortex and is thought to provide information to the basal ganglia from which motor actions are selected and modified. The thalamostriatal pathway arises from specific thalamic nuclei and is involved in attention and possibly strategy switching. Despite these fundamental functional differences, direct comparisons of the properties of these pathways are lacking. N-methyl-D-aspartate (NMDA) receptors at synapses powerfully affect postsynaptic processing, and incorporation of different NR2 subunits into NMDA receptors has profound effects on the pharmacological and biophysical properties of the receptor. Utilization of different NMDA receptors at thalamostriatal and corticostriatal synapses could allow for afferent-specific differences in information processing. We used a novel rat brain slice preparation preserving corticostriatal and thalamostriatal pathways to medium spiny neurons to examine the properties of NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) recorded using the whole-cell, patch-clamp technique. Within the same neuron, the NMDA/non-NMDA ratio is greater for excitatory responses evoked from the thalamostriatal pathway than for those evoked from the corticostriatal pathway. In addition, reversal potentials and decay kinetics of the NMDA receptor-mediated EPSCs suggest that the thalamostriatal synapse is more distant on the dendritic arbor. Finally, results obtained with antagonists specific for NR2B-containing NMDA receptors imply that NMDA receptors at corticostriatal synapses contain more NR2B subunits. These synapse-specific differences in NMDA receptor content and pharmacology provide potential differential sites of action for NMDA receptor subtype-specific antagonists proposed for the treatment of Parkinson's disease.
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Affiliation(s)
- Roy M Smeal
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, USA.
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39
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Du Y, Huang Q, Wu X, Galbraith GC, Li L. Binaural Unmasking of Frequency-Following Responses in Rat Amygdala. J Neurophysiol 2009; 101:1647-59. [DOI: 10.1152/jn.91055.2008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Survival in natural environments for small animals such as rats often depends on precise neural coding of life-threatening acoustic signals, and binaural unmasking of species-specific pain calls is especially critical. This study investigated how species-specific tail-pain chatter is represented in the rat amygdala, which receives afferents from both auditory thalamus and auditory association cortex, and whether the amygdaloid representation of the chatter can be binaurally unmasked. The results show that chatter with a fundamental frequency (F0) of 2.1 kHz was able to elicit salient phase-locked frequency-following responses (FFRs) in the lateral amygdala nucleus in anesthetized rats. FFRs to the F0 of binaurally presented chatter were sensitive to the interaural time difference (ITD), with the preference of ipsilateral-ear leading, as well as showing features of binaural inhibition. When interaurally correlated masking noises were added and ipsilateral chatter led contralateral chatter, introducing an ITD disparity between the chatter and masker significantly enhanced (unmasked) the FFRs. This binaural unmasking was further enhanced by chemically blocking excitatory glutamate receptors in the auditory association cortex. When the chatter was replaced by a harmonic tone complex with an F0 of 0.7 kHz, both the binaural-inhibition feature and the binaural unmasking were preserved only for the harmonic of 2.1 kHz but not the tone F0. These results suggest that both frequency-dependent ascending binaural modulations and cortical descending modulations of the precise auditory coding of the chatter in the amygdala are critical for processing life-threatening acoustic signals in noisy and even reverberant environments.
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40
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Li G, Nair SS, Quirk GJ. A biologically realistic network model of acquisition and extinction of conditioned fear associations in lateral amygdala neurons. J Neurophysiol 2009; 101:1629-46. [PMID: 19036872 PMCID: PMC2666411 DOI: 10.1152/jn.90765.2008] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Accepted: 11/17/2008] [Indexed: 11/22/2022] Open
Abstract
The basolateral amygdala plays an important role in the acquisition and expression of both fear conditioning and fear extinction. To understand how a single structure could encode these "opposite" memories, we developed a biophysical network model of the lateral amygdala (LA) neurons during auditory fear conditioning and extinction. Membrane channel properties were selected to match waveforms and firing properties of pyramidal cells and interneurons in LA, from published in vitro studies. Hebbian plasticity was implemented in excitatory AMPA and inhibitory GABA(A) receptor-mediated synapses to model learning. The occurrence of synaptic potentiation versus depression was determined by intracellular calcium levels, according to the calcium control hypothesis. The model was able to replicate conditioning- and extinction-induced changes in tone responses of LA neurons in behaving rats. Our main finding is that LA activity during both acquisition and extinction can be controlled by a balance between pyramidal cell and interneuron activations. Extinction training depressed conditioned synapses and also potentiated local interneurons, thereby inhibiting the responses of pyramidal cells to auditory input. Both long-term depression and potentiation of inhibition were required to initiate and maintain extinction. The model provides insights into the sites of plasticity in conditioning and extinction, the mechanism of spontaneous recovery, and the role of amygdala NMDA receptors in extinction learning.
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Affiliation(s)
- Guoshi Li
- Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri, USA
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41
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Modulation of SK channel trafficking by beta adrenoceptors enhances excitatory synaptic transmission and plasticity in the amygdala. J Neurosci 2008; 28:10803-13. [PMID: 18945888 DOI: 10.1523/jneurosci.1796-08.2008] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Emotionally arousing events are particularly well remembered. This effect is known to result from the release of stress hormones and activation of beta adrenoceptors in the amygdala. However, the underlying cellular mechanisms are not understood. Small conductance calcium-activated potassium (SK) channels are present at glutamatergic synapses where they limit synaptic transmission and plasticity. Here, we show that beta adrenoceptor activation regulates synaptic SK channels in lateral amygdala pyramidal neurons, through activation of protein kinase A. We show that SK channels are constitutively recycled from the postsynaptic membrane and that activation of beta adrenoceptors removes SK channels from excitatory synapses. This results in enhanced synaptic transmission and plasticity. Our findings demonstrate a novel mechanism by which beta adrenoceptors control synaptic transmission and plasticity, through regulation of SK channel trafficking, and suggest that modulation of synaptic SK channels may contribute to beta adrenoceptor-mediated potentiation of emotional memories.
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42
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Johnson LR, Hou M, Ponce-Alvarez A, Gribelyuk LM, Alphs HH, Albert L, Brown BL, LeDoux JE, Doyère V. A recurrent network in the lateral amygdala: a mechanism for coincidence detection. Front Neural Circuits 2008; 2:3. [PMID: 19104668 PMCID: PMC2605401 DOI: 10.3389/neuro.04.003.2008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Accepted: 09/17/2008] [Indexed: 11/13/2022] Open
Abstract
Synaptic changes at sensory inputs to the dorsal nucleus of the lateral amygdala (LAd) play a key role in the acquisition and storage of associative fear memory. However, neither the temporal nor spatial architecture of the LAd network response to sensory signals is understood. We developed a method for the elucidation of network behavior. Using this approach, temporally patterned polysynaptic recurrent network responses were found in LAd (intra-LA), both in vitro and in vivo, in response to activation of thalamic sensory afferents. Potentiation of thalamic afferents resulted in a depression of intra-LA synaptic activity, indicating a homeostatic response to changes in synaptic strength within the LAd network. Additionally, the latencies of thalamic afferent triggered recurrent network activity within the LAd overlap with known later occurring cortical afferent latencies. Thus, this recurrent network may facilitate temporal coincidence of sensory afferents within LAd during associative learning.
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Affiliation(s)
- Luke R. Johnson
- W. M. Keck Foundation Laboratory of Neurobiology, Center for Neural ScienceNew York, USA
- CSTS, Department of Psychiatry, USUBethesda, USA
| | - Mian Hou
- W. M. Keck Foundation Laboratory of Neurobiology, Center for Neural ScienceNew York, USA
| | | | - Leo M. Gribelyuk
- W. M. Keck Foundation Laboratory of Neurobiology, Center for Neural ScienceNew York, USA
| | - Hannah H. Alphs
- W. M. Keck Foundation Laboratory of Neurobiology, Center for Neural ScienceNew York, USA
| | - Ladislau Albert
- W. M. Keck Foundation Laboratory of Neurobiology, Center for Neural ScienceNew York, USA
| | | | - Joseph E. LeDoux
- W. M. Keck Foundation Laboratory of Neurobiology, Center for Neural ScienceNew York, USA
| | - Valerie Doyère
- W. M. Keck Foundation Laboratory of Neurobiology, Center for Neural ScienceNew York, USA
- CNRS-UMR8620, NAMC, Université Paris-SudOrsay, France
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43
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Fear memory impairing effects of systemic treatment with the NMDA NR2B subunit antagonist, Ro 25-6981, in mice: attenuation with ageing. Pharmacol Biochem Behav 2008; 91:453-60. [PMID: 18809426 DOI: 10.1016/j.pbb.2008.08.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 08/21/2008] [Accepted: 08/26/2008] [Indexed: 12/22/2022]
Abstract
N-methyl-D-aspartate receptors (NMDARs) are mediators of synaptic plasticity and learning and are implicated in the pathophysiology of neuropsychiatric disease and age-related cognitive dysfunction. NMDARs are heteromers, but the relative contribution of specific subunits to NMDAR-mediated learning is not fully understood. We characterized pre-conditioning systemic treatment of the NR2B subunit-selective antagonist Ro 25-6981 for effects on multi-trial, one-trial and low-shock Pavlovian fear conditioning in C57BL/6J mice. Ro 25-6981 was also profiled for effects on novel open field exploration, elevated plus-maze anxiety-like behavior, startle reactivity, prepulse inhibition of startle, and nociception. Three-month (adult) and 12-month old C57BL/6Tac mice were compared for Ro 25-6981 effects on multi-trial fear conditioning, and corticolimbic NR2B protein levels. Ro 25-6981 moderately impaired fear learning in the multi-trial and one-trial (but not low-shock) conditioning paradigms, but did not affect exploratory or anxiety-related behaviors or sensory functions. Memory impairing effects of Ro 25-6981 were absent in 12-month old mice, although NR2B protein levels were not significantly altered. Present data provide further evidence of the memory impairing effects of selective blockade of NR2B-containing NMDARs, and show loss of these effects with ageing. This work could ultimately have implications for elucidating the pathophysiology of learning dysfunction in neuropsychiatric disorders and ageing.
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44
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Sah P, Westbrook RF, Lüthi A. Fear conditioning and long-term potentiation in the amygdala: what really is the connection? Ann N Y Acad Sci 2008; 1129:88-95. [PMID: 18591471 DOI: 10.1196/annals.1417.020] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The cellular mechanisms that underlie learning and memory formation remain one of the most intriguing unknowns about the mammalian brain. A plethora of experimental evidence over the last 30 years has established that long-term synaptic plasticity at excitatory synapses is the most likely mechanism that underlies learning and memory formation. Experiments done largely in acute brain slices maintained in vitro have revealed many of the molecular mechanisms in the induction and maintenance of long-term potentiation (LTP). However, evidence directly liking LTP with learning and memory formation has not been established. Pavlovian fear conditioning is a good candidate to provide such evidence. The relations between events that produce fear conditioning are simple; these relations and their fear products involve circuits in the amygdala that are well understood, as are those circuits in the amygdala that underlie LTP. The evidence that links LTP in the amygdala with fear conditioning is reviewed.
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Affiliation(s)
- P Sah
- Queensland Brain Institute, University of Queensland, Queensland 4072, Australia.
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45
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Yu SY, Wu DC, Liu L, Ge Y, Wang YT. Role of AMPA receptor trafficking in NMDA receptor-dependent synaptic plasticity in the rat lateral amygdala. J Neurochem 2008; 106:889-99. [DOI: 10.1111/j.1471-4159.2008.05461.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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46
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Walker DL, Davis M. Amygdala infusions of an NR2B-selective or an NR2A-preferring NMDA receptor antagonist differentially influence fear conditioning and expression in the fear-potentiated startle test. Learn Mem 2008; 15:67-74. [PMID: 18230675 PMCID: PMC2216678 DOI: 10.1101/lm.798908] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Accepted: 12/02/2007] [Indexed: 11/24/2022]
Abstract
Within the amygdala, most N-methyl-D-aspartic acid (NMDA) receptors consist of NR1 subunits in combination with either NR2A or NR2B subunits. Because the particular subunit composition greatly influences the receptors' properties, we investigated the contribution of both subtypes to fear conditioning and expression. To do so, we infused the NR1/NR2B receptor antagonist CP101,606 (0.5, 1.5, or 4.5 microg/amygdala) or the NR1/NR2A-preferring antagonist NVP-AAM077 (0.075, 0.25, 0.75, or 2.5 microg/amygdala) into the amygdala prior to either fear conditioning (i.e., light-shock pairings) or fear-potentiated startle testing. CP101,606 nonmonotonically disrupted fear conditioning but did not disrupt fear expression. NVP-AAM077 dose-dependently disrupted fear conditioning as well as fear expression. The results suggest that amygdala NR1/NR2B receptors play a special role in fear memory formation, whereas NR1/NR2A receptors participate more generally in synaptic transmission.
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Affiliation(s)
- David L Walker
- Department of Psychiatry and Behavioral Sciences, School of Medicine, Emory University, Atlanta, Georgia 30329, USA.
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47
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Schafe GE, Swank MW, Rodrigues SM, Debiec J, Doyère V. Phosphorylation of ERK/MAP kinase is required for long-term potentiation in anatomically restricted regions of the lateral amygdala in vivo. Learn Mem 2008; 15:55-62. [PMID: 18230673 DOI: 10.1101/lm.746808] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have previously shown that the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/ MAPK) is transiently activated in anatomically restricted regions of the lateral amygdala (LA) following Pavlovian fear conditioning and that blockade of ERK/MAPK activation in the LA impairs both fear memory consolidation and long-term potentiation (LTP) in the amygdala, in vitro. The present experiments evaluated the role of the ERK/MAPK signaling cascade in LTP at thalamo-LA input synapses, in vivo. We first show that ERK/MAPK is transiently activated/phosphorylated in the LA at 5 min, but not 15 or 60 min, after high-frequency, but not low-frequency, stimulation of the auditory thalamus. ERK activation induced by LTP-inducing stimulation was anatomically restricted to the same regions of the LA previously shown to exhibit ERK regulation following fear conditioning. We next show that intra-LA infusion of U0126, an inhibitor of ERK/MAPK activation, impairs LTP at thalamo-LA input synapses. Collectively, results demonstrate that ERK/MAPK activation is necessary for synaptic plasticity in anatomically defined regions of the LA, in vivo.
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Affiliation(s)
- Glenn E Schafe
- Department of Psychology and Interdepartmental Neuroscience Program, Yale University, New Haven, Connecticut 06520, USA.
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48
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Sotres-Bayon F, Bush DEA, LeDoux JE. Acquisition of fear extinction requires activation of NR2B-containing NMDA receptors in the lateral amygdala. Neuropsychopharmacology 2007; 32:1929-40. [PMID: 17213844 DOI: 10.1038/sj.npp.1301316] [Citation(s) in RCA: 231] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
N-methyl-D-aspartate receptors (NMDARs) contribute to synaptic plasticity underlying learning in a variety of brain systems. Fear extinction, which involves learning to suppress the expression of previously learned fear, appears to require NMDAR activation in the amygdala. However, it is unclear whether amygdala NMDARs are required for the acquisition of extinction learning, and it is unknown whether NR2B-containing NMDARs are required in fear extinction. Here, we assessed the effects of selective NR2B blockade with ifenprodil on fear extinction learning, and found that both systemic and intra-amygdala ifenprodil treatment, given before extinction training, impaired the initial acquisition, and subsequent retrieval of fear extinction. These results confirm previous evidence showing that NMDARs in the amygdala are involved in fear extinction, and additionally show that NR2B-containing NMDARs are required. Contrary to the conclusion of previous studies, our findings demonstrate NMDARs are required for the initial acquisition, rather than only the retention, of fear extinction learning. Thus, our results support a previously not known role for NMDA-dependent plasticity in the lateral amygdala during the acquisition of fear extinction.
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Affiliation(s)
- Francisco Sotres-Bayon
- Center for Neural Science, New York University, 4 Washington Place, New York, NY 10003, USA.
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49
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López de Armentia M, Sah P. Bidirectional synaptic plasticity at nociceptive afferents in the rat central amygdala. J Physiol 2007; 581:961-70. [PMID: 17379642 PMCID: PMC2170827 DOI: 10.1113/jphysiol.2006.121822] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Glutamatergic inputs arising from the parabrachial nucleus to neurons in the lateral sector of the central amygdala were studied in vitro. Tetanic stimulation of these inputs led to LTP that did not require activation of NMDA receptors or a rise of postsynaptic calcium. LTP was accompanied by a reduction in the paired-pulse ratio, indicating that LTP results from an increase in transmitter release probability. Activation of adenylyl cyclase with forskolin potentiated these inputs with a similar reduction in paired-pulse facilitation and occluded LTP induction. LTP was inhibited by the protein kinase A blocker H89. Low-frequency stimulation led to LTD that required activation of postsynaptic NMDA receptors and a rise in postsynaptic calcium. There was no change in paired-pulse facilitation with LTD. LTD was blocked by protein phosphatase blockers calyculin and okadaic acid. We conclude that parabrachial inputs to the lateral sector of the central amygdala show presynaptic LTP that requires activation of a presynaptic protein kinase A via a calcium-dependent adenylyl cyclase while LTD at the same synapses is postsynaptic and requires a rise in postsynaptic calcium and activation of protein phosphatase.
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50
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Szinyei C, Narayanan RT, Pape HC. Plasticity of inhibitory synaptic network interactions in the lateral amygdala upon fear conditioning in mice. Eur J Neurosci 2007; 25:1205-11. [PMID: 17331216 DOI: 10.1111/j.1460-9568.2007.05349.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
After fear conditioning, plastic changes of excitatory synaptic transmission occur in the amygdala. Fear-related memory also involves the GABAergic system, although no influence on inhibitory synaptic transmission is known. In the present study we assessed the influence of Pavlovian fear conditioning on the plasticity of GABAergic synaptic interactions in the lateral amygdala (LA) in brain slices prepared from fear-conditioned, pseudo-trained and naïve adult mice. Theta-burst tetanization of thalamic afferent inputs to the LA evoked an input-specific potentiation of inhibitory postsynaptic responses in projection neurons; the cortical input was unaffected. Philanthotoxin (10 microM), an antagonist of Ca2+-permeable AMPA receptors, disabled this plastic phenomenon. Surgical isolation of the LA, extracellular application of a GABA(B) receptor antagonist (CGP 55845A, 10 microM) or an NMDA receptor antagonist (APV, 50 microM), or intracellular application of BAPTA (10 mM), did not influence the plasticity. The plasticity also showed as a potentiation of monosynaptic excitatory responses in putative GABAergic interneurons. Pavlovian fear conditioning, but not pseudo-conditioning, resulted in a significant reduction in this potentiation that was evident 24 h after training. Two weeks after training, the potentiation returned to control levels. In conclusion, a reduction in potentiation of inhibitory synaptic interactions occurs in the LA and may contribute to a shift in synaptic balance towards excitatory signal flow during the processes of fear-memory acquisition or consolidation.
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Affiliation(s)
- Csaba Szinyei
- Institut für Physiologie I, Westfälische Wilhelms-Universität Münster, Robert-Koch-Str. 27a, D-48149 Münster, Germany
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