1
|
Hamati R, Ahrens J, Shvetz C, Holahan MR, Tuominen L. 65 years of research on dopamine's role in classical fear conditioning and extinction: A systematic review. Eur J Neurosci 2024; 59:1099-1140. [PMID: 37848184 DOI: 10.1111/ejn.16157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 09/08/2023] [Accepted: 09/13/2023] [Indexed: 10/19/2023]
Abstract
Dopamine, a catecholamine neurotransmitter, has historically been associated with the encoding of reward, whereas its role in aversion has received less attention. Here, we systematically gathered the vast evidence of the role of dopamine in the simplest forms of aversive learning: classical fear conditioning and extinction. In the past, crude methods were used to augment or inhibit dopamine to study its relationship with fear conditioning and extinction. More advanced techniques such as conditional genetic, chemogenic and optogenetic approaches now provide causal evidence for dopamine's role in these learning processes. Dopamine neurons encode conditioned stimuli during fear conditioning and extinction and convey the signal via activation of D1-4 receptor sites particularly in the amygdala, prefrontal cortex and striatum. The coordinated activation of dopamine receptors allows for the continuous formation, consolidation, retrieval and updating of fear and extinction memory in a dynamic and reciprocal manner. Based on the reviewed literature, we conclude that dopamine is crucial for the encoding of classical fear conditioning and extinction and contributes in a way that is comparable to its role in encoding reward.
Collapse
Affiliation(s)
- Rami Hamati
- Neuroscience Graduate Program, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
- University of Ottawa Institute of Mental Health Research, University of Ottawa, Ottawa, Ontario, Canada
| | - Jessica Ahrens
- Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Cecelia Shvetz
- University of Ottawa Institute of Mental Health Research, University of Ottawa, Ottawa, Ontario, Canada
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Matthew R Holahan
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Lauri Tuominen
- University of Ottawa Institute of Mental Health Research, University of Ottawa, Ottawa, Ontario, Canada
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
- Department of Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| |
Collapse
|
2
|
Sartori SB, Keil TMV, Kummer KK, Murphy CP, Gunduz-Cinar O, Kress M, Ebner K, Holmes A, Singewald N. Fear extinction rescuing effects of dopamine and L-DOPA in the ventromedial prefrontal cortex. Transl Psychiatry 2024; 14:11. [PMID: 38191458 PMCID: PMC10774374 DOI: 10.1038/s41398-023-02708-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 12/01/2023] [Accepted: 12/07/2023] [Indexed: 01/10/2024] Open
Abstract
The ventromedial prefrontal cortex (vmPFC; rodent infralimbic cortex (IL)), is posited to be an important locus of fear extinction-facilitating effects of the dopamine (DA) bio-precursor, L-DOPA, but this hypothesis remains to be formally tested. Here, in a model of impaired fear extinction (the 129S1/SvImJ inbred mouse strain; S1), we monitored extracellular DA dynamics via in vivo microdialysis in IL during fear extinction and following L-DOPA administration. Systemic L-DOPA caused sustained elevation of extracellular DA levels in IL and increased neuronal activation in a subpopulation of IL neurons. Systemic L-DOPA enabled extinction learning and promoted extinction retention at one but not ten days after training. Conversely, direct microinfusion of DA into IL produced long-term fear extinction (an effect that was insensitive to ɑ-/ß-adrenoreceptor antagonism). However, intra-IL delivery of a D1-like or D2 receptor agonist did not facilitate extinction. Using ex vivo multi-electrode array IL neuronal recordings, along with ex vivo quantification of immediate early genes and DA receptor signalling markers in mPFC, we found evidence of reduced DA-evoked mPFC network responses in S1 as compared with extinction-competent C57BL/6J mice that were partially driven by D1 receptor activation. Together, our data demonstrate that locally increasing DA in IL is sufficient to produce lasting rescue of impaired extinction. The finding that systemic L-DOPA increased IL DA levels, but had only transient effects on extinction, suggests L-DOPA failed to reach a threshold level of IL DA or produced opposing behavioural effects in other brain regions. Collectively, our findings provide further insight into the neural basis of the extinction-promoting effects of DA and L-DOPA in a clinically relevant animal model, with possible implications for therapeutically targeting the DA system in anxiety and trauma-related disorders.
Collapse
Affiliation(s)
- Simone B Sartori
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Thomas M V Keil
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Kai K Kummer
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Conor P Murphy
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Ozge Gunduz-Cinar
- Laboratory of Behavioral and Genomic Neuroscience, NIH/NIAAA, Rockville, MD, USA
| | - Michaela Kress
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Karl Ebner
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Andrew Holmes
- Laboratory of Behavioral and Genomic Neuroscience, NIH/NIAAA, Rockville, MD, USA
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.
| |
Collapse
|
3
|
Meamar M, Rashidy-Pour A, Rahmani M, Vafaei AA, Raise-Abdullahi P. Glucocorticoid- β-adrenoceptors interactions in the infralimbic cortex in acquisition and consolidation of auditory fear memory extinction in rats. Pharmacol Biochem Behav 2023; 225:173560. [PMID: 37094708 DOI: 10.1016/j.pbb.2023.173560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/17/2023] [Accepted: 04/19/2023] [Indexed: 04/26/2023]
Abstract
This study investigated the interactive effect of glucocorticoid and β-adrenoceptors in the infralimbic (IL) cortex on the acquisition and consolidation of fear extinction in rats' auditory fear conditioning (AFC) task. On day 1, rats underwent habituation for 9 min (12 tonnes, 10 s, 4 kHz, 80 dB, without footshock). On day 2 (conditioning), rats received 3 mild electrical footshocks (US; 2 s, 0.5 mA) paired with the auditory-conditioned stimulus (CS; tone: 30 s, 4 kHz, 80 dB). On days 3-5 (Ext 1-3), rats received 15 tonnes with no footshock in the test box. Intra-IL injection of corticosterone (CORT, 20 ng/0.5 μl per side) before Ext 1 and after Ext 1-2, respectively, facilitated the acquisition and consolidation of fear memory extinction. Intra-IL injection of the β2-adrenoceptor agonist clenbuterol (CLEN, 50 ng/0.5 μl per side) inhibited, but the β-adrenoceptor antagonist propranolol (PROP, 500 ng/0.5 μl per side) enhanced the facilitatory effects of CORT on fear memory extinction. CORT injection before the acquisition of fear extinction increased p-ERK levels in the IL. Co-injection of CORT with CLEN increased, but PROP decreased p-ERK activities. CORT injection after the consolidation of fear extinction increased p-CREB in the IL. Co-injection of CORT with CLEN increased, but PROP reduced p-CREB activities. Our findings show that corticosterone facilitates the acquisition and consolidation of fear memory extinction. GRs and β-adrenoceptors in the IL jointly regulate fear memory extinction via ERK and CREB signaling pathways. This pre-clinical animal study may highlight the effect of GRs and β-adrenoceptors of the IL cortex in regulating fear memory processes in fear-related disorders such as PTSD.
Collapse
Affiliation(s)
- Morvarid Meamar
- Research Center of Physiology, Semnan University of Medical Sciences, Semnan, Iran
| | - Ali Rashidy-Pour
- Research Center of Physiology, Semnan University of Medical Sciences, Semnan, Iran; Department of Physiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Mehrnoush Rahmani
- Research Center of Physiology, Semnan University of Medical Sciences, Semnan, Iran
| | - Abbas Ali Vafaei
- Research Center of Physiology, Semnan University of Medical Sciences, Semnan, Iran; Department of Physiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran.
| | | |
Collapse
|
4
|
Meamar M, Rashidy-Pour A, Vafaei AA, Raise-Abdullahi P. β-adrenoceptors of the infra-limbic cortex mediate corticosterone-induced enhancement of acquisition and consolidation of fear memory extinction in rats. Behav Brain Res 2023; 442:114310. [PMID: 36706807 DOI: 10.1016/j.bbr.2023.114310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 01/17/2023] [Accepted: 01/23/2023] [Indexed: 01/26/2023]
Abstract
The extinction of auditory fear conditioning (AFC) refers to reducing the fear responses induced following repeated presentation of a conditioned stimulus (tone) in the absence of an unconditioned stimulus (electric foot shock). Glucocorticoid receptors (GRs) play an important role in extinction, but the underlying neurobiological mechanisms are unclear. This study aimed to investigate the interaction between glucocorticoids and β-adrenoceptors of the infra-limbic cortex (IL) in regulating the acquisition and consolidation of fear memory extinction in rats. Male rats were trained to AFC and received three trial tones (30 s, 4 kHz, 80 dB) co-terminated with a footshock (0.8 mA, 1 s; unconditioned stimulus). Extinction trials were conducted over 3 days after training (Ext 1-3). In experiment 1, rats received clenbuterol (0.25 mg/kg/2 ml, IP) as a β2-adrenoceptor agonist or propranolol (2.5 mg/kg/2 ml, IP) as a β-adrenoceptors antagonist before Ext 1 and immediately after Ext 1 and Ext 2 followed by systemic injection of corticosterone (3 mg/kg/2 ml, IP). In Experiment 2, separate groups of rats received a bilateral intra-IL injection of clenbuterol (50 ng/0.5 µl/side) or propranolol (500 ng/0.5 µl/side) followed by a systemic injection of corticosterone (3 mg/kg/2 ml) before Ext 1 and immediately after Ext 1 and Ext 2. Results indicated that systemic and intra-IL injections of clenbuterol and propranolol inhibited and increased the facilitative effects of corticosterone on fear memory extinction, respectively. These findings show that activating β-adrenergic receptors in the IL mediates glucocorticoid effects on the acquisition and consolidation of auditory-conditioned fear memory extinction.
Collapse
Affiliation(s)
- Morvarid Meamar
- Research Center of Physiology, Semnan University of Medical Sciences, Semnan, Iran
| | - Ali Rashidy-Pour
- Research Center of Physiology, Semnan University of Medical Sciences, Semnan, Iran; Department of Physiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Abbas Ali Vafaei
- Research Center of Physiology, Semnan University of Medical Sciences, Semnan, Iran; Department of Physiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran.
| | | |
Collapse
|
5
|
Role of noradrenergic arousal for fear extinction processes in rodents and humans. Neurobiol Learn Mem 2022; 194:107660. [PMID: 35870717 DOI: 10.1016/j.nlm.2022.107660] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/29/2022] [Accepted: 07/17/2022] [Indexed: 01/22/2023]
Abstract
Fear extinction is a learning mechanism that is pivotal for the inhibition of fear responses towards cues or contexts that no longer predict the occurrence of a threat. Failure of fear extinction leads to fear expression under safe conditions and is regarded to be a cardinal characteristic of many anxiety-related disorders and posttraumatic stress disorder. Importantly, the neurotransmitter noradrenaline was shown to be a potent modulator of fear extinction. Rodent studies demonstrated that excessive noradrenaline transmission after acute stress opens a time window of vulnerability, in which fear extinction learning results in attenuated long-term extinction success. In contrast, when excessive noradrenergic transmission subsides, well-coordinated noradrenaline transmission is necessary for the formation of a long-lasting extinction memory. In addition, emerging evidence suggests that the neuropeptide corticotropin releasing hormone (CRF), which strongly regulates noradrenaline transmission under conditions of acute stress, also impedes long-term extinction success. Recent rodent work - using sophisticated methods - provides evidence for a hypothetical mechanistic framework of how noradrenaline and CRF dynamically orchestrate the neural fear and extinction circuitry to attenuate or to improve fear extinction and extinction recall. Accordingly, we review the evidence from rodent studies linking noradrenaline and CRF to fear extinction learning and recall and derive the hypothetical mechanistic framework of how different levels of noradrenaline and CRF may create a time window of vulnerability which impedes successful long-term fear extinction. We also address evidence from human studies linking noradrenaline and fear extinction success. Moreover, we accumulate emerging approaches to non-invasively measure and manipulate the noradrenergic system in healthy humans. Finally, we emphasize the importance of future studies to account for sex (hormone) differences when examining the interaction between fear extinction, noradrenaline, and CRF. To conclude, NA's effects on fear extinction recall strongly depend on the arousal levels at the onset of fear extinction learning. Our review aimed at compiling the available (mainly rodent) data in a neurobiological framework, suited to derive testable hypotheses for future work in humans.
Collapse
|
6
|
Vafaei AA, Rashidy-Pour A, Trahomi P, Omoumi S, Dadkhah M. Role of Amygdala-Infralimbic Cortex Circuitry in Glucocorticoid-induced Facilitation of Auditory Fear Memory Extinction. Basic Clin Neurosci 2022; 13:193-205. [PMID: 36425953 PMCID: PMC9682312 DOI: 10.32598/bcn.2021.2161.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 02/15/2021] [Accepted: 03/10/2021] [Indexed: 05/10/2023] Open
Abstract
INTRODUCTION The basolateral amygdala (BLA) and infralimbic area (IL) of the medial prefrontal cortex (mPFC) are two interconnected brain structures that mediate both fear memory expression and extinction. Besides the well-known role of the BLA in the acquisition and expression of fear memory, projections from IL to BLA inhibit fear expression and have a critical role in fear extinction. However, the details of IL-BLA interaction have remained unclear. Here, we investigated the role of functional reciprocal interactions between BLA and IL in mediating fear memory extinction. METHODS Using lidocaine (LID), male rats underwent unilateral or bilateral inactivation of the BLA and then unilateral intra-IL infusion of corticosterone (CORT) prior to extinction training of the auditory fear conditioning paradigm. Freezing behavior was reported as an index for conditioned fear. Infusions were performed before the extinction training, allowing us to examine the effects on fear expression and further extinction memory. Experiments 1-3 investigated the effects of left or right infusion of CORT into IL and LID unilaterally into BLA on fear memory extinction. RESULTS Intra-IL infusion of CORT in the right hemisphere reduced freezing behavior when administrated before the extinction training. Auditory fear memory extinction was impaired by asymmetric inactivation of BLA and CORT infusion in the right IL; however, the same effect was not observed with symmetric inactivation of BLA. CONCLUSION IL-BLA neural circuit may provide additional evidence for the contribution of this circuit to auditory fear extinction. This study demonstrates dissociable roles for right or left BLA in subserving the auditory fear extinction. Our finding also raises the possibility that left BLA-IL circuitry may mediate auditory fear memory extinction via underlying mechanisms. However, further research is required in this area. HIGHLIGHTS Corticosterone infusion in the right (but not the left) infralimbic area facilitates auditory fear memory extinction.Corticosterone infusion in the right infralimbic area following symmetric basolateral amygdala inactivation has no effect on auditory fear memory extinction.Asymmetric basolateral amygdala inactivation prior to corticosterone infusion into the right infralimbic area impairs auditory fear memory extinction. PLAIN LANGUAGE SUMMARY Previous studies have established that glucocorticoids, which are released in stressful conditions, enhance fear memory extinction. In this study, we found that corticosterone infusion into the right infralimbic area, but not the left one, facilitates auditory fear memory extinction. The effect of corticosterone infusion in the infralimbic area was not blocked by the intra-basolateral amygdala injections of lidocaine when administrated in the ipsilateral hemisphere. However, asymmetric basolateral amygdala inactivation and corticosterone infusion into the right infralimbic area impairs auditory fear memory extinction.
Collapse
Affiliation(s)
- Abbas Ali Vafaei
- Research Center of Physiology, Department of Physiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Ali Rashidy-Pour
- Research Center of Physiology, Department of Physiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Parnia Trahomi
- Student Research Committee, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Samira Omoumi
- Student Research Committee, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran
| | - Masoomeh Dadkhah
- Pharmaceutical Sciences Research Center, Ardabil University of Medical Sciences, Ardabil, Iran
- Corresponding Author: Masoomeh Dadkhah, PhD., Address: Pharmaceutical Sciences Research Center, Ardabil University of Medical Sciences, Ardabil, Iran., Tel: +98 (45) 33522437-39, E-mail:
| |
Collapse
|
7
|
Iordanova MD, Yau JOY, McDannald MA, Corbit LH. Neural substrates of appetitive and aversive prediction error. Neurosci Biobehav Rev 2021; 123:337-351. [PMID: 33453307 PMCID: PMC7933120 DOI: 10.1016/j.neubiorev.2020.10.029] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/24/2020] [Accepted: 10/13/2020] [Indexed: 12/14/2022]
Abstract
Prediction error, defined by the discrepancy between real and expected outcomes, lies at the core of associative learning. Behavioural investigations have provided evidence that prediction error up- and down-regulates associative relationships, and allocates attention to stimuli to enable learning. These behavioural advances have recently been followed by investigations into the neurobiological substrates of prediction error. In the present paper, we review neuroscience data obtained using causal and recording neural methods from a variety of key behavioural designs. We explore the neurobiology of both appetitive (reward) and aversive (fear) prediction error with a focus on the mesolimbic dopamine system, the amygdala, ventrolateral periaqueductal gray, hippocampus, cortex and locus coeruleus noradrenaline. New questions and avenues for research are considered.
Collapse
Affiliation(s)
- Mihaela D Iordanova
- Department of Psychology/Centre for Studies in Behavioral Neurobiology, Concordia University, 7141 Sherbrooke St, Montreal, QC, H4B 1R6, Canada.
| | - Joanna Oi-Yue Yau
- School of Psychology, The University of New South Wales, UNSW Sydney, NSW, 2052, Australia.
| | - Michael A McDannald
- Department of Psychology & Neuroscience, Boston College, 140 Commonwealth Avenue, 514 McGuinn Hall, Chestnut Hill, MA, 02467, USA.
| | - Laura H Corbit
- Departments of Psychology and Cell and Systems Biology, University of Toronto, 100 St. George Street, Toronto, ON, M5S 3G3, Canada.
| |
Collapse
|
8
|
Warren WG, Papagianni EP, Stevenson CW, Stubbendorff C. In it together? The case for endocannabinoid-noradrenergic interactions in fear extinction. Eur J Neurosci 2021; 55:952-970. [PMID: 33759226 DOI: 10.1111/ejn.15200] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 01/26/2021] [Accepted: 03/17/2021] [Indexed: 12/18/2022]
Abstract
Anxiety and trauma-related disorders, such as post-traumatic stress disorder (PTSD), are debilitating mental illnesses with great personal and socioeconomic costs. Examining memory formation and relevant behavioural responding associated with aversive stimuli may improve our understanding of the neurobiology underlying fear memory processing and PTSD treatment. The neurocircuitry underpinning learned fear and its inhibition through extinction is complex, involving synergistic interactions between different neurotransmitter systems in inter-connected brain areas. Endocannabinoid and noradrenergic transmission have both been implicated separately in fear memory processing and PTSD, but potential interactions between these systems in relation to fear extinction have received little attention to date. Their receptors are expressed together in brain areas crucial for fear extinction, which is enhanced by both cannabinoid and noradrenergic receptor activation in these areas. Moreover, cannabinoid signalling modulates the activity of locus coeruleus noradrenaline (NA) neurons and the release of NA in the medial prefrontal cortex, a brain area that is crucial for fear extinction. Interestingly, endocannabinoid-noradrenergic system interactions have been shown to regulate the encoding and retrieval of fear memory. Thus, noradrenergic regulation of fear extinction may also be driven indirectly in part via cannabinoid receptor signalling. In this perspective paper, we collate the available relevant literature and propose a synergistic role for the endocannabinoid and noradrenergic systems in regulating fear extinction, the study of which may further our understanding of the neurobiological substrates of PTSD and its treatment.
Collapse
Affiliation(s)
- William G Warren
- School of Biosciences, University of Nottingham, Loughborough, UK
| | | | - Carl W Stevenson
- School of Biosciences, University of Nottingham, Loughborough, UK
| | - Christine Stubbendorff
- School of Biosciences, University of Nottingham, Loughborough, UK.,Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| |
Collapse
|
9
|
Ney LJ, Akhurst J, Bruno R, Laing PAF, Matthews A, Felmingham KL. Dopamine, endocannabinoids and their interaction in fear extinction and negative affect in PTSD. Prog Neuropsychopharmacol Biol Psychiatry 2021; 105:110118. [PMID: 32991952 DOI: 10.1016/j.pnpbp.2020.110118] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 09/03/2020] [Accepted: 09/22/2020] [Indexed: 12/13/2022]
Abstract
There currently exist few frameworks for common neurobiology between reexperiencing and negative cognitions and mood symptoms of PTSD. Adopting a dopaminergic framework for PTSD unites many aspects of unique symptom clusters, and this approach also links PTSD symptomology to common comorbidities with a common neurobiological deficiency. Here we review the dopamine literature and incorporate it with a growing field of research that describes both the contribution of endocannabinoids to fear extinction and PTSD, as well as the interactions between dopaminergic and endocannabinoid systems underlying this disorder. Based on current evidence, we outline an early, preliminary model that links re-experiencing and negative cognitions and mood in PTSD by invoking the interaction between endocannabinoid and dopaminergic signalling in the brain. These interactions between PTSD, dopamine and endocannabinoids may have implications for future therapies for treatment-resistant and comorbid PTSD patients.
Collapse
Affiliation(s)
- Luke J Ney
- School of Psychology, University of Tasmania, Australia.
| | - Jane Akhurst
- School of Psychology, University of Tasmania, Australia
| | | | - Patrick A F Laing
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, University of Melbourne & Melbourne Health, Australia
| | | | - Kim L Felmingham
- School of Psychological Sciences, University of Melbourne, Australia
| |
Collapse
|
10
|
Salinas-Hernández XI, Duvarci S. Dopamine in Fear Extinction. Front Synaptic Neurosci 2021; 13:635879. [PMID: 33732133 PMCID: PMC7956961 DOI: 10.3389/fnsyn.2021.635879] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/09/2021] [Indexed: 11/30/2022] Open
Abstract
The ability to extinguish fear memories when threats are no longer present is critical for adaptive behavior. Fear extinction represents a new learning process that eventually leads to the formation of extinction memories. Understanding the neural basis of fear extinction has considerable clinical significance as deficits in extinction learning are the hallmark of human anxiety disorders. In recent years, the dopamine (DA) system has emerged as one of the key regulators of fear extinction. In this review article, we highlight recent advances that have demonstrated the crucial role DA plays in mediating different phases of fear extinction. Emerging concepts and outstanding questions for future research are also discussed.
Collapse
Affiliation(s)
| | - Sevil Duvarci
- Institute of Neurophysiology, Neuroscience Center, Goethe University, Frankfurt, Germany
| |
Collapse
|
11
|
Giménez M, Cano M, Martínez-Zalacaín I, Real E, Alonso P, Segalàs C, Munuera J, Kegeles LS, Weinstein JJ, Xu X, Menchón JM, Cardoner N, Soriano-Mas C, Fullana MA. Is glutamate associated with fear extinction and cognitive behavior therapy outcome in OCD? A pilot study. Eur Arch Psychiatry Clin Neurosci 2020; 270:1003-1014. [PMID: 31432262 DOI: 10.1007/s00406-019-01056-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 08/07/2019] [Indexed: 12/15/2022]
Abstract
Cognitive behavioral therapy (CBT) including exposure and response prevention is a well-established treatment for obsessive-compulsive disorder (OCD) and is based on the principles of fear extinction. Fear extinction is linked to structural and functional variability in the ventromedial prefrontal cortex (vmPFC) and has been consistently associated with glutamate neurotransmission. The relationship between vmPFC glutamate and fear extinction and its effects on CBT outcome have not yet been explored in adults with OCD. We assessed glutamate levels in the vmPFC using 3T magnetic resonance spectroscopy, and fear extinction (learning and recall) using skin conductance responses during a 2-day experimental paradigm in OCD patients (n = 17) and in healthy controls (HC; n = 13). Obsessive-compulsive patients (n = 12) then received manualized CBT. Glutamate in the vmPFC was negatively associated with fear extinction recall and positively associated with CBT outcome (with higher glutamate levels predicting a better outcome) in OCD patients. Glutamate levels in the vmPFC in OCD patients were not significantly different from those in HC, and were not associated with OCD severity. Our results suggest that glutamate in the vmPFC is associated with fear extinction recall and CBT outcome in adult OCD patients.
Collapse
Affiliation(s)
- M Giménez
- Department of Psychiatry, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Carlos III Health Institute, Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM, Av. de Monforte de Lemos 5, 28029, Madrid, Spain
| | - M Cano
- Department of Psychiatry, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Carlos III Health Institute, Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM, Av. de Monforte de Lemos 5, 28029, Madrid, Spain.,Department of Clinical Sciences, School of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - I Martínez-Zalacaín
- Department of Psychiatry, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Department of Clinical Sciences, School of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - E Real
- Department of Psychiatry, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Carlos III Health Institute, Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM, Av. de Monforte de Lemos 5, 28029, Madrid, Spain
| | - P Alonso
- Department of Psychiatry, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Carlos III Health Institute, Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM, Av. de Monforte de Lemos 5, 28029, Madrid, Spain.,Department of Clinical Sciences, School of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - C Segalàs
- Department of Psychiatry, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Carlos III Health Institute, Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM, Av. de Monforte de Lemos 5, 28029, Madrid, Spain
| | - J Munuera
- Diagnostic Imaging Department, Fundació de Recerca Hospital Sant Joan de Déu, Passeig Sant Joan de Déu, 2, Esplugues de Llobregat, 08950, Barcelona, Spain
| | - L S Kegeles
- Department of Psychiatry and Radiology, Columbia University, 622 W 168th St, New York, 10032, USA.,New York State Psychiatric Institute, 1051 Riverside Dr, New York, 10032, USA
| | - J J Weinstein
- Department of Psychiatry and Radiology, Columbia University, 622 W 168th St, New York, 10032, USA.,New York State Psychiatric Institute, 1051 Riverside Dr, New York, 10032, USA.,Department of Psychiatry, Stony Brook University, Stony Brook, 101 Nicolls Rd, Stony Brook, New York, 11794, USA
| | - X Xu
- Department of Psychiatry and Radiology, Columbia University, 622 W 168th St, New York, 10032, USA.,New York State Psychiatric Institute, 1051 Riverside Dr, New York, 10032, USA
| | - J M Menchón
- Department of Psychiatry, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Carlos III Health Institute, Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM, Av. de Monforte de Lemos 5, 28029, Madrid, Spain.,Department of Clinical Sciences, School of Medicine, University of Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - N Cardoner
- Depression and Anxiety Program, Department of Mental Health, Parc Taulí Sabadell, Hospital Universitari, Parc Taulí 1, 08208, Sabadell, Spain.,Department of Psychiatry and Legal Medicine, Universitat Autònoma de Barcelona, Av. de Can Domènech, 737, 08193, Cerdanyola Del Vallès Barcelona, Barcelona, Spain
| | - C Soriano-Mas
- Department of Psychiatry, Bellvitge University Hospital, Bellvitge Biomedical Research Institute-IDIBELL, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Carlos III Health Institute, Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM, Av. de Monforte de Lemos 5, 28029, Madrid, Spain.,Department of Psychobiology and Methodology of Health Sciences, Universitat Autònoma de Barcelona, Building B1, Ca n'Altayó, s/n, Bellaterra, 08193, Barcelona, Spain
| | - M A Fullana
- Carlos III Health Institute, Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM, Av. de Monforte de Lemos 5, 28029, Madrid, Spain. .,Department of Psychiatry and Legal Medicine, Universitat Autònoma de Barcelona, Av. de Can Domènech, 737, 08193, Cerdanyola Del Vallès Barcelona, Barcelona, Spain. .,Psychiatry Department, Hospital Clínic-Institute of Neurosciences, CIBERSAM, C/Rosselló 140, 08036, Barcelona, Spain.
| |
Collapse
|
12
|
Mattera A, Pagani M, Baldassarre G. A Computational Model Integrating Multiple Phenomena on Cued Fear Conditioning, Extinction, and Reinstatement. Front Syst Neurosci 2020; 14:569108. [PMID: 33132856 PMCID: PMC7550679 DOI: 10.3389/fnsys.2020.569108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 08/13/2020] [Indexed: 11/23/2022] Open
Abstract
Conditioning, extinction, and reinstatement are fundamental learning processes of animal adaptation, also strongly involved in human pathologies such as post-traumatic stress disorder, anxiety, depression, and dependencies. Cued fear conditioning, extinction, restatement, and systematic manipulations of the underlying brain amygdala and medial prefrontal cortex, represent key experimental paradigms to study such processes. Numerous empirical studies have revealed several aspects and the neural systems and plasticity underlying them, but at the moment we lack a comprehensive view. Here we propose a computational model based on firing rate leaky units that contributes to such integration by accounting for 25 different experiments on fear conditioning, extinction, and restatement, on the basis of a single neural architecture having a structure and plasticity grounded in known brain biology. This allows the model to furnish three novel contributions to understand these open issues: (a) the functioning of the central and lateral amygdala system supporting conditioning; (b) the role played by the endocannabinoids system in within- and between-session extinction; (c) the formation of three important types of neurons underlying fear processing, namely fear, extinction, and persistent neurons. The model integration of the results on fear conditioning goes substantially beyond what was done in previous models.
Collapse
Affiliation(s)
- Andrea Mattera
- Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy
| | - Marco Pagani
- Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy
| | - Gianluca Baldassarre
- Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy
| |
Collapse
|
13
|
Papalini S, Beckers T, Vervliet B. Dopamine: from prediction error to psychotherapy. Transl Psychiatry 2020; 10:164. [PMID: 32451377 PMCID: PMC7248121 DOI: 10.1038/s41398-020-0814-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 04/14/2020] [Accepted: 04/21/2020] [Indexed: 02/07/2023] Open
Abstract
Dopamine, one of the main neurotransmitters in the mammalian brain, has been implicated in the coding of prediction errors that govern reward learning as well as fear extinction learning. Psychotherapy too can be viewed as a form of error-based learning, because it challenges erroneous beliefs and behavioral patterns in order to induce long-term changes in emotions, cognitions, and behaviors. Exposure therapy, for example, relies in part on fear extinction principles to violate erroneous expectancies of danger and induce novel safety learning that inhibits and therefore reduces fear in the long term. As most forms of psychotherapy, however, exposure therapy suffers from non-response, dropout, and relapse. This narrative review focuses on the role of midbrain and prefrontal dopamine in novel safety learning and investigates possible pathways through which dopamine-based interventions could be used as an adjunct to improve both the response and the long-term effects of the therapy. Convincing evidence exists for an involvement of the midbrain dopamine system in the acquisition of new, safe memories. Additionally, prefrontal dopamine is emerging as a key ingredient for the consolidation of fear extinction. We propose that applying a dopamine prediction error perspective to psychotherapy can inspire both pharmacological and non-pharmacological studies aimed at discovering innovative ways to enhance the acquisition of safety memories. Additionally, we call for further empirical investigations on dopamine-oriented drugs that might be able to maximize consolidation of successful fear extinction and its long-term retention after therapy, and we propose to also include investigations on non-pharmacological interventions with putative prefrontal dopaminergic effects, like working memory training.
Collapse
Affiliation(s)
- Silvia Papalini
- Laboratory of Biological Psychology (LBP), Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium. .,Leuven Brain Institute, KU Leuven, Leuven, Belgium.
| | - Tom Beckers
- grid.5596.f0000 0001 0668 7884Leuven Brain Institute, KU Leuven, Leuven, Belgium ,grid.5596.f0000 0001 0668 7884Centre for the Psychology of Learning and Experimental Psychopathology (CLEP), Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium
| | - Bram Vervliet
- grid.5596.f0000 0001 0668 7884Laboratory of Biological Psychology (LBP), Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium ,grid.5596.f0000 0001 0668 7884Leuven Brain Institute, KU Leuven, Leuven, Belgium
| |
Collapse
|
14
|
Lebois LAM, Seligowski AV, Wolff JD, Hill SB, Ressler KJ. Augmentation of Extinction and Inhibitory Learning in Anxiety and Trauma-Related Disorders. Annu Rev Clin Psychol 2019; 15:257-284. [PMID: 30698994 DOI: 10.1146/annurev-clinpsy-050718-095634] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Although the fear response is an adaptive response to threatening situations, a number of psychiatric disorders feature prominent fear-related symptoms caused, in part, by failures of extinction and inhibitory learning. The translational nature of fear conditioning paradigms has enabled us to develop a nuanced understanding of extinction and inhibitory learning based on the molecular substrates to systems neural circuitry and psychological mechanisms. This knowledge has facilitated the development of novel interventions that may augment extinction and inhibitory learning. These interventions include nonpharmacological techniques, such as behavioral methods to implement during psychotherapy, as well as device-based stimulation techniques that enhance or reduce activity in different regions of the brain. There is also emerging support for a number of psychopharmacological interventions that may augment extinction and inhibitory learning specifically if administered in conjunction with exposure-based psychotherapy. This growing body of research may offer promising novel techniques to address debilitating transdiagnostic fear-related symptoms.
Collapse
Affiliation(s)
- Lauren A M Lebois
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| | - Antonia V Seligowski
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| | - Jonathan D Wolff
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| | - Sarah B Hill
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| | - Kerry J Ressler
- Division of Depression and Anxiety Disorders, Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA;
| |
Collapse
|
15
|
Cahill EN, Milton AL. Neurochemical and molecular mechanisms underlying the retrieval-extinction effect. Psychopharmacology (Berl) 2019; 236:111-132. [PMID: 30656364 PMCID: PMC6373198 DOI: 10.1007/s00213-018-5121-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 11/12/2018] [Indexed: 12/26/2022]
Abstract
Extinction within the reconsolidation window, or 'retrieval-extinction', has received much research interest as a possible technique for targeting the reconsolidation of maladaptive memories with a behavioural intervention. However, it remains to be determined whether the retrieval-extinction effect-a long-term reduction in fear behaviour, which appears resistant to spontaneous recovery, renewal and reinstatement-depends specifically on destabilisation of the original memory (the 'reconsolidation-update' account) or represents facilitation of an extinction memory (the 'extinction-facilitation' account). We propose that comparing the neurotransmitter systems, receptors and intracellular signalling pathways recruited by reconsolidation, extinction and retrieval-extinction will provide a way of distinguishing between these accounts.
Collapse
Affiliation(s)
- Emma N Cahill
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Site, Cambridge, CB2 3EG, UK
| | - Amy L Milton
- Department of Psychology, University of Cambridge, Downing Site, Cambridge, CB2 3EB, UK.
- Behavioural and Clinical Neuroscience Institute, Cambridge, CB2 3EB, UK.
| |
Collapse
|
16
|
Murray SB, Strober M, Craske MG, Griffiths S, Levinson CA, Strigo IA. Fear as a translational mechanism in the psychopathology of anorexia nervosa. Neurosci Biobehav Rev 2018; 95:383-395. [DOI: 10.1016/j.neubiorev.2018.10.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 10/11/2018] [Accepted: 10/22/2018] [Indexed: 12/30/2022]
|
17
|
Panitz C, Sperl MF, Hennig J, Klucken T, Hermann C, Mueller EM. Fearfulness, neuroticism/anxiety, and COMT Val158Met in long-term fear conditioning and extinction. Neurobiol Learn Mem 2018; 155:7-20. [DOI: 10.1016/j.nlm.2018.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 05/16/2018] [Accepted: 06/04/2018] [Indexed: 10/14/2022]
|
18
|
β-Adrenoceptor Blockade in the Basolateral Amygdala, But Not the Medial Prefrontal Cortex, Rescues the Immediate Extinction Deficit. Neuropsychopharmacology 2017; 42:2537-2544. [PMID: 28462941 PMCID: PMC5686500 DOI: 10.1038/npp.2017.89] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 04/21/2017] [Accepted: 04/24/2017] [Indexed: 01/09/2023]
Abstract
Early psychological interventions, such as exposure therapy, rely on extinction learning to reduce the development of stress- and trauma-related disorders. However, recent research suggests that extinction often fails to reduce fear when administered soon after trauma. This immediate extinction deficit (IED) may be due to stress-induced dysregulation of neural circuits involved in extinction learning. We have shown that systemic β-adrenoceptor blockade with propranolol rescues the IED, but impairs delayed extinction. Here we sought to determine the neural locus of these effects. Rats underwent auditory fear conditioning and then received either immediate (30 min) or delayed (24 h) extinction training. We used bilateral intracranial infusions of propranolol into either the infralimbic division of the medial prefrontal cortex (mPFC) or the basolateral amygdala (BLA) to examine the effects of β-adrenoceptor blockade on immediate and delayed extinction learning. Interestingly, intra-BLA, but not intra-mPFC, propranolol rescued the IED; animals receiving intra-BLA propranolol prior to immediate extinction showed less spontaneous recovery of fear during extinction retrieval. Importantly, this was not due to impaired consolidation of the conditioning memory. In contrast, neither intra-BLA nor intra-mPFC propranolol affected delayed extinction learning. Overall, these data contribute to a growing literature suggesting dissociable roles for key nodes in the fear extinction circuit depending on the timing of extinction relative to conditioning. These data also suggest that heightened noradrenergic activity in the BLA underlies stress-induced extinction deficits. Propranolol may be a useful adjunct to behavioral therapeutic interventions in recently traumatized individuals who are at risk for developing trauma-related disorders.
Collapse
|
19
|
Modular organization of the brainstem noradrenaline system coordinates opposing learning states. Nat Neurosci 2017; 20:1602-1611. [DOI: 10.1038/nn.4642] [Citation(s) in RCA: 174] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 08/17/2017] [Indexed: 12/13/2022]
|
20
|
Enhancing dopaminergic signaling and histone acetylation promotes long-term rescue of deficient fear extinction. Transl Psychiatry 2016; 6:e974. [PMID: 27922638 PMCID: PMC5315560 DOI: 10.1038/tp.2016.231] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/17/2016] [Accepted: 08/18/2016] [Indexed: 01/04/2023] Open
Abstract
Extinction-based exposure therapy is used to treat anxiety- and trauma-related disorders; however, there is the need to improve its limited efficacy in individuals with impaired fear extinction learning and to promote greater protection against return-of-fear phenomena. Here, using 129S1/SvImJ mice, which display impaired fear extinction acquisition and extinction consolidation, we revealed that persistent and context-independent rescue of deficient fear extinction in these mice was associated with enhanced expression of dopamine-related genes, such as dopamine D1 (Drd1a) and -D2 (Drd2) receptor genes in the medial prefrontal cortex (mPFC) and amygdala, but not hippocampus. Moreover, enhanced histone acetylation was observed in the promoter of the extinction-regulated Drd2 gene in the mPFC, revealing a potential gene-regulatory mechanism. Although enhancing histone acetylation, via administering the histone deacetylase (HDAC) inhibitor MS-275, does not induce fear reduction during extinction training, it promoted enduring and context-independent rescue of deficient fear extinction consolidation/retrieval once extinction learning was initiated as shown following a mild conditioning protocol. This was associated with enhanced histone acetylation in neurons of the mPFC and amygdala. Finally, as a proof-of-principle, mimicking enhanced dopaminergic signaling by L-dopa treatment rescued deficient fear extinction and co-administration of MS-275 rendered this effect enduring and context-independent. In summary, current data reveal that combining dopaminergic and epigenetic mechanisms is a promising strategy to improve exposure-based behavior therapy in extinction-impaired individuals by initiating the formation of an enduring and context-independent fear-inhibitory memory.
Collapse
|
21
|
Stockhorst U, Antov MI. Modulation of Fear Extinction by Stress, Stress Hormones and Estradiol: A Review. Front Behav Neurosci 2016; 9:359. [PMID: 26858616 PMCID: PMC4726806 DOI: 10.3389/fnbeh.2015.00359] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 12/14/2015] [Indexed: 12/25/2022] Open
Abstract
Fear acquisition and extinction are valid models for the etiology and treatment of anxiety, trauma- and stressor-related disorders. These disorders are assumed to involve aversive learning under acute and/or chronic stress. Importantly, fear conditioning and stress share common neuronal circuits. The stress response involves multiple changes interacting in a time-dependent manner: (a) the fast first-wave stress response [with central actions of noradrenaline, dopamine, serotonin, corticotropin-releasing hormone (CRH), plus increased sympathetic tone and peripheral catecholamine release] and (b) the second-wave stress response [with peripheral release of glucocorticoids (GCs) after activation of the hypothalamus-pituitary-adrenocortical (HPA) axis]. Control of fear during extinction is also sensitive to these stress-response mediators. In the present review, we will thus examine current animal and human data, addressing the role of stress and single stress-response mediators for successful acquisition, consolidation and recall of fear extinction. We report studies using pharmacological manipulations targeting a number of stress-related neurotransmitters and neuromodulators [monoamines, opioids, endocannabinoids (eCBs), neuropeptide Y, oxytocin, GCs] and behavioral stress induction. As anxiety, trauma- and stressor-related disorders are more common in women, recent research focuses on female sex hormones and identifies a potential role for estradiol in fear extinction. We will thus summarize animal and human data on the role of estradiol and explore possible interactions with stress or stress-response mediators in extinction. This also aims at identifying time-windows of enhanced (or reduced) sensitivity for fear extinction, and thus also for successful exposure therapy.
Collapse
Affiliation(s)
- Ursula Stockhorst
- Experimental Psychology II and Biological Psychology, Institute of Psychology, University of OsnabrückOsnabrück, Germany
| | - Martin I. Antov
- Experimental Psychology II and Biological Psychology, Institute of Psychology, University of OsnabrückOsnabrück, Germany
| |
Collapse
|
22
|
Haaker J, Lonsdorf TB, Kalisch R. Effects of post-extinction l-DOPA administration on the spontaneous recovery and reinstatement of fear in a human fMRI study. Eur Neuropsychopharmacol 2015; 25:1544-55. [PMID: 26238968 DOI: 10.1016/j.euroneuro.2015.07.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 04/29/2015] [Accepted: 07/14/2015] [Indexed: 12/29/2022]
Abstract
Relapse is a pertinent problem in the treatment of anxiety disorders. In the laboratory, relapse is modeled as return of conditioned fear responses after successful fear extinction and is explained by insufficient retrieval and/or expression of the fear-inhibitory extinction memory that is generated during extinction learning. We have shown in mice and humans that return of fear can be prevented by administration of a single dose of the dopamine precursor l-3,4-dihydroxyphenylalanine (l-DOPA) immediately after extinction. In mice, this effect could be attributed to an enhancement of extinction memory consolidation. In our human study, we could not exclude that l-DOPA might have acted by interfering with the consolidation of the original fear memory. In the present study, we therefore used a combined differential cue and context conditioning paradigm where initial fear conditioning and extinction were conducted one day apart, in analogy to previous mouse studies. l-DOPA (N=21) or placebo (N=19) were administered after extinction, precluding any action on fear memory consolidation. In the return-of-fear test conducted one week later, drug effects on conditioned skin conductance responses were absent. However, we found evidence indicative of reduced neural activity, measured with functional magnetic resonance imaging (fMRI), in the l-DOPA group in areas related to conditioned fear and return of fear (amygdala, posterior hippocampus) and enhanced activity in a key area of extinction retrieval/expression (ventromedial prefrontal cortex), relative to placebo controls. These findings require further corroboration in additional experiments. Implications for further investigations on the role of the dopamine system in extinction and on the neuropharmacological augmentation of extinction-based therapies are discussed.
Collapse
Affiliation(s)
- Jan Haaker
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Karolinska Institutet, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | - Tina B Lonsdorf
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Raffael Kalisch
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Neuroimaging Center (NIC), Focus Program Translational Neuroscience, Johannes Gutenberg University Medical Center Mainz, Germany
| |
Collapse
|
23
|
Uematsu A, Tan BZ, Johansen JP. Projection specificity in heterogeneous locus coeruleus cell populations: implications for learning and memory. Learn Mem 2015; 22:444-51. [PMID: 26330494 PMCID: PMC4561410 DOI: 10.1101/lm.037283.114] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/22/2015] [Indexed: 01/05/2023]
Abstract
Noradrenergic neurons in the locus coeruleus (LC) play a critical role in many functions including learning and memory. This relatively small population of cells sends widespread projections throughout the brain including to a number of regions such as the amygdala which is involved in emotional associative learning and the medial prefrontal cortex which is important for facilitating flexibility when learning rules change. LC noradrenergic cells participate in both of these functions, but it is not clear how this small population of neurons modulates these partially distinct processes. Here we review anatomical, behavioral, and electrophysiological studies to assess how LC noradrenergic neurons regulate these different aspects of learning and memory. Previous work has demonstrated that subpopulations of LC noradrenergic cells innervate specific brain regions suggesting heterogeneity of function in LC neurons. Furthermore, noradrenaline in mPFC and amygdala has distinct effects on emotional learning and cognitive flexibility. Finally, neural recording data show that LC neurons respond during associative learning and when previously learned task contingencies change. Together, these studies suggest a working model in which distinct and potentially opposing subsets of LC neurons modulate particular learning functions through restricted efferent connectivity with amygdala or mPFC. This type of model may provide a general framework for understanding other neuromodulatory systems, which also exhibit cell type heterogeneity and projection specificity.
Collapse
Affiliation(s)
- Akira Uematsu
- RIKEN Brain Science Institute, Laboratory for Neural Circuitry of Memory, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Bao Zhen Tan
- RIKEN Brain Science Institute, Laboratory for Neural Circuitry of Memory, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Joshua P Johansen
- RIKEN Brain Science Institute, Laboratory for Neural Circuitry of Memory, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan
| |
Collapse
|
24
|
Kinoshita KI, Tada Y, Muroi Y, Unno T, Ishii T. Selective loss of dopaminergic neurons in the substantia nigra pars compacta after systemic administration of MPTP facilitates extinction learning. Life Sci 2015. [PMID: 26209139 DOI: 10.1016/j.lfs.2015.07.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive loss of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNpc). In PD, thinking and retrieval deficits often arise from cognitive impairments. However, the mechanism of cognitive disorders in PD remains unknown. Therefore, we investigated cognitive function in PD model mice produced by intraperitoneal administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which specifically destroys the DAergic neurons in the SNpc. MAIN METHODS We evaluated the cognitive function of MPTP-treated mice (PD mice) using the contextual fear conditioning test. In the test, each experiment consists of three phases: training, re-exposure, and testing. Mice were trained with a foot shock (a weak unconditioned stimulus: 1mA/2s duration, once, or an intense unconditioned stimulus: 2mA/2s duration, twice), and 24h later, mice were re-exposed to the training context for 3min to determine reconsolidation or 30min to determine extinction. The percentage of time spent freezing was measured during the test session as indexes of memory consolidation, reconsolidation, and extinction. KEY FINDINGS Reconsolidation of PD mice occurred normally but memory extinction was facilitated in PD mice compared to control mice. Moreover, memory retention in PD mice was attenuated earlier than in controls following repeated conditioned stimuli every day. SIGNIFICANCE PD mice with selective loss of DAergic neurons in the SNpc showed attenuated memory retention, probably via facilitated extinction learning.
Collapse
Affiliation(s)
- Ken-ichi Kinoshita
- Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Yayoi Tada
- Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Yoshikage Muroi
- Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Toshihiro Unno
- Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; The Laboratory of Pharmacology, Faculty of Applied Biological Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Toshiaki Ishii
- Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
| |
Collapse
|
25
|
Baldi E, Bucherelli C. Brain sites involved in fear memory reconsolidation and extinction of rodents. Neurosci Biobehav Rev 2015; 53:160-90. [DOI: 10.1016/j.neubiorev.2015.04.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 03/30/2015] [Accepted: 04/06/2015] [Indexed: 12/21/2022]
|
26
|
Singewald N, Schmuckermair C, Whittle N, Holmes A, Ressler KJ. Pharmacology of cognitive enhancers for exposure-based therapy of fear, anxiety and trauma-related disorders. Pharmacol Ther 2014; 149:150-90. [PMID: 25550231 PMCID: PMC4380664 DOI: 10.1016/j.pharmthera.2014.12.004] [Citation(s) in RCA: 275] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 12/24/2014] [Indexed: 12/20/2022]
Abstract
Pathological fear and anxiety are highly debilitating and, despite considerable advances in psychotherapy and pharmacotherapy they remain insufficiently treated in many patients with PTSD, phobias, panic and other anxiety disorders. Increasing preclinical and clinical evidence indicates that pharmacological treatments including cognitive enhancers, when given as adjuncts to psychotherapeutic approaches [cognitive behavioral therapy including extinction-based exposure therapy] enhance treatment efficacy, while using anxiolytics such as benzodiazepines as adjuncts can undermine long-term treatment success. The purpose of this review is to outline the literature showing how pharmacological interventions targeting neurotransmitter systems including serotonin, dopamine, noradrenaline, histamine, glutamate, GABA, cannabinoids, neuropeptides (oxytocin, neuropeptides Y and S, opioids) and other targets (neurotrophins BDNF and FGF2, glucocorticoids, L-type-calcium channels, epigenetic modifications) as well as their downstream signaling pathways, can augment fear extinction and strengthen extinction memory persistently in preclinical models. Particularly promising approaches are discussed in regard to their effects on specific aspects of fear extinction namely, acquisition, consolidation and retrieval, including long-term protection from return of fear (relapse) phenomena like spontaneous recovery, reinstatement and renewal of fear. We also highlight the promising translational value of the preclinial research and the clinical potential of targeting certain neurochemical systems with, for example d-cycloserine, yohimbine, cortisol, and L-DOPA. The current body of research reveals important new insights into the neurobiology and neurochemistry of fear extinction and holds significant promise for pharmacologically-augmented psychotherapy as an improved approach to treat trauma and anxiety-related disorders in a more efficient and persistent way promoting enhanced symptom remission and recovery.
Collapse
Affiliation(s)
- N Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.
| | - C Schmuckermair
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - N Whittle
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, Leopold-Franzens University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - A Holmes
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - K J Ressler
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
| |
Collapse
|
27
|
Impaired adrenergic-mediated plasticity of prefrontal cortical glutamate synapses in rats with developmental disruption of the ventral hippocampus. Neuropsychopharmacology 2014; 39:2963-73. [PMID: 24917197 PMCID: PMC4229566 DOI: 10.1038/npp.2014.142] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 06/03/2014] [Accepted: 06/05/2014] [Indexed: 01/21/2023]
Abstract
Neonatal ventral hippocampus (nVH) lesion in rats is a useful model to study developmental origins of adult cognitive deficits and certain features of schizophrenia. nVH lesion-induced reorganization of excitatory and inhibitory neurotransmissions within prefrontal cortical (PFC) circuits is widely believed to be responsible for many of the behavioral abnormalities in these animals. Here we provide evidence that development of an aberrant medial PFC (mPFC) α-1 adrenergic receptor (α-1AR) function following neonatal lesion markedly affects glutamatergic synaptic plasticity within PFC microcircuits and contributes to PFC-related behavior abnormalities. Using whole-cell patch-clamp recording, we report that norepinephrine-induced α-1AR-dependent long-term depression (LTD) in a subset of cortico-cortical glutamatergic inputs is strikingly diminished in mPFC slices from nVH-lesioned rats. The LTD impairment occurs in conjunction with completely blunted α-1AR signaling through extracellular signal-regulated kinase 1/2. These α-1AR abnormalities have functional significance in a mPFC-related function, that is, extinction of conditioned fear memory. Post-pubertal animals with nVH lesion show significant resistance to extinction of fear by repeated presentations of the conditioned tone stimulus. mPFC infusion of an α-1AR antagonist (benoxathian) or LTD blocking peptide (Tat-GluR23Y) impaired fear extinction in sham controls, but had no significant effect in the lesioned animals. The data suggest that impaired α-1 adrenergic regulation of cortical glutamatergic synaptic plasticity may be an important mechanism in cognitive dysfunctions reported in neurodevelopmental psychiatric disorders.
Collapse
|
28
|
Bukalo O, Pinard CR, Holmes A. Mechanisms to medicines: elucidating neural and molecular substrates of fear extinction to identify novel treatments for anxiety disorders. Br J Pharmacol 2014; 171:4690-718. [PMID: 24835117 DOI: 10.1111/bph.12779] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/28/2014] [Accepted: 05/04/2014] [Indexed: 12/11/2022] Open
Abstract
The burden of anxiety disorders is growing, but the efficacy of available anxiolytic treatments remains inadequate. Cognitive behavioural therapy for anxiety disorders focuses on identifying and modifying maladaptive patterns of thinking and behaving, and has a testable analogue in rodents in the form of fear extinction. A large preclinical literature has amassed in recent years describing the neural and molecular basis of fear extinction in rodents. In this review, we discuss how this work is being harnessed to foster translational research on anxiety disorders and facilitate the search for new anxiolytic treatments. We begin by summarizing the anatomical and functional connectivity of a medial prefrontal cortex (mPFC)-amygdala circuit that subserves fear extinction, including new insights from optogenetics. We then cover some of the approaches that have been taken to model impaired fear extinction and associated impairments with mPFC-amygdala dysfunction. The principal goal of the review is to evaluate evidence that various neurotransmitter and neuromodulator systems mediate fear extinction by modulating the mPFC-amygdala circuitry. To that end, we describe studies that have tested how fear extinction is impaired or facilitated by pharmacological manipulations of dopamine, noradrenaline, 5-HT, GABA, glutamate, neuropeptides, endocannabinoids and various other systems, which either directly target the mPFC-amygdala circuit, or produce behavioural effects that are coincident with functional changes in the circuit. We conclude that there are good grounds to be optimistic that the progress in defining the molecular substrates of mPFC-amygdala circuit function can be effectively leveraged to identify plausible candidates for extinction-promoting therapies for anxiety disorders.
Collapse
Affiliation(s)
- Olena Bukalo
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | | | | |
Collapse
|
29
|
Dopamine and extinction: a convergence of theory with fear and reward circuitry. Neurobiol Learn Mem 2013; 108:65-77. [PMID: 24269353 DOI: 10.1016/j.nlm.2013.11.007] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 11/01/2013] [Accepted: 11/08/2013] [Indexed: 01/11/2023]
Abstract
Research on dopamine lies at the intersection of sophisticated theoretical and neurobiological approaches to learning and memory. Dopamine has been shown to be critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine's function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in reward-related tasks. A parallel and growing literature indicates that dopamine is involved in fear conditioning and extinction. These studies are consistent with long-standing ideas about appetitive-aversive interactions in learning theory and they speak to the general nature of cellular and molecular processes that underlie behavior. We review the behavioral and neurobiological literature showing a role for dopamine in fear conditioning and extinction. At a cellular level, we review dopamine signaling and receptor pharmacology, cellular and molecular events that follow dopamine receptor activation, and brain systems in which dopamine functions. At a behavioral level, we describe theories of learning and dopamine function that could describe the fundamental rules underlying how dopamine modulates different aspects of learning and memory processes.
Collapse
|
30
|
Pendyam S, Bravo-Rivera C, Burgos-Robles A, Sotres-Bayon F, Quirk GJ, Nair SS. Fear signaling in the prelimbic-amygdala circuit: a computational modeling and recording study. J Neurophysiol 2013; 110:844-61. [PMID: 23699055 PMCID: PMC3742978 DOI: 10.1152/jn.00961.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 05/17/2013] [Indexed: 11/22/2022] Open
Abstract
The acquisition and expression of conditioned fear depends on prefrontal-amygdala circuits. Auditory fear conditioning increases the tone responses of lateral amygdala neurons, but the increase is transient, lasting only a few hundred milliseconds after tone onset. It was recently reported that that the prelimbic (PL) prefrontal cortex transforms transient lateral amygdala input into a sustained PL output, which could drive fear responses via projections to the lateral division of basal amygdala (BL). To explore the possible mechanisms involved in this transformation, we developed a large-scale biophysical model of the BL-PL network, consisting of 850 conductance-based Hodgkin-Huxley-type cells, calcium-based learning, and neuromodulator effects. The model predicts that sustained firing in PL can be derived from BL-induced release of dopamine and norepinephrine that is maintained by PL-BL interconnections. These predictions were confirmed with physiological recordings from PL neurons during fear conditioning with the selective β-blocker propranolol and by inactivation of BL with muscimol. Our model suggests that PL has a higher bandwidth than BL, due to PL's decreased internal inhibition and lower spiking thresholds. It also suggests that variations in specific microcircuits in the PL-BL interconnection can have a significant impact on the expression of fear, possibly explaining individual variability in fear responses. The human homolog of PL could thus be an effective target for anxiety disorders.
Collapse
Affiliation(s)
- Sandeep Pendyam
- Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65211, USA
| | | | | | | | | | | |
Collapse
|
31
|
Archbold GE, Dobbek N, Nader K. Temporal dynamics of recovery from extinction shortly after extinction acquisition. Learn Mem 2013; 20:395-8. [PMID: 23858050 DOI: 10.1101/lm.028225.112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Evidence suggests that extinction is new learning. Memory acquisition involves both short-term memory (STM) and long-term memory (LTM) components; however, few studies have examined early phases of extinction retention. Retention of auditory fear extinction was examined at various time points. Shortly (1-4 h) after extinction acquisition spontaneous recovery was high compared to that after longer delays (8-24 h). Recall of a consolidated extinction trace was also impaired if it was preceded 1 h by extinction of a novel CS; propranolol did not attenuate this effect. These results suggest poor extinction retention reflects a retrieval impairment caused by the aversive experience of extinction training.
Collapse
Affiliation(s)
- Georgina E Archbold
- Department of Psychology, McGill University, Montreal, Quebec, Canada H3A1B1.
| | | | | |
Collapse
|
32
|
Haaker J, Gaburro S, Sah A, Gartmann N, Lonsdorf TB, Meier K, Singewald N, Pape HC, Morellini F, Kalisch R. Single dose of L-dopa makes extinction memories context-independent and prevents the return of fear. Proc Natl Acad Sci U S A 2013; 110:E2428-36. [PMID: 23754384 PMCID: PMC3696794 DOI: 10.1073/pnas.1303061110] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Traumatic events can engender persistent excessive fear responses to trauma reminders that may return even after successful treatment. Extinction, the laboratory analog of behavior therapy, does not erase conditioned fear memories but generates competing, fear-inhibitory "extinction memories" that, however, are tied to the context in which extinction occurred. Accordingly, a dominance of fear over extinction memory expression--and, thus, return of fear--is often observed if extinguished fear stimuli are encountered outside the extinction (therapy) context. We show that postextinction administration of the dopamine precursor L-dopa makes extinction memories context-independent, thus strongly reducing the return of fear in both mice and humans. Reduced fear is accompanied by decreased amygdala and enhanced ventromedial prefrontal cortex activation in both species. In humans, ventromedial prefrontal cortex activity is predicted by enhanced resting-state functional coupling of the area with the dopaminergic midbrain during the postextinction consolidation phase. Our data suggest that dopamine-dependent boosting of extinction memory consolidation is a promising avenue to improving anxiety therapy.
Collapse
Affiliation(s)
- Jan Haaker
- Institute for Systems Neuroscience, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Stefano Gaburro
- Institute of Physiology I (Neurophysiology), Westfaelische Wilhems-University Münster, 48149 Münster, Germany
| | - Anupam Sah
- Deparment of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences (CMBI) Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria
| | - Nina Gartmann
- Institute for Systems Neuroscience, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Tina B. Lonsdorf
- Institute for Systems Neuroscience, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Kolja Meier
- Experimental Neuropediatrics, Center for Molecular Neurobiology Hamburg (ZNMH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany; and
| | - Nicolas Singewald
- Deparment of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences (CMBI) Innsbruck, University of Innsbruck, 6020 Innsbruck, Austria
| | - Hans-Christian Pape
- Institute of Physiology I (Neurophysiology), Westfaelische Wilhems-University Münster, 48149 Münster, Germany
| | - Fabio Morellini
- Experimental Neuropediatrics, Center for Molecular Neurobiology Hamburg (ZNMH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany; and
| | - Raffael Kalisch
- Institute for Systems Neuroscience, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
- Neuroimaging Center Mainz (NIC), Focus Program Translational Neuroscience, Johannes Gutenberg University Medical Center, 55131 Mainz, Germany
| |
Collapse
|
33
|
Fliegel S, Brand I, Spanagel R, Noori HR. Ethanol-induced alterations of amino acids measured by in vivo microdialysis in rats: a meta-analysis. In Silico Pharmacol 2013; 1:7. [PMID: 25505652 PMCID: PMC4230485 DOI: 10.1186/2193-9616-1-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 05/07/2013] [Indexed: 12/14/2022] Open
Abstract
PURPOSE In recent years in vivo microdialysis has become an important method in research studies investigating the alterations of neurotransmitters in the extracellular fluid of the brain. Based on the major involvement of glutamate and γ-aminobutyric acid (GABA) in mediating a variety of alcohol effects in the mammalian brain, numerous microdialysis studies have focused on the dynamical behavior of these systems in response to alcohol. METHODS Here we performed multiple meta-analyses on published datasets from the rat brain: (i) we studied basal extracellular concentrations of glutamate and GABA in brain regions that belong to a neurocircuitry involved in neuropsychiatric diseases, especially in alcoholism (Noori et al., Addict Biol 17:827-864, 2012); (ii) we examined the effect of acute ethanol administration on glutamate and GABA levels within this network and (iii) we studied alcohol withdrawal-induced alterations in glutamate and GABA levels within this neurocircuitry. RESULTS For extraction of basal concentrations of these neurotransmitters, datasets of 6932 rats were analyzed and the absolute basal glutamate and GABA levels were estimated for 18 different brain sites. In response to different doses of acute ethanol administration, datasets of 529 rats were analyzed and a non-linear dose response (glutamate and GABA release) relationship was observed in several brain sites. Specifically, glutamate in the nucleus accumbens shows a decreasing logarithmic dose response curve. Finally, regression analysis of 11 published reports employing brain microdialysis experiments in 104 alcohol-dependent rats reveals very consistent augmented extracellular glutamate and GABA levels in various brain sites that correlate with the intensity of the withdrawal response were identified. CONCLUSIONS In summary, our results provide standardized basal values for future experimental and in silico studies on neurotransmitter release in the rat brain and may be helpful to understand the effect of ethanol on neurotransmitter release. Furthermore, this study illustrates the benefit of meta-analyses using the generalization of a wide range of preclinical data.
Collapse
Affiliation(s)
- Sarah Fliegel
- Institute of Psychopharmacology, Central Institute of Mental Health, Faculty of Medicine Mannheim, University of Heidelberg, J5, 68159 Mannheim, Germany
| | - Ines Brand
- Institute of Psychopharmacology, Central Institute of Mental Health, Faculty of Medicine Mannheim, University of Heidelberg, J5, 68159 Mannheim, Germany
| | - Rainer Spanagel
- Institute of Psychopharmacology, Central Institute of Mental Health, Faculty of Medicine Mannheim, University of Heidelberg, J5, 68159 Mannheim, Germany
| | - Hamid R Noori
- Institute of Psychopharmacology, Central Institute of Mental Health, Faculty of Medicine Mannheim, University of Heidelberg, J5, 68159 Mannheim, Germany
| |
Collapse
|
34
|
Saito Y, Matsumoto M, Yanagawa Y, Hiraide S, Inoue S, Kubo Y, Shimamura KI, Togashi H. Facilitation of fear extinction by the 5-HT(1A) receptor agonist tandospirone: possible involvement of dopaminergic modulation. Synapse 2012; 67:161-70. [PMID: 23152167 DOI: 10.1002/syn.21621] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 09/20/2012] [Accepted: 10/07/2012] [Indexed: 12/30/2022]
Abstract
Fear extinction-based exposure treatment is an important component of psychotherapy for anxiety disorders such as posttraumatic stress disorder (PTSD). Recent studies have focused on pharmacological approaches combined with exposure therapy to augment extinction. In this study, we elucidated the therapeutic potential of the serotonin 1A (5-HT(1A) ) receptor agonist tandospirone compared with the effects of the N-methyl-D-aspartate partial agonist D-cycloserine (DCS), focusing on the possible involvement of dopaminergic mechanisms. We used a rat model of juvenile stress [aversive footshock (FS)] exposure during the third postnatal week (3wFS). The 3wFS group exhibited extinction deficit reflected in sustained fear-related behavior and synaptic dysfunction in the hippocampal CA1 field and medial prefrontal cortex (mPFC), which are responsible for extinction processes. Tandospirone administration (5 mg/kg, i.p.) before and after the extinction trials ameliorated both the behavioral deficit and synaptic dysfunction, i.e., synaptic efficacy in the CA1 field and mPFC associated with extinction training and retrieval, respectively, was potentiated in the tandospirone-treated 3wFS group. Extracellular dopamine release in the mPFC was increased by extinction retrieval in the non-FS control group. This facilitation was not observed in the 3wFS group; however, tandospirone treatment increased cortical dopamine levels after extinction retrieval. DCS (15 mg/kg, i.p.) also ameliorated the extinction deficit in the 3wFS group, but impaired extinction in the non-FS control group. These results suggest that tandospirone has therapeutic potential for enhancing synaptic efficacy associated with extinction processes by involving dopaminergic mechanisms. Pharmacological agents that target cortical dopaminergic systems may provide new insights into the development of therapeutic treatments of anxiety disorders, including PTSD.
Collapse
Affiliation(s)
- Yasuhiro Saito
- Department of Pharmacology, School of Pharmaceutical Science, Health Sciences University of Hokkaido, Ishikari-Tobetsu 061-0293, Japan
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Muscarinic receptors modulate the intrinsic excitability of infralimbic neurons and consolidation of fear extinction. Neuropsychopharmacology 2012; 37:2047-56. [PMID: 22510723 PMCID: PMC3398732 DOI: 10.1038/npp.2012.52] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There is considerable interest in identifying pharmacological compounds that could be used to facilitate fear extinction. Recently, we showed that the modulation of M-type K(+) channels regulates the intrinsic excitability of infralimbic (IL) neurons and fear expression. As muscarinic acetylcholine receptors inhibit M-type K(+) channels, cholinergic inputs to IL may have an important role in controlling IL excitability and, thereby, fear expression and extinction. To test this model, we combined whole-cell patch-clamp electrophysiology and auditory fear conditioning. In prefrontal brain slices, muscarine enhanced the intrinsic excitability of IL neurons by reducing the M-current and the slow afterhyperpolarization, resulting in an increased number of spikes with shorter inter-spike intervals. Next, we examined the role of endogenous activation of muscarinic receptors in fear extinction. Systemic injected scopolamine (Scop) (muscarinic receptor antagonist) before or immediately after extinction training impaired recall of extinction 24-h later, suggesting that muscarinic receptors are critically involved in consolidation of extinction memory. Similarly, infusion of Scop into IL before extinction training also impaired recall of extinction 24-h later. Finally, we demonstrated that systemic injections of the muscarinic agonist, cevimeline (Cev), given before or immediately after extinction training facilitated recall of extinction the following day. Taken together, these findings suggest that cholinergic inputs to IL have a critical role in modulating consolidation of fear extinction and that muscarinic agonists such as Cev might be useful for facilitating extinction memory in patients suffering from anxiety disorders.
Collapse
|
36
|
Learning-induced changes in mPFC-BLA connections after fear conditioning, extinction, and reinstatement of fear. Neuropsychopharmacology 2011; 36:2276-85. [PMID: 21750582 PMCID: PMC3176564 DOI: 10.1038/npp.2011.115] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The neural circuit linking the medial prefrontal cortex (mPFC) and the basolateral amygdala (BLA) has crucial roles in both the acquisition and the extinction of fear. However, the mechanism by which this circuit encodes fear and extinction remains unknown. In this study, we monitored changes in the magnitude of evoked field potentials (EFPs) in the mPFC-BLA and BLA-mPFC pathways following auditory fear conditioning and extinction, in freely moving rats. We report that extinction of fear is mediated by depression of the EFPs in the mPFC-BLA and by potentiation in the reciprocal pathway of BLA-mPFC. Interestingly, reinstatement of fear was associated with recovery of freezing and with reversal of the changes in EFPs that were observed following extinction in both pathways. The findings indicate that the mPFC-BLA circuit expresses differential changes following fear and extinction and point to dynamic and plastic changes underlying fear, extinction, and reinstatement. Manipulations targeting these different types of plasticity could constitute a therapeutic tool for the treatment of anxiety disorders.
Collapse
|
37
|
Tonic and phasic release of glutamate and acetylcholine neurotransmission in sub-regions of the rat prefrontal cortex using enzyme-based microelectrode arrays. J Neurosci Methods 2011; 202:199-208. [PMID: 21896284 DOI: 10.1016/j.jneumeth.2011.08.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 08/10/2011] [Accepted: 08/11/2011] [Indexed: 12/22/2022]
Abstract
The medial prefrontal cortex (mPFC) is an area of the brain critical for higher cognitive processes and implicated in disorders of the CNS such as drug addiction, depression and schizophrenia. Glutamate and acetylcholine are neurotransmitters that are essential for cortical functioning, yet little is known about the dynamic function of these neurotransmitters in subregions of the mPFC. In these studies we used a novel microelectrode array technology to measure resting levels (tonic release) of glutamate and acetylcholine as well as KCl-evoked release (stimulated phasic release) in the mPFC of the anesthetized rat to further our understanding of both tonic and phasic neurotransmission in the cingulate cortex, prelimbic cortex, and infralimbic cortex of the mPFC. Studies revealed homogeneity of tonic and phasic signaling among brain subregions for each neurotransmitter. However, resting levels of glutamate were significantly higher as compared to acetylcholine levels in all subregions. Additionally, KCl-evoked acetylcholine release in the cingulate cortex (7.1 μM) was significantly greater than KCl-evoked glutamate release in any of the three subregions (Cg1, 2.9 μM; PrL, 2.0 μM; IL, 1.8 μM). Interestingly, the time for signal decay following KCl-evoked acetylcholine release was significantly longer by an average of 240% as compared to KCL-evoked glutamate release for all three brain subregions. Finally, we observed a negative relationship between acetylcholine resting levels and KCl-evoked release in the Cg1. These data suggest a homogenous distribution of both glutamatergic and acetylcholinergic innervation in the mPFC, with alterations in tonic and phasic release regulation accounting for differences between these neurotransmitters.
Collapse
|
38
|
Prenatal stress induces long term stress vulnerability, compromising stress response systems in the brain and impairing extinction of conditioned fear after adult stress. Neuroscience 2011; 192:438-51. [PMID: 21723377 DOI: 10.1016/j.neuroscience.2011.06.041] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 06/13/2011] [Accepted: 06/14/2011] [Indexed: 10/18/2022]
Abstract
Stress is a risk factor for the development of affective disorders, including depression, post-traumatic stress disorder, and other anxiety disorders. However, not all individuals who experience either chronic stress or traumatic acute stress develop such disorders. Thus, other factors must confer a vulnerability to stress, and exposure to early-life stress may be one such factor. In this study we examined prenatal stress (PNS) as a potential vulnerability factor that may produce stable changes in central stress response systems and susceptibility to develop fear- and anxiety-like behaviors after adult stress exposure. Pregnant Sprague-Dawley rats were immobilized for 1 h daily during the last week of pregnancy. Controls were unstressed. The male offspring were then studied as adults. As adults, PNS or control rats were first tested for shock-probe defensive burying behavior, then half from each group were exposed to a combined chronic plus acute prolonged stress (CAPS) treatment, consisting of chronic intermittent cold stress (4 °C, 6 h/d, 14 days) followed on day 15 by a single session of sequential acute stressors (social defeat, immobilization, cold swim). After CAPS or control treatment, different groups were tested for open field exploration, social interaction, or cued fear conditioning and extinction. Rats were sacrificed at least 5 days after behavioral testing for measurement of tyrosine hydroxylase (TH) and glucocorticoid receptor (GR) expression in specific brain regions, and plasma adrenocorticotropic hormone (ACTH) and corticosterone. Shock-probe burying, open field exploration and social interaction were unaffected by any treatment. However, PNS elevated basal corticosterone, decreased GR protein levels in hippocampus and prefrontal cortex, and decreased TH mRNA expression in noradrenergic neurons in the dorsal pons. Further, rats exposed to PNS plus CAPS showed attenuated extinction of cue-conditioned fear. These results suggest that PNS induces vulnerability to subsequent adult stress, resulting in an enhanced fear-like behavioral profile, and dysregulation of brain noradrenergic and hypothalamic-pituitary-adrenal axis (HPA) activity.
Collapse
|
39
|
Infralimbic D2 receptors are necessary for fear extinction and extinction-related tone responses. Biol Psychiatry 2010; 68:1055-60. [PMID: 20926066 PMCID: PMC2981677 DOI: 10.1016/j.biopsych.2010.08.014] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Revised: 08/13/2010] [Accepted: 08/13/2010] [Indexed: 02/05/2023]
Abstract
BACKGROUND Fear extinction is dependent on plasticity in the infralimbic prefrontal cortex, an area heavily innervated by midbrain dopaminergic inputs. Dopamine D2 receptors are concentrated in infralimbic output neurons that are involved in the suppression of conditioned fear after extinction. Here, we examined the specific role of infralimbic D2 receptors in mediating associative learning underlying fear extinction using the selective D2 antagonist raclopride. METHODS Raclopride was administered systemically or infused into the infralimbic prefrontal cortex before fear extinction, and extinction retention was tested the following day. Rats were also prepared for single-unit recording in the infralimbic prefrontal cortex to assess the effect of raclopride on firing properties. RESULTS We found that systemic injection of raclopride given before extinction impaired retrieval of extinction when rats were tested drug-free the next day but also induced catalepsy during extinction training. To determine whether impaired extinction was due to impaired motor function or disruption of extinction consolidation, we infused raclopride directly into the infralimbic prefrontal cortex. Raclopride infused immediately before extinction training did not produce motor deficits but impaired recall of extinction when tested drug-free. Furthermore, in animals that underwent extinction training, systemic raclopride reduced the tone responsiveness of infralimbic prefrontal cortex neurons in layers 5/6, with no changes in average firing rate. CONCLUSIONS We suggest that D2 receptors facilitate extinction by increasing the signal-to-noise of infralimbic prefrontal cortex neurons that consolidate extinction.
Collapse
|
40
|
Thompson BM, Baratta MV, Biedenkapp JC, Rudy JW, Watkins LR, Maier SF. Activation of the infralimbic cortex in a fear context enhances extinction learning. Learn Mem 2010; 17:591-9. [PMID: 21041382 DOI: 10.1101/lm.1920810] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Activation of the infralimbic region (IL) of the medial prefrontal cortex (mPFC) reduces conditioned fear in a variety of situations, and the IL is thought to play an important role in the extinction of conditioned fear. Here we report a series of experiments using contextual fear conditioning in which the IL is activated with the GABAa antagonist picrotoxin (Ptx) during a single extinction session in the fear context. We investigate the impact of this manipulation on subsequent extinction sessions in which Ptx is no longer present. First, we demonstrate that a single treatment with intra-IL Ptx administered in a conditioned fear context greatly accelerates the rate of extinction on the following days. Importantly, IL-Ptx also enhances extinction to a different fear context than the one in which IL-Ptx was administered. Thus, IL-Ptx primes extinction learning regardless of the fear context in which the IL was initially activated. Second, activation of the IL must occur in conjunction with a fear context in order to enhance extinction; the extinction enhancing effect is not observable if IL-Ptx is administered in a neutral context. Finally, this extinction enhancing effect is specific to the IL for it does not occur if Ptx is injected into the prelimbic region (PL) of the mPFC. The results indicate a novel persisting control of fear induced by activation of the IL and suggest that IL activation induces changes in extinction-related circuitry that prime extinction learning.
Collapse
Affiliation(s)
- Brittany M Thompson
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado 80309-0345, USA.
| | | | | | | | | | | |
Collapse
|
41
|
Fontanez-Nuin DE, Santini E, Quirk GJ, Porter JT. Memory for fear extinction requires mGluR5-mediated activation of infralimbic neurons. ACTA ACUST UNITED AC 2010; 21:727-35. [PMID: 20705895 DOI: 10.1093/cercor/bhq147] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Consolidation of fear extinction involves enhancement of N-methyl D aspartate (NMDA) receptor-dependent bursting in the infralimbic region (IL) of the medial prefrontal cortex (mPFC). Previous studies have shown that systemic blockade of metabotropic glutamate receptor type 5 (mGluR5) reduces bursting in the mPFC and mGluR5 agonists enhance NMDA receptor currents in vitro, suggesting that mGluR5 activation in IL may contribute to fear extinction. In the current study, rats injected with the mGluR5 antagonist 2-methyl-6-(phenylethyl)-pyridine (MPEP) systemically, or intra-IL, prior to extinction exhibited normal within-session extinction, but were impaired in their ability to recall extinction the following day. To directly determine whether mGluR5 stimulation enhances the burst firing of IL neurons, we used patch-clamp electrophysiology in prefrontal slices. The mGluR5 agonist, (RS)-2-chloro-5-hydroxyphenylglycine (CHPG), increased intrinsic bursting in IL neurons. Increased bursting was correlated with a reduction in the slow after hyperpolarizing potential and was prevented by coapplication of MPEP. CHPG did not increase NMDA currents, suggesting that an NMDA receptor-independent enhancement of IL bursting via stimulation of mGluR5 receptors contributes to fear extinction. Therefore, the mGluR5 receptor could be a suitable target for pharmacological adjuncts to extinction-based therapies for anxiety disorders.
Collapse
Affiliation(s)
- Darah E Fontanez-Nuin
- Department of Physiology and Pharmacology, Ponce School of Medicine, Ponce, Puerto Rico 00732-7004
| | | | | | | |
Collapse
|
42
|
Mueller D, Cahill SP. Noradrenergic modulation of extinction learning and exposure therapy. Behav Brain Res 2009; 208:1-11. [PMID: 19931568 DOI: 10.1016/j.bbr.2009.11.025] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2009] [Revised: 11/12/2009] [Accepted: 11/15/2009] [Indexed: 11/16/2022]
Abstract
Memory consolidation is enhanced by emotional arousal, an effect mediated by noradrenergic beta-receptor signaling. Norepinephrine strengthens consolidation of both appetitive and aversive learning, and is implicated in extinction of conditioned responses. In this review, we summarize work on the noradrenergic mechanisms of extinction learning and implications for extinction-based exposure therapy. The evidence suggests that norepinephrine release evoked by conditioned stimuli during extinction strengthens extinction memory via beta-receptor signaling. The modulatory effect of norepinephrine during extinction depends on predictable presentation of conditioned stimuli and optimal levels of norepinephrine release. Mechanistically, norepinephrine acts to increase cellular excitability and enhance synaptic plasticity within extinction-related neural circuitry. Currently, drugs that modulate norepinephrine are being used to treat symptoms of anxiety disorders, and are now being tested as pharmacotherapeutic prophalactics in the prevention of chronic posttraumatic stress reactions and as adjuncts to extinction-based exposure therapy. Studies of these new applications of noradrenergic drugs show a converging pattern of results with basic science suggesting ways in which basic laboratory findings can be translated into procedures to enhance clinical outcomes.
Collapse
Affiliation(s)
- Devin Mueller
- Department of Psychology, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201-0413, USA.
| | | |
Collapse
|
43
|
Sustained conditioned responses in prelimbic prefrontal neurons are correlated with fear expression and extinction failure. J Neurosci 2009; 29:8474-82. [PMID: 19571138 DOI: 10.1523/jneurosci.0378-09.2009] [Citation(s) in RCA: 396] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During auditory fear conditioning, it is well established that lateral amygdala (LA) neurons potentiate their response to the tone conditioned stimulus, and that this potentiation is required for conditioned fear behavior. Conditioned tone responses in LA, however, last only a few hundred milliseconds and cannot be responsible for sustained fear responses to a tone lasting tens of seconds. Recent evidence from inactivation and stimulation studies suggests that the prelimbic (PL) prefrontal cortex is necessary for expression of learned fears, but the timing of PL tone responses and correlations with fear behavior have not been studied. Using multichannel unit recording techniques in behaving rats, we observed sustained conditioned tone responses in PL that were correlated with freezing behavior on a second-to-second basis during the presentation of a 30 s tone. PL tone responses were also correlated with conditioned freezing across different experimental phases (habituation, conditioning, extinction). Moreover, the persistence of PL responses after extinction training was associated with failure to express extinction memory. Together with previous inactivation findings, the present results suggest that PL transforms transient amygdala inputs to a sustained output that drives conditioned fear responses and gates the expression of extinction. Given the relatively long latency of conditioned responses we observed in PL (approximately 100 ms after tone onset), we propose that PL integrates inputs from the amygdala, hippocampus, and other cortical sources to regulate the expression of fear memories.
Collapse
|
44
|
Rodriguez-Romaguera J, Sotres-Bayon F, Mueller D, Quirk GJ. Systemic propranolol acts centrally to reduce conditioned fear in rats without impairing extinction. Biol Psychiatry 2009; 65:887-92. [PMID: 19246030 PMCID: PMC2695810 DOI: 10.1016/j.biopsych.2009.01.009] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 01/04/2009] [Accepted: 01/07/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND Previous work has implicated noradrenergic beta-receptors in the consolidation and reconsolidation of conditioned fear. Less is known, however, about their role in fear expression and extinction. The beta-receptor blocker propranolol has been used clinically to reduce anxiety. With an auditory fear conditioning task in rats, we assessed the effects of systemic propranolol on the expression and extinction of two measures of conditioned fear: freezing and suppression of bar-pressing. METHODS One day after receiving auditory fear conditioning, rats were injected with saline, propranolol, or peripheral beta-receptor blocker sotalol (both 10 mg/kg, IP). Twenty minutes after injection, rats were given either 6 or 12 extinction trials and were tested for extinction retention the following day. The effect of propranolol on the firing rate of neurons in prelimbic (PL) prefrontal cortex was also assessed. RESULTS Propranolol reduced freezing by more than 50%, an effect that was evident from the first extinction trial. Suppression was also significantly reduced. Despite this, propranolol had no effect on the acquisition or retention of extinction. Unlike propranolol, sotalol did not affect fear expression, although both drugs significantly reduced heart rate. This suggests that propranolol acts centrally to reduce fear. Consistent with this, propranolol reduced the firing rate of PL neurons. CONCLUSION Propranolol reduced the expression of conditioned fear, without interfering with extinction learning. Reduced fear with intact extinction suggests a possible use for propranolol in reducing anxiety during extinction-based exposure therapies, without interfering with long-term clinical response.
Collapse
Affiliation(s)
- Jose Rodriguez-Romaguera
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, PR 00936
| | - Francisco Sotres-Bayon
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, PR 00936
| | | | - Gregory J. Quirk
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, San Juan, PR 00936
| |
Collapse
|
45
|
Mueller D, Porter JT, Quirk GJ. Noradrenergic signaling in infralimbic cortex increases cell excitability and strengthens memory for fear extinction. J Neurosci 2008; 28:369-75. [PMID: 18184779 PMCID: PMC6670514 DOI: 10.1523/jneurosci.3248-07.2008] [Citation(s) in RCA: 217] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 10/12/2007] [Accepted: 11/01/2007] [Indexed: 12/14/2022] Open
Abstract
Emotional arousal strengthens memory. This is most apparent in aversive conditioning, in which the stress-related neurotransmitter norepinephrine (NE) enhances associations between sensory stimuli and fear-inducing events. In contrast to conditioning, extinction decreases fear responses, and is thought to form a new memory. It is not known, however, whether NE is necessary for extinction learning. Previous work has shown that the infralimbic prefrontal cortex (IL) is a site of extinction consolidation. Here, we show that blocking noradrenergic beta-receptors in IL before extinction training impaired retrieval of extinction the following day, consistent with a weakened extinction memory. We further found that the sequelae of beta-receptor activation, including protein kinase A (PKA), gene transcription and translation in IL, are necessary for extinction. To determine whether activation of this cascade modulates IL excitability, we measured the response of IL pyramidal neurons to injected current. NE increased the excitability of IL neurons in a beta-receptor- and PKA-dependent manner. We suggest that NE released in IL during fear extinction activates a PKA-mediated molecular cascade that strengthens extinction memory. Thus, emotional arousal evoked by conditioned fear paradoxically promotes the subsequent extinction of that fear, thereby ensuring behavioral flexibility.
Collapse
Affiliation(s)
- Devin Mueller
- Department of Psychiatry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico.
| | | | | |
Collapse
|
46
|
Abstract
Emotional learning is necessary for individuals to survive and prosper. Once acquired, however, emotional associations are not always expressed. Indeed, the regulation of emotional expression under varying environmental conditions is essential for mental health. The simplest form of emotional regulation is extinction, in which conditioned responding to a stimulus decreases when the reinforcer is omitted. Two decades of research on the neural mechanisms of fear conditioning have laid the groundwork for understanding extinction. In this review, we summarize recent work on the neural mechanisms of extinction learning. Like other forms of learning, extinction occurs in three phases: acquisition, consolidation, and retrieval, each of which depends on specific structures (amygdala, prefrontal cortex, hippocampus) and molecular mechanisms (receptors and signaling pathways). Pharmacological methods to facilitate consolidation and retrieval of extinction, for both aversive and appetitive conditioning, are setting the stage for novel treatments for anxiety disorders and addictions.
Collapse
Affiliation(s)
- Gregory J Quirk
- Department of Psychiatry, University of Puerto Rico School of Medicine, San Juan, Puerto Rico.
| | | |
Collapse
|