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Osorio-Gómez D, Miranda MI, Guzmán-Ramos K, Bermúdez-Rattoni F. Transforming experiences: Neurobiology of memory updating/editing. Front Syst Neurosci 2023; 17:1103770. [PMID: 36896148 PMCID: PMC9989287 DOI: 10.3389/fnsys.2023.1103770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 02/07/2023] [Indexed: 02/23/2023] Open
Abstract
Long-term memory is achieved through a consolidation process where structural and molecular changes integrate information into a stable memory. However, environmental conditions constantly change, and organisms must adapt their behavior by updating their memories, providing dynamic flexibility for adaptive responses. Consequently, novel stimulation/experiences can be integrated during memory retrieval; where consolidated memories are updated by a dynamic process after the appearance of a prediction error or by the exposure to new information, generating edited memories. This review will discuss the neurobiological systems involved in memory updating including recognition memory and emotional memories. In this regard, we will review the salient and emotional experiences that promote the gradual shifting from displeasure to pleasure (or vice versa), leading to hedonic or aversive responses, throughout memory updating. Finally, we will discuss evidence regarding memory updating and its potential clinical implication in drug addiction, phobias, and post-traumatic stress disorder.
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Affiliation(s)
- Daniel Osorio-Gómez
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Maria Isabel Miranda
- Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Kioko Guzmán-Ramos
- División de Ciencias Biológicas y de la Salud, Departamento de Ciencias de la Salud, Universidad Autónoma Metropolitana, Lerma de Villada, Mexico
| | - Federico Bermúdez-Rattoni
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Infection, Learning, and Memory: Focus on Immune Activation and Aversive Conditioning. Neurosci Biobehav Rev 2022; 142:104898. [PMID: 36183862 DOI: 10.1016/j.neubiorev.2022.104898] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 09/19/2022] [Accepted: 09/27/2022] [Indexed: 11/22/2022]
Abstract
Here we review the effects of immune activation primarily via lipopolysaccharide (LPS), a cell wall component of Gram-negative bacteria, on hippocampal and non-hippocampal-dependent learning and memory. Rodent studies have found that LPS alters both the acquisition and consolidation of aversive learning and memory, such as those evoking evolutionarily adaptive responses like fear and disgust. The inhibitory effects of LPS on the acquisition and consolidation of contextual fear memory are discussed. LPS-induced alterations in the acquisition of taste and place-related conditioned disgust memory within bottle preference tasks and taste reactivity tests (taste-related), in addition to conditioned context avoidance tasks and the anticipatory nausea paradigm (place-related), are highlighted. Further, conditioned disgust memory consolidation may also be influenced by LPS-induced effects. Growing evidence suggests a central role of immune activation, especially pro-inflammatory cytokine activity, in eliciting the effects described here. Understanding how infection-induced immune activation alters learning and memory is increasingly important as bacterial and viral infections are found to present a risk of learning and memory impairment.
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Cheng C, Exton-McGuinness MTJ, Lee JLC. Procedures between training and reactivation influence the destabilization of instrumental sucrose memory. Front Behav Neurosci 2022; 16:953629. [PMID: 36187375 PMCID: PMC9524351 DOI: 10.3389/fnbeh.2022.953629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 08/24/2022] [Indexed: 11/21/2022] Open
Abstract
Memory destabilization and reconsolidation is hypothesized to be a fundamental mnemonic process that can underpin memory updating. Instrumental memories have been shown recently to be destabilized following a reactivation session that involves a change in instrumental reward contingency. However, the acquisition and performance of an instrumental response occurs in the presence of the learning of other reward-related memories. This may influence the ability of a given reactivation session to destabilize the previously learned instrumental memory. Here we present a series of experiments in male rats involving an instrumental memory trained on an FR1 schedule over 10 days, and then reactivated in a session that imposed a VR5 schedule of reinforcement. When MK-801 was injected prior to the VR5 reactivation session, it reliably impaired subsequent instrumental performance at test only when the reactivation session occurred 48 h, and not 24 h, after the end of training. The interposition between the end of training and the reactivation session of a context extinction session, an additional VR5 reactivation session, or indeed the simple experience of being handled and injected with vehicle, resulted in MK-801 no longer having an amnestic effect on test performance. While we do not have a clear account for the process and mechanism underpinning this apparent selectivity of the effect of the VR5 session to destabilize the instrumental memory, it does additionally highlight the need for greater understanding of the conditions that facilitate reactivation-induced memory destabilization.
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Affiliation(s)
| | | | - Jonathan L. C. Lee
- School of Psychology, University of Birmingham, Birmingham, United Kingdom
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4
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Grigoryan GA. Neuroinflammation and Reconsolidation of Memory. NEUROCHEM J+ 2022. [DOI: 10.1134/s1819712422020076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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José Olvera M, Miranda MI. Differential effects of NMDA receptors activation in the insular cortex during memory formation and updating of a motivational conflict task. Neuroscience 2022; 497:39-52. [PMID: 35276308 DOI: 10.1016/j.neuroscience.2022.02.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 02/24/2022] [Accepted: 02/28/2022] [Indexed: 10/18/2022]
Abstract
Recognizing and weighing the value of stimuli is necessary for survival, as it allows living things to respond quickly and adequately to new experiences by comparing them with previous ones. Recent evidence shows that context change could affect flavor learning, suggesting a more intricate scenario during complex associations of stimuli with opposite or different valence in a motivational conflict task. Furthermore, linked to the ability to weigh the value of stimuli is the ability to predict the consequences associated with them from previous experiences. The insular cortex (IC) is a brain hub connecting and integrating different sensory, emotional, motivational, and cognitive processing systems. In this regard, previous evidence indicates that glutamatergic activity in this area, mediated by N-methyl-D-aspartate receptors (NMDARs), could be important during positive or negative valence encoding. Hence, the present study examines the involvement of NMDARs in the IC during a complex association of stimuli with opposite valence through the modified inhibitory avoidance (MIA) task and memory updating of a previously learned appetitive context during latent inhibition of the MIA process. This study demonstrates that during a motivational conflict-learning task with stimuli of opposite valences, avoidance memory formation will prevail. NMDARs activation in the IC decreases avoidance memory formation during a complex task (MIA) but not memory formation for an appetitive context. Furthermore, NMDARs activation does not affect the transition from appetitive to aversive learning. Overall, our results propose a different IC-NMDARs function during novel learning and memory updating.
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Affiliation(s)
- María José Olvera
- Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Boulevard Juriquilla No. 3001, Juriquilla, Querétaro, Querétaro 76230, México
| | - María-Isabel Miranda
- Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Boulevard Juriquilla No. 3001, Juriquilla, Querétaro, Querétaro 76230, México.
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Grau-Perales AB, Gámiz F, Gallo M. Effect of hippocampal 6-OHDA lesions on the contextual modulation of taste recognition memory. Behav Brain Res 2021; 409:113320. [PMID: 33901433 DOI: 10.1016/j.bbr.2021.113320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/23/2022]
Abstract
Taste recognition memory is evident in rodents because the initial neophobia to novel tastes attenuates across exposures as the taste becomes familiar and safe. This attenuation of taste neophobia (AN) is context-dependent and an auditory background change could induce the recovery of the neophobic response. The AN auditory context-dependency requires the hippocampal integrity but the neurochemical mechanisms underlying the interaction with the taste memory circuit remain unexplored. We have applied pharmacological intervention by 6-hidroxydopamine (6-OHDA) hippocampal lesion for assessing the role of catecholamines in the hippocampal system to Wistar rats that drank a novel 3% vinegar solution for several consecutive days. Additionally, we manipulated the auditory background as a context that could either change or remain constant across all the drinking sessions. We found that a disruption of the context-dependent AN was induced by intracerebral administration of 6-OHDA targeted to the ventral CA1 hippocampus (vCA1). We conclude that the ability of the auditory context to modulate taste recognition memory involves the catecholaminergic activity in the ventral hippocampal circuit for the proper acquisition of safe taste memory.
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Affiliation(s)
- Alejandro Borja Grau-Perales
- Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain.
| | - Fernando Gámiz
- Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain
| | - Milagros Gallo
- Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain
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7
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Radiske A, Gonzalez MC, Nôga DA, Rossato JI, Bevilaqua LRM, Cammarota M. GluN2B and GluN2A-containing NMDAR are differentially involved in extinction memory destabilization and restabilization during reconsolidation. Sci Rep 2021; 11:186. [PMID: 33420399 PMCID: PMC7794413 DOI: 10.1038/s41598-020-80674-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/24/2020] [Indexed: 12/01/2022] Open
Abstract
Extinction memory destabilized by recall is restabilized through mTOR-dependent reconsolidation in the hippocampus, but the upstream pathways controlling these processes remain unknown. Hippocampal NMDARs drive local protein synthesis via mTOR signaling and may control active memory maintenance. We found that in adult male Wistar rats, intra dorsal-CA1 administration of the non-subunit selective NMDAR antagonist AP5 or of the GluN2A subunit-containing NMDAR antagonist TCN201 after step down inhibitory avoidance (SDIA) extinction memory recall impaired extinction memory retention and caused SDIA memory recovery. On the contrary, pre-recall administration of AP5 or of the GluN2B subunit-containing NMDAR antagonist RO25-6981 had no effect on extinction memory recall or retention per se but hindered the recovery of the avoidance response induced by post-recall intra-CA1 infusion of the mTOR inhibitor rapamycin. Our results indicate that GluN2B-containing NMDARs are necessary for extinction memory destabilization whereas GluN2A-containing NMDARs are involved in its restabilization, and suggest that pharmacological modulation of the relative activation state of these receptor subtypes around the moment of extinction memory recall may regulate the dominance of extinction memory over the original memory trace.
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Affiliation(s)
- Andressa Radiske
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, Natal, RN, 59056-450, Brazil
| | - Maria Carolina Gonzalez
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, Natal, RN, 59056-450, Brazil.,Edmond and Lily Safra International Institute of Neuroscience, Av. Alberto Santos Dumont 1560, Macaiba, RN, 59280-000, Brazil
| | - Diana A Nôga
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, Natal, RN, 59056-450, Brazil
| | - Janine I Rossato
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, Natal, RN, 59056-450, Brazil.,Department of Physiology, Federal University of Rio Grande do Norte, Av. Sen. Salgado Filho 3000, Natal, RN, 59064-741, Brazil
| | - Lia R M Bevilaqua
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, Natal, RN, 59056-450, Brazil
| | - Martín Cammarota
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Av. Nascimento de Castro 2155, Natal, RN, 59056-450, Brazil.
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The Basolateral Nucleus of the Amygdala Executes the Parallel Processes of Avoidance and Palatability in the Retrieval of Conditioned Taste Aversion in Male Rats. eNeuro 2019; 6:ENEURO.0004-19.2019. [PMID: 31235467 PMCID: PMC6620391 DOI: 10.1523/eneuro.0004-19.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 04/03/2019] [Accepted: 04/26/2019] [Indexed: 12/25/2022] Open
Abstract
Conditioned taste aversion (CTA) is an essential behavior for animal survival. Conditioned animals show avoidance and decreased palatability to a conditioned stimulus (CS) on CTA retrieval. In this study, we aimed to determine whether the basolateral nucleus of the amygdala (BLA) is involved in CTA retrieval and whether avoidance and palatability in CTA retrieval are processed in the BLA. We developed an experimental chamber for time-course analysis of the behavior to approach a spout and lick a CS. In this experimental chamber, we analyzed the behavior of male rats following microinjections of GABAA receptor agonist muscimol or saline into the BLA. The rats showed two types of approach behavior: they either (1) approached and licked the spout or (2) approached but did not lick the spout. Muscimol injection into the BLA decreased the frequency of the latter type of approach behavior, indicating that BLA inactivation reduced avoidance to the CS. The muscimol injection into the BLA also significantly increased the consumption of the CS. Lick microstructure analysis demonstrated that intra-BLA muscimol significantly increased licking burst number and size, indicating that BLA inactivation attenuated aversion to the CS as large burst licking is an indicator of high palatability. These results suggest that the increase in CS consumption with intra-BLA muscimol injection was due to alterations in approach and aversive responses to the CS. Therefore, we conclude that the BLA plays an essential role in CTA retrieval by parallel processing of avoidance and palatability.
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Grau-Perales AB, Levy ERJ, Fenton AA, Gallo M. Dorsal hippocampal damage disrupts the auditory context-dependent attenuation of taste neophobia in mice. Neurobiol Learn Mem 2018; 157:121-127. [PMID: 30562590 DOI: 10.1016/j.nlm.2018.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 11/19/2018] [Accepted: 12/15/2018] [Indexed: 11/19/2022]
Abstract
Rodents exhibit neophobia for novel tastes, demonstrated by an initial reluctance to drink novel-tasting, potentially-aversive solutions. Taste neophobia attenuates across days if the solution is not aversive, demonstrated by increased consumption as the solution becomes familiar. This attenuation of taste neophobia is context dependent, which has been demonstrated by maintained reluctance to drink the novel tasting solution if the subject has to drink it after being brought to a novel environment. This spatial context-dependent attenuation of taste neophobia has been described and likely depends on the integrity of the dorsal hippocampus because this brain area is crucial for representing space and spatial context associations, but is unnecessary for processing taste memories per se. Whether changing the non-spatial auditory context causes a similar effect on attenuation of taste neophobia and the potential role of the dorsal hippocampus in processing this decidedly non-spatial information has not been determined. Here we demonstrate that changing the non-spatial auditory context affects the attenuation of taste neophobia in mice, and investigate the consequence of hippocampal lesion. The results demonstrate that the non-spatial auditory context-dependent attenuation of taste neophobia in mice is lost following NMDA excitotoxic lesions of the CA1 region of the dorsal hippocampus. These findings demonstrate that the dorsal hippocampus is crucial for the modulation non-associative taste learning by auditory context, neither of which provide information about space.
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Affiliation(s)
- A B Grau-Perales
- Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain.
| | - E R J Levy
- Center for Neural Science, New York University, New York, NY, USA
| | - A A Fenton
- Center for Neural Science, New York University, New York, NY, USA; Neuroscience Institute at the New York University Langone Medical Center, New York, NY, USA; Department of Physiology & Pharmacology, The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY, Downstate Medical Center, Brooklyn, NY, USA
| | - M Gallo
- Department of Psychobiology, Institute of Neurosciences, Center for Biomedical Research (CIBM), University of Granada, Spain
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Arguello AA, Wang R, Lyons CM, Higginbotham JA, Hodges MA, Fuchs RA. Role of the agranular insular cortex in contextual control over cocaine-seeking behavior in rats. Psychopharmacology (Berl) 2017; 234:2431-2441. [PMID: 28462472 PMCID: PMC5538945 DOI: 10.1007/s00213-017-4632-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 04/15/2017] [Indexed: 11/30/2022]
Abstract
RATIONALE Environmental stimulus control over drug relapse requires the retrieval of context-response-cocaine associations, maintained in long-term memory through active reconsolidation processes. Identifying the neural substrates of these phenomena is important from a drug addiction treatment perspective. OBJECTIVES The present study evaluated whether the agranular insular cortex (AI) plays a role in drug context-induced cocaine-seeking behavior and cocaine memory reconsolidation. METHODS Rats were trained to lever press for cocaine infusions in a distinctive context, followed by extinction training in a different context. Rats in experiment 1 received bilateral microinfusions of vehicle or a GABA agonist cocktail (baclofen and muscimol (BM)) into the AI or the overlying somatosensory cortex (SSJ, anatomical control region) immediately before a test of drug-seeking behavior (i.e., non-reinforced lever presses) in the previously cocaine-paired context. The effects of these manipulations on locomotor activity were also assessed in a novel context. Rats in experiment 2 received vehicle or BM into the AI after a 15-min reexposure to the cocaine-paired context, intended to reactivate context-response-cocaine memories and initiate their reconsolidation. The effects of these manipulations on drug context-induced cocaine-seeking behavior were assessed 72 h later. RESULTS BM-induced pharmacological inactivation of the AI, but not the SSJ, attenuated drug context-induced reinstatement of cocaine-seeking behavior without altering locomotor activity. Conversely, AI inactivation after memory reactivation failed to impair subsequent drug-seeking behavior and thus cocaine memory reconsolidation. CONCLUSIONS These findings suggest that the AI is a critical element of the neural circuitry that mediates contextual control over cocaine-seeking behavior.
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Affiliation(s)
- Amy A. Arguello
- Department of Psychology, Michigan State University, East Lansing, MI, 48824, USA
| | - Rong Wang
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA
| | - Carey M. Lyons
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA
| | - Jessica A. Higginbotham
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA
| | - Matthew A. Hodges
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA
| | - Rita A. Fuchs
- Integrative Physiology and Neuroscience, Washington State University, VBRB #231 Pullman, WA, 99164-7620, USA,Corresponding Author: Dr. Rita A. Fuchs, Washington State University, College of Veterinary Medicine, Integrative Physiology and Neuroscience, P.O. Box 647620, Pullman, WA 99164-7620, USA, Phone: 509-335-6164, Fax: 509-335-4650,
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Zubedat S, Akirav I. The involvement of cannabinoids and mTOR in the reconsolidation of an emotional memory in the hippocampal-amygdala-insular circuit. Eur Neuropsychopharmacol 2017; 27:336-349. [PMID: 28131675 DOI: 10.1016/j.euroneuro.2017.01.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 11/13/2016] [Accepted: 01/05/2017] [Indexed: 12/20/2022]
Abstract
Memory reconsolidation is the process in which reactivated long-term memory becomes transiently sensitive to amnesic agents. We evaluated the ability of post reactivation administration of the mTOR inhibitor rapamycin, separately and in combination with the cannabinoid CB1/2 receptor agonist WIN55,212-2 (WIN), given systemically or specifically into the hippocampal CA1 area, basolateral amygdala (BLA) or insular cortex (IC), to reduce inhibitory avoidance fear in rats. Systemic administration of rapamycin after reactivation of fear memory impaired reconsolidation and facilitated extinction. A combined treatment with WIN and rapamycin resulted in similar effects. WIN injected systemically facilitated extinction, with no effect on reconsolidation. WIN alone and with rapamycin also decreased anxiety-like behavior. Further, when spontaneous recovery was tested, the WIN+rapamycin group did not demonstrate recovery of fear which can occur spontaneously after the passage of time. Rapamycin and WIN had differential effects on reconsolidation and extinction when microinjected into the CA1, BLA and IC. Furthermore, exposure to shock increased p70s6K activation in the BLA, indicating activation by mTOR. Treatment with rapamycin, WIN or WIN+rapamycin decreased activation and there was a strong positive correlation between fear retrieval and p70s6K activation in the BLA, suggesting that enhanced fear retrieval is associated with enhanced p70s6K activation. Taken together, the results suggest that rapamycin or a combined treatment that involves blocking mTOR and activating cannabinoids may be a promising pharmacological approach for the attenuation of reactivated emotional memories, and thus, it could represent a potential treatment strategy for disorders associated with traumatic memories.
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Affiliation(s)
- Salman Zubedat
- Department of Psychology, University of Haifa, Haifa 3498838, Israel
| | - Irit Akirav
- Department of Psychology, University of Haifa, Haifa 3498838, Israel.
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Rodriguez-Ortiz CJ, Bermúdez-Rattoni F. Determinants to trigger memory reconsolidation: The role of retrieval and updating information. Neurobiol Learn Mem 2016; 142:4-12. [PMID: 28011191 DOI: 10.1016/j.nlm.2016.12.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/07/2016] [Accepted: 12/10/2016] [Indexed: 12/13/2022]
Abstract
Long-term memories can undergo destabilization/restabilization processes, collectively called reconsolidation. However, the parameters that trigger memory reconsolidation are poorly understood and are a matter of intense investigation. Particularly, memory retrieval is widely held as requisite to initiate reconsolidation. This assumption makes sense since only relevant cues will induce reconsolidation of a specific memory. However, recent studies show that pharmacological inhibition of retrieval does not avoid memory from undergoing reconsolidation, indicating that memory reconsolidation occurs through a process that can be dissociated from retrieval. We propose that retrieval is not a unitary process but has two dissociable components; one leading to the expression of memory and the other to reconsolidation, referred herein as executer and integrator respectively. The executer would lead to the behavioral expression of the memory. This component would be the one disrupted on the studies that show reconsolidation independence from retrieval. The integrator would deal with reconsolidation. This component of retrieval would lead to long-term memory destabilization when specific conditions are met. We think that an important number of reports are consistent with the hypothesis that reconsolidation is only initiated when updating information is acquired. We suggest that the integrator would initiate reconsolidation to integrate updating information into long-term memory.
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Affiliation(s)
- Carlos J Rodriguez-Ortiz
- Department of Medicine, University of California, Irvine, 2216 Gillespie Neuroscience Research Facility, 837 Health Sciences Rd., Irvine, CA 92697-4545, USA.
| | - Federico Bermúdez-Rattoni
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, 04510 México City, Mexico.
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Abstract
Fear memory is the best-studied form of memory. It was thoroughly investigated in the past 60 years mostly using two classical conditioning procedures (contextual fear conditioning and fear conditioning to a tone) and one instrumental procedure (one-trial inhibitory avoidance). Fear memory is formed in the hippocampus (contextual conditioning and inhibitory avoidance), in the basolateral amygdala (inhibitory avoidance), and in the lateral amygdala (conditioning to a tone). The circuitry involves, in addition, the pre- and infralimbic ventromedial prefrontal cortex, the central amygdala subnuclei, and the dentate gyrus. Fear learning models, notably inhibitory avoidance, have also been very useful for the analysis of the biochemical mechanisms of memory consolidation as a whole. These studies have capitalized on in vitro observations on long-term potentiation and other kinds of plasticity. The effect of a very large number of drugs on fear learning has been intensively studied, often as a prelude to the investigation of effects on anxiety. The extinction of fear learning involves to an extent a reversal of the flow of information in the mentioned structures and is used in the therapy of posttraumatic stress disorder and fear memories in general.
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Affiliation(s)
- Ivan Izquierdo
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Cristiane R. G. Furini
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Jociane C. Myskiw
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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Dissociation of the Role of Infralimbic Cortex in Learning and Consolidation of Extinction of Recent and Remote Aversion Memory. Neuropsychopharmacology 2015; 40:2566-75. [PMID: 25872918 PMCID: PMC4569946 DOI: 10.1038/npp.2015.103] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 03/18/2015] [Accepted: 03/29/2015] [Indexed: 01/04/2023]
Abstract
Medial prefrontal circuits have been reported to undergo a major reorganization over time and gradually take a more important role for remote emotional memories such as contextual fear memory or food aversion memory. The medial prefrontal cortex, and specifically its ventral subregion, the infralimbic cortex (IL), was also reported to be critical for recent memory extinction of contextual fear conditioning and conditioned odor aversion. However, its exact role in the extinction of remotely acquired information is still not clear. Using postretrieval blockade of protein synthesis or inactivation of the IL, we showed that the IL is similarly required for extinction consolidation of recent and remote fear memory. However, in odor aversion memory, the IL was only involved in extinction consolidation of recent, but not remote, memory. In contrast, only remote retrieval of aversion memory induced c-Fos activation in the IL and preretrieval inactivation of the IL with lidocaine impaired subsequent extinction of remote but not recent memory, indicating IL is necessary for extinction learning of remote aversion memory. In contrast to the effects in odor aversion, our data show that the involvement of the IL in the consolidation of fear extinction does not depend on the memory age. More importantly, our data indicate that the IL is implicated in the extinction of fear and nonfear-based associations and suggest dissociation in the engagement of the IL in the learning and consolidation of food aversion extinction over time.
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15
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The learning of fear extinction. Neurosci Biobehav Rev 2015; 47:670-83. [PMID: 25452113 DOI: 10.1016/j.neubiorev.2014.10.016] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 10/19/2014] [Accepted: 10/20/2014] [Indexed: 11/23/2022]
Abstract
Recent work on the extinction of fear-motivated learning places emphasis on its putative circuitry and on its modulation. Extinction is the learned inhibition of retrieval of previously acquired responses. Fear extinction is used as a major component of exposure therapy in the treatment of fear memories such as those of the posttraumatic stress disorder (PTSD). It is initiated and maintained by interactions between the hippocampus, basolateral amygdala and ventromedial prefrontal cortex, which involve feedback regulation of the latter by the other two areas. Fear extinction depends on NMDA receptor activation. It is positively modulated by d-serine acting on the glycine site of NMDA receptors and blocked by AP5 (2-amino-5-phosphono propionate) in the three structures. In addition, histamine acting on H2 receptors and endocannabinoids acting on CB1 receptors in the three brain areas mentioned, and muscarinic cholinergic fibers from the medial septum to hippocampal CA1 positively modulate fear extinction. Importantly, fear extinction can be made state-dependent on circulating epinephrine, which may play a role in situations of stress. Exposure to a novel experience can strongly enhance the consolidation of fear extinction through a synaptic tagging and capture mechanism; this may be useful in the therapy of states caused by fear memory like PTSD.
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de Carvalho Myskiw J, Furini CRG, Schmidt B, Ferreira F, Izquierdo I. Extinction learning, which consists of the inhibition of retrieval, can be learned without retrieval. Proc Natl Acad Sci U S A 2015; 112:E230-3. [PMID: 25550507 PMCID: PMC4299186 DOI: 10.1073/pnas.1423465112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In the present study we test the hypothesis that extinction is not a consequence of retrieval in unreinforced conditioned stimulus (CS) presentation but the mere perception of the CS in the absence of a conditioned response. Animals with cannulae implanted in the CA1 region of hippocampus were subjected to extinction of contextual fear conditioning. Muscimol infused intra-CA1 before an extinction training session of contextual fear conditioning (CFC) blocks retrieval but not consolidation of extinction measured 24 h later. Additionally, this inhibition of retrieval does not affect early persistence of extinction when tested 7 d later or its spontaneous recovery after 2 wk. Furthermore, both anisomycin, an inhibitor of ribosomal protein synthesis, and rapamycin, an inhibitor of extraribosomal protein synthesis, given into the CA1, impair extinction of CFC regardless of whether its retrieval was blocked by muscimol. Therefore, retrieval performance in the first unreinforced session is not necessary for the installation, maintenance, or spontaneous recovery of extinction of CFC.
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Affiliation(s)
- Jociane de Carvalho Myskiw
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul, 90610-000 Porto Alegre, RS, Brazil
| | - Cristiane Regina Guerino Furini
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul, 90610-000 Porto Alegre, RS, Brazil
| | - Bianca Schmidt
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul, 90610-000 Porto Alegre, RS, Brazil
| | - Flávia Ferreira
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul, 90610-000 Porto Alegre, RS, Brazil
| | - Ivan Izquierdo
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul, 90610-000 Porto Alegre, RS, Brazil
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Differential contribution of hippocampal subfields to components of associative taste learning. J Neurosci 2014; 34:11007-15. [PMID: 25122900 DOI: 10.1523/jneurosci.0956-14.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The ability to associate the consumption of a taste with its positive or negative consequences is fundamental to survival and influences the behavior of species ranging from invertebrate to human. As a result, for both research and clinical reasons, there has been a great effort to understand the neuronal circuits, as well as the cellular and molecular mechanisms, underlying taste learning. From a neuroanatomical perspective, the contributions of the cortex and amygdala are well documented; however, the literature is riddled with conflicting results regarding the role of the hippocampus in different facets of taste learning. Here, we use conditional genetics in mice to block NMDA receptor-dependent plasticity individually in each of the three major hippocampal subfields, CA1, CA3, and the dentate gyrus, via deletion of the NR1 subunit. Across the CA1, CA3, and dentate gyrus NR1 knock-out lines, we uncover a pattern of differential deficits that establish the dispensability of hippocampal plasticity in incidental taste learning, the requirement of CA1 plasticity for associative taste learning, and a specific requirement for plasticity in the dentate gyrus when there is a long temporal gap between the taste and its outcome. Together, these data establish that the hippocampus is involved in associative taste learning and suggest an episodic component to this type of memory.
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Rosa J, Myskiw JC, Furini CR, Sapiras GG, Izquierdo I. Fear extinction can be made state-dependent on peripheral epinephrine: Role of norepinephrine in the nucleus tractus solitarius. Neurobiol Learn Mem 2014; 113:55-61. [DOI: 10.1016/j.nlm.2013.09.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/11/2013] [Accepted: 09/18/2013] [Indexed: 11/16/2022]
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Modulation of the extinction of fear learning. Brain Res Bull 2014; 105:61-9. [DOI: 10.1016/j.brainresbull.2014.04.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 11/19/2022]
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Role of glutamate receptors of central and basolateral amygdala nuclei on retrieval and reconsolidation of taste aversive memory. Neurobiol Learn Mem 2014; 111:35-40. [DOI: 10.1016/j.nlm.2014.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 03/05/2014] [Accepted: 03/06/2014] [Indexed: 11/24/2022]
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21
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Reichelt AC, Lee JLC. Memory reconsolidation in aversive and appetitive settings. Front Behav Neurosci 2013; 7:118. [PMID: 24058336 PMCID: PMC3766793 DOI: 10.3389/fnbeh.2013.00118] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/20/2013] [Indexed: 11/16/2022] Open
Abstract
Memory reconsolidation has been observed across species and in a number of behavioral paradigms. The majority of memory reconsolidation studies have been carried out in Pavlovian fear conditioning and other aversive memory settings, with potential implications for the treatment of post-traumatic stress disorder. However, there is a growing literature on memory reconsolidation in appetitive reward-related memory paradigms, including translational models of drug addiction. While there appears to be substantial similarity in the basic phenomenon and underlying mechanisms of memory reconsolidation across unconditioned stimulus valence, there are also notable discrepancies. These arise both when comparing aversive to appetitive paradigms and also across different paradigms within the same valence of memory. We review the demonstration of memory reconsolidation across different aversive and appetitive memory paradigms, the commonalities and differences in underlying mechanisms and the conditions under which each memory undergoes reconsolidation. We focus particularly on whether principles derived from the aversive literature are applicable to appetitive settings, and also whether the expanding literature in appetitive paradigms is informative for fear memory reconsolidation.
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Affiliation(s)
- Amy C Reichelt
- School of Psychology, University of Birmingham Birmingham, UK
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Role of activity-dependent BDNF expression in hippocampal-prefrontal cortical regulation of behavioral perseverance. Proc Natl Acad Sci U S A 2013; 110:15103-8. [PMID: 23980178 DOI: 10.1073/pnas.1222872110] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Activity-dependent gene transcription, including that of the brain-derived neurotrophic factor (Bdnf) gene, has been implicated in various cognitive functions. We previously demonstrated that mutant mice with selective disruption of activity-dependent BDNF expression (BDNF-KIV mice) exhibit deficits in GABA-mediated inhibition in the prefrontal cortex (PFC). Here, we show that disruption of activity-dependent BDNF expression impairs BDNF-dependent late-phase long-term potentiation (L-LTP) in CA1, a site of hippocampal output to the PFC. Interestingly, early-phase LTP and conventional L-LTP induced by strong tetanic stimulation were completely normal in BDNF-KIV mice. In parallel, attenuation of activity-dependent BDNF expression significantly impairs spatial memory reversal and contextual memory extinction, two executive functions that require intact hippocampal-PFC circuitry. In contrast, spatial and contextual memory per se were not affected. Thus, activity-dependent BDNF expression in the hippocampus and PFC may contribute to cognitive and behavioral flexibility. These results suggest distinct roles for different forms of L-LTP and provide a link between activity-dependent BDNF expression and behavioral perseverance, a hallmark of several psychiatric disorders.
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Molero-Chamizo A. Excitotoxic lesion of the hippocampus of Wistar rats disrupts the circadian control of the latent inhibition of taste aversion learning. Brain Res 2013; 1533:105-13. [PMID: 23973606 DOI: 10.1016/j.brainres.2013.08.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/14/2013] [Accepted: 08/16/2013] [Indexed: 12/27/2022]
Abstract
Previous experiments have shown that changes in the time of day between taste pre-exposure and conditioning prevent the latent inhibition of conditioning taste aversion. The effect of these changes in circadian context between pre-exposure and conditioning on the magnitude of the learned aversion appears to be similar to the effect of changes in spatial context on this type of learning. To elucidate the brain areas involved in this circadian dependence of latent inhibition of conditioning taste aversion, the effect of excitotoxic lesions of the hippocampus, a region related to spatial-contextual modulation in this learning process, was analyzed. The latent inhibition of conditioning taste aversion in animals with hippocampal lesions, that were pre-exposed and conditioned to the same or different time of day, was compared with the response of animals exposed to either conditions ("same" or "different") but had undergone amygdala lesions or sham lesions. The results showed that selective dorsal hippocampus lesion eliminated the circadian dependence of latent inhibition of taste aversion. A change in the time of day between pre-exposure and conditioning did not prevent latent inhibition in animals with hippocampal lesions. In contrast, this change prevented latent inhibition in the amygdala-lesioned and sham groups. These findings suggest that the hippocampus contains a selective mechanism that modulates the contextual dependency of the latent inhibition of conditioning taste aversion without interfering with the effect of taste pre-exposure itself. This study may help to understand the possible common involvement of the hippocampus in different types of contextual control of associative learning.
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Gazarini L, Stern CAJ, Carobrez AP, Bertoglio LJ. Enhanced noradrenergic activity potentiates fear memory consolidation and reconsolidation by differentially recruiting 1- and -adrenergic receptors. Learn Mem 2013; 20:210-9. [DOI: 10.1101/lm.030007.112] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fiorenza NG, Sartor D, Myskiw JC, Izquierdo I. Treatment of fear memories: interactions between extinction and reconsolidation. AN ACAD BRAS CIENC 2012; 83:1363-72. [PMID: 22146964 DOI: 10.1590/s0001-37652011000400023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 09/08/2011] [Indexed: 01/28/2023] Open
Abstract
Retrieval labilizes memory traces and these gates two protein synthesis-dependent processes in the brain: extinction, which inhibits further retrieval, and reconsolidation, which may enhance retrieval or change its content. Extinction may itself suffer reconsolidation. Interactions among these processes may be applied to treatments of fear memories, such as those underlying post-traumatic stress disorders.
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Affiliation(s)
- Natália G Fiorenza
- Centro de Memória, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brasil
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Adaikkan C, Rosenblum K. The role of protein phosphorylation in the gustatory cortex and amygdala during taste learning. Exp Neurobiol 2012; 21:37-51. [PMID: 22792024 PMCID: PMC3381211 DOI: 10.5607/en.2012.21.2.37] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 02/17/2012] [Indexed: 01/22/2023] Open
Abstract
Protein phosphorylation and dephosphorylation form a major post-translation mechanism that enables a given cell to respond to ever-changing internal and external environments. Neurons, similarly to any other cells, use protein phosphorylation/dephosphorylation to maintain an internal homeostasis, but they also use it for updating the state of synaptic and intrinsic properties, following activation by neurotransmitters and growth factors. In the present review we focus on the roles of several families of kinases, phosphatases, and other synaptic-plasticity-related proteins, which activate membrane receptors and various intracellular signals to promote transcription, translation and protein degradation, and to regulate the appropriate cellular proteomes required for taste memory acquisition, consolidation and maintenance. Attention is especially focused on the protein phosphorylation state in two forebrain areas that are necessary for taste-memory learning and retrieval: the insular cortex and the amygdala. The various temporal phases of taste learning require the activation of appropriate waves of biochemical signals. These include: extracellular signal regulated kinase I and II (ERKI/II) signal transduction pathways; Ca(2+)-dependent pathways; tyrosine kinase/phosphatase-dependent pathways; brain-derived neurotrophicfactor (BDNF)-dependent pathways; cAMP-responsive element bindingprotein (CREB); and translation-regulation factors, such as initiation and elongation factors, and the mammalian target of rapamycin (mTOR). Interestingly, coding of hedonic and aversive taste information in the forebrain requires activation of different signal transduction pathways.
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Yamamoto T, Ueji K. Brain mechanisms of flavor learning. Front Syst Neurosci 2011; 5:76. [PMID: 21922004 PMCID: PMC3166791 DOI: 10.3389/fnsys.2011.00076] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Accepted: 08/15/2011] [Indexed: 11/16/2022] Open
Abstract
Once the flavor of the ingested food (conditioned stimulus, CS) is associated with a preferable (e.g., good taste or nutritive satisfaction) or aversive (e.g., malaise with displeasure) signal (unconditioned stimulus, US), animals react to its subsequent exposure by increasing or decreasing ingestion to the food. These two types of association learning (preference learning vs. aversion learning) are known as classical conditioned reactions which are basic learning and memory phenomena, leading selection of food and proper food intake. Since the perception of flavor is generated by interaction of taste and odor during food intake, taste and/or odor are mainly associated with bodily signals in the flavor learning. After briefly reviewing flavor learning in general, brain mechanisms of conditioned taste aversion is described in more detail. The CS-US association leading to long-term potentiation in the amygdala, especially in its basolateral nucleus, is the basis of establishment of conditioned taste aversion. The novelty of the CS detected by the cortical gustatory area may be supportive in CS-US association. After the association, CS input is conveyed through the amygdala to different brain regions including the hippocampus for contextual fear formation, to the supramammillary and thalamic paraventricular nuclei for stressful anxiety or memory dependent fearful or stressful emotion, to the reward system to induce aversive expression to the CS, or hedonic shift from positive to negative, and to the CS-responsive neurons in the gustatory system to enhance the responsiveness to facilitate to detect the harmful stimulus.
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Affiliation(s)
- Takashi Yamamoto
- Department of Health and Nutrition, Faculty of Health Science, Kio UniversityNara, Japan
| | - Kayoko Ueji
- Department of Health and Nutrition, Faculty of Health Science, Kio UniversityNara, Japan
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Izquierdo I, Myskiw JC. Brain interactions between processes triggered by memory retrieval and their use in the treatment of fear memories. FUTURE NEUROLOGY 2011. [DOI: 10.2217/fnl.11.20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Iván Izquierdo
- National Institute of Translational Neuroscience, National Research Council of Brazil, Sau Paulo, Brazil
- Memory Center, Brain institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Jociane C Myskiw
- National Institute of Translational Neuroscience, National Research Council of Brazil, Sau Paulo, Brazil
- Memory Center, Brain institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
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Lensu S, Tuomisto JT, Tuomisto J, Pohjanvirta R. Characterization of the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-provoked strong and rapid aversion to unfamiliar foodstuffs in rats. Toxicology 2011; 283:140-50. [DOI: 10.1016/j.tox.2011.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 03/12/2011] [Indexed: 11/27/2022]
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Abstract
The nonreinforced expression of long-tem memory may lead to two opposite protein synthesis-dependent processes: extinction and reconsolidation. Extinction weakens consolidated memories, whereas reconsolidation allows incorporation of additional information into them. Knowledge about these two processes has accumulated in recent years, but their possible interaction has not been evaluated yet. Here, we report that inhibition of protein synthesis in the CA1 region of the dorsal hippocampus after retrieval of fear extinction impedes subsequent reactivation of the extinction memory trace without affecting its storage or that of the initial fear memory. Our results suggest that extinction memory is susceptible to a retrieval-induced process similar to reconsolidation in the hippocampus.
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