32 results on '"Milton, Amy L."'
Search Results
2. Targeting drug memory reconsolidation: a neural analysis.
- Author
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Taujanskaitė U, Cahill EN, and Milton AL
- Subjects
- Amygdala, Humans, Learning, Memory, Pharmaceutical Preparations
- Abstract
Addiction can be conceptualised as a disorder of maladaptive learning and memory. Therefore, maladaptive drug memories supporting drug-seeking and relapse behaviours may present novel treatment targets for therapeutic approaches based upon reconsolidation-blockade. It is known that different structures within the limbic corticostriatal system contribute differentially to different types of maladaptive drug memories, including pavlovian associations between environmental cues and contexts with the drug high, and instrumental memories underlying drug-seeking. Here, we review the mechanisms underlying drug memory reconsolidation in the amygdala, striatum, and hippocampus, noting similarities and differences, and opportunities for future research., (Copyright © 2020 Elsevier Ltd. All rights reserved.)
- Published
- 2021
- Full Text
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3. Neurochemical and molecular mechanisms underlying the retrieval-extinction effect.
- Author
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Cahill EN and Milton AL
- Subjects
- Animals, Conditioning, Psychological physiology, Humans, Receptors, Dopamine metabolism, Receptors, N-Methyl-D-Aspartate metabolism, Extinction, Psychological physiology, Fear physiology, Fear psychology, Memory physiology
- Abstract
Extinction within the reconsolidation window, or 'retrieval-extinction', has received much research interest as a possible technique for targeting the reconsolidation of maladaptive memories with a behavioural intervention. However, it remains to be determined whether the retrieval-extinction effect-a long-term reduction in fear behaviour, which appears resistant to spontaneous recovery, renewal and reinstatement-depends specifically on destabilisation of the original memory (the 'reconsolidation-update' account) or represents facilitation of an extinction memory (the 'extinction-facilitation' account). We propose that comparing the neurotransmitter systems, receptors and intracellular signalling pathways recruited by reconsolidation, extinction and retrieval-extinction will provide a way of distinguishing between these accounts.
- Published
- 2019
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4. Saccharin fading is not required for the acquisition of alcohol self-administration, and can alter the dynamics of cue-alcohol memory reconsolidation.
- Author
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Puaud M, Ossowska Z, Barnard J, and Milton AL
- Subjects
- Animals, Conditioning, Operant drug effects, Conditioning, Operant physiology, Dizocilpine Maleate pharmacology, Male, Memory physiology, Rats, Rats, Wistar, Receptors, N-Methyl-D-Aspartate antagonists & inhibitors, Receptors, N-Methyl-D-Aspartate physiology, Self Administration, Alcohol Drinking psychology, Cues, Ethanol administration & dosage, Memory drug effects, Saccharin administration & dosage
- Abstract
Rationale: Animal models of alcohol-seeking are useful for understanding alcohol addiction and for treatment development, but throughput in these models is limited by the extensive pretraining required to overcome the aversive taste of ethanol. Work by Augier et al. (Psychopharmacology 231: 4561-4568, 2014) indicates that Wistar rats will self-administer alcohol without water deprivation, exposure to sweetened ethanol solutions or intermittent access to ethanol., Objectives and Methods: We sought to replicate and extend the work of Augier et al. by comparing the acquisition of instrumental self-administration of ethanol in Lister-Hooded rats that had been previously saccharin faded (SF group) or not (NSF group). We also aimed to determine whether NMDA receptor antagonism with MK-801, given at memory reactivation, reduced subsequent ethanol-seeking behaviour in both groups of animals. Finally, we assessed the ethanol preference of SF and NSF rats using the two-bottle choice procedure., Results: Both SF and NSF groups acquired instrumental self-administration of ethanol, though SF rats consumed fewer of the earned reinforcers. MK-801, given at memory reactivation, had different effects on NSF and SF rats: impairing the capacity of an ethanol-paired conditioned stimulus (CS) to support reinstatement in NSF rats, and enhancing it in SF rats. Finally, neither SF nor NSF rats showed a preference for ethanol., Conclusions: Our data support those of Augier et al. (Psychopharmacology 231: 4561-4568, 2014) that pretraining is unnecessary for rats to acquire instrumental self-administration of ethanol. Indeed, saccharin fading may produce a weaker memory that extinguishes more readily, thus accounting for the different effects of MK-801 on SF and NSF rats.
- Published
- 2018
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5. A Novel Retrieval-Dependent Memory Process Revealed by the Arrest of ERK1/2 Activation in the Basolateral Amygdala.
- Author
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Merlo E, Milton AL, and Everitt BJ
- Subjects
- Amygdala drug effects, Amygdala metabolism, Animals, Extinction, Psychological, MAP Kinase Signaling System, Male, Protein Kinase Inhibitors pharmacology, Rats, Amygdala physiology, Memory, Mitogen-Activated Protein Kinase 1 antagonists & inhibitors, Mitogen-Activated Protein Kinase 3 antagonists & inhibitors
- Abstract
Fully consolidated fear memories can be maintained or inhibited by retrieval-dependent mechanisms depending on the degree of re-exposure to fear cues. Short exposures promote memory maintenance through reconsolidation, and long exposures promote inhibition through extinction. Little is known about the neural mechanisms by which increasing cue exposure overrides reconsolidation and instead triggers extinction. Using auditory fear conditioning in male rats, we analyzed the role of a molecular mechanism common to reconsolidation and extinction of fear, ERK1/2 activation within the basolateral amygdala (BLA), after intermediate conditioned stimulus (CS) exposure events. We show that an intermediate re-exposure (four CS presentations) failed to activate ERK1/2 in the BLA, suggesting the absence of reconsolidation or extinction mechanisms. Supporting this hypothesis, pharmacologically inhibiting the BLA ERK1/2-dependent signaling pathway in conjunction with four CS presentations had no effect on fear expression, and the NMDA receptor partial agonist d-cycloserine, which enhanced extinction and ERK1/2 activation in partial extinction protocols (seven CSs), had no behavioral or molecular effect when given in association with four CS presentations. These molecular and behavioral data reveal a novel retrieval-dependent memory phase occurring along the transition between conditioned fear maintenance and inhibition. CS-dependent molecular events in the BLA may arrest reconsolidation intracellular signaling mechanism in an extinction-independent manner. These findings are critical for understanding the molecular underpinnings of fear memory persistence after retrieval both in health and disease. SIGNIFICANCE STATEMENT Consolidated fear memories can be altered by retrieval-dependent mechanisms. Whereas a brief conditioned stimulus (CS) exposure promotes fear memory maintenance through reconsolidation, a prolonged exposure engages extinction and fear inhibition. The nature of this transition and whether an intermediate degree of CS exposure engages reconsolidation or extinction is unknown. We show that an intermediate cue exposure session (four CSs) produces the arrest of ERK1/2 activation in the basolateral amygdala, a common mechanism for reconsolidation and extinction. Amnestic or hypermnestic treatments given in association with four CSs had no behavioral or molecular effects, respectively. This evidence reveals a novel retrieval-dependent memory phase. Intermediate degrees of CS exposure fail to trigger reconsolidation or extinction, leaving the original memory in an insensitive state., (Copyright © 2018 the authors 0270-6474/18/383199-09$15.00/0.)
- Published
- 2018
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6. Knockdown of zif268 in the Posterior Dorsolateral Striatum Does Not Enduringly Disrupt a Response Memory of a Rewarded T-Maze Task.
- Author
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Cahill EN, Vousden GH, Exton-McGuinness MTJ, Beh IRC, Swerner CB, Macak M, Abas S, Cole CC, Kelleher BF, Everitt BJ, and Milton AL
- Subjects
- Animals, Conditioning, Classical physiology, Early Growth Response Protein 1 genetics, Gene Knockdown Techniques, Habits, Male, Random Allocation, Rats, Corpus Striatum metabolism, Early Growth Response Protein 1 metabolism, Maze Learning physiology, Memory physiology, Reward
- Abstract
Under certain conditions pavlovian memories undergo reconsolidation, whereby the reactivated memory can be disrupted by manipulations such as knockdown of zif268. For instrumental memories, reconsolidation disruption is less well established. Our previous, preliminary data identified that there was an increase in Zif268 in the posterior dorsolateral striatum (pDLS) after expression of an instrumental habit-like 'response' memory, but not an instrumental goal-directed 'place' memory on a T-maze task. Here, the requirement for Zif268 in the reconsolidation of a response memory was tested by knockdown of Zif268, using antisense oligodeoxynucleotide infusion into the pDLS, at memory reactivation. Zif268 knockdown reduced response memory expression 72H, but not 7d later. Western blotting revealed a non-significant increase in Zif268 in the pDLS in rats using response memories, but there was no change in Zif268 expression in the hippocampus following retrieval of a place memory. Zif268 expression increased in the basolateral amygdala after memory reactivation whether a response or place strategy was used during reactivation. We propose that Zif268 expression in the basolateral amygdala may be linked to prediction error, generated by the absence of reward at reactivation. Taken together, these results suggest a complex role for Zif268 in the maintenance of instrumental memories., (Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2018
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7. The CB1 receptor antagonist AM251 impairs reconsolidation of pavlovian fear memory in the rat basolateral amygdala.
- Author
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Ratano P, Everitt BJ, and Milton AL
- Subjects
- Amidohydrolases antagonists & inhibitors, Amidohydrolases metabolism, Animals, Auditory Perception drug effects, Auditory Perception physiology, Basolateral Nuclear Complex physiology, Benzamides pharmacology, Bicuculline pharmacology, Carbamates pharmacology, Conditioning, Classical, Electroshock, Enzyme Inhibitors pharmacology, Fear physiology, GABA-A Receptor Antagonists pharmacology, Male, Memory physiology, Rats, Receptor, Cannabinoid, CB1 metabolism, Receptors, GABA-A metabolism, Basolateral Nuclear Complex drug effects, Cannabinoid Receptor Antagonists pharmacology, Fear drug effects, Memory drug effects, Piperidines pharmacology, Pyrazoles pharmacology, Receptor, Cannabinoid, CB1 antagonists & inhibitors
- Abstract
We have investigated the requirement for signaling at CB1 receptors in the reconsolidation of a previously consolidated auditory fear memory, by infusing the CB1 receptor antagonist AM251, or the FAAH inhibitor URB597, directly into the basolateral amygdala (BLA) in conjunction with memory reactivation. AM251 disrupted memory restabilization, but only when administered after reactivation. URB597 produced a small, transient enhancement of memory restabilization when administered after reactivation. The amnestic effect of AM251 was rescued by coadministration of the GABAA receptor antagonist bicuculline at reactivation, indicating that the disruption of reconsolidation was mediated by altered GABAergic transmission in the BLA. These data show that the endocannabinoid system in the BLA is an important modulator of fear memory reconsolidation and that its effects on memory are mediated by an interaction with the GABAergic system. Thus, targeting the endocannabinoid system may have therapeutic potential to reduce the impact of maladaptive memories in neuropsychiatric disorders such as posttraumatic stress disorder.
- Published
- 2014
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8. Reconsolidation and extinction are dissociable and mutually exclusive processes: behavioral and molecular evidence.
- Author
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Merlo E, Milton AL, Goozée ZY, Theobald DE, and Everitt BJ
- Subjects
- Animals, Blotting, Western, Male, Rats, Amygdala metabolism, Behavior, Animal, Calcineurin metabolism, Extinction, Psychological physiology, Fear, Memory physiology
- Abstract
Memory persistence is critically influenced by retrieval. In rats, a single presentation of a conditioned fear stimulus induces memory reconsolidation and fear memory persistence, while repeated fear cue presentations result in loss of fear through extinction. These two opposite behavioral outcomes are operationally linked by the number of cue presentations at memory retrieval. However, the behavioral properties and mechanistic determinants of the transition have not yet been explored; in particular, whether reconsolidation and extinction processes coexist or are mutually exclusive, depending on the exposure to non-reinforced retrieval events. We characterized both behaviorally and molecularly the transition from reconsolidation to extinction of conditioned fear and showed that an increase in calcineurin (CaN) in the basolateral amygdala (BLA) supports the shift from fear maintenance to fear inhibition. Gradually increasing the extent of retrieval induces a gradual decrease in freezing responses to the conditioned stimulus and a gradual increase in amygdala CaN level. This newly synthesized CaN is required for the extinction, but not the reconsolidation, of conditioned fear. During the transition from reconsolidation to extinction, we have revealed an insensitive state of the fear memory where NMDA-type glutamate receptor agonist and antagonist drugs are unable either to modulate CaN levels in the BLA or alter the reconsolidation or extinction processes. Together, our data indicate both that reconsolidation and extinction are mutually exclusive processes and also reveal the presence of a transitional, or "limbo," state of the original memory between these two alternative outcomes of fear memory retrieval, when neither process is engaged.
- Published
- 2014
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9. Ketamine effects on memory reconsolidation favor a learning model of delusions.
- Author
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Corlett PR, Cambridge V, Gardner JM, Piggot JS, Turner DC, Everitt JC, Arana FS, Morgan HL, Milton AL, Lee JL, Aitken MR, Dickinson A, Everitt BJ, Absalom AR, Adapa R, Subramanian N, Taylor JR, Krystal JH, and Fletcher PC
- Subjects
- Adult, Case-Control Studies, Conditioning, Classical, Female, Humans, Magnetic Resonance Imaging, Male, Memory physiology, Association Learning physiology, Delusions physiopathology, Fear psychology, Ketamine pharmacology, Memory drug effects, Receptors, N-Methyl-D-Aspartate antagonists & inhibitors
- Abstract
Delusions are the persistent and often bizarre beliefs that characterise psychosis. Previous studies have suggested that their emergence may be explained by disturbances in prediction error-dependent learning. Here we set up complementary studies in order to examine whether such a disturbance also modulates memory reconsolidation and hence explains their remarkable persistence. First, we quantified individual brain responses to prediction error in a causal learning task in 18 human subjects (8 female). Next, a placebo-controlled within-subjects study of the impact of ketamine was set up on the same individuals. We determined the influence of this NMDA receptor antagonist (previously shown to induce aberrant prediction error signal and lead to transient alterations in perception and belief) on the evolution of a fear memory over a 72 hour period: they initially underwent Pavlovian fear conditioning; 24 hours later, during ketamine or placebo administration, the conditioned stimulus (CS) was presented once, without reinforcement; memory strength was then tested again 24 hours later. Re-presentation of the CS under ketamine led to a stronger subsequent memory than under placebo. Moreover, the degree of strengthening correlated with individual vulnerability to ketamine's psychotogenic effects and with prediction error brain signal. This finding was partially replicated in an independent sample with an appetitive learning procedure (in 8 human subjects, 4 female). These results suggest a link between altered prediction error, memory strength and psychosis. They point to a core disruption that may explain not only the emergence of delusional beliefs but also their persistence.
- Published
- 2013
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10. Double dissociation of the requirement for GluN2B- and GluN2A-containing NMDA receptors in the destabilization and restabilization of a reconsolidating memory.
- Author
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Milton AL, Merlo E, Ratano P, Gregory BL, Dumbreck JK, and Everitt BJ
- Subjects
- Amygdala metabolism, Animals, Anisomycin pharmacology, Excitatory Amino Acid Antagonists pharmacology, Fear drug effects, Male, Piperidines pharmacology, Protein Synthesis Inhibitors pharmacology, Quinoxalines pharmacology, Rats, Receptors, N-Methyl-D-Aspartate metabolism, Amygdala drug effects, Association Learning drug effects, Memory drug effects, Receptors, N-Methyl-D-Aspartate antagonists & inhibitors
- Abstract
Signaling at NMDA receptors (NMDARs) is known to be important for memory reconsolidation, but while most studies show that NMDAR antagonists prevent memory restabilization and produce amnesia, others have shown that GluN2B-selective NMDAR antagonists prevent memory destabilization, protecting the memory. These apparently paradoxical, conflicting data provide an opportunity to define more precisely the requirement for different NMDAR subtypes in the mechanisms underlying memory reconsolidation and to further understand the contribution of glutamatergic signaling to this process. Here, using rats with fully consolidated pavlovian auditory fear memories, we demonstrate a double dissociation in the requirement for GluN2B-containing and GluN2A-containing NMDARs within the basolateral amygdala in the memory destabilization and restabilization processes, respectively. We further show a double dissociation in the mechanisms underlying memory retrieval and memory destabilization, since AMPAR antagonism prevented memory retrieval while still allowing the destabilization process to occur. These data demonstrate that glutamatergic signaling mechanisms within the basolateral amygdala differentially and dissociably mediate the retrieval, destabilization, and restabilization of previously consolidated fear memories.
- Published
- 2013
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11. Neuroscience. Wiping drug memories.
- Author
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Milton AL and Everitt BJ
- Subjects
- Animals, Humans, Male, Behavior, Addictive prevention & control, Cocaine-Related Disorders psychology, Extinction, Psychological, Heroin Dependence psychology, Memory
- Published
- 2012
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12. The persistence of maladaptive memory: addiction, drug memories and anti-relapse treatments.
- Author
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Milton AL and Everitt BJ
- Subjects
- Adaptation, Psychological drug effects, Conditioning, Classical, Conditioning, Operant, Conditioning, Psychological, Extinction, Psychological, Humans, Learning drug effects, Learning physiology, Limbic System physiology, Neural Pathways physiology, Secondary Prevention, Substance-Related Disorders drug therapy, Memory physiology, Substance-Related Disorders psychology, Substance-Related Disorders rehabilitation
- Abstract
Addiction is a chronic, relapsing disorder, characterised by the long-term propensity of addicted individuals to relapse. A major factor that obstructs the attainment of abstinence is the persistence of maladaptive drug-associated memories, which can maintain drug-seeking and taking behaviour and promote unconscious relapse of these habits. Thus, addiction can be conceptualised as a disorder of aberrant learning of the formation of strong instrumental memories linking actions to drug-seeking and taking outcomes that ultimately are expressed as persistent stimulus-response habits; of previously neutral environmental stimuli that become associated with drug highs (and/or withdrawal states) through pavlovian conditioning, and of the subsequent interactions between pavlovian and instrumental memories to influence relapse behaviour. Understanding the psychological, neurobiological and molecular basis of these drug memories may produce new methods of pro-abstinence, anti-relapse treatments for addiction., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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13. The psychological and neurochemical mechanisms of drug memory reconsolidation: implications for the treatment of addiction.
- Author
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Milton AL and Everitt BJ
- Subjects
- Animals, Glutamic Acid metabolism, Humans, Receptors, Adrenergic metabolism, Receptors, Glutamate metabolism, Reinforcement, Psychology, Conditioning, Psychological, Extinction, Psychological, Memory physiology, Neurochemistry, Substance-Related Disorders physiopathology, Substance-Related Disorders therapy
- Abstract
Memory reconsolidation is the process by which memories, destabilised at retrieval, require restabilisation to persist in the brain. It has been demonstrated that even old, well-established memories require reconsolidation following retrieval; therefore, memory reconsolidation could potentially be exploited to disrupt, or even erase, aberrant memories that underlie psychiatric disorders, thereby providing a novel therapeutic target. Drug addiction is one such disorder; it is both chronic and relapsing, and one prominent risk factor for a relapse episode is the presentation of environmental cues that have previously been associated with drugs of abuse. This 'cue-induced relapse' can be accounted for in psychological terms by reinforcing memories of the pavlovian association between the cue and the drug, which can thus influence behaviour through at least three psychologically and neurobiologically dissociable mechanisms: conditioned reinforcement, conditioned approach and conditioned motivation. As each of these psychological processes could contribute to the resumption of drug-seeking following abstinence, it is important to develop treatments that can reduce drug-seeking re-established via influences on each or all of these pavlovian processes, in order to minimise the risk of a subsequent relapse. Investigation of the memory reconsolidation mechanisms of the memories underlying conditioned reinforcement, conditioned approach and conditioned motivation indicate that they depend upon different neurochemical systems, including the glutamatergic and adrenergic systems within limbic corticostriatal circuitry. We also discuss here the subsequent translation to the clinic of this preclinical work.
- Published
- 2010
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14. Intra-amygdala and systemic antagonism of NMDA receptors prevents the reconsolidation of drug-associated memory and impairs subsequently both novel and previously acquired drug-seeking behaviors.
- Author
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Milton AL, Lee JL, Butler VJ, Gardner R, and Everitt BJ
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- 2-Amino-5-phosphonovalerate administration & dosage, Amygdala drug effects, Animals, Behavior, Addictive physiopathology, Conditioning, Psychological drug effects, Conditioning, Psychological physiology, Dizocilpine Maleate administration & dosage, Exploratory Behavior drug effects, Infusion Pumps, Male, Memory drug effects, Rats, Self Administration, Amygdala physiology, Behavior, Addictive prevention & control, Exploratory Behavior physiology, Memory physiology, Receptors, N-Methyl-D-Aspartate antagonists & inhibitors, Receptors, N-Methyl-D-Aspartate physiology
- Abstract
The amygdala has long been considered a primary locus in mediating the effects of previously drug-associated stimuli on subsequent drug-seeking behavior, and the NMDA subtype of glutamate receptor within the amygdala is important for the consolidation of associations between environmental conditioned stimuli and the effects of addictive drugs. Here we demonstrate that amygdala NMDA receptors are also necessary for the reconsolidation of drug-associated memories. Using a behavioral task that specifically measures the conditioned reinforcing properties of a previously drug-paired stimulus, we show that infusion of the NMDA receptor antagonist D(-)-2-amino-5-phosphonopentanoic acid (D-APV) into the basolateral amygdala before a memory reactivation session disrupted the drug-associated memory and abolished subsequent instrumental responding for conditioned reinforcement. This effect was memory reactivation dependent, and the memory deficit persisted for at least 4 weeks. In contrast, infusion of d-APV immediately after the memory reactivation session had no effect on subsequent responding for conditioned reinforcement, indicating that NMDA receptors have a temporally limited role in the reconsolidation process. Furthermore, in molecular studies, we show that the reconsolidation-impairing effect of D-APV is correlated with downstream reductions in expression of the plasticity-related immediate early gene, zif268. We also demonstrate that systemic antagonism of NMDA receptors with MK-801 [(+)-5-methyl-10,11-dihydro-SH-dibenzo[a,d]cyclohepten-5,10-imine maleate] before memory reactivation subsequently reduced previously acquired instrumental drug-seeking behavior that depends on drug-associated cues acting as conditioned reinforcers. These data suggest that drugs modulating glutamatergic transmission at the NMDA receptor may be useful in the future treatment of relapse prevention in drug addiction through memory reconsolidation blockade.
- Published
- 2008
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15. Reconsolidation of appetitive memories for both natural and drug reinforcement is dependent on {beta}-adrenergic receptors.
- Author
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Milton AL, Lee JL, and Everitt BJ
- Subjects
- Adrenergic beta-Antagonists pharmacology, Animals, Cocaine administration & dosage, Conditioning, Classical drug effects, Extinction, Psychological, Male, Propranolol pharmacology, Rats, Rats, Inbred Strains, Self Administration, Sucrose, Conditioning, Classical physiology, Memory physiology, Receptors, Adrenergic, beta metabolism, Reinforcement, Psychology, Signal Transduction physiology
- Abstract
We have investigated the neurochemical mechanisms of memory reconsolidation and, in particular, the functional requirement for intracellular mechanisms initiated by beta-adrenergic signaling. We show that propranolol, given in conjunction with a memory reactivation session, can specifically disrupt the conditioned reinforcing properties of a previously appetitively reinforced conditioned stimulus (CS), whether the stimulus had been associated with self-administered cocaine or with sucrose. These data show that memories for both drug and nondrug CS-US associations are dependent on beta-adrenergic receptor-mediated signaling for their reconsolidation, with implications for the potential development of a novel treatment for drug addiction and some forms of obesity.
- Published
- 2008
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16. Reconsolidation and extinction of conditioned fear: inhibition and potentiation.
- Author
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Lee JL, Milton AL, and Everitt BJ
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- Acoustic Stimulation, Amygdala drug effects, Animals, Conditioning, Operant physiology, Electroshock, Extinction, Psychological drug effects, Extinction, Psychological physiology, Freezing Reaction, Cataleptic drug effects, Male, Memory physiology, Rats, Receptors, N-Methyl-D-Aspartate agonists, Receptors, N-Methyl-D-Aspartate antagonists & inhibitors, Amygdala physiology, Conditioning, Operant drug effects, Cycloserine pharmacology, Dizocilpine Maleate pharmacology, Excitatory Amino Acid Agonists pharmacology, Excitatory Amino Acid Antagonists pharmacology, Fear physiology, Freezing Reaction, Cataleptic physiology, Memory drug effects, Receptors, N-Methyl-D-Aspartate physiology
- Abstract
NMDA receptors are important for the acquisition, reconsolidation, and extinction of memories. NMDA receptor antagonists impair these memory processes, whereas the partial agonist D-cycloserine (DCS) potentiates both learning and extinction. Here, we used DCS and the noncompetitive NMDA receptor antagonist (+)-5-methyl-10,11-dihydro-SH-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801) to investigate the effects of enhancing and blocking NMDA receptor-mediated glutamatergic transmission on the reconsolidation and extinction of a conditioned fear memory. Either long extinction training or short memory reactivation sessions were used to preferentially engage extinction and reconsolidation processes, respectively. MK-801 blocked extinction to maintain high levels of conditioned freezing, and DCS potentiated extinction to reduce freezing, when they were administered before a long extinction training session. However, the opposite behavioral outcome was observed when the brief memory reactivation session was used: MK-801 administration impaired, whereas DCS increased, freezing, likely reflecting impairment and enhancement of reconsolidation, respectively. Finally, by using localized intracerebral infusions, we showed that the basolateral amygdala is a primary locus of action of systemically administered DCS. Thus, intrabasolateral amygdala DCS potentiated both the extinction and the reconsolidation of fear conditioning, depending on the length of the extinction/memory reactivation session. Therefore, memory reconsolidation can be both disrupted and enhanced, and extinction can be both potentiated and impaired, either to reduce or increase conditioned fear. These results have important implications for the use of reconsolidation blockade and potentiation of extinction as treatment strategies for maladaptive memory disorders.
- Published
- 2006
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17. Cue-induced cocaine seeking and relapse are reduced by disruption of drug memory reconsolidation.
- Author
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Lee JL, Milton AL, and Everitt BJ
- Subjects
- Animals, Conditioning, Psychological, Memory drug effects, Mutation, Missense, Rats, Cocaine administration & dosage, Cocaine-Related Disorders physiopathology, Cues, Exploratory Behavior physiology, Memory physiology, Memory Disorders etiology, Self Administration
- Abstract
Long-lasting vulnerability to drug cue-induced relapse to a drug-taking habit is a major challenge to the treatment of drug addiction. Here we show that blockade of drug memory reconsolidation, through infusion of Zif268 antisense oligodeoxynucleotides into the basolateral amygdala shortly before reexposure to a cocaine-associated stimulus but not simply to the training context, severely impaired subsequently cue-maintained cocaine seeking under a second-order schedule of reinforcement and abolished cue-induced reinstatement of and relapse to cocaine seeking. This reduction in relapse after disrupted memory reconsolidation was not only seen after several hundred pairings of the stimulus with self-administered cocaine, but older, as well as recent, memories were also disrupted. Reconsolidation blockade may thus provide a potential therapeutic strategy for the prevention of relapse in drug addiction.
- Published
- 2006
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18. The Basolateral Amygdala and Nucleus Accumbens Core Mediate Dissociable Aspects of Drug Memory Reconsolidation
- Author
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Theberge, Florence R. M., Milton, Amy L., and Belin, David
- Abstract
A distributed limbic-corticostriatal circuitry is implicated in cue-induced drug craving and relapse. Exposure to drug-paired cues not only precipitates relapse, but also triggers the reactivation and reconsolidation of the cue-drug memory. However, the limbic cortical-striatal circuitry underlying drug memory reconsolidation is unclear. The aim of this study was to investigate the involvement of the nucleus accumbens core and the basolateral amygdala in the reconsolidation of a cocaine-conditioned stimulus-evoked memory. Antisense oligodeoxynucleotides (ASO) were infused into each structure to knock down the expression of the immediate-early gene "zif268," which is known to be required for memory reconsolidation. Control infusions used missense oligodeoxynucleotides (MSO). The effects of zif268 knockdown were measured in two complementary paradigms widely used to assess the impact of drug-paired CSs upon drug seeking: the acquisition of a new instrumental response with conditioned reinforcement and conditioned place preference. The results show that both intranucleus accumbens core and intrabasolateral amygdala zif268 ASO infusions at memory reactivation impaired the reconsolidation of the memory underlying a cocaine-conditioned place preference. However, knockdown of zif268 in the nucleus accumbens at memory reactivation had no effect on the memory underlying the conditioned reinforcing properties of the cocaine-paired CS measured subsequently, and this is in contrast to the marked impairment observed previously following intrabasolateral amygdala zif268 ASO infusions. These results suggest that both the basolateral amygdala and nucleus accumbens core are key structures within limbic cortical-striatal circuitry where reconsolidation of a cue-drug memory occurs. However reconsolidation of memory representations formed during Pavlovian conditioning are differentially localized in each site.
- Published
- 2010
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19. Reconsolidation of Appetitive Memories for Both Natural and Drug Reinforcement Is Dependent on [beta]-Adrenergic Receptors
- Author
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Milton, Amy L., Lee, Jonathan L. C., and Everitt, Barry J.
- Abstract
We have investigated the neurochemical mechanisms of memory reconsolidation and, in particular, the functional requirement for intracellular mechanisms initiated by [beta]-adrenergic signaling. We show that propranolol, given in conjunction with a memory reactivation session, can specifically disrupt the conditioned reinforcing properties of a previously appetitively reinforced conditioned stimulus (CS), whether the stimulus had been associated with self-administered cocaine or with sucrose. These data show that memories for both drug and nondrug CS-US associations are dependent on [beta]-adrenergic receptor-mediated signaling for their reconsolidation, with implications for the potential development of a novel treatment for drug addiction and some forms of obesity.
- Published
- 2008
- Full Text
- View/download PDF
20. The challenge of memory destabilisation: From prediction error to prior expectations and biomarkers
- Author
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Milton, Amy L, Das, Ravi K, Merlo, Emiliano, Milton, Amy [0000-0003-0175-9417], and Apollo - University of Cambridge Repository
- Subjects
Stress Disorders, Post-Traumatic ,Motivation ,Memory ,General Neuroscience ,Reconsolidation ,Humans ,Memory modulation ,Neuropsychiatric disorders ,Memory Consolidation - Abstract
The re-ignition of memory reconsolidation research sparked by Karim Nader in the early 2000s led to great excitement that 'reconsolidation-based' interventions might be developed for mental health disorders such as post-traumatic stress disorder and substance use disorder. Two decades on, it is clear that reconsolidation-based interventions have been more challenging to translate to the clinic than initially thought. We argue that this challenge could be addressed with a better understanding of how prior expectations interact with information presented in a putative memory reactivation / cue reminder session, and through the identification of non-invasive biomarkers for memory destabilisation that would allow reminder sessions to be 'tuned' to enhance memory lability in an ad hoc manner.
- Published
- 2023
21. Editorial: On the destabilization of maladaptive memory: updates and future perspectives.
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Radiske, Andressa, Cahill, Emma N., Milton, Amy L., and Cammarota, Martín
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MEMORY ,NEUROPHARMACOLOGY ,ADDICTIONS ,ANXIETY - Abstract
This document is an editorial published in the journal Frontiers in Behavioral Neuroscience. It discusses the destabilization of maladaptive memory and provides updates and future perspectives on this topic. The editorial highlights the importance of understanding the molecular and physiological signatures of memory destabilization and the potential for therapies based on the modulation of this process. It also presents original research articles that explore the boundary conditions and mechanisms underlying memory destabilization, with a focus on fear and anxiety disorders and drug addiction. The editorial concludes by emphasizing the contributions of this research to the theoretical framework and future studies on the modulation of maladaptive memories. [Extracted from the article]
- Published
- 2024
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22. Making Leaps and Hitting Boundaries in Reconsolidation: Overcoming Boundary Conditions to Increase Clinical Translatability of Reconsolidation-based Therapies.
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Bui, Uyen T.D. and Milton, Amy L
- Subjects
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MENTAL health services , *AGE factors in memory , *MENTAL illness , *POST-traumatic stress disorder , *DRUG addiction , *AUTOBIOGRAPHICAL memory - Abstract
• Disrupting reconsolidation may allow new treatments for mental health disorders. • There are challenges in translating reconsolidation-based approaches to the clinic. • Understanding boundary conditions should facilitate clinical translation. Reconsolidation results in the restabilisation, and thus persistence, of a memory made labile by retrieval, and interfering with this process is thought to enable modification or weakening of the original trace. As such, reconsolidation-blockade has been a focus of research aiming to target the maladaptive memories underlying mental health disorders, including post-traumatic stress disorder and drug addiction. Current first-line therapies are not effective for all patients, and a substantial proportion of those for whom therapies are effective later relapse. A reconsolidation-based intervention would be invaluable as an alternative treatment for these conditions. However, the translation of reconsolidation-based therapies to the clinic presents a number of challenges, with arguably the greatest being the overcoming of the boundary conditions governing the opening of the reconsolidation window. These include factors such as the age and strength of memory, and can broadly be divided into two categories: intrinsic features of the targeted memory itself, and parameters of the reactivation procedure used. With maladaptive memory characteristics inevitably varying amongst individuals, manipulation of the other limitations imposed by procedural variables have been explored to circumvent the boundary conditions on reconsolidation. Although several apparently discrepant results remain to be reconciled and these limitations yet to be truly defined, many studies have produced successful results which encouragingly demonstrate that boundary conditions may be overcome using various proposed strategies to enable translation of a reconsolidation-based intervention to clinical use. [ABSTRACT FROM AUTHOR]
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- 2023
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23. Lack of Effect of Propranolol on the Reconsolidation of Conditioned Fear Memory due to a Failure to Engage Memory Destabilisation
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Rotondo, Federico, Biddle, Kathryn, Chen, John, Ferencik, Josh, D'Esneval, Mathilde, Milton, Amy L, Milton, Amy [0000-0003-0175-9417], and Apollo - University of Cambridge Repository
- Subjects
Shank ,memory ,reconsolidation ,Adrenergic beta-Antagonists ,fear ,Humans ,rat ,propranolol - Abstract
The prospect of exploiting memory reconsolidation to treat mental health disorders has received great research interest, particularly following demonstrations that the β-adrenergic receptor antagonist propranolol, which is safe for use in humans, can disrupt the reconsolidation of pavlovian conditioned fear memories. However, recent studies have failed to replicate the effects of propranolol on fear memory reconsolidation, and have questioned whether treatments based upon reconsolidation blockade would be robust enough for clinical translation. It remains possible, though, that studies reporting no effect of propranolol on memory reconsolidation could be due to a failure to engage the memory destabilisation process, which is necessary for the memory to become susceptible to disruption with amnestic agents. Demonstrating that memory destabilisation has not been engaged is challenging when only using behavioural measures, but there are molecular correlates of memory destabilisation that can be used to determine whether memory lability has been induced. Here, we attempted to replicate the classic finding that systemic administration of propranolol disrupts the reconsolidation of a pavlovian auditory fear memory. Following a failure to replicate, we manipulated the parameters of the memory reactivation session to enhance prediction error in an attempt to overcome the boundary conditions of reconsolidation. On finding no disruption of memory despite these manipulations, we examined the expression of the post-synaptic density protein Shank in the basolateral amygdala. Degradation of Shank has been shown to correlate with the induction of memory lability, but we found no effect on Shank expression, consistent with the lack of observed behavioural effects.
- Published
- 2022
24. Wiping Drug Memories
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Milton, Amy L. and Everitt, Barry J.
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- 2012
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25. Fear not: recent advances in understanding the neural basis of fear memories and implications for treatment development
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Milton, Amy L, Milton, Amy L [0000-0003-0175-9417], and Apollo - University of Cambridge Repository
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0301 basic medicine ,Fear memory ,hippocampus ,Review ,Optogenetics ,Amygdala ,infralimbic ,General Biochemistry, Genetics and Molecular Biology ,memory ,Stress Disorders, Post-Traumatic ,03 medical and health sciences ,0302 clinical medicine ,Treatment targets ,reconsolidation ,medicine ,Humans ,General Pharmacology, Toxicology and Pharmaceutics ,Cognitive science ,General Immunology and Microbiology ,prelimbic ,Treatment development ,PTSD ,Articles ,General Medicine ,amygdala ,030104 developmental biology ,medicine.anatomical_structure ,Expression (architecture) ,Anxiety ,fear ,Memory consolidation ,medicine.symptom ,Psychology ,030217 neurology & neurosurgery - Abstract
Fear is a highly adaptive emotion that has evolved to promote survival and reproductive fitness. However, maladaptive expression of fear can lead to debilitating stressor-related and anxiety disorders such as post-traumatic stress disorder. Although the neural basis of fear has been extensively researched for several decades, recent technological advances in pharmacogenetics and optogenetics have allowed greater resolution in understanding the neural circuits that underlie fear. Alongside conceptual advances in the understanding of fear memory, this increased knowledge has clarified mechanisms for some currently available therapies for post-traumatic stress disorder and has identified new potential treatment targets.
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- 2019
26. The role of prediction error and memory destabilization in extinction of cued-fear within the reconsolidation window
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Cahill, EN, Wood, Melissa A, Everitt, Barry J, Milton, Amy L, Cahill, Emma [0000-0003-3054-1708], Everitt, Barry [0000-0003-4431-6536], Milton, Amy [0000-0003-0175-9417], and Apollo - University of Cambridge Repository
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Male ,Basolateral Nuclear Complex ,Receptors, Dopamine D1 ,Conditioning, Classical ,social sciences ,Fear ,Article ,humanities ,Extinction, Psychological ,Rats ,Memory ,Mental Recall ,Animals ,Cues ,Reinforcement, Psychology - Abstract
Extinction of a cued-fear memory within the reconsolidation window has been proposed to prevent fear reacquisition by reconsolidation interference. This ‘retrieval-extinction’ procedure has received interest for its therapeutic potential to reduce the impact of fear memories on behavior. To fully exploit its therapeutic potential, it is critical to understand the mechanisms that underlie the ‘retrieval-extinction’ effect. If the effect depends upon reconsolidation of the original memory, then it would be predicted that destabilization, induced by prediction error, would be critical for observing the effect. Here, the dependency of the retrieval-extinction effect on memory destabilization or prediction error was investigated in pavlovian cued-fear conditioned adult male rats. The requirement for memory destabilization, and thus reconsolidation, for the retrieval-extinction effect was subsequently investigated using region-specific pharmacological blockade of dopamine D1-receptors. Intra-basolateral amygdala antagonism of dopamine D1-receptors did not prevent the reacquisition of fear associated with the retrieval-extinction procedure. The requirement for prediction error was assessed by using a reinforced or non-reinforced memory retrieval trial before extinction, compared to a no-retrieval, extinction-only control. Both the reinforced (no prediction error) and non-reinforced retrieval sessions led to a decrease in fear reacquisition, suggesting that engagement of prediction error does not influence the occurrence of retrieval-extinction. Together, these data suggest that retrieval-extinction does not require memory destabilization, since behavioral or pharmacological interventions that prevent destabilization did not disrupt any capacity to attenuate fear.
- Published
- 2019
27. Retrieval-Dependent Mechanisms Affecting Emotional Memory Persistence: Reconsolidation, Extinction, and the Space in Between.
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Vaverková, Zuzana, Milton, Amy L., and Merlo, Emiliano
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MNEMONICS ,MEMORY ,LONG-term memory ,MENTAL health ,FORECASTING ,MENTAL illness - Abstract
Maladaptive emotional memories contribute to the persistence of many mental health disorders, and therefore the prospect of disrupting these memories to produce long-term reductions in relapse is of great clinical appeal. Reducing the impact of maladaptive emotional memories on behaviour could be achieved by two retrieval-dependent manipulations that engage separate mnemonic processes: "reconsolidation disruption" and "extinction enhancement." Extinction occurs during a prolonged re-exposure session in the absence of the expected emotional outcome and is widely accepted as reflecting the formation of a new, inhibitory memory that prevents behavioural expression of the original trace. Reconsolidation, by contrast, involves the destabilisation of the original memory, allowing for subsequent updating and restabilisation in specific brain regions, unless the re-stabilization process is prevented through specific pharmacological or behavioural interventions. Both destabilisation of the original memory and memory extinction require that re-exposure induces prediction error—a mismatch between what is expected and what actually occurs—but the parameters that allow reconsolidation and extinction to occur, and control the transition between them, have not been well-characterised. Here, we review what is known about the induction of memory destabilisation and extinction, and the transition period that separates these mnemonic processes, drawing on preclinical and clinical examples. A deeper understanding of the processes that determine the alternative routes to memory persistence or inhibition is critical for designing new and more reliable clinical treatments targeting maladaptive emotional memories. [ABSTRACT FROM AUTHOR]
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- 2020
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28. Retrieval-Extinction and Relapse Prevention: Rewriting Maladaptive Drug Memories?
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Kuijer, Eloise J., Ferragud, Antonio, and Milton, Amy L.
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SUBSTANCE abuse relapse ,INDIVIDUAL differences ,MEMORY - Abstract
Addicted individuals are highly susceptible to relapse when exposed to drug-associated conditioned stimuli (CSs; "drug cues") even after extensive periods of abstinence. Until recently, these maladaptive emotional drug memories were believed to be permanent and resistant to change. The rediscovery of the phenomenon of memory reconsolidation—by which retrieval of the memory can, under certain conditions, destabilize the previously stable memory before it restabilizes in its new, updated form—has led to the hypothesis that it may be possible to disrupt the strong maladaptive drug-memories that trigger a relapse. Furthermore, recent work has suggested that extinction training "within the reconsolidation window" may lead to a long-term reduction in relapse without the requirement for pharmacological amnestic agents. However, this so-called "retrieval-extinction" effect has been inconsistently observed in the literature, leading some to speculate that rather than reflecting memory updating, it may be the product of facilitation of extinction. In this mini review article, we will focus on factors that might be responsible for the retrieval-extinction effects on preventing drug-seeking relapse and how inter-individual differences may influence this therapeutically promising effect. A better understanding of the psychological and neurobiological mechanisms underpinning the "retrieval-extinction" paradigm, and individual differences in boundary conditions, should provide insights with the potential to optimize the translation of "retrieval-extinction" to clinical populations. [ABSTRACT FROM AUTHOR]
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- 2020
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29. The amygdala: securing pleasure and avoiding pain.
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Fernando, Anushka B. P., Murray, Jennifer E., and Milton, Amy L.
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AMYGDALOID body ,CLASSICAL conditioning ,CONDITIONED response ,EMOTIONAL conditioning ,MEMORY ,AVERSIVE stimuli ,FEAR ,MOTIVATION (Psychology) ,PHYSIOLOGY - Abstract
The amygdala has traditionally been associated with fear, mediating the impact of negative emotions on memory. However, this view does not fully encapsulate the function of the amygdala, nor the impact that processing in this structure has on the motivational limbic corticostriatal circuitry of which it is an important structure. Here we discuss the interactions between different amygdala nuclei with cortical and striatal regions involved in motivation; interconnections and parallel circuitries that have become increasingly understood in recent years. We review the evidence that the amygdala stores memories that allow initially motivationally neutral stimuli to become associated through pavlovian conditioning with motivationally relevant outcomes which, importantly, can be either appetitive (e.g. food) or aversive (e.g. electric shock). We also consider how different psychological processes supported by the amygdala such as conditioned reinforcement and punishment, conditioned motivation and suppression, and conditioned approach and avoidance behavior, are not only psychologically but also neurobiologically dissociable, being mediated by distinct yet overlapping neural circuits within the limbic corticostriatal circuitry. Clearly the role of the amygdala goes beyond encoding aversive stimuli to also encode the appetitive, requiring an appreciation of the amygdala's mediation of both appetitive and fearful behavior through diverse psychological processes. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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30. An assessment of reconsolidation blockade to disrupt memories relevant to psychiatric disorders
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Vousden, George Henry, Milton, Amy L., and Everitt, Barry J.
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616.85 ,reconsolidation ,memory ,addiction ,consolidation ,nmda ,ptsd ,post-traumatic stress disorder ,instrumental - Abstract
Consolidated memories can become reactivated in order to permit the integration of new information into the memory trace. Blockade of the resultant process, reconsolidation, with NMDA receptor antagonists or protein synthesis inhibition can lead to a decrease in subsequent memory expression. This may offer a potential tool for the treatment of psychiatric disorders characterised by maladaptive memories, including drug addiction and post-traumatic disorder. Given the importance of instrumental associations in supporting drug addiction experiments in Chapters 3 & 4 aimed to disrupt reconsolidation of these memories. Treatment with an NMDA receptor antagonist prior to retrieval sessions of various durations was not able to consistently prevent reconsolidation of these associations. Drug addiction is characterised by memories that have been formed not over days or weeks, but months or years. Experiments in Chapters 5 & 6 therefore investigated how the extent of training affects the propensity of an appetitive pavlovian memory to reconsolidate. Experiments in Chapter 5 were not able disrupt reconsolidation of these memories after a relatively short period of training. In Chapter 6 attempts to disrupt reconsolidation of a cocaine-seeking memory having undergone extensive training (>1 month, designed to promote the formation of drug-seeking habits) were also unsuccessful. However, when animals were trained in a similar fashion to respond for a food reinforcer treatment with a NMDA receptor antagonist prior to a reactivation session resulted in a decrease in food-seeking behaviour the following day. However, this deficit was only found in the first test session; drug treatment had no effect on responding following reminder of the memory. If data from preclinical studies are to inform future psychiatric treatments the findings from these works must be robust and replicable. Experiments in previous chapters encountered several issues in this regard, namely the repeated inability to prevent reconsolidation with NMDA receptor antagonism. Given that reconsolidation of auditory fear memories is well characterised a final series of experiments in Chapter 7 used this procedure to explore the possible reasons for the fleeting or absent effects of disrupted memory reconsolidation in previous chapters. Despite the use of similar methods as published reports showing decreases in memory expression as a result of blockade of reconsolidation it was not possible to disrupt this process with NMDA receptor antagonism or protein synthesis inhibition. Results suggested that the failure to observe reactivation-dependent amnesia was due to the amnestic agent used not being able to prevent reconsolidation, should it be taking place, and a failure of the given retrieval trial to result in memory reactivation. On numerous occasions throughout this thesis it was not possible to disrupt memory reconsolidation. One difficulty in interpreting null data of this nature is that it is often unclear whether the results are due to insufficient retrieval conditions to result in memory reconsolidation, or an inability of the pharmacological agent to disrupt this process. The final experiments of this thesis raised the possibility both of these issues may have contributed in tandem towards this inability to prevent memory reconsolidation.
- Published
- 2017
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31. To catch a memory through covert ops
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Amy L. Milton, Milton, Amy L [0000-0003-0175-9417], and Apollo - University of Cambridge Repository
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0301 basic medicine ,General Neuroscience ,Fear ,behavioral disciplines and activities ,Hippocampus ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Transformative learning ,Covert ,Memory ,Memory consolidation ,Psychology ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Disrupting reconsolidation of the maladaptive memories underlying post-traumatic stress disorder (PTSD) could be transformative for treatment. However, patients cannot undergo the direct re-exposure to trauma-cues used to induce reconsolidation in animal studies. Ressler and colleagues report ‘covert’ memory reactivation in rats, bolstering hopes for translation of reconsolidation-based interventions.
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- 2021
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32. Neurochemical and molecular mechanisms underlying the retrieval-extinction effect
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Emma N. Cahill, Amy L. Milton, Milton, Amy L [0000-0003-0175-9417], and Apollo - University of Cambridge Repository
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Spontaneous recovery ,Neurotransmitter systems ,Review ,Receptors, N-Methyl-D-Aspartate ,Extinction, Psychological ,Receptors, Dopamine ,03 medical and health sciences ,0302 clinical medicine ,Neurochemical ,Memory ,Conditioning, Psychological ,Animals ,Humans ,natural sciences ,Behaviour ,Pharmacology ,Behavioural intervention ,Reconsolidation ,Extinction (psychology) ,social sciences ,Extinction ,Fear ,musculoskeletal system ,humanities ,030227 psychiatry ,Extinction memory ,Facilitation ,Memory consolidation ,Retrieval-Extinction ,Psychology ,Neuroscience ,030217 neurology & neurosurgery ,geographic locations - Abstract
Extinction within the reconsolidation window, or 'retrieval-extinction', has received much research interest as a possible technique for targeting the reconsolidation of maladaptive memories with a behavioural intervention. However, it remains to be determined whether the retrieval-extinction effect-a long-term reduction in fear behaviour, which appears resistant to spontaneous recovery, renewal and reinstatement-depends specifically on destabilisation of the original memory (the 'reconsolidation-update' account) or represents facilitation of an extinction memory (the 'extinction-facilitation' account). We propose that comparing the neurotransmitter systems, receptors and intracellular signalling pathways recruited by reconsolidation, extinction and retrieval-extinction will provide a way of distinguishing between these accounts.
- Published
- 2019
- Full Text
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