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Yang YC, Wang GH, Chou P, Hsueh SW, Lai YC, Kuo CC. Dynamic electrical synapses rewire brain networks for persistent oscillations and epileptogenesis. Proc Natl Acad Sci U S A 2024; 121:e2313042121. [PMID: 38346194 PMCID: PMC10895348 DOI: 10.1073/pnas.2313042121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 01/09/2024] [Indexed: 02/15/2024] Open
Abstract
One of the very fundamental attributes for telencephalic neural computation in mammals involves network activities oscillating beyond the initial trigger. The continuing and automated processing of transient inputs shall constitute the basis of cognition and intelligence but may lead to neuropsychiatric disorders such as epileptic seizures if carried so far as to engross part of or the whole telencephalic system. From a conventional view of the basic design of the telencephalic local circuitry, the GABAergic interneurons (INs) and glutamatergic pyramidal neurons (PNs) make negative feedback loops which would regulate the neural activities back to the original state. The drive for the most intriguing self-perpetuating telencephalic activities, then, has not been posed and characterized. We found activity-dependent deployment and delineated functional consequences of the electrical synapses directly linking INs and PNs in the amygdala, a prototypical telencephalic circuitry. These electrical synapses endow INs dual (a faster excitatory and a slower inhibitory) actions on PNs, providing a network-intrinsic excitatory drive that fuels the IN-PN interconnected circuitries and enables persistent oscillations with preservation of GABAergic negative feedback. Moreover, the entities of electrical synapses between INs and PNs are engaged in and disengaged from functioning in a highly dynamic way according to neural activities, which then determine the spatiotemporal scale of recruited oscillating networks. This study uncovers a special wide-range and context-dependent plasticity for wiring/rewiring of brain networks. Epileptogenesis or a wide spectrum of clinical disorders may ensue, however, from different scales of pathological extension of this unique form of telencephalic plasticity.
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Affiliation(s)
- Ya-Chin Yang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan333, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan333, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan333, Taiwan
- Department of Psychiatry, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan333, Taiwan
| | - Guan-Hsun Wang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan333, Taiwan
- Department of Medical Education, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan333, Taiwan
- Department of Neurology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan333, Taiwan
| | - Ping Chou
- Department of Physiology, National Taiwan University College of Medicine, Taipei100, Taiwan
| | - Shu-Wei Hsueh
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan333, Taiwan
| | - Yi-Chen Lai
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan333, Taiwan
| | - Chung-Chin Kuo
- Department of Physiology, National Taiwan University College of Medicine, Taipei100, Taiwan
- Department of Neurology, National Taiwan University Hospital, Taipei100, Taiwan
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2
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Ahmed N, Headley DB, Paré D. Optogenetic study of central medial and paraventricular thalamic projections to the basolateral amygdala. J Neurophysiol 2021; 126:1234-1247. [PMID: 34469705 PMCID: PMC8560422 DOI: 10.1152/jn.00253.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 08/27/2021] [Accepted: 08/27/2021] [Indexed: 11/22/2022] Open
Abstract
The central medial (CMT) and paraventricular (PVT) thalamic nuclei project strongly to the basolateral amygdala (BL). Similarities between the responsiveness of CMT, PVT, and BL neurons suggest that these nuclei strongly influence BL activity. Supporting this possibility, an electron microscopic study reported that, in contrast with other extrinsic afferents, CMT and PVT axon terminals form very few synapses with BL interneurons. However, since limited sampling is a concern in electron microscopic studies, the present investigation was undertaken to compare the impact of CMT and PVT thalamic inputs on principal and local-circuit BL neurons with optogenetic methods and whole cell recordings in vitro. Optogenetic stimulation of CMT and PVT axons elicited glutamatergic excitatory postsynaptic potentials (EPSPs) or excitatory postsynaptic currents (EPSCs) in principal cells and interneurons, but they generally had a longer latency in interneurons. Moreover, after blockade of polysynaptic interactions with tetrodotoxin (TTX), a lower proportion of interneurons (50%) than principal cells (90%) remained responsive to CMT and PVT inputs. Although the presence of TTX-resistant responses in some interneurons indicates that CMT and PVT inputs directly contact some local-circuit cells, their lower incidence and amplitude after TTX suggest that CMT and PVT inputs form fewer synapses with them than with principal BL cells. Together, these results indicate that CMT and PVT inputs mainly contact principal BL neurons such that when CMT or PVT neurons fire, limited feedforward inhibition counters their excitatory influence over principal BL cells. However, CMT and PVT axons can also recruit interneurons indirectly, via the activation of principal cells, thereby generating feedback inhibition.NEW & NOTEWORTHY Midline thalamic (MTh) nuclei contribute major projections to the basolateral amygdala (BL). Similarities between the responsiveness of MTh and BL neurons suggest that MTh neurons exert a significant influence over BL activity. Using optogenetic techniques, we show that MTh inputs mainly contact principal BL neurons such that when MTh neurons fire, little feedforward inhibition counters their excitatory influence over principal cells. Thus, MTh inputs may be major determinants of BL activity.
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Affiliation(s)
- Nowrin Ahmed
- Center for Molecular and Behavioral Neuroscience, Rutgers University-Newark, Newark, New Jersey
| | - Drew B Headley
- Center for Molecular and Behavioral Neuroscience, Rutgers University-Newark, Newark, New Jersey
| | - Denis Paré
- Center for Molecular and Behavioral Neuroscience, Rutgers University-Newark, Newark, New Jersey
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3
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Chou P, Wang GH, Hsueh SW, Yang YC, Kuo CC. Delta-Frequency Augmentation and Synchronization in Seizure Discharges and Telencephalic Transmission. iScience 2020; 23:101666. [PMID: 33134896 PMCID: PMC7586134 DOI: 10.1016/j.isci.2020.101666] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/09/2020] [Accepted: 10/07/2020] [Indexed: 02/06/2023] Open
Abstract
Epileptic seizures constitute a common neurological disease primarily diagnosed by characteristic rhythms or waves in the local field potentials (LFPs) of cerebral cortices or electroencephalograms. With a basolateral amygdala (BLA) kindling model, we found that the dominant frequency of BLA oscillations is in the delta range (1-5 Hz) in both normal and seizure conditions. Multi-unit discharges are increased with higher seizure staging but remain phase-locked to the delta waves in LFPs. Also, the change in synchrony precedes and outlasts the changes in discharging units as well as behavioral seizures. One short train of stimuli readily drives the pyramidal-inhibitory neuronal networks in BLA slices into prolonged reverberating activities, where the burst and interburst intervals may concurrently set a "natural wavelength" for delta frequencies. Seizures thus could be viewed as erroneous temporospatial continuums to normal oscillations in a system with a built-in synchronizing and resonating nature for information relay.
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Affiliation(s)
- Ping Chou
- Department of Physiology, National Taiwan University College of Medicine, 1 Jen-Ai Road, 1st Section, Taipei 100, Taiwan
| | - Guan-Hsun Wang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan
- School of Medicine, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Department of Medical Education, Chang Gung Memorial Hospital, Linkou Medical Center, Tao-Yuan, Taiwan
| | - Shu-Wei Hsueh
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Ya-Chin Yang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou Medical Center, Tao-Yuan, Taiwan
| | - Chung-Chin Kuo
- Department of Physiology, National Taiwan University College of Medicine, 1 Jen-Ai Road, 1st Section, Taipei 100, Taiwan
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
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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: 18] [Impact Index Per Article: 4.5] [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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Derman RC, Bass CE, Ferrario CR. Effects of hM4Di activation in CamKII basolateral amygdala neurons and CNO treatment on sensory-specific vs. general PIT: refining PIT circuits and considerations for using CNO. Psychopharmacology (Berl) 2020; 237:1249-1266. [PMID: 31980843 PMCID: PMC7196513 DOI: 10.1007/s00213-020-05453-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 01/05/2020] [Indexed: 12/25/2022]
Abstract
BACKGROUND Pavlovian stimuli can influence instrumental behaviors via phenomena such as Pavlovian-to-instrumental transfer (PIT). PIT arises via dissociable processes as sensory-specific PIT (SS-PIT) and general PIT. The basolateral amygdala (BLA) mediates SS-PIT, but not general PIT. However, the specific BLA neuronal populations involved are unknown. AIMS To determine the contribution of glutamatergic BLA neurons to the expression of SS-PIT and to the recall of sensory-specific properties of stimulus-outcome associations. METHODS BLA neurons were transduced with virus containing either GFP or hM4Di, driven by the CamKII promoter. Rats were then tested for SS and general PIT and subsequently for expression of Pavlovian outcome devaluation effects and conditioned taste aversion following injections of vehicle or clozapine-N-oxide (CNO, the hM4Di agonist). RESULTS CNO selectively blocked SS-PIT in the hM4Di-expressing group, but not controls, without altering expression of Pavlovian outcome devaluation or sensory-specific taste aversion in either group. Unexpectedly, CNO disrupted general PIT in both groups. CONCLUSIONS CamKII BLA neurons mediate the expression of SS-PIT by enabling Pavlovian stimuli to trigger recall of the correct action-outcome associations rather than by mediating recall of the sensory-specific properties of the stimulus-outcome association. Separately, our data demonstrate that CNO alone is sufficient to disrupt affective, but not sensory-specific processes, an effect that was not due to generalized motor disruption. This non-specific effect on general PIT may be related to CNO-induced shifts in internal state. Together, these data identify BLA CamKII neurons as critical for the expression of SS-PIT and reveal important considerations for using CNO to study general affective motivation.
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Affiliation(s)
- Rifka C. Derman
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA;,Department of Behavioral Neuroscience, Oregon Health and Sciences University, Portland, OR, 97239
| | - Caroline E. Bass
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, NY, USA
| | - Carrie R. Ferrario
- Department of Behavioral Neuroscience, Oregon Health and Sciences University, Portland, OR, 97239;,Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109, USA
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McDonald AJ. Functional neuroanatomy of the basolateral amygdala: Neurons, neurotransmitters, and circuits. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2020; 26:1-38. [PMID: 34220399 PMCID: PMC8248694 DOI: 10.1016/b978-0-12-815134-1.00001-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Alexander J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, United States
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Gregoriou GC, Kissiwaa SA, Patel SD, Bagley EE. Dopamine and opioids inhibit synaptic outputs of the main island of the intercalated neurons of the amygdala. Eur J Neurosci 2018; 50:2065-2074. [PMID: 30099803 DOI: 10.1111/ejn.14107] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/11/2018] [Accepted: 08/07/2018] [Indexed: 12/15/2022]
Abstract
Neural circuits in the amygdala are important for associating the positive experience of drug taking with the coincident environmental cues. During abstinence, cue re-exposure activates the amygdala, increases dopamine release in the amygdala and stimulates relapse to drug use in an opioid dependent manner. Neural circuits in the amygdala and the learning that underlies these behaviours are inhibited by GABAergic synaptic inhibition. A specialised subtype of GABAergic neurons in the amygdala are the clusters of intercalated cells. We focussed on the main-island of intercalated cells because these neurons, located ventromedial to the basolateral amygdala, express very high levels of dopamine D1-receptor and μ-opioid receptor, release enkephalin and are densely innervated by the ventral tegmental area. However, where these neurons project to was not fully described and their regulation by opioids and dopamine was incomplete. To address this issue we electrically stimulated in the main-island of the intercalated cells in rat brain slices and made patch-clamp recordings of GABAergic synaptics from amygdala neurons. We found that main-island neurons had a strong GABAergic inhibitory output to pyramidal neurons of the basolateral nucleus and the medial central nucleus, the major output zones of the amygdala. Opioids inhibited both these synaptic outputs of the intercalated neurons and thus would disinhibit these target zones. Additionally, dopamine acting at D1-receptors inhibited main-island neuron synapses onto other main-island neurons. This data indicates that the inhibitory projections from the main-island neurons could influence multiple aspects of addiction and emotional processing in an opioid and dopamine dependent manner.
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Affiliation(s)
- Gabrielle C Gregoriou
- Discipline of Pharmacology & Charles Perkins Centre, Charles Perkins Centre D17, University of Sydney, Camperdown, NSW, 2006, Australia
| | - Sarah A Kissiwaa
- Discipline of Pharmacology & Charles Perkins Centre, Charles Perkins Centre D17, University of Sydney, Camperdown, NSW, 2006, Australia
| | - Sahil D Patel
- Discipline of Pharmacology & Charles Perkins Centre, Charles Perkins Centre D17, University of Sydney, Camperdown, NSW, 2006, Australia
| | - Elena E Bagley
- Discipline of Pharmacology & Charles Perkins Centre, Charles Perkins Centre D17, University of Sydney, Camperdown, NSW, 2006, Australia
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Shen W, Nan C, Nelson PT, Ripps H, Slaughter MM. GABA B receptor attenuation of GABA A currents in neurons of the mammalian central nervous system. Physiol Rep 2017; 5:5/6/e13129. [PMID: 28348006 PMCID: PMC5371550 DOI: 10.14814/phy2.13129] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 11/18/2016] [Indexed: 11/24/2022] Open
Abstract
Ionotropic receptors are tightly regulated by second messenger systems and are often present along with their metabotropic counterparts on a neuron's plasma membrane. This leads to the hypothesis that the two receptor subtypes can interact, and indeed this has been observed in excitatory glutamate and inhibitory GABA receptors. In both systems the metabotropic pathway augments the ionotropic receptor response. However, we have found that the metabotropic GABAB receptor can suppress the ionotropic GABAA receptor current, in both the in vitro mouse retina and in human amygdala membrane fractions. Expression of amygdala membrane microdomains in Xenopus oocytes by microtransplantation produced functional ionotropic and metabotropic GABA receptors. Most GABAA receptors had properties of α‐subunit containing receptors, with ~5% having ρ‐subunit properties. Only GABAA receptors with α‐subunit‐like properties were regulated by GABAB receptors. In mouse retinal ganglion cells, where only α‐subunit‐containing GABAA receptors are expressed, GABAB receptors suppressed GABAA receptor currents. This suppression was blocked by GABAB receptor antagonists, G‐protein inhibitors, and GABAB receptor antibodies. Based on the kinetic differences between metabotropic and ionotropic receptors, their interaction would suppress repeated, rapid GABAergic inhibition.
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Affiliation(s)
- Wen Shen
- Department of Biomedical Science, Charles E. Schmidt College of Medicine Florida Atlantic University, Boca Raton, Florida
| | - Changlong Nan
- Department of Biomedical Science, Charles E. Schmidt College of Medicine Florida Atlantic University, Boca Raton, Florida
| | - Peter T Nelson
- Division of Neuropathology, Department of Pathology, University of Kentucky, Lexington, Kentucky.,Sanders-Brown Centre on Aging, University of Kentucky, Lexington, Kentucky
| | - Harris Ripps
- Department of Ophthalmology and Visual Sciences, University of Illinois College of Medicine, Chicago, Illinois.,Whitman Investigator, Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Malcolm M Slaughter
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York
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Parvalbumin, but not calretinin, neurons express high levels of α1-containing GABA A receptors, α7-containing nicotinic acetylcholine receptors and D2-dopamine receptors in the basolateral amygdala of the rat. J Chem Neuroanat 2017; 86:41-51. [PMID: 28834708 DOI: 10.1016/j.jchemneu.2017.08.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/15/2017] [Accepted: 08/15/2017] [Indexed: 01/28/2023]
Abstract
The generation of emotional responses by the basolateral amygdala is largely determined by the balance of excitatory and inhibitory inputs to its principal neurons - the pyramidal cells. The activity of these neurons is tightly controlled by g-aminobutyric acid (GABA)ergic interneurons, especially by those expressing parvalbumin (PV) and calretinin (CR). Although it is known that GABAergic, cholinergic and dopaminergic fibres make synapses on PV and CR cells, knowledge of the various receptors which are used by these cells is still incomplete. Thus, the present study investigates whether neurons expressing PV or CR co-express specific GABA, acetylcholine and/or dopamine receptors in the basolateral amygdala of the rat. The results show that almost two-thirds of PV neurons co-express high concentrations of α1 subunit of GABAA receptor, and more than half of them co-express high levels of α7 subunit of nicotinic acetylcholine receptor and/or D2-subtype of dopamine receptor. In contrast, a smaller percentage of CR neurons had detectable amounts of these receptors and at lower levels of abundance in most cases. In conclusion, the present results indicate that not only principal neurons but also GABAergic interneurons have specific receptors, which allow these cells to respond to the GABAergic, cholinergic and dopaminergic inputs coming to the basolateral amygdala of the rat. Since these cells receive intrinsic GABAergic inputs, they are strongly interconnected. Since they also receive extrinsic cholinergic and dopaminergic inputs, such stimulation may result in stimulus-driven feed-forward control of the principal neurons. The effects of such control may be either feed-forward inhibition of the principal neurons via α7 nicotinic acetylcholine receptors or disinhibition of these cells via D2-dopamine receptors.
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Luczynski P, Whelan SO, O'Sullivan C, Clarke G, Shanahan F, Dinan TG, Cryan JF. Adult microbiota-deficient mice have distinct dendritic morphological changes: differential effects in the amygdala and hippocampus. Eur J Neurosci 2016; 44:2654-2666. [PMID: 27256072 PMCID: PMC5113767 DOI: 10.1111/ejn.13291] [Citation(s) in RCA: 216] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 04/28/2016] [Accepted: 05/31/2016] [Indexed: 12/30/2022]
Abstract
Increasing evidence implicates the microbiota in the regulation of brain and behaviour. Germ-free mice (GF; microbiota deficient from birth) exhibit altered stress hormone signalling and anxiety-like behaviours as well as deficits in social cognition. Although the mechanisms underlying the ability of the gut microbiota to influence stress responsivity and behaviour remain unknown, many lines of evidence point to the amygdala and hippocampus as likely targets. Thus, the aim of this study was to determine if the volume and dendritic morphology of the amygdala and hippocampus differ in GF versus conventionally colonized (CC) mice. Volumetric estimates revealed significant amygdalar and hippocampal expansion in GF compared to CC mice. We also studied the effect of GF status on the level of single neurons in the basolateral amygdala (BLA) and ventral hippocampus. In the BLA, the aspiny interneurons and pyramidal neurons of GF mice exhibited dendritic hypertrophy. The BLA pyramidal neurons of GF mice had more thin, stubby and mushroom spines. In contrast, the ventral hippocampal pyramidal neurons of GF mice were shorter, less branched and had less stubby and mushroom spines. When compared to controls, dentate granule cells of GF mice were less branched but did not differ in spine density. These findings suggest that the microbiota is required for the normal gross morphology and ultrastructure of the amygdala and hippocampus and that this neural remodelling may contribute to the maladaptive stress responsivity and behavioural profile observed in GF mice.
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Affiliation(s)
- Pauline Luczynski
- APC Microbiome Institute, University College Cork, Room 3.86, Western Gateway Building, Cork, Ireland
| | - Seán O Whelan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Colette O'Sullivan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Gerard Clarke
- APC Microbiome Institute, University College Cork, Room 3.86, Western Gateway Building, Cork, Ireland
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - Fergus Shanahan
- APC Microbiome Institute, University College Cork, Room 3.86, Western Gateway Building, Cork, Ireland
| | - Timothy G Dinan
- APC Microbiome Institute, University College Cork, Room 3.86, Western Gateway Building, Cork, Ireland
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - John F Cryan
- APC Microbiome Institute, University College Cork, Room 3.86, Western Gateway Building, Cork, Ireland.
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.
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11
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Belmer A, Klenowski PM, Patkar OL, Bartlett SE. Mapping the connectivity of serotonin transporter immunoreactive axons to excitatory and inhibitory neurochemical synapses in the mouse limbic brain. Brain Struct Funct 2016; 222:1297-1314. [PMID: 27485750 PMCID: PMC5368196 DOI: 10.1007/s00429-016-1278-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/20/2016] [Indexed: 12/25/2022]
Abstract
Serotonin neurons arise from the brainstem raphe nuclei and send their projections throughout the brain to release 5-HT which acts as a modulator of several neuronal populations. Previous electron microscopy studies in rats have morphologically determined the distribution of 5-HT release sites (boutons) in certain brain regions and have shown that 5-HT containing boutons form synaptic contacts that are either symmetric or asymmetric. In addition, 5-HT boutons can form synaptic triads with the pre- and postsynaptic specializations of either symmetrical or asymmetrical synapses. However, due to the labor intensive processing of serial sections required by electron microscopy, little is known about the neurochemical properties or the quantitative distribution of 5-HT triads within whole brain or discrete subregions. Therefore, we used a semi-automated approach that combines immunohistochemistry and high-resolution confocal microscopy to label serotonin transporter (SERT) immunoreactive axons and reconstruct in 3D their distribution within limbic brain regions. We also used antibodies against key pre- (synaptophysin) and postsynaptic components of excitatory (PSD95) or inhibitory (gephyrin) synapses to (1) identify putative 5-HTergic boutons within SERT immunoreactive axons and, (2) quantify their close apposition to neurochemical excitatory or inhibitory synapses. We provide a 5-HTergic axon density map and have determined the ratio of synaptic triads consisting of a 5-HT bouton in close proximity to either neurochemical excitatory or inhibitory synapses within different limbic brain areas. The ability to model and map changes in 5-HTergic axonal density and the formation of triadic connectivity within whole brain regions using this rapid and quantitative approach offers new possibilities for studying neuroplastic changes in the 5-HTergic pathway.
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Affiliation(s)
- Arnauld Belmer
- Translational Research Institute, Queensland University of Technology, Brisbane, Qld 4059, Australia
| | - Paul M Klenowski
- Translational Research Institute, Queensland University of Technology, Brisbane, Qld 4059, Australia
| | - Omkar L Patkar
- Translational Research Institute, Queensland University of Technology, Brisbane, Qld 4059, Australia
| | - Selena E Bartlett
- Translational Research Institute, Queensland University of Technology, Brisbane, Qld 4059, Australia. .,Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology, Brisbane, Australia.
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12
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Prager EM, Wynn GH, Ursano RJ. The tenth annual amygdala, stress, and PTSD conference: "The amygdala: Dysfunction, hyperfunction, and connectivity". J Neurosci Res 2016; 94:433-6. [PMID: 27091310 DOI: 10.1002/jnr.23742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
| | - 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
| | - Robert J Ursano
- 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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13
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Gouty-Colomer LA, Hosseini B, Marcelo IM, Schreiber J, Slump DE, Yamaguchi S, Houweling AR, Jaarsma D, Elgersma Y, Kushner SA. Arc expression identifies the lateral amygdala fear memory trace. Mol Psychiatry 2016; 21:364-75. [PMID: 25802982 PMCID: PMC4759206 DOI: 10.1038/mp.2015.18] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 11/28/2014] [Accepted: 01/08/2015] [Indexed: 12/21/2022]
Abstract
Memories are encoded within sparsely distributed neuronal ensembles. However, the defining cellular properties of neurons within a memory trace remain incompletely understood. Using a fluorescence-based Arc reporter, we were able to visually identify the distinct subset of lateral amygdala (LA) neurons activated during auditory fear conditioning. We found that Arc-expressing neurons have enhanced intrinsic excitability and are preferentially recruited into newly encoded memory traces. Furthermore, synaptic potentiation of thalamic inputs to the LA during fear conditioning is learning-specific, postsynaptically mediated and highly localized to Arc-expressing neurons. Taken together, our findings validate the immediate-early gene Arc as a molecular marker for the LA neuronal ensemble recruited during fear learning. Moreover, these results establish a model of fear memory formation in which intrinsic excitability determines neuronal selection, whereas learning-related encoding is governed by synaptic plasticity.
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Affiliation(s)
- L A Gouty-Colomer
- Department of Psychiatry, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - B Hosseini
- Department of Psychiatry, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - I M Marcelo
- Department of Psychiatry, Erasmus University Medical Center, Rotterdam, The Netherlands,Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal
| | - J Schreiber
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - D E Slump
- Department of Psychiatry, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - S Yamaguchi
- Division of Morphological Neuroscience, Gifu University Graduate School of Medicine, Gifu, Japan,PRESTO, Japan Science and Technology Agency (JST), Saitama, Japan
| | - A R Houweling
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - D Jaarsma
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Y Elgersma
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - S A Kushner
- Department of Psychiatry, Erasmus University Medical Center, Rotterdam, The Netherlands,Department of Psychiatry, Erasmus University Medical Center, Dr Molewaterplein 50, Ee-1442, Rotterdam, 3015 GE, The Netherlands. E-mail:
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14
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McDonald AJ, Mott DD. Functional neuroanatomy of amygdalohippocampal interconnections and their role in learning and memory. J Neurosci Res 2016; 95:797-820. [PMID: 26876924 DOI: 10.1002/jnr.23709] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/01/2015] [Accepted: 12/14/2015] [Indexed: 01/31/2023]
Abstract
The amygdalar nuclear complex and hippocampal/parahippocampal region are key components of the limbic system that play a critical role in emotional learning and memory. This Review discusses what is currently known about the neuroanatomy and neurotransmitters involved in amygdalo-hippocampal interconnections, their functional roles in learning and memory, and their involvement in mnemonic dysfunctions associated with neuropsychiatric and neurological diseases. Tract tracing studies have shown that the interconnections between discrete amygdalar nuclei and distinct layers of individual hippocampal/parahippocampal regions are robust and complex. Although it is well established that glutamatergic pyramidal cells in the amygdala and hippocampal region are the major players mediating interconnections between these regions, recent studies suggest that long-range GABAergic projection neurons are also involved. Whereas neuroanatomical studies indicate that the amygdala only has direct interconnections with the ventral hippocampal region, electrophysiological studies and behavioral studies investigating fear conditioning and extinction, as well as amygdalar modulation of hippocampal-dependent mnemonic functions, suggest that the amygdala interacts with dorsal hippocampal regions via relays in the parahippocampal cortices. Possible pathways for these indirect interconnections, based on evidence from previous tract tracing studies, are discussed in this Review. Finally, memory disorders associated with dysfunction or damage to the amygdala, hippocampal region, and/or their interconnections are discussed in relation to Alzheimer's disease, posttraumatic stress disorder (PTSD), and temporal lobe epilepsy. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Alexander J McDonald
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina
| | - David D Mott
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina
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15
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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: 112] [Impact Index Per Article: 12.4] [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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16
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Lu Y, Sun XD, Hou FQ, Bi LL, Yin DM, Liu F, Chen YJ, Bean JC, Jiao HF, Liu X, Li BM, Xiong WC, Gao TM, Mei L. Maintenance of GABAergic Activity by Neuregulin 1-ErbB4 in Amygdala for Fear Memory. Neuron 2014; 84:835-46. [DOI: 10.1016/j.neuron.2014.09.029] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2014] [Indexed: 12/11/2022]
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17
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Pathophysiological mechanisms underlying increased anxiety after soman exposure: reduced GABAergic inhibition in the basolateral amygdala. Neurotoxicology 2014; 44:335-43. [PMID: 25150775 DOI: 10.1016/j.neuro.2014.08.007] [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] [Received: 06/05/2014] [Revised: 07/22/2014] [Accepted: 08/13/2014] [Indexed: 11/21/2022]
Abstract
The recent sarin attack in Syria killed 1429 people, including 426 children, and left countless more to deal with the health consequences of the exposure. Prior to the Syrian chemical assault, nerve agent attacks in Japan left many victims suffering from neuropsychiatric illnesses, particularly anxiety disorders, more than a decade later. Uncovering the neuro-pathophysiological mechanisms underlying the development of anxiety after nerve agent exposure is necessary for successful treatment. Anxiety is associated with hyperexcitability of the basolateral amygdala (BLA). The present study sought to determine the nature of the nerve agent-induced alterations in the BLA, which could explain the development of anxiety. Rats were exposed to soman, at a dose that induced prolonged status epilepticus. Twenty-four hours and 14-days after exposure, neurons from the BLA were recorded using whole-cell patch-clamp techniques. At both the 24h and 14-day post-exposure time-points, the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs) in the BLA were reduced, along with reduction in the frequency but not amplitude of miniature IPSCs. In addition, activation of α7-nicotinic acetylcholine receptors, a cholinergic receptor that participates in the regulation of BLA excitability and is involved in anxiety, increased spontaneous excitatory postsynaptic currents (sEPSCs) in both soman-exposed rats and controls, but was less effective in increasing sIPSCs in soman-exposed rats. Despite the loss of both interneurons and principal cells after soman-induced status epilepticus, the frequency of sEPSCs was increased in the soman-exposed rats. Impaired function and cholinergic modulation of GABAergic inhibition in the BLA may underlie anxiety disorders that develop after nerve agent exposure.
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18
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Prager EM, Aroniadou-Anderjaska V, Almeida-Suhett CP, Figueiredo TH, Apland JP, Rossetti F, Olsen CH, Braga MFM. The recovery of acetylcholinesterase activity and the progression of neuropathological and pathophysiological alterations in the rat basolateral amygdala after soman-induced status epilepticus: relation to anxiety-like behavior. Neuropharmacology 2014; 81:64-74. [PMID: 24486384 PMCID: PMC4005290 DOI: 10.1016/j.neuropharm.2014.01.035] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 12/12/2013] [Accepted: 01/21/2014] [Indexed: 02/05/2023]
Abstract
Organophosphorus nerve agents are powerful neurotoxins that irreversibly inhibit acetylcholinesterase (AChE) activity. One of the consequences of AChE inhibition is the generation of seizures and status epilepticus (SE), which cause brain damage, resulting in long-term neurological and behavioral deficits. Increased anxiety is the most common behavioral abnormality after nerve agent exposure. This is not surprising considering that the amygdala, and the basolateral nucleus of the amygdala (BLA) in particular, plays a central role in anxiety, and this structure suffers severe damage by nerve agent-induced seizures. In the present study, we exposed male rats to the nerve agent soman, at a dose that induce SE, and determined the time course of recovery of AChE activity, along with the progression of neuropathological and pathophysiological alterations in the BLA, during a 30-day period after exposure. Measurements were taken at 24 h, 7 days, 14 days, and 30 days after exposure, and at 14 and 30 days, anxiety-like behavior was also evaluated. We found that more than 90% of AChE is inhibited at the onset of SE, and AChE inhibition remains at this level 24 h later, in the BLA, as well as in the hippocampus, piriform cortex, and prelimbic cortex, which we analyzed for comparison. AChE activity recovered by day 7 in the BLA and day 14 in the other three regions. Significant neuronal loss and neurodegeneration were present in the BLA at 24 h and throughout the 30-day period. There was no significant loss of GABAergic interneurons in the BLA at 24 h post-exposure. However, by day 7, the number of GABAergic interneurons in the BLA was reduced, and at 14 and 30 days after soman, the ratio of GABAergic interneurons to the total number of neurons was lower compared to controls. Anxiety-like behavior in the open-field and the acoustic startle response tests was increased at 14 and 30 days post-exposure. Accompanying pathophysiological alterations in the BLA - studied in in vitro brain slices - included a reduction in the amplitude of field potentials evoked by stimulation of the external capsule, along with prolongation of their time course and an increase in the paired-pulse ratio. Long-term potentiation was impaired at 24 h, 7 days, and 14 days post-exposure. The loss of GABAergic interneurons in the BLA and the decreased interneuron to total number of neurons ratio may be the primary cause of the development of anxiety after nerve agent exposure.
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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, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Camila P Almeida-Suhett
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Taiza H Figueiredo
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - James P Apland
- Neurotoxicology Branch, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA
| | - Franco Rossetti
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Cara H Olsen
- Biostatistics Consulting Center, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
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19
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Unal G, Paré JF, Smith Y, Paré D. Cortical inputs innervate calbindin-immunoreactive interneurons of the rat basolateral amygdaloid complex. J Comp Neurol 2014; 522:1915-28. [PMID: 24285470 PMCID: PMC3984626 DOI: 10.1002/cne.23511] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/15/2013] [Accepted: 11/25/2013] [Indexed: 01/04/2023]
Abstract
The present study was undertaken to shed light on the synaptic organization of the rat basolateral amygdala (BLA). The BLA contains multiple types of GABAergic interneurons that are differentially connected with extrinsic afferents and other BLA cells. Previously, it was reported that parvalbumin immunoreactive (PV(+) ) interneurons receive strong excitatory inputs from principal BLA cells but very few cortical inputs, implying a prevalent role in feedback inhibition. However, because prior physiological studies indicate that cortical afferents do trigger feedforward inhibition in principal cells, the present study aimed to determine whether a numerically important subtype of interneurons, expressing calbindin (CB(+) ), receives cortical inputs. Rats received injections of the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHAL) in the perirhinal cortex or adjacent temporal neocortex. Light and electron microscopic observations of the relations between cortical inputs and BLA neurons were performed in the lateral (LA) and basolateral (BL) nuclei. Irrespective of the injection site (perirhinal or temporal neocortex) and target nucleus (LA or BL), ~90% of cortical axon terminals formed asymmetric synapses with dendritic spines of principal BLA neurons, while 10% contacted the dendritic shafts of presumed interneurons, half of which were CB(+) . Given the previously reported pattern of CB coexpression among GABAergic interneurons of the BLA, these results suggest that a subset of PV-immunonegative cells that express CB, most likely the somatostatin-positive interneurons, are important mediators of cortically evoked feedforward inhibition in the BLA.
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Affiliation(s)
- Gunes Unal
- Center for Molecular & Behavioral Neuroscience, Rutgers University, Newark, NJ 07102
| | - Jean-Francois Paré
- Yerkes National Primate Research Center and Department of Neurology, Emory University, 954 Gatewood Road, Atlanta, GA 30329
| | - Yoland Smith
- Yerkes National Primate Research Center and Department of Neurology, Emory University, 954 Gatewood Road, Atlanta, GA 30329
| | - Denis Paré
- Center for Molecular & Behavioral Neuroscience, Rutgers University, Newark, NJ 07102
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20
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Capogna M. GABAergic cell type diversity in the basolateral amygdala. Curr Opin Neurobiol 2014; 26:110-6. [PMID: 24486420 DOI: 10.1016/j.conb.2014.01.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 12/10/2013] [Accepted: 01/08/2014] [Indexed: 11/20/2022]
Abstract
Here I review the diversity of GABAergic neurons in the rodent basolateral amygdala (BLA). In spite of the recent identification of the role played by certain neurons of BLA in learning and memory of fear, the diversity of GABAergic neurons has not been fully explored. I describe analogies and differences between GABAergic neurons in BLA and cerebral cortex. Emphasis is given to a comprehensive functional, neurochemical and anatomical classification of GABAergic neuron types.
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Affiliation(s)
- Marco Capogna
- MRC Anatomical Neuropharmacology Unit, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK.
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21
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The response of juxtacellular labeled GABA interneurons in the basolateral amygdaloid nucleus anterior part to 5-HT2A/2C receptor activation is decreased in rats with 6-hydroxydopamine lesions. Neuropharmacology 2013; 73:404-14. [DOI: 10.1016/j.neuropharm.2013.06.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 06/17/2013] [Accepted: 06/19/2013] [Indexed: 11/19/2022]
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22
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Pidoplichko VI, Prager EM, Aroniadou-Anderjaska V, Braga MFM. α7-Containing nicotinic acetylcholine receptors on interneurons of the basolateral amygdala and their role in the regulation of the network excitability. J Neurophysiol 2013; 110:2358-69. [PMID: 24004528 DOI: 10.1152/jn.01030.2012] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The basolateral amygdala (BLA) plays a key role in fear-related learning and memory, in the modulation of cognitive functions, and in the overall regulation of emotional behavior. Pathophysiological alterations involving hyperexcitability in this brain region underlie anxiety and other emotional disorders as well as some forms of epilepsy. GABAergic interneurons exert a tight inhibitory control over the BLA network; understanding the mechanisms that regulate their activity is necessary for understanding physiological and disordered BLA functions. The BLA receives dense cholinergic input from the basal forebrain, affecting both normal functions and dysfunctions of the amygdala, but the mechanisms involved in the cholinergic regulation of inhibitory activity in the BLA are unclear. Using whole cell recordings in rat amygdala slices, here we demonstrate that the α(7)-containing nicotinic acetylcholine receptors (α(7)-nAChRs) are present on somatic or somatodendritic regions of BLA interneurons. These receptors are active in the basal state enhancing GABAergic inhibition, and their further, exogenous activation produces a transient but dramatic increase of spontaneous inhibitory postsynaptic currents in principal BLA neurons. In the absence of AMPA/kainate receptor antagonists, activation of α(7)-nAChRs in the BLA network increases both GABAergic and glutamatergic spontaneous currents in BLA principal cells, but the inhibitory currents are enhanced significantly more than the excitatory currents, reducing overall excitability. The anxiolytic effects of nicotine as well as the role of the α(7)-nAChRs in seizure activity involving the amygdala and in mental illnesses, such as schizophrenia and Alzheimer's disease, may be better understood in light of the present findings.
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Affiliation(s)
- Volodymyr I Pidoplichko
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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23
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Lee S, Kim SJ, Kwon OB, Lee JH, Kim JH. Inhibitory networks of the amygdala for emotional memory. Front Neural Circuits 2013; 7:129. [PMID: 23914157 PMCID: PMC3729980 DOI: 10.3389/fncir.2013.00129] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 07/17/2013] [Indexed: 11/19/2022] Open
Abstract
The amygdala is important for emotional memory, including learned fear. A number of studies for amygdala neural circuits that underlie fear conditioning have elucidated specific cellular and molecular mechanisms of emotional memory. Recent technical advances such as optogenetic approaches have not only confirmed the importance of excitatory circuits in fear conditioning, but have also shed new light for a direct role of inhibitory circuits in both the acquisition and extinction of fear memory in addition to their role in fine tuning of excitatory neural circuitry. As a result, the circuits in amygdala could be drawn more elaborately, and it led us to understand how fear or extinction memories are formed in the detailed circuit level, and various neuromodulators affect these circuit activities, inducing subtle behavioral changes.
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Affiliation(s)
- Seungho Lee
- Department of Life Science, Pohang University of Science and Technology Pohang, South Korea
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24
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Kim D, Paré D, Nair SS. Mechanisms contributing to the induction and storage of Pavlovian fear memories in the lateral amygdala. Learn Mem 2013; 20:421-30. [PMID: 23864645 PMCID: PMC3718199 DOI: 10.1101/lm.030262.113] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 05/21/2013] [Indexed: 11/24/2022]
Abstract
The relative contributions of plasticity in the amygdala vs. its afferent pathways to conditioned fear remain controversial. Some believe that thalamic and cortical neurons transmitting information about the conditioned stimulus (CS) to the lateral amygdala (LA) serve a relay function. Others maintain that thalamic and/or cortical plasticity is critically involved in fear conditioning. To address this question, we developed a large-scale biophysical model of the LA that could reproduce earlier findings regarding the cellular correlates of fear conditioning in LA. We then conducted model experiments that examined whether fear memories depend on (1) training-induced increases in the responsiveness of thalamic and cortical neurons projecting to LA, (2) plasticity at the synapses they form in LA, and/or (3) plasticity at synapses between LA neurons. These tests revealed that training-induced increases in the responsiveness of afferent neurons are required for fear memory formation. However, once the memory has been formed, this factor is no longer required because the efficacy of the synapses that thalamic and cortical neurons form with LA cells has augmented enough to maintain the memory. In contrast, our model experiments suggest that plasticity at synapses between LA neurons plays a minor role in maintaining the fear memory.
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Affiliation(s)
- Dongbeom Kim
- Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65211, USA
| | - Denis Paré
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, Newark, New Jersey 07102, USA
| | - Satish S. Nair
- Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65211, USA
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25
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Sturm V, Fricke O, Bührle CP, Lenartz D, Maarouf M, Treuer H, Mai JK, Lehmkuhl G. DBS in the basolateral amygdala improves symptoms of autism and related self-injurious behavior: a case report and hypothesis on the pathogenesis of the disorder. Front Hum Neurosci 2013; 6:341. [PMID: 23346052 PMCID: PMC3549527 DOI: 10.3389/fnhum.2012.00341] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 12/11/2012] [Indexed: 01/06/2023] Open
Abstract
We treated a 13-year-old boy for life-threatening self-injurious behavior (SIB) and severe Kanner's autism with deep brain stimulation (DBS) in the amygdaloid complex as well as in the supra-amygdaloid projection system. Two DBS-electrodes were placed in both structures of each hemisphere. The stimulation contacts targeted the paralaminar, the basolateral (BL), the central amygdala as well as the supra-amygdaloid projection system. DBS was applied to each of these structures, but only stimulation of the BL part proved effective in improving SIB and core symptoms of the autism spectrum in the emotional, social, and even cognitive domains over a follow up of now 24 months. These results, which have been gained for the first time in a patient, support hypotheses, according to which the amygdala may be pivotal in the pathogeneses of autism and point to the special relevance of the BL part.
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Affiliation(s)
- Volker Sturm
- Department of Stereotactic and Functional Neurosurgery, University of Cologne Cologne, Germany
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26
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Palomares-Castillo E, Hernández-Pérez OR, Pérez-Carrera D, Crespo-Ramírez M, Fuxe K, Pérez de la Mora M. The intercalated paracapsular islands as a module for integration of signals regulating anxiety in the amygdala. Brain Res 2012; 1476:211-34. [DOI: 10.1016/j.brainres.2012.03.047] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 03/15/2012] [Accepted: 03/19/2012] [Indexed: 11/30/2022]
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Orsini CA, Maren S. Neural and cellular mechanisms of fear and extinction memory formation. Neurosci Biobehav Rev 2012; 36:1773-802. [PMID: 22230704 PMCID: PMC3345303 DOI: 10.1016/j.neubiorev.2011.12.014] [Citation(s) in RCA: 321] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Revised: 12/16/2011] [Accepted: 12/23/2011] [Indexed: 02/08/2023]
Abstract
Over the course of natural history, countless animal species have evolved adaptive behavioral systems to cope with dangerous situations and promote survival. Emotional memories are central to these defense systems because they are rapidly acquired and prepare organisms for future threat. Unfortunately, the persistence and intrusion of memories of fearful experiences are quite common and can lead to pathogenic conditions, such as anxiety and phobias. Over the course of the last 30 years, neuroscientists and psychologists alike have attempted to understand the mechanisms by which the brain encodes and maintains these aversive memories. Of equal interest, though, is the neurobiology of extinction memory formation as this may shape current therapeutic techniques. Here we review the extant literature on the neurobiology of fear and extinction memory formation, with a strong focus on the cellular and molecular mechanisms underlying these processes.
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Affiliation(s)
- Caitlin A. Orsini
- Department of Psychology, University of Michigan, Ann Arbor, MI, 48109-1043, USA
| | - Stephen Maren
- Department of Psychology, University of Michigan, Ann Arbor, MI, 48109-1043, USA
- Department of Neuroscience Program, University of Michigan, Ann Arbor, MI, 48109-1043, USA
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Serotonergic innervation and serotonin receptor expression of NPY-producing neurons in the rat lateral and basolateral amygdaloid nuclei. Brain Struct Funct 2012; 218:421-35. [PMID: 22527118 PMCID: PMC3580143 DOI: 10.1007/s00429-012-0406-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 03/13/2012] [Indexed: 01/28/2023]
Abstract
Pharmacobehavioral studies in experimental animals, and imaging studies in humans, indicate that serotonergic transmission in the amygdala plays a key role in emotional processing, especially for anxiety-related stimuli. The lateral and basolateral amygdaloid nuclei receive a dense serotonergic innervation in all species studied to date. We investigated interrelations between serotonergic afferents and neuropeptide Y (NPY)-producing neurons, which are a subpopulation of inhibitory interneurons in the rat lateral and basolateral nuclei with particularly strong anxiolytic properties. Dual light microscopic immunolabeling showed numerous appositions of serotonergic afferents on NPY-immunoreactive somata. Using electron microscopy, direct membrane appositions and synaptic contacts between serotonin-containing axon terminals and NPY-immunoreactive cellular profiles were unequivocally established. Double in situ hybridization documented that more than 50 %, and about 30–40 % of NPY mRNA-producing neurons, co-expressed inhibitory 5-HT1A and excitatory 5-HT2C mRNA receptor subtype mRNA, respectively, in both nuclei with no gender differences. Triple in situ hybridization showed that individual NPY mRNA-producing interneurons co-express both 5-HT1A and 5-HT2C mRNAs. Co-expression of NPY and 5-HT3 mRNA was not observed. The results demonstrate that serotonergic afferents provide substantial innervation of NPY-producing neurons in the rat lateral and basolateral amygdaloid nuclei. Studies of serotonin receptor subtype co-expression indicate a differential impact of the serotonergic innervation on this small, but important, population of anxiolytic interneurons, and provide the basis for future studies of the circuitry underlying serotonergic modulation of emotional stimulus processing in the amygdala.
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Cruz MT, Herman MA, Kallupi M, Roberto M. Nociceptin/orphanin FQ blockade of corticotropin-releasing factor-induced gamma-aminobutyric acid release in central amygdala is enhanced after chronic ethanol exposure. Biol Psychiatry 2012; 71:666-76. [PMID: 22153590 PMCID: PMC3838304 DOI: 10.1016/j.biopsych.2011.10.032] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/26/2011] [Accepted: 10/29/2011] [Indexed: 11/24/2022]
Abstract
BACKGROUND The central nucleus of the amygdala (CeA) mediates stress- and addiction-related processes. Corticotropin-releasing factor (CRF) and nociceptin/orphanin FQ (nociceptin) regulate ethanol intake and anxiety-like behavior. In the rat, CRF and ethanol significantly augment CeA gamma-aminobutyric acid (GABA) release, whereas nociceptin diminishes it. METHODS Using electrophysiologic techniques in an in vitro slice preparation, we investigated the interaction of nociceptin and CRF on evoked and spontaneous GABAergic transmission in CeA slices of naive and ethanol-dependent rats and the mechanistic role of protein kinase A. RESULTS In neurons from naive animals, nociceptin dose-dependently diminished basal-evoked GABA(A) receptor-mediated inhibitory postsynaptic potentials (IPSPs) by decreasing GABA release and prevented, as well as reversed, CRF-induced augmentation of IPSPs, actions that required PKA signaling. In neurons from ethanol-dependent animals, nociceptin decreased basal GABAergic transmission and blocked the CRF-induced increase in GABA release to a greater extent than in naive controls. CONCLUSIONS These data provide new evidence for an interaction between the nociceptin and CRF systems in the CeA. Nociceptin opposes CRF effects on CeA GABAergic transmission with sensitization of this effect in dependent animals. These properties of nociceptin may underlie its anti-alcohol and anxiolytic properties and identify the nociceptin receptor as a useful therapeutic target for alcoholism.
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Affiliation(s)
- Maureen T Cruz
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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Alterations of emotion, cognition and firing activity of the basolateral nucleus of the amygdala after partial bilateral lesions of the nigrostriatal pathway in rats. Brain Res Bull 2011; 85:329-38. [PMID: 21624440 DOI: 10.1016/j.brainresbull.2011.05.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Revised: 02/26/2011] [Accepted: 05/15/2011] [Indexed: 11/20/2022]
Abstract
Although increasing evidence indicates that psychiatric symptoms are crucial characteristic of the early stage of Parkinson's disease (PD) and precede motor impairments, the neuronal firing activity of the basolateral nucleus of the amygdala (BLA) in the psychiatric symptom of PD and the involved mechanism are still unclear. In the present study, we examined the changes in emotional and cognitive tests not focused on motor fluency and firing activity of projection neurons in the BLA rats with 6-hydroxydopamine (6-OHDA) injected bilaterally into dorsal striatum, and the effects of apomorphine and the medial prefrontal cortex (mPFC) on these changes. Injection of 6-OHDA (10.5 μg) into the dorsal striatum produced 18-22% and 26-30% loss of tyrosine hydroxylase immunoreactive neurons in the ventral tegmental area and substantia nigra pars compacta of rats, respectively. The striatal lesions induced anxiety-like responses in the rats but did not result in depressive-like behavior or cognitive impairments. In the lesioned rats, the firing rate of BLA projection neurons decreased significantly compared with sham-operated rats, and the firing pattern of BLA projection neurons was not changed. No significant differences were observed either in behaviors or firing activity of BLA projection neurons by further ibotenic acid lesions of the mPFC in the lesioned rats. Systemic administration of cumulative apomorphine (10-160 μg/kg) inhibited the firing rate of BLA projection neurons in sham-operated, 6-OHDA-lesioned and combined 6-OHDA- and mPFC-lesioned rats, but the latter needed more apomorphine stimulation. These data suggest that the anxiety in early stage of PD is possibly related to the decrease in firing activity of BLA projection neurons, which may be regulated by the activation of dopamine receptor in the mPFC.
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Chronic, systemic treatment with a metabotropic glutamate receptor 5 antagonist produces anxiolytic-like effects and reverses abnormal firing activity of projection neurons in the basolateral nucleus of the amygdala in rats with bilateral 6-OHDA lesions. Brain Res Bull 2011; 84:215-23. [PMID: 21255635 DOI: 10.1016/j.brainresbull.2011.01.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 12/09/2010] [Accepted: 01/05/2011] [Indexed: 12/17/2022]
Abstract
Although 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a selective metabotropic glutamate receptor 5 antagonist, improves the motor symptoms of Parkinson's disease (PD), the effects of MPEP on the psychiatric symptom of PD and the mechanism involved are still unclear. In the present study, we examined the effects of MPEP in anxiolytic-like behavior and firing activity of projection neurons in the basolateral nucleus of the amygdala (BLA) in rats with 6-hydroxydopamine (6-OHDA) injected bilaterally into dorsal striatum. Rats were divided into three groups, sham-operated group, 6-OHDA lesion with vehicle treatment group and 6-OHDA lesion with MPEP treatment group. Injection of 6-OHDA (10.5 μg) into the dorsal striatum produced 31.5% loss of tyrosine hydroxylase immunoreactive (TH-ir) neurons in the SNpc. The 6-OHDA-lesioned rats showed anxiety behavior and the firing rate of BLA projection neurons decreased significantly compared with sham-operated rats, and no difference was found in the firing pattern of these neurons. Whereas chronic, systemic treatment of MPEP (3 mg/kg/day, i.p.; 14 days) attenuated loss of TH-ir neurons, produced anxiolytic-like effect and normalized the abnormal firing rate of projection neurons of the BLA in rats with the bilateral lesions. Systemic administration of cumulative apomorphine (10-160 μg/kg, i.v.) inhibited the firing rate of BLA projection neurons in sham-operated, 6-OHDA lesion with vehicle-treated and MPEP-treated rats, but the 6-OHDA lesion decreased the response of BLA projection neurons to apomorphine stimulation, while MPEP reversed the reactivity of these neurons. These data demonstrate that the partial lesion of the nigrostriatal pathway causes anxiety symptom and decreases firing rate of BLA projection neurons in the rat. Furthermore, chronic, systemic MPEP treatment has the neuroprotective and anxiolytic-like effects, and reverses the abnormal firing rate of BLA projection neurons, suggesting that MPEP has important implication for the treatment of PD.
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32
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Diaz MR, Christian DT, Anderson NJ, McCool BA. Chronic ethanol and withdrawal differentially modulate lateral/basolateral amygdala paracapsular and local GABAergic synapses. J Pharmacol Exp Ther 2011; 337:162-70. [PMID: 21209156 DOI: 10.1124/jpet.110.177121] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Withdrawal-related anxiety is cited as a major contributor to relapse in recovering alcoholics. Changes in lateral/basolateral amygdala (BLA) neurotransmission could directly influence anxiety-like behaviors after chronic ethanol exposure and withdrawal. We have shown that these treatments enhance BLA glutamatergic function and neurotransmission. However, the BLA GABAergic system tightly controls the expression of anxiety-like behavior, and additional neuroadaptations in this system are potentially important as well. The intrinsic BLA GABAergic system consists of at least two populations of interneurons: local feed-back interneurons scattered throughout the region and feed-forward interneurons concentrated within groups found in the lateral/paracapsular region of the BLA. In the present study, we found that withdrawal from chronic ethanol robustly decreased presynaptic function at feed-forward GABA synapses but did not alter neurotransmitter release from local interneurons. Differential presynaptic changes at these synapses were complemented by decreased zolpidem sensitivity at feed-forward synapses and decreased midazolam sensitivity at local synapses. Consistent with this, chronic ethanol/withdrawal decreased expression of GABA α1-subunit total protein and increased surface expression of α4-subunit protein. We also found transient increases in GABA-receptor-associated protein levels and persistent increases in γ2-subunit and gephyrin proteins that would suggest alterations in GABA(A) receptor trafficking that might help regulate changes in α4-subunit localization. These data together suggest that chronic ethanol and withdrawal differentially modulate local and lateral paracapsular cell GABAergic synapses via distinct presynaptic and postsynaptic mechanisms. These findings extend our understanding of the neurobiological mechanisms governing changes in anxiety-like behavior after chronic ethanol exposure and withdrawal.
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Affiliation(s)
- Marvin R Diaz
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
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33
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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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34
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Popescu AT, Paré D. Synaptic interactions underlying synchronized inhibition in the basal amygdala: evidence for existence of two types of projection cells. J Neurophysiol 2010; 105:687-96. [PMID: 21084688 DOI: 10.1152/jn.00732.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The basal amygdala (BA) plays a key role in mediating the facilitating effects of emotions on memory. Recent findings indicate that this function depends on the ability of BA neurons to generate coherent oscillatory activity, facilitating synaptic plasticity in target neurons. However, the mechanisms allowing BA neurons to synchronize their activity remain poorly understood. Here, we aimed to shed light on this question, focusing on a slow periodic inhibitory oscillation previously observed in the BA in vitro. Paired patch recordings showed that these large inhibitory postsynaptic potentials (IPSPs) occur almost synchronously in BA projection neurons, that they were typically not preceded by excitatory postsynaptic potentials (EPSPs), and that they had little or no correlate in neighboring amygdala nuclei or cortical fields. The initial phase of the IPSPs was associated with an increase in membrane potential fluctuations at 50-100 Hz. In keeping with this, the IPSPs seen in projection cells were correlated with repetitive firing at 50-100 Hz in presumed interneurons and they could be abolished by picrotoxin. However, the IPSPs were also sensitive to 6-cyano-7-nitroquinoxaline-2,3-dione, implying that they arose from the interplay between glutamatergic and GABAergic BA neurons. In support of this idea, we identified a small subset of projection cells (15%), positively identified as such by retrograde labeling from BA projection sites, that began firing shortly before the IPSP onset and presumably drove interneuronal firing. These results add to a rapidly growing body of data indicating that the BA contains at least two distinct types of projection cells that vary in their relation with interneurons and extra-amygdala targets.
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Affiliation(s)
- Andrei T Popescu
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, Newark, New Jersey 07102, USA
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35
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Zhou R, Wang S, Zhu X. Prenatal ethanol exposure attenuates GABAergic inhibition in basolateral amygdala leading to neuronal hyperexcitability and anxiety-like behavior of adult rat offspring. Neuroscience 2010; 170:749-57. [PMID: 20688136 DOI: 10.1016/j.neuroscience.2010.07.055] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 07/26/2010] [Accepted: 07/28/2010] [Indexed: 11/16/2022]
Abstract
Prenatal exposure to a relatively high-dose ethanol (EtOH) caused anxiety-like behavior of adult male rat offspring. Previous studies have demonstrated that GABA system in the basolateral amygdala complex (BLA) is involved in the pathogensis of anxiety-related disorders. The role of GABAergic system in the BLA was investigated in anxiety-like behavior evoked by prenatal EtOH exposure. The infusion of midazolam (MDZ), a positive modulator of GABA(A) receptor, into the BLA prevented anxiety-like behavior in EtOH-offspring without affecting the corresponding behavior of control offspring. The data suggest that anxiety-like behavior could be causally related to increased neuronal excitability attributable to depressed GABAergic inhibition in the BLA. To test this hypothesis, evoked potential was studied using brain slices from EtOH-offspring. Potential evoked in the BLA by single stimuli applied to external capsule showed multispike responses, indicative of GABAergic disinhibition. These multiple responses were no longer evident after the perfusion with MDZ. In the slices from EtOH-offspring, paired-pulse inhibition (GABA(A)-dependent) was suppressed. Also, in EtOH-offspring, long-term potentiation (LTP) was induced by a single train of high frequency stimulation, which did not induce LTP in control rats. Moreover, MDZ pretreatment prevented the facilitating effect of EtOH on LTP induction. The data provide the functional evidence that prenatal EtOH exposure attenuates GABAergic inhibition in the BLA resulting in neuronal hyperexcitability and anxiety-like behavior of adult rat offspring.
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Affiliation(s)
- R Zhou
- Department of Physiology, Nanjing Medical University, Hanzhong Road 140, Jiangsu, PR China.
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36
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Hadjab-Lallemend S, Wallis K, van Hogerlinden M, Dudazy S, Nordström K, Vennström B, Fisahn A. A mutant thyroid hormone receptor alpha1 alters hippocampal circuitry and reduces seizure susceptibility in mice. Neuropharmacology 2010; 58:1130-9. [PMID: 20153760 DOI: 10.1016/j.neuropharm.2010.02.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 01/12/2010] [Accepted: 02/04/2010] [Indexed: 11/23/2022]
Abstract
Thyroid hormone deficiency during early developmental stages causes a multitude of functional and morphological deficits in the brain. In the present study we investigate the effects of a mutated thyroid hormone receptor TR alpha 1 and the resulting receptor-mediated hypothyroidism on the development of GABAergic neurotransmission and seizure susceptibility of neuronal networks. We show that mutant mice have a strong resistance to seizures induced by antagonizing the GABA(A) receptor complex. Likewise the hippocampal network of mutant mice shows a decreased likelihood to transform physiological into pathological rhythmic network activity such as seizure-like interictal waves. As we demonstrate the cellular basis for this behavior is formed by the excitatory nature of GABAergic neurotransmission in the mutant mice, possibly caused by altered Cl(-) homeostasis, and/or the altered patterning of calretinin-positive cells in the hippocampal hilus. This study is, to our knowledge, the first to show an effect of maternal and early postnatal hypothyroidism via TR alpha 1 on the development of GABAergic neurotransmission and susceptibility to epileptic seizures.
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Affiliation(s)
- Saïda Hadjab-Lallemend
- Department of Cell and Molecular Biology, Karolinska Institutet, von Eulers väg 3, SE-171 77 Stockholm, Sweden
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37
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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: 756] [Impact Index Per Article: 54.0] [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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38
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Role of dopamine receptor mechanisms in the amygdaloid modulation of fear and anxiety: Structural and functional analysis. Prog Neurobiol 2010; 90:198-216. [DOI: 10.1016/j.pneurobio.2009.10.010] [Citation(s) in RCA: 185] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 06/05/2009] [Accepted: 10/09/2009] [Indexed: 11/18/2022]
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Pan BX, Dong Y, Ito W, Yanagawa Y, Shigemoto R, Morozov A. Selective gating of glutamatergic inputs to excitatory neurons of amygdala by presynaptic GABAb receptor. Neuron 2009; 61:917-29. [PMID: 19324000 DOI: 10.1016/j.neuron.2009.01.029] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 12/01/2008] [Accepted: 01/29/2009] [Indexed: 12/12/2022]
Abstract
GABAb receptor (GABAbR)-mediated suppression of glutamate release is critical for limiting glutamatergic transmission across the central nervous system (CNS). Here we show that, upon tetanic stimulation of afferents to lateral amygdala, presynaptic GABAbR-mediated inhibition only occurs in glutamatergic inputs to principle neurons (PNs), not to interneurons (INs), despite the presence of GABAbR in terminals to both types of neurons. The selectivity is caused by differential local GABA accumulation; it requires GABA reuptake and parallels distinct spatial distributions of presynaptic GABAbR in terminals to PNs and INs. Moreover, GABAbR-mediated suppression of theta-burst-induced long-term potentiation (LTP) occurs only in the inputs to PNs, not to INs. Thus, target-cell-specific control of glutamate release by presynaptic GABAbR orchestrates the inhibitory dominance inside amygdala and might contribute to prevention of nonadaptive defensive behaviors.
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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, 35 Convent Drive, Bethesda, MD 20892, USA.
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40
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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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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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Orexin neurons in the hypothalamus mediate cardiorespiratory responses induced by disinhibition of the amygdala and bed nucleus of the stria terminalis. Brain Res 2009; 1262:25-37. [PMID: 19368849 DOI: 10.1016/j.brainres.2009.01.022] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 01/13/2009] [Accepted: 01/14/2009] [Indexed: 02/06/2023]
Abstract
We previously showed that the defense response elicited by stressors was attenuated in prepro-orexin knockout mice and in orexin neuron-ablated mice, and we proposed that orexin serves as a master switch within multiple efferent pathways that mediate the defense response. In this study we sought to determine whether excitation of the amygdala (AMG) or the bed nucleus of stria terminalis (BNST) activates orexin-containing neurons and whether those neurons are essential in eliciting cardiorespiratory responses to the stimulus. In urethane-anesthetized mice, the GABA-A receptor antagonist bicuculline was microinjected into the AMG or BNST and blood pressure, heart rate, and respiration were measured. Injection of bicuculline in either site induced long-lasting dose-dependent cardiorespiratory excitation in wild-type mice. In contrast, mice in which orexin neurons had been ablated demonstrated no such response after activation of the AMG and an attenuated response after activation of the BNST. Double immunohistochemical staining for orexin and c-Fos, an indicator of neural activation, revealed that an injection of bicuculline induced significantly larger numbers of orexin positive neurons that expressed c-Fos in the perifornical/dorsomedial hypothalamus (58.2+/-6.4% into AMG and 66.4+/-6.6% into BNST, n=3 each) than did vehicle (18.2+/-4.4% into AMG and 28.3+/-2.1% into BNST). Disinhibition to the BNST induced widespread expression of c-Fos not only in orexin-containing neurons but also other neurons in the hypothalamus. We conclude that orexin-containing neurons in the medial hypothalamus mediate at least a part of AMG- and BNST-induced cardiorespiratory responses.
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Zheng J, Wu X, Li L. Metabotropic glutamate receptors subtype 5 are necessary for the enhancement of auditory evoked potentials in the lateral nucleus of the amygdala by tetanic stimulation of the auditory thalamus. Neuroscience 2008; 152:254-64. [PMID: 18065158 DOI: 10.1016/j.neuroscience.2007.10.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2007] [Revised: 10/30/2007] [Accepted: 10/31/2007] [Indexed: 11/17/2022]
Abstract
The lateral nucleus of the amygdala (LA) receives axonal projections from the auditory thalamus, the medial geniculate nucleus (MGN), and mediates auditory fear conditioning. Tetanic electrical stimulation of the MGN can induce long-term potentiation of acoustically-evoked responses (AEPs) recorded in the LA of anesthetized rats. The present study investigated the temporal development of tetanus-induced AEP potentiation recorded in the LA of anesthetized rats during the recording time up to 120 min after tetanization. In addition, the present study investigated whether the artificially-induced AEP potentiation is mediated by the metabotropic glutamate receptors subtype 5 (mGluR5). The results show that AEPs recorded in the LA to a broadband-noise burst were significantly enhanced immediately after tetanic but not low-frequency stimulation of the MGN. The AEP potentiation was well retained up to 120 min after tetanization. High-dose (1.5 microg/4 microl) microinjection of the selective antagonist of mGluR5, 2-methyl-6-(phenylethynyl)-pyridine (MPEP), into the ipsilateral lateral ventricle 30 min before tetanization completely blocked the AEP potentiation without affecting the baseline AEP. Low-dose (0.5 microg/4 microl) microinjection partially suppressed the AEP potentiation. When the high-dose MPEP was injected 40 min after tetanization, the AEP potentiation was not affected. These results indicate that in anesthetized rats mGluR5 receptors are necessary for the induction or early maintenance (40 min) of AEP potentiation in the LA by tetanic stimulation of the MGN.
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Affiliation(s)
- J Zheng
- Department of Psychology, Speech and Hearing Research Center, State Key Laboratory on Machine Perception, Peking University, 5 Yiheyuan Road, Beijing, China 100871
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Poulin JF, Castonguay-Lebel Z, Laforest S, Drolet G. Enkephalin co-expression with classic neurotransmitters in the amygdaloid complex of the rat. J Comp Neurol 2008; 506:943-59. [DOI: 10.1002/cne.21587] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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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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Abstract
The amygdala is a temporal lobe structure that is required for processing emotional information. Polymodal sensory information enters the amygdala at the level of the basolateral amygdala (BLA) and undergoes local processing, after which the behavioral and autonomic responses that accompany emotions are initiated. Two main neuron types are present in the BLA, pyramidal-like principal neurons that use glutamate as their transmitter, and local circuit interneurons that use GABA as their transmitter. Although the properties of principal neurons are known in some detail, very little is known about the properties of BLA interneurons or the local circuits in which they are involved. Using mice in which EGFP (enhanced green fluorescent protein) is expressed under the control of the parvalbumin promoter, we characterized the properties of parvalbumin-positive interneurons in the BLA. By making recordings from interneuron-interneuron and interneuron-principal neuron pairs, we analyzed the intrinsic circuitry of the BLA. We show that parvalbumin-positive interneurons can be divided into four subtypes as defined by their firing properties. Interneurons are electrically coupled in subtype-specific networks and exhibit subtype-specific heterogeneities in their synaptic dynamics and patterns of connectivity. We propose that these properties allow networks of parvalbumin-expressing neurons to perform an array of information-processing tasks within the BLA.
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Affiliation(s)
- Alan R. Woodruff
- Queensland Brain Institute and School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Pankaj Sah
- Queensland Brain Institute and School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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Sosulina L, Meis S, Seifert G, Steinhäuser C, Pape HC. Classification of projection neurons and interneurons in the rat lateral amygdala based upon cluster analysis. Mol Cell Neurosci 2006; 33:57-67. [PMID: 16861000 DOI: 10.1016/j.mcn.2006.06.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 06/06/2006] [Accepted: 06/09/2006] [Indexed: 10/24/2022] Open
Abstract
Neurons in the rat lateral amygdala in situ were classified based upon electrophysiological and molecular parameters, as studied by patch-clamp, single-cell RT-PCR and unsupervised cluster analyses. Projection neurons (class I) were characterized by low firing rates, frequency adaptation and expression of the vesicular glutamate transporter (VGLUT1). Two classes were distinguished based upon electrotonic properties and the presence (IB) or absence (IA) of vasointestinal peptide (VIP). Four classes of glutamate decarboxylase (GAD67) containing interneurons were encountered. Class III reflected "classical" interneurons, generating fast spikes with no frequency adaptation. Class II neurons generated fast spikes with early frequency adaptation and differed from class III by the presence of VIP and the relatively rare presence of neuropeptide Y (NPY) and somatostatin (SOM). Class IV and V were not clearly separated by molecular markers, but by membrane potential values and spike patterns. Morphologically, projection neurons were large, spiny cells, whereas the other neuronal classes displayed smaller somata and spine-sparse dendrites.
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Affiliation(s)
- Ludmila Sosulina
- Institut für Physiologie I, Westfälische Wilhelms-Universität Münster, Robert-Koch-Str. 27a, D-48149 Münster, Germany
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Roberto M, Siggins GR. Nociceptin/orphanin FQ presynaptically decreases GABAergic transmission and blocks the ethanol-induced increase of GABA release in central amygdala. Proc Natl Acad Sci U S A 2006; 103:9715-20. [PMID: 16788074 PMCID: PMC1480472 DOI: 10.1073/pnas.0601899103] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Indexed: 02/07/2023] Open
Abstract
Behavioral studies show that the GABAergic system in the central amygdala (CeA) nucleus has a complex role in the reinforcing effects effects of ethanol and the anxiogenic response to ethanol withdrawal. Opioid peptides and nociceptin/orphanin FQ (nociceptin) within the CeA are implicated also in regulating voluntary ethanol consumption and ethanol relapse. Recently, we reported that basal GABAergic transmission was increased in ethanol-dependent rats, and that acute ethanol increases GABA(A) receptor-mediated inhibitory postsynaptic currents (IPSCs) in CeA neurons from both naïve and ethanol-dependent rats to the same extent, suggesting lack of tolerance for the acute effect of ethanol. Here, we investigated the effect of nociceptin on IPSCs in CeA neurons and its interaction with ethanol effects on these GABA synapses. We found that nociceptin moderately decreased IPSC amplitudes, acting mostly presynaptically as it increased paired-pulse facilitation ratio of IPSCs and decreased miniature IPSC frequencies (but not amplitudes). Nociceptin also prevented the ethanol-induced augmentation of IPSCs in CeA of naïve rats. Interestingly, in CeA of ethanol-dependent rats, the nociceptin-induced inhibition of IPSCs was increased, indicating an enhanced sensitivity to nociceptin. Nociceptin also blocked the ethanol-induced augmentation of IPSCs in ethanol-dependent rats. Our data suggest that nociceptin has a role in regulating the GABAergic system and opposing the effect elicited by ethanol. Thus, nociceptin may represent a therapeutic target for alleviating alcohol dependence.
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Affiliation(s)
- Marisa Roberto
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Samson RD, Paré D. A spatially structured network of inhibitory and excitatory connections directs impulse traffic within the lateral amygdala. Neuroscience 2006; 141:1599-609. [PMID: 16753264 DOI: 10.1016/j.neuroscience.2006.04.077] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Revised: 04/20/2006] [Accepted: 04/28/2006] [Indexed: 11/30/2022]
Abstract
The lateral nucleus of the amygdala is the entry point of most sensory inputs into the amygdala. However, the way information is processed and distributed within the lateral nucleus still eludes us. To gain some insight into this issue, we have examined the spatial organization of excitatory and inhibitory connections in the lateral nucleus. To this end, we performed whole-cell recordings of principal lateral amygdala neurons and studied their responses to local pressure applications of glutamate in coronal and horizontal slices of the guinea-pig amygdala. In coronal sections, glutamate puffs performed at a distance from the recorded cells usually evoked inhibitory responses, except when the recorded neuron was adjacent to the external capsule, in which case excitatory responses could be evoked from ejection sites along the external capsule. In contrast, glutamate puffs evoked a mixture of excitatory and inhibitory responses in horizontal slices. Excitatory responses were generally evoked from stimulation sites located lateral to the recorded cell whereas inhibitory responses were commonly elicited from medial stimulation sites, irrespective of their rostrocaudal position. These findings confirm and extend previous tract-tracing studies where it was found that intrinsic connections within the lateral amygdala prevalently run in the dorsoventral and lateromedial directions. However, our results also reveal a hitherto unsuspected level of spatial heterogeneity in the intrinsic circuit of the lateral amygdala. The prevalence of excitatory responses in horizontal slices coupled to the ubiquity of inhibitory responses in coronal slices suggest that the lateral amygdala network is designed to allow associative interactions within the rostrocaudal plane while preventing runaway excitation locally.
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Affiliation(s)
- R D Samson
- Center for Molecular and Behavioral Neuroscience, Rutgers State University, The State University of New Jersey, 197 University Avenue, Newark, NJ 07102, USA
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