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Giustino TF, Maren S. The Role of the Medial Prefrontal Cortex in the Conditioning and Extinction of Fear. Front Behav Neurosci 2015; 9:298. [PMID: 26617500 PMCID: PMC4637424 DOI: 10.3389/fnbeh.2015.00298] [Citation(s) in RCA: 348] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Accepted: 10/26/2015] [Indexed: 12/18/2022] Open
Abstract
Once acquired, a fearful memory can persist for a lifetime. Although learned fear can be extinguished, extinction memories are fragile. The resilience of fear memories to extinction may contribute to the maintenance of disorders of fear and anxiety, including post-traumatic stress disorder (PTSD). As such, considerable effort has been placed on understanding the neural circuitry underlying the acquisition, expression, and extinction of emotional memories in rodent models as well as in humans. A triad of brain regions, including the prefrontal cortex, hippocampus, and amygdala, form an essential brain circuit involved in fear conditioning and extinction. Within this circuit, the prefrontal cortex is thought to exert top-down control over subcortical structures to regulate appropriate behavioral responses. Importantly, a division of labor has been proposed in which the prelimbic (PL) and infralimbic (IL) subdivisions of the medial prefrontal cortex (mPFC) regulate the expression and suppression of fear in rodents, respectively. Here, we critically review the anatomical and physiological evidence that has led to this proposed dichotomy of function within mPFC. We propose that under some conditions, the PL and IL act in concert, exhibiting similar patterns of neural activity in response to aversive conditioned stimuli and during the expression or inhibition of conditioned fear. This may stem from common synaptic inputs, parallel downstream outputs, or cortico-cortical interactions. Despite this functional covariation, these mPFC subdivisions may still be coding for largely opposing behavioral outcomes, with PL biased towards fear expression and IL towards suppression.
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Affiliation(s)
- Thomas F Giustino
- Department of Psychology and Institute for Neuroscience, Texas A&M University College Station, TX, USA
| | - Stephen Maren
- Department of Psychology and Institute for Neuroscience, Texas A&M University College Station, TX, USA
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102
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Huang CC, Chou D, Yeh CM, Hsu KS. Acute food deprivation enhances fear extinction but inhibits long-term depression in the lateral amygdala via ghrelin signaling. Neuropharmacology 2015; 101:36-45. [PMID: 26384653 DOI: 10.1016/j.neuropharm.2015.09.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/11/2015] [Accepted: 09/14/2015] [Indexed: 10/23/2022]
Abstract
Fear memory-encoding thalamic input synapses to the lateral amygdala (T-LA) exhibit dynamic efficacy changes that are tightly correlated with fear memory strength. Previous studies have shown that auditory fear conditioning involves strengthening of synaptic strength, and conversely, fear extinction training leads to T-LA synaptic weakening and occlusion of long-term depression (LTD) induction. These findings suggest that the mechanisms governing LTD at T-LA synapses may determine the behavioral outcomes of extinction training. Here, we explored this hypothesis by implementing food deprivation (FD) stress in mice to determine its effects on fear extinction and LTD induction at T-LA synapses. We found that FD increased plasma acylated ghrelin levels and enhanced fear extinction and its retention. Augmentation of fear extinction by FD was blocked by pretreatment with growth hormone secretagogue receptor type-1a antagonist D-Lys(3)-GHRP-6, suggesting an involvement of ghrelin signaling. Confirming previous findings, two distinct forms of LTD coexist at thalamic inputs to LA pyramidal neurons that can be induced by low-frequency stimulation (LFS) or paired-pulse LFS (PP-LFS) paired with postsynaptic depolarization, respectively. Unexpectedly, we found that FD impaired the induction of PP-LFS- and group I metabotropic glutamate receptor agonist (S)-3,5-dihydroxyphenylglycine (DHPG)-induced LTD, but not LFS-induced LTD. Ghrelin mimicked the effects of FD to impair the induction of PP-LFS- and DHPG-induced LTD at T-LA synapses, which were blocked by co-application of D-Lys(3)-GHRP-6. The sensitivity of synaptic transmission to 1-naphthyl acetyl spermine was not altered by either FD or ghrelin treatment. These results highlight distinct features of fear extinction and LTD at T-LA synapses.
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Affiliation(s)
- Chiung-Chun Huang
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Dylan Chou
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Che-Ming Yeh
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Kuei-Sen Hsu
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
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103
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Exposure to extinction-associated contextual tone during slow-wave sleep and wakefulness differentially modulates fear expression. Neurobiol Learn Mem 2015; 123:159-67. [DOI: 10.1016/j.nlm.2015.06.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 05/16/2015] [Accepted: 06/03/2015] [Indexed: 12/15/2022]
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104
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Noradrenergic blockade stabilizes prefrontal activity and enables fear extinction under stress. Proc Natl Acad Sci U S A 2015; 112:E3729-37. [PMID: 26124100 DOI: 10.1073/pnas.1500682112] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Stress-induced impairments in extinction learning are believed to sustain posttraumatic stress disorder (PTSD). Noradrenergic signaling may contribute to extinction impairments by modulating medial prefrontal cortex (mPFC) circuits involved in fear regulation. Here we demonstrate that aversive fear conditioning rapidly and persistently alters spontaneous single-unit activity in the prelimbic and infralimbic subdivisions of the mPFC in behaving rats. These conditioning-induced changes in mPFC firing were mitigated by systemic administration of propranolol (10 mg/kg, i.p.), a β-noradrenergic receptor antagonist. Moreover, propranolol administration dampened the stress-induced impairment in extinction observed when extinction training is delivered shortly after fear conditioning. These findings suggest that β-adrenoceptors mediate stress-induced changes in mPFC spike firing that contribute to extinction impairments. Propranolol may be a helpful adjunct to behavioral therapy for PTSD, particularly in patients who have recently experienced trauma.
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105
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Pile V, Barnhofer T, Wild J. Updating versus Exposure to Prevent Consolidation of Conditioned Fear. PLoS One 2015; 10:e0122971. [PMID: 25902141 PMCID: PMC4406712 DOI: 10.1371/journal.pone.0122971] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 02/17/2015] [Indexed: 11/23/2022] Open
Abstract
Targeting the consolidation of fear memories following trauma may offer a promising method for preventing the development of flashbacks and other unwanted re-experiencing symptoms that characterise Posttraumatic Stress Disorder (PTSD). Research has demonstrated that performing visuo-spatial tasks after analogue trauma can block the consolidation of fear memory and reduce the frequency of flashbacks. However, no research has yet used verbal techniques to alter memories during the consolidation window. This is surprising given that the most effective treatments for PTSD are verbally-based with exposure therapy and trauma-focused cognitive behavioural therapy gaining the most evidence of efficacy. Psychological therapies aim to reduce the conditioned fear response, which is in keeping with the preliminary finding that an increased propensity for fear conditioning may be a vulnerability factor for PTSD. Our research had two aims. We investigated the degree to which individual differences in fear conditioning predict the development of PTSD symptoms. We also compared the preventative effects of two clinically informed psychological techniques administered during the consolidation window: exposure to the trauma memory and updating the meaning of the trauma. 115 healthy participants underwent a fear conditioning paradigm in which traumatic film stimuli (unconditioned stimuli) were paired with neutral stimuli (conditioned stimuli). Participants were randomly allocated to an updating, exposure or control group to compare the effects on the conditioned fear response and on PTSD symptomatology. The results showed that stronger conditioned responses at acquisition significantly predicted the development of PTSD symptoms. The updating group, who verbally devalued the unconditioned stimulus within the consolidation window, experienced significantly lower levels of PTSD symptoms during follow-up than the exposure and control groups. These findings are consistent with clinical interventions for chronic PTSD and have important implications for identifying those at risk as well as for designing novel early interventions to prevent the development of PTSD.
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Affiliation(s)
- Victoria Pile
- Department of Psychology, Institute of Psychiatry, King’s College London, London, United Kingdom
| | - Thorsten Barnhofer
- Department of Psychology, Institute of Psychiatry, King’s College London, London, United Kingdom
| | - Jennifer Wild
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
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106
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Goode TD, Kim JJ, Maren S. Relapse of extinguished fear after exposure to a dangerous context is mitigated by testing in a safe context. Learn Mem 2015; 22:170-8. [PMID: 25691517 PMCID: PMC4340132 DOI: 10.1101/lm.037028.114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 01/13/2015] [Indexed: 12/30/2022]
Abstract
Aversive events can trigger relapse of extinguished fear memories, presenting a major challenge to the long-term efficacy of therapeutic interventions. Here, we examined factors regulating the relapse of extinguished fear after exposure of rats to a dangerous context. Rats received unsignaled shock in a distinct context ("dangerous" context) 24 h prior to auditory fear conditioning in another context. Fear to the auditory conditioned stimulus (CS) was subsequently extinguished either in the conditioning context ("ambiguous" context) or in a third novel context ("safe" context). Exposure to the dangerous context 30 min before a CS retention test caused relapse to the CS in the ambiguous and safe test contexts relative to nonextinguished controls. When rats were tested 24 h later (with or without short-term testing), rats tested in the ambiguous context continued to exhibit relapse, whereas rats tested in the safe context did not. Additionally, exposure of rats to the conditioning context--in place of the unsignaled shock context--did not result in relapse of fear to the CS in the safe testing context. Our work highlights the vulnerabilities of extinction recall to interference, and demonstrates the importance of context associations in the relapse of fear after extinction.
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Affiliation(s)
- Travis D Goode
- Institute for Neuroscience, Texas A&M University, College Station, Texas 77843-3473, USA
| | - Janice J Kim
- Department of Psychology, Texas A&M University, College Station, Texas 77843-3473, USA
| | - Stephen Maren
- Institute for Neuroscience, Texas A&M University, College Station, Texas 77843-3473, USA Department of Psychology, Texas A&M University, College Station, Texas 77843-3473, USA
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107
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Kuhn M, Höger N, Feige B, Blechert J, Normann C, Nissen C. Fear extinction as a model for synaptic plasticity in major depressive disorder. PLoS One 2014; 9:e115280. [PMID: 25545818 PMCID: PMC4278908 DOI: 10.1371/journal.pone.0115280] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/23/2014] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The neuroplasticity hypothesis of major depressive disorder proposes that a dysfunction of synaptic plasticity represents a basic pathomechanism of the disorder. Animal models of depression indicate enhanced plasticity in a ventral emotional network, comprising the amygdala. Here, we investigated fear extinction learning as a non-invasive probe for amygdala-dependent synaptic plasticity in patients with major depressive disorder and healthy controls. METHODS Differential fear conditioning was measured in 37 inpatients with severe unipolar depression (International Classification of Diseases, 10th revision, criteria) and 40 healthy controls. The eye-blink startle response, a subcortical output signal that is modulated by local synaptic plasticity in the amygdala in fear acquisition and extinction learning, was recorded as the primary outcome parameter. RESULTS After robust and similar fear acquisition in both groups, patients with major depressive disorder showed significantly enhanced fear extinction learning in comparison to healthy controls, as indicated by startle responses to conditioned stimuli. The strength of extinction learning was positively correlated with the total illness duration. CONCLUSIONS The finding of enhanced fear extinction learning in major depressive disorder is consistent with the concept that the disorder is characterized by enhanced synaptic plasticity in the amygdala and the ventral emotional network. Clinically, the observation emphasizes the potential of successful extinction learning, the basis of exposure therapy, in anxiety-related disorders despite the frequent comorbidity of major depressive disorder.
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Affiliation(s)
- Marion Kuhn
- Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Freiburg, Germany
| | - Nora Höger
- Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Freiburg, Germany
| | - Bernd Feige
- Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Freiburg, Germany
| | - Jens Blechert
- Division of Clinical Psychology, Psychotherapy, and Health Psychology, Department of Psychology, University of Salzburg, Salzburg, Austria
| | - Claus Normann
- Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Freiburg, Germany
| | - Christoph Nissen
- Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Freiburg, Germany
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108
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Bernier BE, Lacagnina AF, Drew MR. Potent attenuation of context fear by extinction training contiguous with acquisition. ACTA ACUST UNITED AC 2014; 22:31-8. [PMID: 25512575 PMCID: PMC4274325 DOI: 10.1101/lm.036673.114] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Studies on the behavioral mechanisms underlying contextual fear conditioning (CFC) have demonstrated the importance of preshock context exposure in the formation of aversive context memories. However, there has been comparatively little investigation of the effects of context exposure immediately after the shock. Some models predict that nonreinforced context exposure at the end of the acquisition session will strongly influence the strength of conditioning and/or recruit distinct neural mechanisms relative to extinction after acquisition. Here we investigate the effects of manipulating postshock context exposure on CFC in mice. Prolonging the period of context exposure immediately following the shock caused a significant and durable reduction in conditioned fear. This immediate postshock context exposure was more effective at attenuating conditioned fear than was an equivalent amount of context exposure a day or more after acquisition. The results suggest that nonreinforced exposure to the context influences conditioned fear through distinct mechanisms depending on whether it occurs during acquisition or after it. The superiority of immediate postshock context exposure was specific to single-shock CFC; in two-shock CFC, immediate and delayed postshock context exposure had similar effects. Consistent with previous reports, we hypothesize that the effectiveness of extinction is modulated by emotional state, and procedures engendering higher postshock freezing (such as two-shock CFC) are associated with weaker immediate extinction.
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Affiliation(s)
- Brian E Bernier
- Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Anthony F Lacagnina
- Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Michael R Drew
- Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
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109
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Abstract
Unhealthy behavior is responsible for much human disease, and a common goal of contemporary preventive medicine is therefore to encourage behavior change. However, while behavior change often seems easy in the short run, it can be difficult to sustain. This article provides a selective review of research from the basic learning and behavior laboratory that provides some insight into why. The research suggests that methods used to create behavior change (including extinction, counterconditioning, punishment, reinforcement of alternative behavior, and abstinence reinforcement) tend to inhibit, rather than erase, the original behavior. Importantly, the inhibition, and thus behavior change more generally, is often specific to the "context" in which it is learned. In support of this view, the article discusses a number of lapse and relapse phenomena that occur after behavior has been changed (renewal, spontaneous recovery, reinstatement, rapid reacquisition, and resurgence). The findings suggest that changing a behavior can be an inherently unstable and unsteady process; frequent lapses should be expected. In the long run, behavior-change therapies might benefit from paying attention to the context in which behavior change occurs.
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110
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Cavallo JS, Hamilton BN, Farley J. In vitro extinction learning in Hermissenda: involvement of conditioned inhibition molecules. Front Behav Neurosci 2014; 8:354. [PMID: 25374517 PMCID: PMC4204529 DOI: 10.3389/fnbeh.2014.00354] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 09/23/2014] [Indexed: 11/30/2022] Open
Abstract
Extinction of a conditioned association is typically viewed as the establishment of new learning rather than the erasure of the original memory. However, recent research in the nudibranch, Hermissenda crassicornis (H.c.) demonstrated that extinction training (using repeated light-alone presentations) given 15 min, but not 23 h, after memory acquisition reversed both the cellular correlates of learning (enhanced Type B cell excitability) and the behavioral changes (reduced phototaxis) produced by associative conditioning (pairings of light, CS, and rotation, US). Here, we investigated the putative molecular signaling pathways that underlie this extinction in H.c. by using a novel in vitro protocol combined with pharmacological manipulations. After intact H.c. received either light-rotation pairings (Paired), random presentations of light and rotation (Random), or no stimulation (Untrained), B cells from isolated CNSs were recorded from during exposure to extinction training consisting of two series of 15 consecutive light-steps (LSs). When in vitro extinction was administered shortly (2 h, but not 24 h) after paired training, B cells from Paired animals showed progressive and robust declines in spike frequency by the 30th LS, while control cells (Random and Untrained) did not. We found that several molecules implicated in H.c. conditioned inhibitory (CI) learning, protein phosphatase 1 (PP1) and arachidonic acid (AA)/12-lipoxygenase (12-LOX) metabolites, also contributed to the spike frequency decreases produced by in vitro extinction. Protein phosphatase 2B (PP2B) also appeared to play a role. Calyculin A (PP1 inhibitor), cyclosporin A (PP2B inhibitor), and baicalein (a 12-LOX inhibitor) all blocked the spike frequency declines in Paired B cells produced by 30 LSs. Conversely, injection of catalytically-active PP1 (caPP1) or PP2B (caPP2B) into Untrained B cells partially mimicked the spike frequency declines observed in Paired cells, as did bath-applied AA, and occluded additional LS-produced reductions in spiking in Paired cells.
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Affiliation(s)
- Joel S Cavallo
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University Bloomington, IN, USA
| | - Brittany N Hamilton
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University Bloomington, IN, USA
| | - Joseph Farley
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University Bloomington, IN, USA
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111
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Mosig C, Merz CJ, Mohr C, Adolph D, Wolf OT, Schneider S, Margraf J, Zlomuzica A. Enhanced discriminative fear learning of phobia-irrelevant stimuli in spider-fearful individuals. Front Behav Neurosci 2014; 8:328. [PMID: 25324745 PMCID: PMC4181334 DOI: 10.3389/fnbeh.2014.00328] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/03/2014] [Indexed: 01/01/2023] Open
Abstract
Avoidance is considered as a central hallmark of all anxiety disorders. The acquisition and expression of avoidance, which leads to the maintenance and exacerbation of pathological fear is closely linked to Pavlovian and operant conditioning processes. Changes in conditionability might represent a key feature of all anxiety disorders but the exact nature of these alterations might vary across different disorders. To date, no information is available on specific changes in conditionability for disorder-irrelevant stimuli in specific phobia (SP). The first aim of this study was to investigate changes in fear acquisition and extinction in spider-fearful individuals as compared to non-fearful participants by using the de novo fear conditioning paradigm. Secondly, we aimed to determine whether differences in the magnitude of context-dependent fear retrieval exist between spider-fearful and non-fearful individuals. Our findings point to an enhanced fear discrimination in spider-fearful individuals as compared to non-fearful individuals at both the physiological and subjective level. The enhanced fear discrimination in spider-fearful individuals was neither mediated by increased state anxiety, depression, nor stress tension. Spider-fearful individuals displayed no changes in extinction learning and/or fear retrieval. Surprisingly, we found no evidence for context-dependent modulation of fear retrieval in either group. Here, we provide first evidence that spider-fearful individuals show an enhanced discriminative fear learning of phobia-irrelevant (de novo) stimuli. Our findings provide novel insights into the role of fear acquisition and expression for the development and maintenance of maladaptive responses in the course of SP.
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Affiliation(s)
- Carina Mosig
- Mental Health Research and Treatment Center, Ruhr-University Bochum , Bochum , Germany
| | - Christian J Merz
- Department of Cognitive Psychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum , Bochum , Germany
| | - Cornelia Mohr
- Mental Health Research and Treatment Center, Ruhr-University Bochum , Bochum , Germany
| | - Dirk Adolph
- Mental Health Research and Treatment Center, Ruhr-University Bochum , Bochum , Germany
| | - Oliver T Wolf
- Department of Cognitive Psychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum , Bochum , Germany
| | - Silvia Schneider
- Mental Health Research and Treatment Center, Ruhr-University Bochum , Bochum , Germany
| | - Jürgen Margraf
- Mental Health Research and Treatment Center, Ruhr-University Bochum , Bochum , Germany
| | - Armin Zlomuzica
- Mental Health Research and Treatment Center, Ruhr-University Bochum , Bochum , Germany
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112
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Haaker J, Golkar A, Hermans D, Lonsdorf TB. A review on human reinstatement studies: an overview and methodological challenges. Learn Mem 2014; 21:424-40. [PMID: 25128533 PMCID: PMC4138360 DOI: 10.1101/lm.036053.114] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 06/17/2014] [Indexed: 12/19/2022]
Abstract
In human research, studies of return of fear (ROF) phenomena, and reinstatement in particular, began only a decade ago and recently are more widely used, e.g., as outcome measures for fear/extinction memory manipulations (e.g., reconsolidation). As reinstatement research in humans is still in its infancy, providing an overview of its stability and boundary conditions and summarizing methodological challenges is timely to foster fruitful future research. As a translational endeavor, clarifying the circumstances under which (experimental) reinstatement occurs may offer a first step toward understanding relapse as a clinical phenomenon and pave the way for the development of new pharmacological or behavioral ways to prevent ROF. The current state of research does not yet allow pinpointing these circumstances in detail and we hope this review will aid the research field to advance in this direction. As an introduction, we begin with a synopsis of rodent work on reinstatement and theories that have been proposed to explain the findings. The review however mainly focuses on reinstatement in humans. We first describe details and variations of the experimental setup in reinstatement studies in humans and give a general overview of results. We continue with a compilation of possible experimental boundary conditions and end with the role of individual differences and behavioral and/or pharmacological manipulations. Furthermore, we compile important methodological and design details on the published studies in humans and end with open research questions and some important methodological and design recommendations as a guide for future research.
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Affiliation(s)
- Jan Haaker
- Institute for Systems Neuroscience, University Hospital Hamburg-Eppendorf, 20246 Hamburg, Germany Karolinska Institute, Department of Clinical Neuroscience, 171 77 Stockholm, Sweden
| | - Armita Golkar
- Karolinska Institute, Department of Clinical Neuroscience, 171 77 Stockholm, Sweden
| | - Dirk Hermans
- Faculty of Psychology and Educational Sciences, University of Leuven, 3000 Leuven, Belgium
| | - Tina B Lonsdorf
- Institute for Systems Neuroscience, University Hospital Hamburg-Eppendorf, 20246 Hamburg, Germany
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113
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Cavallo JS, Hamilton BN, Farley J. Behavioral and neural bases of extinction learning in Hermissenda. Front Behav Neurosci 2014; 8:277. [PMID: 25191236 PMCID: PMC4137458 DOI: 10.3389/fnbeh.2014.00277] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 07/29/2014] [Indexed: 11/13/2022] Open
Abstract
Extinction of classical conditioning is thought to produce new learning that masks or interferes with the original memory. However, research in the nudibranch Hermissenda crassicornis (H.c.) has challenged this view, and instead suggested that extinction erased the original associative memory. We have re-examined extinction in H.c. to test whether extinguished associative memories can be detected on the behavioral and cellular levels, and to characterize the temporal variables involved. Associative conditioning using pairings of light (CS) and rotation (US) produced characteristic suppression of H.c. phototactic behavior. A single session of extinction training (repeated light-alone presentations) reversed suppressed behavior back to pre-training levels when administered 15 min after associative conditioning. This effect was abolished if extinction was delayed by 23 h, and yet was recovered using extended extinction training (three consecutive daily extinction sessions). Extinguished phototactic suppression did not spontaneously recover at any retention interval (RI) tested (2-, 24-, 48-, 72-h), or after additional US presentations (no observed reinstatement). Extinction training (single session, 15 min interval) also reversed the pairing-produced increases in light-evoked spike frequencies of Type B photoreceptors, an identified site of associative memory storage that is causally related to phototactic suppression. These results suggest that the behavioral effects of extinction training are not due to temporary suppression of associative memories, but instead represent a reversal of the underlying cellular changes necessary for the expression of learning. In the companion article, we further elucidate mechanisms responsible for extinction-produced reversal of memory-related neural plasticity in Type B photoreceptors.
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Affiliation(s)
- Joel S Cavallo
- Program in Neuroscience, Indiana University Bloomington, IN, USA ; Department of Psychological and Brain Sciences, Indiana University Bloomington, IN, USA
| | - Brittany N Hamilton
- Program in Neuroscience, Indiana University Bloomington, IN, USA ; Department of Psychological and Brain Sciences, Indiana University Bloomington, IN, USA
| | - Joseph Farley
- Program in Neuroscience, Indiana University Bloomington, IN, USA ; Department of Psychological and Brain Sciences, Indiana University Bloomington, IN, USA
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114
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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.
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Affiliation(s)
- Olena Bukalo
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
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115
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McGuire JF, Lewin AB, Storch EA. Enhancing exposure therapy for anxiety disorders, obsessive-compulsive disorder and post-traumatic stress disorder. Expert Rev Neurother 2014; 14:893-910. [PMID: 24972729 DOI: 10.1586/14737175.2014.934677] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Translating findings from basic science, several compounds have been identified that may enhance therapeutic outcomes and/or expedite treatment gains when administered alongside exposure-based treatments. Four of these compounds (referred to as cognitive enhancers) have been evaluated in the context of randomized controlled trials for anxiety disorders (e.g., specific phobias, panic disorder, social anxiety disorder), obsessive-compulsive disorder and post-traumatic stress disorder. These cognitive enhancers include D-cycloserine, yohimbine hydrochloride, glucocorticoids and cortisol and brain-derived neurotrophic factor. There is consistent evidence that cognitive enhancers can enhance therapeutic outcomes and/or expedite treatment gains across anxiety disorders, obsessive-compulsive disorder and post-traumatic stress disorder. Emerging evidence has highlighted the importance of within-session fear habituation and between-session fear learning, which can either enhance fear extinction or reconsolidate of fear responses. Although findings from these trials are promising, there are several considerations that warrant further evaluation prior to widespread use of cognitive enhancers in exposure-based treatments. Consistent trial design and large sample sizes are important in future studies of cognitive enhancers.
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Affiliation(s)
- Joseph F McGuire
- Department of Psychology, University of South Florida, 4202 E. Fowler Avenue, PCD 4118G, Tampa, FL, USA
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Clark SM, Sand J, Francis TC, Nagaraju A, Michael KC, Keegan AD, Kusnecov A, Gould TD, Tonelli LH. Immune status influences fear and anxiety responses in mice after acute stress exposure. Brain Behav Immun 2014; 38:192-201. [PMID: 24524915 PMCID: PMC3989422 DOI: 10.1016/j.bbi.2014.02.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 01/27/2014] [Accepted: 02/01/2014] [Indexed: 12/15/2022] Open
Abstract
Significant evidence suggests that exposure to traumatic and/or acute stress in both mice and humans results in compromised immune function that in turn may affect associated brain processes. Additionally, recent studies in mouse models of immune deficiency have suggested that adaptive immunity may play a role during traumatic stress exposure and that impairments in lymphocyte function may contribute to increased susceptibility to various psychogenic stressors. However, rodent studies on the relationship between maladaptive stress responses and lymphocyte deficiency have been complicated by the fact that genetic manipulations in these models may also result in changes in CNS function due to the expression of targeted genes in tissues other than lymphocytes, including the brain. To address these issues we utilized mice with a deletion of recombination-activating gene 2 (Rag2), which has no confirmed expression in the CNS; thus, its loss should result in the absence of mature lymphocytes without altering CNS function directly. Stress responsiveness of immune deficient Rag2(-/-) mice on a BALB/c background was evaluated in three different paradigms: predator odor exposure (POE), fear conditioning (FC) and learned helplessness (LH). These models are often used to study different aspects of stress responsiveness after the exposure to an acute stressor. In addition, immunoblot analysis was used to assess hippocampal BDNF expression under both stressed and non-stressed conditions. Subsequent to POE, Rag2(-/-) mice exhibited a reduced acoustic startle response compared to BALB/c mice; no significant differences in behavior were observed in either FC or LH. Furthermore, analysis of hippocampal BDNF indicated that Rag2(-/-) mice have elevated levels of the mature form of BDNF compared to BALB/c mice. Results from our studies suggest that the absence of mature lymphocytes is associated with increased resilience to stress exposure in the POE and does not affect behavioral responses in the FC and LH paradigms. These findings indicate that lymphocytes play a specific role in stress responsiveness dependent upon the type, nature and intensity of the stressor.
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Affiliation(s)
- Sarah M Clark
- Laboratory of Behavioral Neuroimmunology, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, United States; Research and Development Service, Department of Veterans Affairs, VA Maryland Health Care System, Baltimore, MD, United States
| | - Joseph Sand
- Laboratory of Behavioral Neuroimmunology, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, United States
| | - T Chase Francis
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Anitha Nagaraju
- Laboratory of Behavioral Neuroimmunology, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Kerry C Michael
- Laboratory of Behavioral Neuroimmunology, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Achsah D Keegan
- Center for Vascular and Inflammatory Diseases, Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, United States; Research and Development Service, Department of Veterans Affairs, VA Maryland Health Care System, Baltimore, MD, United States
| | | | - Todd D Gould
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, United States; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, United States; Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, United States; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States; Research and Development Service, Department of Veterans Affairs, VA Maryland Health Care System, Baltimore, MD, United States
| | - Leonardo H Tonelli
- Laboratory of Behavioral Neuroimmunology, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, United States; Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, United States; Research and Development Service, Department of Veterans Affairs, VA Maryland Health Care System, Baltimore, MD, United States.
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Bulganin L, Bach DR, Wittmann BC. Prior fear conditioning and reward learning interact in fear and reward networks. Front Behav Neurosci 2014; 8:67. [PMID: 24624068 PMCID: PMC3940965 DOI: 10.3389/fnbeh.2014.00067] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 02/17/2014] [Indexed: 01/22/2023] Open
Abstract
The ability to flexibly adapt responses to changes in the environment is important for survival. Previous research in humans separately examined the mechanisms underlying acquisition and extinction of aversive and appetitive conditioned responses. It is yet unclear how aversive and appetitive learning interact on a neural level during counterconditioning in humans. This functional magnetic resonance imaging (fMRI) study investigated the interaction of fear conditioning and subsequent reward learning. In the first phase (fear acquisition), images predicted aversive electric shocks or no aversive outcome. In the second phase (counterconditioning), half of the CS+ and CS− were associated with monetary reward in the absence of electric stimulation. The third phase initiated reinstatement of fear through presentation of electric shocks, followed by CS presentation in the absence of shock or reward. Results indicate that participants were impaired at learning the reward contingencies for stimuli previously associated with shock. In the counterconditioning phase, prior fear association interacted with reward representation in the amygdala, where activation was decreased for rewarded compared to unrewarded CS− trials, while there was no reward-related difference in CS+ trials. In the reinstatement phase, an interaction of previous fear association and previous reward status was observed in a reward network consisting of substantia nigra/ventral tegmental area (SN/VTA), striatum and orbitofrontal cortex (OFC), where activation was increased by previous reward association only for CS− but not for CS+ trials. These findings suggest that during counterconditioning, prior fear conditioning interferes with reward learning, subsequently leading to lower activation of the reward network.
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Affiliation(s)
- Lisa Bulganin
- Department of Psychology and Sports Science, University of Giessen Giessen, Germany
| | - Dominik R Bach
- Psychiatric Hospital, University of Zurich Zurich, Switzerland ; Wellcome Trust Centre for Neuroimaging, University College London London, UK
| | - Bianca C Wittmann
- Department of Psychology and Sports Science, University of Giessen Giessen, Germany
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Delamater AR, Westbrook RF. Psychological and neural mechanisms of experimental extinction: a selective review. Neurobiol Learn Mem 2014; 108:38-51. [PMID: 24104049 PMCID: PMC3946186 DOI: 10.1016/j.nlm.2013.09.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 09/24/2013] [Accepted: 09/26/2013] [Indexed: 11/24/2022]
Abstract
The present review examines key psychological concepts in the study of experimental extinction and implications these have for an understanding of the underlying neurobiology of extinction learning. We suggest that many of the signature characteristics of extinction learning (spontaneous recovery, renewal, reinstatement, rapid reacquisition) can be accommodated by the standard associative learning theory assumption that extinction results in partial erasure of the original learning together with new inhibitory learning. Moreover, we consider recent behavioral and neural evidence that supports the partial erasure view of extinction, but also note shortcomings in our understanding of extinction circuits as these relate to the negative prediction error concept. Recent work suggests that common prediction error and stimulus-specific prediction error terms both may be required to explain neural plasticity both in acquisition and extinction learning. In addition, we suggest that many issues in the content of extinction learning have not been fully addressed in current research, but that neurobiological approaches should be especially helpful in addressing such issues. These include questions about the nature of extinction learning (excitatory CS-No US, inhibitory CS-US learning, occasion setting processes), especially as this relates to studies of the micro-circuitry of extinction, as well as its representational content (sensory, motivational, response). An additional understudied problem in extinction research is the role played by attention processes and their underlying neural networks, although some research and theory converge on the idea that extinction is accompanied by attention decrements (i.e., habituation-like processes).
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Affiliation(s)
- Andrew R Delamater
- Brooklyn College of the City University of New York, USA; University of New South Wales, Australia.
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119
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Abstract
Whereas fear memories are rapidly acquired and enduring over time, extinction memories are slow to form and are susceptible to disruption. Consequently, behavioral therapies that involve extinction learning (e.g., exposure therapy) often produce only temporary suppression of fear and anxiety. This review focuses on the factors that are known to influence the relapse of extinguished fear. Several phenomena associated with the return of fear after extinction are discussed, including renewal, spontaneous recovery, reacquisition, and reinstatement. Additionally, this review describes recent work, which has focused on the role of psychological stress in the relapse of extinguished fear. Recent developments in behavioral and pharmacological research are examined in light of treatment of pathological fear in humans.
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120
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Briscione MA, Jovanovic T, Norrholm SD. Conditioned fear associated phenotypes as robust, translational indices of trauma-, stressor-, and anxiety-related behaviors. Front Psychiatry 2014; 5:88. [PMID: 25101010 PMCID: PMC4104832 DOI: 10.3389/fpsyt.2014.00088] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 07/08/2014] [Indexed: 12/12/2022] Open
Abstract
Post-traumatic stress disorder (PTSD) is a heterogeneous disorder that affects individuals exposed to trauma (e.g., combat, interpersonal violence, and natural disasters). It is characterized by hyperarousal, intrusive reminders of the trauma, avoidance of trauma-related cues, and negative cognition and mood. This heterogeneity indicates the presence of multiple neurobiological mechanisms underlying the development and maintenance of PTSD. Fear conditioning is a robust, translational experimental paradigm that can be employed to elucidate these mechanisms by allowing for the study of fear-related dimensions of PTSD (e.g., fear extinction, fear inhibition, and generalization of fear) across multiple units of analysis. Fear conditioning experiments have identified varying trajectories of the dimensions described, highlighting exciting new avenues of targeted, focused study. Additionally, fear conditioning studies provide a translational platform to develop novel interventions. The current review highlights the versatility of fear conditioning paradigms, the implications for pharmacological and non-pharmacological treatments, the robustness of these paradigms to span an array of neuroscientific measures (e.g., genetic studies), and finally the need to understand the boundary conditions under which these paradigms are effective. Further understanding these paradigms will ultimately allow for optimization of fear conditioning paradigms, a necessary step towards the advancement of PTSD treatment methods.
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Affiliation(s)
- Maria Anne Briscione
- Trauma Recovery Program, Mental Health Service Line, Atlanta Veterans Affairs Medical Center , Decatur, GA , USA ; Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine , Atlanta, GA , USA
| | - Tanja Jovanovic
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine , Atlanta, GA , USA
| | - Seth Davin Norrholm
- Trauma Recovery Program, Mental Health Service Line, Atlanta Veterans Affairs Medical Center , Decatur, GA , USA ; Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine , Atlanta, GA , USA
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121
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Sijbrandij M, Engelhard IM, Lommen MJJ, Leer A, Baas JMP. Impaired fear inhibition learning predicts the persistence of symptoms of posttraumatic stress disorder (PTSD). J Psychiatr Res 2013; 47:1991-7. [PMID: 24090716 DOI: 10.1016/j.jpsychires.2013.09.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 07/18/2013] [Accepted: 09/13/2013] [Indexed: 10/26/2022]
Abstract
Recent cross-sectional studies have shown that the inability to suppress fear under safe conditions is a key problem in people with posttraumatic stress disorder (PTSD). The current longitudinal study examined whether individual differences in fear inhibition predict the persistence of PTSD symptoms. Approximately 2 months after deployment to Afghanistan, 144 trauma-exposed Dutch soldiers were administered a conditional discrimination task (AX+/BX-). In this paradigm, A, B, and X are neutral stimuli. X combined with A is paired with a shock (AX+ trials); X combined with B is not (BX- trials). Fear inhibition was measured (AB trials). Startle electromyogram responses and shock expectancy ratings were recorded. PTSD symptoms were measured at 2 months and at 9 months after deployment. Results showed that greater startle responses during AB trials in individuals who discriminated between danger (AX+) and safety (BX-) during conditioning, predicted higher PTSD symptoms at 2 months and 9 months post-deployment. The predictive effect at 9 months remained significant after controlling for critical incidents during previous deployments and PTSD symptoms at 2 months. Responses to AX+ or BX- trials, or discrimination learning (AX+ minus BX-) did not predict PTSD symptoms. It is concluded that impaired fear inhibition learning seems to be involved in the persistence of PTSD symptoms.
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Affiliation(s)
- Marit Sijbrandij
- Clinical and Health Psychology, Utrecht University, The Netherlands; Department of Clinical Psychology, VU University Amsterdam, The Netherlands; EMGO Institute for Health and Care Research, The Netherlands.
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Nature and causes of the immediate extinction deficit: a brief review. Neurobiol Learn Mem 2013; 113:19-24. [PMID: 24176924 DOI: 10.1016/j.nlm.2013.10.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 10/17/2013] [Accepted: 10/19/2013] [Indexed: 11/22/2022]
Abstract
Recent data in both rodents and humans suggests that the timing of extinction trials after conditioning influences the magnitude and duration of extinction. For example, administering extinction trials soon after Pavlovian fear conditioning in rats, mice, and humans results in minimal fear suppression - the so-called immediate extinction deficit. Here I review recent work examining the behavioral and neural substrates of the immediate extinction deficit. I suggest that extinction is most effective at some delay after conditioning, because brain systems involved in encoding and retrieving extinction memories function sub-optimally under stress.
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123
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Antov MI, Wölk C, Stockhorst U. Differential impact of the first and second wave of a stress response on subsequent fear conditioning in healthy men. Biol Psychol 2013; 94:456-68. [DOI: 10.1016/j.biopsycho.2013.08.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 08/24/2013] [Accepted: 08/26/2013] [Indexed: 01/21/2023]
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Jovanovic T, Nylocks KM, Gamwell KL. Translational neuroscience measures of fear conditioning across development: applications to high-risk children and adolescents. BIOLOGY OF MOOD & ANXIETY DISORDERS 2013; 3:17. [PMID: 24004567 PMCID: PMC3846696 DOI: 10.1186/2045-5380-3-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 06/25/2013] [Indexed: 12/05/2022]
Abstract
Several mental illnesses, including anxiety, can manifest during development, with onsets in late childhood. Understanding the neurobiological underpinnings of risk for anxiety is of crucial importance for early prevention and intervention approaches. Translational neuroscience offers tools to investigate such mechanisms in human and animal models. The current review describes paradigms derived from neuroscience, such as fear conditioning and extinction and overviews studies that have used these paradigms in animals and humans across development. The review also briefly discusses developmental trajectories of the relevant neural circuits and the emergence of clinical anxiety. Future studies should focus on developmental changes in these paradigms, paying close attention to neurobiological and hormonal changes associated with childhood and adolescence.
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Affiliation(s)
- Tanja Jovanovic
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 49 Jesse Hill Jr Dr, Suite 331, Atlanta, GA 30303, USA
| | - Karin Maria Nylocks
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 49 Jesse Hill Jr Dr, Suite 331, Atlanta, GA 30303, USA
| | - Kaitlyn L Gamwell
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, 49 Jesse Hill Jr Dr, Suite 331, Atlanta, GA 30303, USA
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Abstract
Research has identified distinct neuronal circuits within the basolateral amygdala (BLA) that differentially mediate fear expression versus inhibition; however, molecular markers of these populations remain unknown. Here we examine whether optogenetic activation of a cellular subpopulation, which may correlate with the physiologically identified extinction neurons in the BLA, would differentially support fear conditioning versus fear inhibition/extinction. We first molecularly characterized Thy1-channelrhodopsin-2 (Thy1-ChR2-EYFP)-expressing neurons as a subpopulation of glutamatergic pyramidal neurons within the BLA. Optogenetic stimulation of these neurons inhibited a subpopulation of medial central amygdala neurons and shunted excitation from the lateral amygdala. Brief activation of these neurons during fear training disrupted later fear memory in male mice. Optogenetic activation during unreinforced stimulus exposure enhanced extinction retention, but had no effect on fear expression, locomotion, or open-field behavior. Together, these data suggest that the Thy1-expressing subpopulation of BLA pyramidal neurons provide an important molecular and pharmacological target for inhibiting fear and enhancing extinction and for furthering our understanding of the molecular mechanisms of fear processing.
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126
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Initiation, labile, and stabilization phases of experience-dependent plasticity at neocortical synapses. J Neurosci 2013; 33:8483-93. [PMID: 23658185 DOI: 10.1523/jneurosci.3575-12.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alteration of sensory input can change the strength of neocortical synapses. Selective activation of a subset of whiskers is sufficient to potentiate layer 4-layer 2/3 excitatory synapses in the mouse somatosensory (barrel) cortex, a process that is NMDAR dependent. By analyzing the time course of sensory-induced synaptic change, we have identified three distinct phases for synaptic strengthening in vivo. After an early, NMDAR-dependent phase where selective whisker activation is rapidly translated into increased synaptic strength, we identify a second phase where this potentiation is profoundly reduced by an input-specific, NMDAR-dependent depression. This labile phase is transient, lasting only a few hours, and may require ongoing sensory input for synaptic weakening. Residual synaptic strength is maintained in a third phase, the stabilization phase, which requires mGluR5 signaling. Identification of these three phases will facilitate a molecular dissection of the pathways that regulate synaptic lability and stabilization, and suggest potential approaches to modulate learning.
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Zusman M. Associative memory for movement-evoked chronic back pain and its extinction with musculoskeletal physiotherapy. PHYSICAL THERAPY REVIEWS 2013. [DOI: 10.1179/174328808x251948] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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128
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MacPherson K, Whittle N, Camp M, Gunduz-Cinar O, Singewald N, Holmes A. Temporal factors in the extinction of fear in inbred mouse strains differing in extinction efficacy. BIOLOGY OF MOOD & ANXIETY DISORDERS 2013; 3:13. [PMID: 23830244 PMCID: PMC3726460 DOI: 10.1186/2045-5380-3-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Accepted: 05/23/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND Various neuropsychiatric conditions, including posttraumatic stress disorder (PTSD), are characterized by deficient fear extinction, but individuals differ greatly in risk for these. While there is growing evidence that fear extinction is influenced by certain procedural variables, it is unclear how these influences might vary across individuals and subpopulations. To model individual differences in fear extinction, prior studies identified a strain of inbred mouse, 129S1/SvImJ (S1), which exhibits a profound deficit in fear extinction, as compared to other inbred strains, such as C57BL/6J (B6). METHODS Here, we assessed the effects of procedural variables on the impaired extinction phenotype of the S1 strain and, by comparison, the extinction-intact B6 strain. The variables studied were 1) the interval between conditioning and extinction, 2) the interval between cues during extinction training, 3) single-cue exposure before extinction training, and 4) extinction of a second-order conditioned cue. RESULTS Conducting extinction training soon after ('immediately') conditioning attenuated fear retrieval in S1 mice and impaired extinction in B6 mice. Spacing cue presentations with long inter-trial intervals during extinction training augmented fear in S1 and B6 mice. The effect of spacing was lost with one-trial fear conditioning in B6, but not S1 mice. A single exposure to a conditioned cue before extinction training did not alter extinction retrieval, either in B6 or S1 mice. Both the S1 and B6 strains exhibited robust second-order fear conditioning, in which a cue associated with footshock was sufficient to serve as a conditioned exciter to condition a fear association to a second cue. B6 mice extinguished the fear response to the second-order conditioned cue, but S1 mice failed to do so. CONCLUSIONS These data provide further evidence that fear extinction is strongly influenced by multiple procedural variables and is so in a highly strain-dependent manner. This suggests that the efficacy of extinction-based behavioral interventions, such as exposure therapy, for trauma-related anxiety disorders will be determined by the procedural parameters employed and the degree to which the patient can extinguish.
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Affiliation(s)
- Kathryn MacPherson
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - Nigel Whittle
- Department of Pharmacology & Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innsbruck, Austria
| | - Marguerite Camp
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - Ozge Gunduz-Cinar
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - Nicolas Singewald
- Department of Pharmacology & Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innsbruck, Austria
| | - Andrew Holmes
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
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Admon R, Milad MR, Hendler T. A causal model of post-traumatic stress disorder: disentangling predisposed from acquired neural abnormalities. Trends Cogn Sci 2013; 17:337-47. [PMID: 23768722 DOI: 10.1016/j.tics.2013.05.005] [Citation(s) in RCA: 189] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/06/2013] [Accepted: 05/08/2013] [Indexed: 12/11/2022]
Abstract
Discriminating neural abnormalities into the causes versus consequences of psychopathology would enhance the translation of neuroimaging findings into clinical practice. By regarding the traumatic encounter as a reference point for disease onset, neuroimaging studies of post-traumatic stress disorder (PTSD) can potentially allocate PTSD neural abnormalities to either predisposing (pre-exposure) or acquired (post-exposure) factors. Based on novel research strategies in PTSD neuroimaging, including genetic, environmental, twin, and prospective studies, we provide a causal model that accounts for neural abnormalities in PTSD, and outline its clinical implications. Current data suggest that abnormalities within the amygdala and dorsal anterior cingulate cortex represent predisposing risk factors for developing PTSD, whereas dysfunctional hippocampal-ventromedial prefrontal cortex (vmPFC) interactions may become evident only after having developed the disorder.
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Affiliation(s)
- Roee Admon
- Center for Depression, Anxiety and Stress Research, McLean Hospital, Harvard Medical School, Boston, MA, USA.
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130
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Hofmann SG, Asmundson GJG, Beck AT. The science of cognitive therapy. Behav Ther 2013; 44:199-212. [PMID: 23611069 DOI: 10.1016/j.beth.2009.01.007] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 01/13/2009] [Accepted: 01/29/2009] [Indexed: 01/11/2023]
Abstract
Cognitive therapy (CT) refers to a family of interventions and a general scientific approach to psychological disorders. This family has evolved from a specific treatment model into a scientific approach that incorporates a wide variety of disorder-specific interventions and treatment techniques. The goal of this article is to describe the scientific approach of CT, review the efficacy and validity of the CT model, and exemplify important differences and commonalities of the CT approaches based on two specific disorders, posttraumatic stress disorder and health anxiety.
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Affiliation(s)
- Stefan G Hofmann
- Department of Psychology, Boston University, 648 Beacon Street, 6th Floor, Boston, MA 02215–2002, USA.
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Lissek S, Glaubitz B, Uengoer M, Tegenthoff M. Hippocampal activation during extinction learning predicts occurrence of the renewal effect in extinction recall. Neuroimage 2013; 81:131-143. [PMID: 23684875 DOI: 10.1016/j.neuroimage.2013.05.025] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 04/29/2013] [Accepted: 05/04/2013] [Indexed: 10/26/2022] Open
Abstract
The renewal effect describes the reoccurrence of a previously extinguished response in situations where the context of extinction differs from that of acquisition, thus illustrating the context-dependency of extinction learning. A number of studies on contextual fear extinction have implicated hippocampus and vmPFC in processing and retrieval of context both during extinction learning and recall of extinction. In this functional magnetic resonance imaging (fMRI) study we explored the neural correlates of the renewal effect in associative learning, using a predictive learning task that required participants to learn relations between cues and outcomes presented in particular contexts. During extinction in a novel context, compared to extinction in a context identical to the acquisition context, participants who exhibited the renewal effect (REN) showed increased activation in brain regions including bilateral posterior hippocampus and left parahippocampal gyrus. This activation pattern was absent in participants that did not show the renewal effect (NOREN). In direct comparisons between the groups, the REN group exhibited higher activation in bilateral hippocampus, while the NOREN group showed higher activation in left dlPFC (BA 46) and right anterior cingulate (BA 32). During extinction recall, stimuli that had been extinguished in a different context were again presented in the context of acquisition. Here both groups exhibited predominantly prefrontal activation, with the REN group's focus upon bilateral OFC (BA 47) and bilateral vmPFC (BA 10), while the NOREN group showed generally more widespread activation, predominantly in large clusters of dlPFC (BA 8,9,45). In a direct comparison, the REN group showed higher activation than the NOREN group in left vmPFC (BA 10), while NOREN participants exhibited more activation in dlPFC (BA 9, 46). Activation in left vmPFC during extinction recall correlated with the number of renewal effect responses, while the dlPFC activation showed a negative correlation with renewal effect responses. These results highlight the differential activation patterns of processes that will eventually produce or not produce a renewal effect, indicating that during extinction learning hippocampus encodes the relation between context and cue-outcome, while in extinction recall vmPFC is active to retrieve this association.
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Affiliation(s)
- Silke Lissek
- Department of Neurology, BG University Hospital Bergmannsheil, Ruhr-Universitaet Bochum, Bochum, Germany.
| | - Benjamin Glaubitz
- Department of Neurology, BG University Hospital Bergmannsheil, Ruhr-Universitaet Bochum, Bochum, Germany
| | - Metin Uengoer
- Faculty of Psychology, Philipps-Universitaet Marburg, Marburg, Germany
| | - Martin Tegenthoff
- Department of Neurology, BG University Hospital Bergmannsheil, Ruhr-Universitaet Bochum, Bochum, Germany
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132
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Powell EJ, Escobar M, Kimble W. Delaying interference training has equivalent effects in various Pavlovian interference paradigms. Learn Mem 2013; 20:241-4. [PMID: 23589090 DOI: 10.1101/lm.030650.113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Spontaneous recovery in extinction appears to be inversely related to the acquisition-to-extinction interval, but it remains unclear why this is the case. Rat subjects trained with one of three interference paradigms exhibited less spontaneous recovery of the original response after delayed than immediate interference, regardless of whether interference resulted in attenuated fear (extinction, CS-Shock followed by CS-noShock), acquisition of conditioned fear (latent inhibition, CS-noShock followed by CS-Shock), or acquisition of a response (counterconditioning, CS-Shock followed by CS-Sucrose). We suggest that delaying interference treatment increases the relative similarity of the interference and test contexts, facilitating retrieval of the interfering association and attenuating recovery of the original response.
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Affiliation(s)
- Elizabeth J Powell
- Department of Psychology, Auburn University, Auburn, Alabama 36849-5214, USA
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133
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Affiliation(s)
- Bram Vervliet
- Department of Psychology, University of Leuven, Leuven 3000, Belgium; ,
| | - Michelle G. Craske
- Department of Psychology, University of California, Los Angeles, California 90095-1563;
| | - Dirk Hermans
- Department of Psychology, University of Leuven, Leuven 3000, Belgium; ,
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134
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Stafford JM, Maughan DK, Ilioi EC, Lattal KM. Exposure to a fearful context during periods of memory plasticity impairs extinction via hyperactivation of frontal-amygdalar circuits. Learn Mem 2013; 20:156-63. [PMID: 23422280 PMCID: PMC3578276 DOI: 10.1101/lm.029801.112] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 12/20/2012] [Indexed: 11/25/2022]
Abstract
An issue of increasing theoretical and translational importance is to understand the conditions under which learned fear can be suppressed, or even eliminated. Basic research has pointed to extinction, in which an organism is exposed to a fearful stimulus (such as a context) in the absence of an expected aversive outcome (such as a shock). This extinction process results in the suppression of fear responses, but is generally thought to leave the original fearful memory intact. Here, we investigate the effects of extinction during periods of memory lability on behavioral responses and on expression of the immediate-early gene c-Fos within fear conditioning and extinction circuits. Our results show that long-term extinction is impaired when it occurs during time periods during which the memory should be most vulnerable to disruption (soon after conditioning or retrieval). These behavioral effects are correlated with hyperactivation of medial prefrontal cortex and amygdala subregions associated with fear expression rather than fear extinction. These findings demonstrate that behavioral experiences during periods of heightened fear prevent extinction and prolong the conditioned fear response.
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Affiliation(s)
| | | | | | - K. Matthew Lattal
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97239-3098, USA
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135
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Zelikowsky M, Hast TA, Bennett RZ, Merjanian M, Nocera NA, Ponnusamy R, Fanselow MS. Cholinergic blockade frees fear extinction from its contextual dependency. Biol Psychiatry 2013; 73:345-52. [PMID: 22981655 PMCID: PMC3525775 DOI: 10.1016/j.biopsych.2012.08.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 07/12/2012] [Accepted: 08/07/2012] [Indexed: 11/17/2022]
Abstract
BACKGROUND Fears that are maladaptive or inappropriate can be reduced through extinction training. However, extinction is highly context-sensitive, resulting in the renewal of fear after shifts in context and limiting the clinical efficacy of extinction training. Lesion and inactivation studies have shown that the contextualization of extinction depends on the hippocampus. Parallel studies have found that intrahippocampal scopolamine (Scop) blocks contextual fear conditioning. Importantly, this effect was replicated with a noninvasive technique in which a low dose of Scop was administered systemically. We aimed to transfer the effects of this noninvasive approach to block the contextualization of fear extinction. METHODS Rats were tone fear conditioned and extinguished under various systemic doses of Scop or the saline vehicle. They were subsequently tested (off drug) for tone fear in a context that was the same (control subjects) or shifted (renewal group) with respect to the extinction context. RESULTS The lowest dose of Scop produced a significant attenuation of fear renewal when renewal was tested either in the original training context or a novel context. The drug also slowed the rate of long-term extinction memory formation, which was readily overcome by extending extinction training. Scopolamine only gave this effect when it was administered during but not after extinction training. Higher doses of Scop severely disrupted extinction learning. CONCLUSIONS We discovered that disrupting contextual processing during extinction with the cholinergic antagonist Scop blocked subsequent fear renewal. Low doses of Scop might be a clinically promising adjunct to exposure therapy by making extinction more relapse-resistant.
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Affiliation(s)
- Moriel Zelikowsky
- Departments of Psychology and Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA 90095, USA
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136
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Parsons RG, Ressler KJ. Implications of memory modulation for post-traumatic stress and fear disorders. Nat Neurosci 2013; 16:146-53. [PMID: 23354388 DOI: 10.1038/nn.3296] [Citation(s) in RCA: 310] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 12/03/2012] [Indexed: 02/07/2023]
Abstract
Post-traumatic stress disorder, panic disorder and phobia manifest in ways that are consistent with an uncontrollable state of fear. Their development involves heredity, previous sensitizing experiences, association of aversive events with previous neutral stimuli, and inability to inhibit or extinguish fear after it is chronic and disabling. We highlight recent progress in fear learning and memory, differential susceptibility to disorders of fear, and how these findings are being applied to the understanding, treatment and possible prevention of fear disorders. Promising advances are being translated from basic science to the clinic, including approaches to distinguish risk versus resilience before trauma exposure, methods to interfere with fear development during memory consolidation after a trauma, and techniques to inhibit fear reconsolidation and to enhance extinction of chronic fear. It is hoped that this new knowledge will translate to more successful, neuroscientifically informed and rationally designed approaches to disorders of fear regulation.
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Affiliation(s)
- Ryan G Parsons
- Department of Psychiatry and Behavioral Sciences, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA
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137
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Early intervention may prevent the development of posttraumatic stress disorder: a randomized pilot civilian study with modified prolonged exposure. Biol Psychiatry 2012; 72:957-63. [PMID: 22766415 PMCID: PMC3467345 DOI: 10.1016/j.biopsych.2012.06.002] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/01/2012] [Accepted: 06/05/2012] [Indexed: 12/14/2022]
Abstract
BACKGROUND Posttraumatic stress disorder (PTSD) is a major public health concern with long-term sequelae. There are no accepted interventions delivered in the immediate aftermath of trauma. This study tested an early intervention aimed at modifying the memory to prevent the development of PTSD before memory consolidation. METHODS Patients (n = 137) were randomly assigned to receive three sessions of an early intervention beginning in the emergency department compared with an assessment only control group. Posttraumatic stress reactions (PTSR) were assessed at 4 and 12 weeks postinjury and depression at baseline and week 4. The intervention consisted of modified prolonged exposure including imaginal exposure to the trauma memory, processing of traumatic material, and in vivo and imaginal exposure homework. RESULTS Patients were assessed an average of 11.79 hours posttrauma. Intervention participants reported significantly lower PTSR than the assessment group at 4 weeks postinjury, p < .01, and at 12 weeks postinjury, p < .05, and significantly lower depressive symptoms at week 4 than the assessment group, p < .05. In a subgroup analysis, the intervention was the most effective at reducing PTSD in rape victims at week 4 (p = .004) and week 12 (p = .05). CONCLUSIONS These findings suggest that the modified prolonged exposure intervention initiated within hours of the trauma in the emergency department is successful at reducing PTSR and depression symptoms 1 and 3 months after trauma exposure and is safe and feasible. This is the first behavioral intervention delivered immediately posttrauma that has been shown to be effective at reducing PTSR.
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138
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An B, Hong I, Choi S. Long-term neural correlates of reversible fear learning in the lateral amygdala. J Neurosci 2012; 32:16845-56. [PMID: 23175837 PMCID: PMC6621751 DOI: 10.1523/jneurosci.3017-12.2012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 08/31/2012] [Accepted: 09/24/2012] [Indexed: 11/21/2022] Open
Abstract
Fear conditioning and extinction are behavioral models that reflect the association and dissociation of environmental cues to aversive outcomes, both known to involve the lateral amygdala (LA). Accordingly, responses of LA neurons to conditioned stimuli (CS) increase after fear conditioning and decrease partially during extinction. However, the long-term effects of repeated fear conditioning and extinction on LA neuronal firing have not been explored. Here we show, using stable, high signal-to-noise ratio single-unit recordings, that the ensemble activity of all recorded LA neurons correlates tightly with conditioned fear responses of rats in a conditioning/extinction/reconditioning paradigm spanning 3 d. This CS-evoked ensemble activity increased after conditioning, decreased after extinction, and was repotentiated after reconditioning. Cell-by-cell analysis revealed that among the LA neurons that displayed potentiated responses after initial fear conditioning, some exhibited weakened CS responses after extinction (extinction-susceptible), whereas others remained potentiated (extinction-resistant). The majority of extinction-susceptible neurons exhibited strong potentiation after reconditioning, suggesting that this distinct subpopulation (reversible fear neurons) encodes updated CS-unconditioned stimulus (US) association strength. Interestingly, these reversible fear neurons displayed larger, more rapid potentiation during reconditioning compared with the initial conditioning, providing a neural correlate of savings after extinction. In contrast, the extinction-resistant fear neurons did not show further increases after reconditioning, suggesting that this subpopulation encodes persistent fear memory representing the original CS-US association. This longitudinal report on LA neuronal activity during reversible fear learning suggests the existence of distinct populations encoding various facets of fear memory and provides insight into the neuronal mechanisms of fear memory modulation.
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Affiliation(s)
- Bobae An
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Ingie Hong
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-742, Republic of Korea
| | - Sukwoo Choi
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-742, Republic of Korea
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139
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Abstract
Enhanced fear learning occurs subsequent to traumatic or stressful events and is a persistent challenge to the treatment of post-traumatic stress disorder (PTSD). Facilitation of learning produced by prior stress can elicit an exaggerated fear response to a minimally aversive event or stimulus. Stress-enhanced fear learning (SEFL) is a rat model of PTSD; rats previously exposed to the SEFL 15 electrical shocks procedure exhibit several behavioral responses similar to those seen in patients with PTSD. However, past reports found that SEFL is not mitigated by extinction (a model of exposure therapy) when the spaced extinction began 24 h after stress. Recent studies found that extinction from 10 min to 1 h subsequent to fear conditioning "erased" learning, whereas later extinction, occurring from 24 to 72 h after conditioning did not. Other studies indicate that massed extinction is more effective than spaced procedures. Therefore, we examined the time-dependent nature of extinction on the stress-induced enhancement of fear learning using a massed trial's procedure. Experimental rats received 15 foot shocks and were given either no extinction or massed extinction 10 min or 72 h later. Our present data indicate that SEFL, following traumatic stress, is resistant to immediate massed extinction. Experimental rats showed exaggerated new fear learning regardless of when extinction training occurred. Thus, post-traumatic reactivity such as SEFL does not seem responsive to extinction treatments.
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Affiliation(s)
- Virginia A Long
- Ernest Gall Clinic and Research Center, University of California San Francisco, Emeryville, CA 94608, USA.
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140
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Kearns MC, Ressler KJ, Zatzick D, Rothbaum BO. Early interventions for PTSD: a review. Depress Anxiety 2012; 29:833-42. [PMID: 22941845 PMCID: PMC3665083 DOI: 10.1002/da.21997] [Citation(s) in RCA: 177] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 06/05/2012] [Accepted: 08/03/2012] [Indexed: 11/10/2022] Open
Abstract
The high prevalence of trauma exposure and subsequent negative consequences for both survivors and society as a whole emphasize the need for secondary prevention of posttraumatic stress disorder. However, clinicians and relief workers remain limited in their ability to intervene effectively in the aftermath of trauma and alleviate traumatic stress reactions that can lead to chronic PTSD. The scientific literature on early intervention for PTSD is reviewed, including early studies on psychological debriefing, pharmacological, and psychosocial interventions aimed at preventing chronic PTSD. Studies on fear extinction and memory consolidation are discussed in relation to PTSD prevention and the potential importance of immediate versus delayed intervention approaches and genetic predictors are briefly reviewed. Preliminary results from a modified prolonged exposure intervention applied within hours of trauma exposure in an emergency room setting are discussed, along with considerations related to intervention reach and overall population impact. Suggestions for future research are included. Prevention of PTSD, although currently not yet a reality, remains an exciting and hopeful possibility with current research approaches translating work from the laboratory to the clinic.
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Affiliation(s)
| | | | - Doug Zatzick
- University of Washington School of Medicine, Seattle, Washington
| | - Barbara Olasov Rothbaum
- Emory University School of Medicine, Atlanta, Georgia,Correspondence to: Barbara Olasov Rothbaum, Ph.D., A.B.P.P., Emory University School of Medicine, 1256 Briarcliff Road, Atlanta, GA 30306.
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141
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Huang ACW, Shyu BC, Hsiao S, Chen TC, He ABH. Neural substrates of fear conditioning, extinction, and spontaneous recovery in passive avoidance learning: a c-fos study in rats. Behav Brain Res 2012; 237:23-31. [PMID: 23018123 DOI: 10.1016/j.bbr.2012.09.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/10/2012] [Accepted: 09/14/2012] [Indexed: 10/27/2022]
Abstract
Extinguishing fear conditioning and preventing the return of fear are the goal in the treatment of anxiety disorders. However, the neural substrates that mediate fear conditioning, extinction, and spontaneous recovery (i.e., the return of fear) remain uncertain. We utilized the aversive passive avoidance learning paradigm and Fos-like immunoreactivity to elucidate this issue. Exception for naïve rats that did not receive any treatment served as the control group, the other rats were subjected to three sessions of context/footshock (0.5 mA, 2s) pairings followed by 12 extinction sessions (context-no footshock). After the last extinction test, these rats were assigned to one of three groups reflecting the number of resting days before the test session (context-no footshock): Day 8, Day 9, and Day 10 groups. Only the Day 10 group exhibited spontaneous recovery during the test session. Fos-like immunoreactivity associated with fear conditioning was seen in the amygdala and cingulate cortex area 1 (Cg1). The extinction of fear was seen to be related to Cg1, cingulate cortex area 2 (Cg2), piriform cortex (Pir), and entorhinal cortex (Ect). Spontaneous recovery was seen to be related to amygdala, Pir, and Ect. The present findings indicate that the brain substrates of fear acquisition, extinction and spontaneous recovery have different ensembles of brain activations. These differences suggest that different brain targets may be considered for fear extinction and for avoiding the return of fear in anxiety disorders.
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142
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Low-frequency stimulation depresses the primate anterior-cingulate-cortex and prevents spontaneous recovery of aversive memories. J Neurosci 2012; 32:8589-97. [PMID: 22723700 DOI: 10.1523/jneurosci.6481-11.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Functional abnormalities in the dorsal-anterior-cingulate-cortex (dACC) underlie anxiety disorders and specifically post-traumatic stress disorder (PTSD). Promising and common behavioral approaches have limited effectiveness and many subjects exhibit spontaneous recovery of fear, as also evident in animal models following extinction training. Here, we use low-frequency stimulation (LFS), a protocol shown to induce long-term depression, with the aim of affecting synaptic plasticity induced by fear acquisition and extinction. We use aversive conditioning of either tone or visual stimuli paired with an aversive air-puff to the eye in a trace-conditioning paradigm. We find that LFS in the nonhuman primate (Macaca fascicularis) dACC, when combined with extinction training, was successful in preventing spontaneous recovery of the memory 24-72 h following extinction. We simultaneously record single-units and local-field-potentials across the dACC, and show that LFS gradually depressed evoked responses. Moreover, this decrease in neural excitability predicted the successful reduction of overnight spontaneous recovery on a day-by-day basis. Finally, we show that this effect occurs when using either visual or auditory modality as the conditioned stimulus, and that the reduction was specific to the conditioned modality. Our results suggest that the primate dACC is actively involved in maintaining the original aversive memory, and propose that a combination of LFS with behavioral therapy might significantly improve treatment in severe cases.
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143
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Gisquet-Verrier P, Riccio DC. Memory reactivation effects independent of reconsolidation. Learn Mem 2012; 19:401-9. [PMID: 22904371 DOI: 10.1101/lm.026054.112] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Memory reactivation is an important process resulting from reexposure to salient training-related information whereby a memory is brought from an inactive to an active state. Reactivation is the first stage of memory retrieval but can result from the exposure to salient cues without any behavioral output. Such cue-induced reactivation, although frequently used by neuroscientists to study reconsolidation, has seldom been considered as a process in its own right and studied as such. This review presents arguments indicating that memory reactivation has two main consequences: (1) to enhance the accessibility of the target memory and (2) to make the memory malleable. Accordingly, reactivation creates a transient state during which the content of the memory is easily accessible and can be modified and/or updated. As both of these aspects can be observed shortly after memory reactivation, this review emphasizes that reconsolidation is not necessarily required for these processes and calls attention to reactivation as a factor in the dynamics of the memory.
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144
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Gao Z, van Beugen BJ, De Zeeuw CI. Distributed synergistic plasticity and cerebellar learning. Nat Rev Neurosci 2012; 13:619-35. [PMID: 22895474 DOI: 10.1038/nrn3312] [Citation(s) in RCA: 352] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Studies on synaptic plasticity in the context of learning have been dominated by the view that a single, particular type of plasticity forms the underlying mechanism for a particular type of learning. However, emerging evidence shows that many forms of synaptic and intrinsic plasticity at different sites are induced conjunctively during procedural memory formation in the cerebellum. Here, we review the main forms of long-term plasticity in the cerebellar cortex that underlie motor learning. We propose that the different forms of plasticity in the granular layer and the molecular layer operate synergistically in a temporally and spatially distributed manner, so as to ultimately create optimal output for behaviour.
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Affiliation(s)
- Zhenyu Gao
- Department of Neuroscience, Erasmus Medical Center, 3000 DR Rotterdam, The Netherlands
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145
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Golkar A, Öhman A. Fear extinction in humans: effects of acquisition-extinction delay and masked stimulus presentations. Biol Psychol 2012; 91:292-301. [PMID: 22898744 DOI: 10.1016/j.biopsycho.2012.07.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 07/27/2012] [Accepted: 07/29/2012] [Indexed: 10/28/2022]
Abstract
Fear extinction can be viewed as an inhibitory learning process. This is supported by post-extinction phenomena demonstrating the return of fear, such as reinstatement. Recent work has questioned this account, claiming that extinction initiated immediately after fear acquisition can abolish the return of fear. In the current study, participants were fear conditioned to four different conditioned stimuli (CS) and underwent extinction either immediately or after a 24 h delay. During extinction, we manipulated CS contingency awareness by presenting two of the CSs (one CS+, one CS-) under non-masked conditions and the other two CSs under masked conditions. Compared to delayed extinction, immediate extinction of non-masked CSs promoted less extinction of fear-potentiated startle and shock expectancy ratings and less reinstatement of fear-potentiated startle without affecting shock expectancy ratings. Critically, future research should clarify how the differences between immediate and delayed extinction in within-session extinction modulate the recovery of fear.
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Affiliation(s)
- Armita Golkar
- Karolinska Institutet, Department of Clinical Neuroscience, Psychology Section, 17177 Stockholm, Sweden.
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146
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Orsini CA, Maren S. Neural and cellular mechanisms of fear and extinction memory formation. Neurosci Biobehav Rev 2012; 36:1773-802. [PMID: 22230704 PMCID: PMC3345303 DOI: 10.1016/j.neubiorev.2011.12.014] [Citation(s) in RCA: 321] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Revised: 12/16/2011] [Accepted: 12/23/2011] [Indexed: 02/08/2023]
Abstract
Over the course of natural history, countless animal species have evolved adaptive behavioral systems to cope with dangerous situations and promote survival. Emotional memories are central to these defense systems because they are rapidly acquired and prepare organisms for future threat. Unfortunately, the persistence and intrusion of memories of fearful experiences are quite common and can lead to pathogenic conditions, such as anxiety and phobias. Over the course of the last 30 years, neuroscientists and psychologists alike have attempted to understand the mechanisms by which the brain encodes and maintains these aversive memories. Of equal interest, though, is the neurobiology of extinction memory formation as this may shape current therapeutic techniques. Here we review the extant literature on the neurobiology of fear and extinction memory formation, with a strong focus on the cellular and molecular mechanisms underlying these processes.
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Affiliation(s)
- Caitlin A. Orsini
- Department of Psychology, University of Michigan, Ann Arbor, MI, 48109-1043, USA
| | - Stephen Maren
- Department of Psychology, University of Michigan, Ann Arbor, MI, 48109-1043, USA
- Department of Neuroscience Program, University of Michigan, Ann Arbor, MI, 48109-1043, USA
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147
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Translational approaches to the treatment of anxiety disorders. Transl Neurosci 2012. [DOI: 10.1017/cbo9780511980053.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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148
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Jasnow AM, Cullen PK, Riccio DC. Remembering another aspect of forgetting. Front Psychol 2012; 3:175. [PMID: 22675315 PMCID: PMC3365651 DOI: 10.3389/fpsyg.2012.00175] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 05/16/2012] [Indexed: 11/30/2022] Open
Abstract
Although forgetting is most often thought of in terms of declines in performance (response loss or impairment), another class of memory phenomena, the forgetting of stimulus attributes, has begun to attract experimental attention. In non-human animals, the loss of memory for stimulus features is reflected in the flattening of stimulus generalization gradients as well as in the attenuation of the disrupting effect of a shift in context at testing. In both cases, a delay between the learning episode and testing results in increased responding in the presence of previously ineffective stimuli. Thus, previously discriminable cues become more functionally interchangeable. The implications of the forgetting of attributes for some theoretical issues of memory loss and for methodological strategies have been noted earlier. However, relatively little is known about the neurobiological mechanisms underlying stimulus attribute forgetting, and why some memories are maintained while others are not. In this paper we review the evidence for the forgetting of stimulus attributes, discuss recent findings identifying neurobiological underpinnings of forgetting and generalization of fear responses, and discuss relevant clinical implications of fear generalization.
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Affiliation(s)
- Aaron M. Jasnow
- Department of Psychology, Kent State UniversityKent, OH, USA
| | | | - David C. Riccio
- Department of Psychology, Kent State UniversityKent, OH, USA
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149
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Halladay LR, Zelikowsky M, Blair HT, Fanselow MS. Reinstatement of extinguished fear by an unextinguished conditional stimulus. Front Behav Neurosci 2012; 6:18. [PMID: 22586379 PMCID: PMC3343277 DOI: 10.3389/fnbeh.2012.00018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 04/13/2012] [Indexed: 11/13/2022] Open
Abstract
Anxiety disorders are often treated using extinction-based exposure therapy, but relapse is common and can occur as a result of reinstatement, whereby an aversive "trigger" can reinstate extinguished fear. Animal models of reinstatement commonly utilize a Pavlovian fear conditioning procedure, in which subjects are first trained to fear a conditional stimulus (CS) by pairing it with an aversive unconditional stimulus (US), and then extinguished by repeated presentations of the CS alone. Reinstatement is typically induced by exposing subjects to an aversive US after extinction, but here we show that exposure to a non-extinguished CS can reinstate conditional fear responding to an extinguished CS, a phenomenon we refer to as "conditional reinstatement" (CRI). Rats were trained to fear two CSs (light and tone) and subsequently underwent extinction training to only one CS (counterbalanced). Presenting the unextinguished CS (but not a novel cue) immediately after extinction reinstated conditional fear responding to the extinguished CS in a test session given 24 h later. These findings indicate that reinstatement of extinguished fear can be triggered by exposure to conditional as well as unconditional aversive stimuli, and this may help to explain why relapse is common following clinical extinction therapy in humans. Further study of CRI using animal models may prove useful for developing refined extinction therapies that are more resistant to reinstatement.
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Affiliation(s)
- Lindsay R. Halladay
- Department of Psychology, University of California at Los Angeles,Los Angeles, CA, USA
| | - Moriel Zelikowsky
- Department of Psychology, University of California at Los Angeles,Los Angeles, CA, USA
| | - Hugh T. Blair
- Department of Psychology, University of California at Los Angeles,Los Angeles, CA, USA
| | - Michael S. Fanselow
- Department of Psychology, University of California at Los Angeles,Los Angeles, CA, USA
- Department of Psychiatry and Biobehavioral Sciences, University of California at Los Angeles,Los Angeles, CA, USA
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150
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Gallistel CR. Extinction from a rationalist perspective. Behav Processes 2012; 90:66-80. [PMID: 22391153 PMCID: PMC3350810 DOI: 10.1016/j.beproc.2012.02.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 01/25/2012] [Accepted: 02/21/2012] [Indexed: 10/28/2022]
Abstract
The merging of the computational theory of mind and evolutionary thinking leads to a kind of rationalism, in which enduring truths about the world have become implicit in the computations that enable the brain to cope with the experienced world. The dead reckoning computation, for example, is implemented within the brains of animals as one of the mechanisms that enables them to learn where they are (Gallistel, 1990, 1995). It integrates a velocity signal with respect to a time signal. Thus, the manner in which position and velocity relate to one another in the world is reflected in the manner in which signals representing those variables are processed in the brain. I use principles of information theory and Bayesian inference to derive from other simple principles explanations for: (1) the failure of partial reinforcement to increase reinforcements to acquisition; (2) the partial reinforcement extinction effect; (3) spontaneous recovery; (4) renewal; (5) reinstatement; (6) resurgence (aka facilitated reacquisition). Like the principle underlying dead-reckoning, these principles are grounded in analytic considerations. They are the kind of enduring truths about the world that are likely to have shaped the brain's computations.
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Affiliation(s)
- C R Gallistel
- Rutgers University, 152 Frelinghuysen Rd, Piscataway, NJ 08854-8020, USA.
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