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Santos TB, de Oliveira Coelho CA, Kramer-Soares JC, Frankland PW, Oliveira MGM. Reactivation of encoding ensembles in the prelimbic cortex supports temporal associations. Neuropsychopharmacology 2024:10.1038/s41386-024-01825-2. [PMID: 38454052 DOI: 10.1038/s41386-024-01825-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 01/14/2024] [Accepted: 02/05/2024] [Indexed: 03/09/2024]
Abstract
Fear conditioning is encoded by strengthening synaptic connections between the neurons activated by a conditioned stimulus (CS) and those activated by an unconditioned stimulus (US), forming a memory engram, which is reactivated during memory retrieval. In temporal associations, activity within the prelimbic cortex (PL) plays a role in sustaining a short-term, transient memory of the CS, which is associated with the US after a temporal gap. However, it is unknown whether the PL has only a temporary role, transiently representing the CS, or is part of the neuronal ensembles that support the retrieval, i.e., whether PL neurons support both transient, short-term memories and stable, long-term memories. We investigated neuronal ensembles underlying temporal associations using fear conditioning with a 5-s interval between the CS and US (CFC-5s). Controls were trained in contextual fear conditioning (CFC), in which the CS-US overlaps. We used Robust Activity Marking (RAM) to selectively manipulate PL neurons activated by CFC-5s learning and Targeted Recombination in Active Populations (TRAP2) mice to label neurons activated by CFC-5s learning and reactivated by memory retrieval in the amygdala, medial prefrontal cortex, hippocampus, perirhinal cortices (PER) and subiculum. We also computed their co-reactivation to generate correlation-based networks. The optogenetic reactivation or silencing of PL encoding ensembles either promoted or impaired the retrieval of CFC-5s but not CFC. CFC-5s retrieval reactivated encoding ensembles in the PL, PER, and basolateral amygdala. The engram network of CFC-5s had higher amygdala and PER centralities and interconnectivity. The same PL neurons support learning and stable associative memories.
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Affiliation(s)
- Thays Brenner Santos
- Departamento de Psicobiologia, Universidade Federal de São Paulo - UNIFESP, São Paulo, 04023-062, Brazil.
| | | | - Juliana Carlota Kramer-Soares
- Departamento de Psicobiologia, Universidade Federal de São Paulo - UNIFESP, São Paulo, 04023-062, Brazil
- Universidade Cruzeiro do Sul - UNICSUL, São Paulo, 08060-070, Brazil
| | - Paul W Frankland
- Neuroscience and Mental Health, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
- Department of Physiology, University of Toronto, Toronto, ON, M5G 1X8, Canada
- Department of Psychology, University of Toronto, Toronto, ON, M5G 1X8, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, M5G 1X8, Canada
- Child & Brain Development Program, Canadian Institute for Advanced Research, Toronto, ON, M5G 1M1, Canada
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Santos TB, Kramer-Soares JC, Coelho CAO, Oliveira MGM. Temporal association activates projections from the perirhinal cortex and ventral CA1 to the prelimbic cortex and from the prelimbic cortex to the basolateral amygdala. Cereb Cortex 2023; 33:11456-11470. [PMID: 37823340 DOI: 10.1093/cercor/bhad375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/22/2023] [Accepted: 09/22/2023] [Indexed: 10/13/2023] Open
Abstract
In trace fear conditioning, the prelimbic cortex exhibits persistent activity during the interval between the conditioned and unconditioned stimuli, which maintains a conditioned stimulus representation. Regions cooperating for this function or encoding the conditioned stimulus before the interval could send inputs to the prelimbic cortex, supporting learning. The basolateral amygdala has conditioned stimulus- and unconditioned stimulus-responsive neurons, convergently activated. The prelimbic cortex could directly project to the basolateral amygdala to associate the transient memory of the conditioned stimulus with the unconditioned stimulus. We investigated the neuronal circuit supporting temporal associations using contextual fear conditioning with a 5-s interval, in which 5 s separates the contextual conditioned stimulus from the unconditioned stimulus. Injecting retrobeads, we quantified c-Fos in prelimbic cortex- or basolateral amygdala-projecting neurons from 9 regions after contextual fear conditioning with a 5-s interval or contextual fear conditioning, in which the conditioned and unconditioned stimuli overlap. The contextual fear conditioning with a 5-s interval activated ventral CA1 and perirhinal cortex neurons projecting to the prelimbic cortex and prelimbic cortex neurons projecting to basolateral amygdala. Both fear conditioning activated ventral CA1 and lateral entorhinal cortex neurons projecting to basolateral amygdala and basolateral amygdala neurons projecting to prelimbic cortex. The perirhinal cortex → prelimbic cortex and ventral CA1 → prelimbic cortex connections are the first identified prelimbic cortex afferent projections participating in temporal associations. These results help to understand time-linked memories, a process required in episodic and working memories.
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Affiliation(s)
- Thays B Santos
- Departamento de Psicobiologia, Universidade Federal de São Paulo-UNIFESP, São Paulo 04023-062, Brazil
| | - Juliana C Kramer-Soares
- Departamento de Psicobiologia, Universidade Federal de São Paulo-UNIFESP, São Paulo 04023-062, Brazil
- Universidade Cruzeiro do Sul-UNICSUL, São Paulo 08060-070, Brazil
| | - Cesar A O Coelho
- Neuroscience and Mental Health, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Maria G M Oliveira
- Departamento de Psicobiologia, Universidade Federal de São Paulo-UNIFESP, São Paulo 04023-062, Brazil
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Santos TB, Kramer-Soares JC, de Oliveira Coelho CA, Oliveira MGM. Functional network of contextual and temporal memory has increased amygdala centrality and connectivity with the retrosplenial cortex, thalamus, and hippocampus. Sci Rep 2023; 13:13087. [PMID: 37567967 PMCID: PMC10421896 DOI: 10.1038/s41598-023-39946-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 08/02/2023] [Indexed: 08/13/2023] Open
Abstract
In fear conditioning with time intervals between the conditioned (CS) and unconditioned (US) stimuli, a neural representation of the CS must be maintained over time to be associated with the later US. Usually, temporal associations are studied by investigating individual brain regions. It remains unknown, however, the effect of the interval at the network level, uncovering functional connections cooperating for the CS transient memory and its fear association. We investigated the functional network supporting temporal associations using a task in which a 5-s interval separates the contextual CS from the US (CFC-5s). We quantified c-Fos expression in forty-nine brain regions of male rats following the CFC-5s training, used c-Fos correlations to generate functional networks, and analyzed them by graph theory. Control groups were trained in contextual fear conditioning, in which CS and US overlap. The CFC-5s training additionally activated subdivisions of the basolateral, lateral, and medial amygdala; prelimbic, infralimbic, perirhinal, postrhinal, and intermediate entorhinal cortices; ventral CA1 and subiculum. The CFC-5s network had increased amygdala centrality and higher amygdala internal and external connectivity with the retrosplenial cortex, thalamus, and hippocampus. Amygdala and thalamic nuclei were network hubs. Functional connectivity among these brain regions could support CS transient memories and their association.
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Affiliation(s)
- Thays Brenner Santos
- Departamento de Psicobiologia, Universidade Federal de São Paulo - UNIFESP, São Paulo, 04023-062, Brazil
| | - Juliana Carlota Kramer-Soares
- Departamento de Psicobiologia, Universidade Federal de São Paulo - UNIFESP, São Paulo, 04023-062, Brazil
- Universidade Cruzeiro do Sul - UNICSUL, São Paulo, 08060-070, Brazil
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Herbst MR, Twining RC, Gilmartin MR. Ventral hippocampal shock encoding modulates the expression of trace cued fear. Neurobiol Learn Mem 2022; 190:107610. [PMID: 35302040 DOI: 10.1016/j.nlm.2022.107610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 02/02/2022] [Accepted: 03/03/2022] [Indexed: 12/24/2022]
Abstract
The hippocampus is crucial for associative fear learning when the anticipation of threat requires temporal or contextual binding of predictive stimuli as in trace and contextual fear conditioning. Compared with the dorsal hippocampus, far less is known about the contribution of the ventral hippocampus to fear learning. The ventral hippocampus, which is highly interconnected with defensive and emotional networks, has a prominent role in both innate and learned affective behaviors including anxiety, fear, and reward. Lesions or temporary inactivation of the ventral hippocampus impair both cued and contextual fear learning, but whether the ventral hippocampal role in learning is driven by affective processing, associative encoding, or both is not clear. Here, we used trace fear conditioning in mixed sex cohorts to assess the contribution of shock-encoding to the acquisition of cued and contextual fear memories. Trace conditioning requires subjects to associate an auditory conditional stimulus (CS) with a shock unconditional stimulus (UCS) that are separated in time by a 20-s trace interval. We first recorded neuronal activity in the ventral hippocampus during trace fear conditioning and found that ventral CA1 predominantly encoded the shock reinforcer. Potentiated firing to the CS was evident at testing, but no encoding of the trace interval was observed. We then tested the necessity of shock encoding for conditional fear acquisition by optogenetically silencing ventral hippocampal activity during the UCS on each trial of training. Contrary to our predictions, preventing hippocampal shock-evoked firing did not impair associative fear. Instead, it led to a more prolonged expression of CS freezing across test trials, an effect observed in males, but not females. Contextual fear learning was largely intact, although a subset of animals in each sex were differentially affected by shock-silencing. Taken together, the results show that shock encoding in the ventral hippocampus modulates the expression of learned fear in a sex-specific manner.
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Affiliation(s)
- Matthew R Herbst
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Robert C Twining
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Marieke R Gilmartin
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53233, USA.
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Namkung H, Thomas KL, Hall J, Sawa A. Parsing neural circuits of fear learning and extinction across basic and clinical neuroscience: Towards better translation. Neurosci Biobehav Rev 2022; 134:104502. [PMID: 34921863 DOI: 10.1016/j.neubiorev.2021.12.025] [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: 06/12/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 12/22/2022]
Abstract
Over the past decades, studies of fear learning and extinction have advanced our understanding of the neurobiology of threat and safety learning. Animal studies can provide mechanistic/causal insights into human brain regions and their functional connectivity involved in fear learning and extinction. Findings in humans, conversely, may further enrich our understanding of neural circuits in animals by providing macroscopic insights at the level of brain-wide networks. Nevertheless, there is still much room for improvement in translation between basic and clinical research on fear learning and extinction. Through the lens of neural circuits, in this article, we aim to review the current knowledge of fear learning and extinction in both animals and humans, and to propose strategies to fill in the current knowledge gap for the purpose of enhancing clinical benefits.
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Affiliation(s)
- Ho Namkung
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA; Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Kerrie L Thomas
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, UK; School of Biosciences, Cardiff University, Cardiff, UK
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, UK; School of Medicine, Cardiff University, Cardiff, UK
| | - Akira Sawa
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA; Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA; Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA; Department of Mental Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, 21287, USA.
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Yokose J, Marks WD, Yamamoto N, Ogawa SK, Kitamura T. Entorhinal cortical Island cells regulate temporal association learning with long trace period. ACTA ACUST UNITED AC 2021; 28:319-328. [PMID: 34400533 PMCID: PMC8372565 DOI: 10.1101/lm.052589.120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 07/08/2021] [Indexed: 11/24/2022]
Abstract
Temporal association learning (TAL) allows for the linkage of distinct, nonsynchronous events across a period of time. This function is driven by neural interactions in the entorhinal cortical-hippocampal network, especially the neural input from the pyramidal cells in layer III of medial entorhinal cortex (MECIII) to hippocampal CA1 is crucial for TAL. Successful TAL depends on the strength of event stimuli and the duration of the temporal gap between events. Whereas it has been demonstrated that the neural input from pyramidal cells in layer II of MEC, referred to as Island cells, to inhibitory neurons in dorsal hippocampal CA1 controls TAL when the strength of event stimuli is weak, it remains unknown whether Island cells regulate TAL with long trace periods as well. To understand the role of Island cells in regulating the duration of the learnable trace period in TAL, we used Pavlovian trace fear conditioning (TFC) with a 60-sec long trace period (long trace fear conditioning [L-TFC]) coupled with optogenetic and chemogenetic neural activity manipulations as well as cell type-specific neural ablation. We found that ablation of Island cells in MECII partially increases L-TFC performance. Chemogenetic manipulation of Island cells causes differential effectiveness in Island cell activity and leads to a circuit imbalance that disrupts L-TFC. However, optogenetic terminal inhibition of Island cell input to dorsal hippocampal CA1 during the temporal association period allows for long trace intervals to be learned in TFC. These results demonstrate that Island cells have a critical role in regulating the duration of time bridgeable between associated events in TAL.
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Affiliation(s)
| | | | | | | | - Takashi Kitamura
- Department of Psychiatry.,Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Ehlers VL, Smies CW, Moyer JR. Apoaequorin differentially modulates fear memory in adult and aged rats. Brain Behav 2020; 10:e01832. [PMID: 32945630 PMCID: PMC7667302 DOI: 10.1002/brb3.1832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/11/2020] [Accepted: 08/18/2020] [Indexed: 01/06/2023] Open
Abstract
INTRODUCTION Cognitive deficits during aging are pervasive across species and learning paradigms. One of the major mechanisms thought to play a role in age-related memory decline is dysregulated calcium (Ca2+ ) homeostasis. Aging is associated with impaired function of several calcium-regulatory mechanisms, including calcium-binding proteins that normally support intracellular Ca2+ regulation. This age-related calcium-binding protein dysfunction and changes in expression lead to disrupted maintenance of intracellular Ca2+ , thus contributing to memory decline. Other work has found that age-related cognitive deficits can be mitigated by either blocking Ca2+ entry into the cytosol or preventing its release from intracellular Ca2+ stores. However, the effect of calcium-binding protein administration on cognitive function during aging is not well-understood. Our laboratory has previously shown that the calcium-binding protein apoaequorin (AQ) is neuroprotective during oxygen-glucose deprivation, a model of in vitro ischemia characterized by calcium-induced excitotoxicity. The current experiments assessed the effect of direct dorsal hippocampal AQ infusion on trace and context fear memory in adult and aged rats. METHODS Adult (3-6 months) and aged (22-26 months) male F344 rats were randomly assigned to different experimental infusion groups before undergoing trace fear conditioning and testing. In experiment 1, rats received bilateral dorsal hippocampal infusions of either vehicle or AQ (4% w/v) 24 hr before trace fear conditioning. In experiment 2, rats received bilateral dorsal hippocampal infusions of either vehicle or 4% AQ 1 hr before trace fear conditioning and 1 hr before testing. RESULTS Aged rats displayed impaired trace and context fear memory. While a single AQ infusion 24 hr before trace fear conditioning was insufficient to rescue age-related trace fear memory deficits, AQ infusion 1 hr before both conditioning and testing abolished age-related context fear memory deficits. CONCLUSIONS These results suggest that intrahippocampal infusion of AQ may reverse aging-related deficits in hippocampus-dependent context fear memory.
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Affiliation(s)
- Vanessa L Ehlers
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Chad W Smies
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - James R Moyer
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.,Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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Durieux L, Mathis V, Herbeaux K, Muller M, Barbelivien A, Mathis C, Schlichter R, Hugel S, Majchrzak M, Lecourtier L. Involvement of the lateral habenula in fear memory. Brain Struct Funct 2020; 225:2029-2044. [DOI: 10.1007/s00429-020-02107-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 06/16/2020] [Indexed: 02/07/2023]
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Kirry AJ, Twining RC, Gilmartin MR. Prelimbic input to basolateral amygdala facilitates the acquisition of trace cued fear memory under weak training conditions. Neurobiol Learn Mem 2020; 172:107249. [DOI: 10.1016/j.nlm.2020.107249] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/28/2020] [Accepted: 05/12/2020] [Indexed: 11/30/2022]
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Functional interaction of ventral hippocampal CA1 region and prelimbic cortex contributes to the encoding of contextual fear association of stimuli separated in time. Neurobiol Learn Mem 2020; 171:107216. [DOI: 10.1016/j.nlm.2020.107216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 11/22/2022]
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Twining RC, Lepak K, Kirry AJ, Gilmartin MR. Ventral Hippocampal Input to the Prelimbic Cortex Dissociates the Context from the Cue Association in Trace Fear Memory. J Neurosci 2020; 40:3217-3230. [PMID: 32188770 PMCID: PMC7159889 DOI: 10.1523/jneurosci.1453-19.2020] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 03/02/2020] [Accepted: 03/05/2020] [Indexed: 12/17/2022] Open
Abstract
The PFC, through its high degree of interconnectivity with cortical and subcortical brain areas, mediates cognitive and emotional processes in support of adaptive behaviors. This includes the formation of fear memories when the anticipation of threat demands learning about temporal or contextual cues, as in trace fear conditioning. In this variant of fear learning, the association of a cue and shock across an empty trace interval of several seconds requires sustained cue-elicited firing in the prelimbic cortex (PL). However, it is unknown how and when distinct PL afferents contribute to different associative components of memory. Among the prominent inputs to PL, the hippocampus shares with PL a role in both working memory and contextual processing. Here we tested the necessity of direct hippocampal input to the PL for the acquisition of trace-cued fear memory and the simultaneously acquired contextual fear association. Optogenetic silencing of ventral hippocampal (VH) terminals in the PL of adult male Long-Evans rats selectively during paired trials revealed that direct communication between the VH and PL during training is necessary for contextual fear memory, but not for trace-cued fear acquisition. The pattern of the contextual memory deficit and the disruption of local PL firing during optogenetic silencing of VH-PL suggest that the VH continuously updates the PL with the current contextual state of the animal, which, when disrupted during memory acquisition, is detrimental to the subsequent rapid retrieval of aversive contextual associations.SIGNIFICANCE STATEMENT Learning to anticipate threat from available contextual and discrete cues is crucial for survival. The prelimbic cortex is required for forming fear memories when temporal or contextual complexity is involved, as in trace fear conditioning. However, the respective contribution of distinct prelimbic afferents to the temporal and contextual components of memory is not known. We report that direct input from the ventral hippocampus enables the formation of the contextual, but not trace-cued, fear memory necessary for the subsequent rapid expression of a fear response. This finding dissociates the contextual and working-memory contributions of prelimbic cortex to the formation of a fear memory and demonstrates the crucial role for hippocampal input in contextual fear learning.
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Affiliation(s)
- Robert C Twining
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53233
| | - Katie Lepak
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53233
| | - Adam J Kirry
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53233
| | - Marieke R Gilmartin
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin 53233
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Yousuf H, Ehlers VL, Sehgal M, Song C, Moyer JR. Modulation of intrinsic excitability as a function of learning within the fear conditioning circuit. Neurobiol Learn Mem 2019; 167:107132. [PMID: 31821881 DOI: 10.1016/j.nlm.2019.107132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/27/2019] [Indexed: 11/28/2022]
Abstract
Experience-dependent neuronal plasticity is a fundamental substrate of learning and memory. Intrinsic excitability is a form of neuronal plasticity that can be altered by learning and indicates the pattern of neuronal responding to external stimuli (e.g. a learning or synaptic event). Associative fear conditioning is one form of learning that alters intrinsic excitability, reflecting an experience-dependent change in neuronal function. After fear conditioning, intrinsic excitability changes are evident in brain regions that are a critical part of the fear circuit, including the amygdala, hippocampus, retrosplenial cortex, and prefrontal cortex. Some of these changes are transient and/or reversed by extinction as well as learning-specific (i.e. they are not observed in neurons from control animals). This review will explore how intrinsic neuronal excitability changes within brain structures that are critical for fear learning, and it will also discuss evidence promoting intrinsic excitability as a vital mechanism of associative fear memories. This work has raised interesting questions regarding the role of fear learning in changes of intrinsic excitability within specific subpopulations of neurons, including those that express immediate early genes and thus demonstrate experience-dependent activity, as well as in neurons classified as having a specific firing type (e.g. burst-spiking vs. regular-spiking). These findings have interesting implications for how intrinsic excitability can serve as a neural substrate of learning and memory, and suggest that intrinsic plasticity within specific subpopulations of neurons may promote consolidation of the memory trace in a flexible and efficient manner.
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Affiliation(s)
- Hanna Yousuf
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Vanessa L Ehlers
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Megha Sehgal
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Chenghui Song
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - James R Moyer
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA; Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
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Zhang L, Chen X, Sindreu C, Lu S, Storm DR, Zweifel LS, Xia Z. Dynamics of a hippocampal neuronal ensemble encoding trace fear memory revealed by in vivo Ca2+ imaging. PLoS One 2019; 14:e0219152. [PMID: 31269057 PMCID: PMC6608968 DOI: 10.1371/journal.pone.0219152] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/17/2019] [Indexed: 11/18/2022] Open
Abstract
Although the biochemical signaling events in area CA1 of the hippocampus underlying memory acquisition, consolidation, retrieval, and extinction have been extensively studied, little is known about the activity dynamics of hippocampal neurons in CA1 during Pavlovian fear conditioning. Here, we use fiber-optic confocal microscopy coupled with the calcium indicator GCaMP6m to monitor neuron activity in freely moving mice during trace fear conditioning. We show that the activity of a group of CA1 neurons increases not only after the stimulus presentations, but also during the stimulus-free trace period when the conditioned mice exhibit a high level of freezing behavior. Therefore, we designate these cells “trace cells”. Interestingly, the activity of the trace cells increases in response to the conditioned stimuli during memory retrieval but diminishes during memory extinction. Importantly, the dynamics of neuron activity exhibit a high degree of correlation with the freezing behavior of the mice, suggesting that a neuronal ensemble responsible for encoding the trace fear memory is repeatedly reactivated during memory retrieval and later extinguished during memory extinction.
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Affiliation(s)
- Liang Zhang
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America
| | - Xuanmao Chen
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Carlos Sindreu
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Song Lu
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America
| | - Daniel R. Storm
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Larry S. Zweifel
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, United States of America
| | - Zhengui Xia
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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Huang CCY, Muszynski KJ, Bolshakov VY, Balu DT. Deletion of Dtnbp1 in mice impairs threat memory consolidation and is associated with enhanced inhibitory drive in the amygdala. Transl Psychiatry 2019; 9:132. [PMID: 30967545 PMCID: PMC6456574 DOI: 10.1038/s41398-019-0465-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 03/23/2019] [Indexed: 11/19/2022] Open
Abstract
Schizophrenia is a severe and highly heritable disorder. Dystrobrevin-binding protein 1 (DTNBP1), also known as dysbindin-1, has been implicated in the pathophysiology of schizophrenia. Specifically, dysbindin-1 mRNA and protein expression are decreased in the brains of subjects with this disorder. Mice lacking dysbinidn-1 also display behavioral phenotypes similar to those observed in schizophrenic patients. However, it remains unknown whether deletion of dysbindin-1 impacts functions of the amygdala, a brain region that is critical for emotional processing, which is disrupted in patients with schizophrenia. Here, we show that dysbindin-1 is expressed in both excitatory and inhibitory neurons of the basolateral amygdala (BLA). Deletion of dysbindin-1 in male mice (Dys-/-) impaired cued and context-dependent threat memory, without changes in measures of anxiety. The behavioral deficits observed in Dys-/- mice were associated with perturbations in the BLA, including the enhancement of GABAergic inhibition of pyramidal neurons, increased numbers of parvalbumin interneurons, and morphological abnormalities of dendritic spines on pyramidal neurons. Our findings highlight an important role for dysbindin-1 in the regulation of amygdalar function and indicate that enhanced inhibition of BLA pyramidal neuron activity may contribute to the weakened threat memory expression observed in Dys-/- mice.
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Affiliation(s)
- Cathy C Y Huang
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
- Translational Psychiatry laboratory, McLean Hospital, Belmont, MA, USA.
- Department of Life Sciences, National Central University, Taoyuan, Taiwan.
| | - Kevin J Muszynski
- Translational Psychiatry laboratory, McLean Hospital, Belmont, MA, USA
| | - Vadim Y Bolshakov
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
- Cellular Neurobiology laboratory, McLean Hospital, Belmont, MA, USA
| | - Darrick T Balu
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
- Translational Psychiatry laboratory, McLean Hospital, Belmont, MA, USA.
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Estrous cycle stage gates sex differences in prefrontal muscarinic control of fear memory formation. Neurobiol Learn Mem 2019; 161:26-36. [PMID: 30851433 DOI: 10.1016/j.nlm.2019.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 02/08/2019] [Accepted: 03/05/2019] [Indexed: 11/20/2022]
Abstract
The association of a sensory cue and an aversive footshock that are separated in time, as in trace fear conditioning, requires persistent activity in prelimbic cortex during the cue-shock interval. The activation of muscarinic acetylcholine receptors has been shown to facilitate persistent firing of cortical cells in response to brief stimulation, and muscarinic antagonists in the prefrontal cortex impair working memory. It is unknown, however, if the acquisition of associative trace fear conditioning is dependent on muscarinic signaling in the prefrontal cortex. Here, we delivered the muscarinic receptor antagonist scopolamine to the prelimbic cortex of rats prior to trace fear conditioning and tested their memories of the cue and training context the following day. The effect of scopolamine on working memory performance was also tested using a spatial delayed non-match to sample task. Male and female subjects were included to examine potential sex differences in the modulation of memory formation, as we have previously observed for pituitary adenylate cyclase-activating polypeptide signaling in the prefrontal cortex (Kirry et al., 2018). We found that pre-training administration of intra-prelimbic scopolamine impaired the formation of cued and contextual fear memories in males, but not females at a dose that impairs spatial working memory in both sexes. Fear memory formation in females was impaired by a higher dose of scopolamine and this impairment was gated by estrous cycle stage: scopolamine failed to impair memory in rats in the diestrus or proestrus stages of the estrous cycle. These findings add to the growing body of evidence that the prefrontal cortex is sexually dimorphic in learning and memory and additionally suggest that males and females differentially engage prefrontal neuromodulatory systems in support of learning.
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16
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Wotjak CT. Sound check, stage design and screen plot - how to increase the comparability of fear conditioning and fear extinction experiments. Psychopharmacology (Berl) 2019; 236:33-48. [PMID: 30470861 PMCID: PMC6373201 DOI: 10.1007/s00213-018-5111-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/05/2018] [Indexed: 11/16/2022]
Abstract
In the recent decade, fear conditioning has evolved as a standard procedure for testing cognitive abilities such as memory acquisition, consolidation, recall, reconsolidation, and extinction, preferentially in genetically modified mice. The reasons for the popularity of this powerful approach are its ease to perform, the short duration of training and testing, and its well-described neural basis. So why to bother about flaws in standardization of test procedures and analytical routines? Simplicity does not preclude the existence of fallacies. A short survey of the literature revealed an indifferent use of acoustic stimuli in terms of quality (i.e., white noise vs. sine wave), duration, and intensity. The same applies to the shock procedures. In the present article, I will provide evidence for the importance of qualitative and quantitative parameters of conditioned and unconditioned stimuli for the experimental outcome. Moreover, I will challenge frequently applied interpretations of short-term vs. long-term extinction and spontaneous recovery. On the basis of these concerns, I suggest a guideline for standardization of fear conditioning experiments in mice to improve the comparability of the experimental data.
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Affiliation(s)
- Carsten T. Wotjak
- 0000 0000 9497 5095grid.419548.5Max Planck Institute of Psychiatry, RG “Neuronal Plasticity”, Kraepelinstr. 2-10, 80804 Munich, Germany
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Pituitary adenylate cyclase-activating polypeptide (PACAP) signaling in the prefrontal cortex modulates cued fear learning, but not spatial working memory, in female rats. Neuropharmacology 2018; 133:145-154. [DOI: 10.1016/j.neuropharm.2018.01.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 12/04/2017] [Accepted: 01/07/2018] [Indexed: 11/19/2022]
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Serine Racemase and D-serine in the Amygdala Are Dynamically Involved in Fear Learning. Biol Psychiatry 2018; 83:273-283. [PMID: 29025687 PMCID: PMC5806199 DOI: 10.1016/j.biopsych.2017.08.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 02/05/2023]
Abstract
BACKGROUND The amygdala is a central component of the neural circuitry that underlies fear learning. N-methyl-D-aspartate receptor-dependent plasticity in the amygdala is required for pavlovian fear conditioning and extinction. N-methyl-D-aspartate receptor activation requires the binding of a coagonist, D-serine, which is synthesized from L-serine by the neuronal enzyme serine racemase (SR). However, little is known about SR and D-serine function in the amygdala. METHODS We used immunohistochemical methods to characterize the cellular localization of SR and D-serine in the mouse and human amygdala. Using biochemical and molecular techniques, we determined whether trace fear conditioning and extinction engages the SR/D-serine system in the brain. D-serine was administered systemically to mice to evaluate its effect on fear extinction. Finally, we investigated whether the functional single nucleotide polymorphism rs4523957, which is an expression quantitative trait locus of the human serine racemase (SRR) gene, was associated with fear-related phenotypes in a highly traumatized human cohort. RESULTS We demonstrate that approximately half of the neurons in the amygdala express SR, including both excitatory and inhibitory neurons. We find that the acquisition and extinction of fear memory engages the SR/D-serine system in the mouse amygdala and that D-serine administration facilitates fear extinction. We also demonstrate that the SRR single nucleotide polymorphism, rs4523957, is associated with posttraumatic stress disorder in humans, consistent with the facilitatory effect of D-serine on fear extinction. CONCLUSIONS These new findings have important implications for understanding D-serine-mediated N-methyl-D-aspartate receptor plasticity in the amygdala and how this system could contribute to disorders with maladaptive fear circuitry.
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19
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Kwapis JL, Jarome TJ, Ferrara NC, Helmstetter FJ. Updating Procedures Can Reorganize the Neural Circuit Supporting a Fear Memory. Neuropsychopharmacology 2017; 42:1688-1697. [PMID: 28139682 PMCID: PMC5518901 DOI: 10.1038/npp.2017.23] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 11/08/2022]
Abstract
Established memories undergo a period of vulnerability following retrieval, a process termed 'reconsolidation.' Recent work has shown that the hypothetical process of reconsolidation is only triggered when new information is presented during retrieval, suggesting that this process may allow existing memories to be modified. Reconsolidation has received increasing attention as a possible therapeutic target for treating disorders that stem from traumatic memories, yet little is known about how this process changes the original memory. In particular, it is unknown whether reconsolidation can reorganize the neural circuit supporting an existing memory after that memory is modified with new information. Here, we show that trace fear memory undergoes a protein synthesis-dependent reconsolidation process following exposure to a single updating trial of delay conditioning. Further, this reconsolidation-dependent updating process appears to reorganize the neural circuit supporting the trace-trained memory, so that it better reflects the circuit supporting delay fear. Specifically, after a trace-to-delay update session, the amygdala is now required for extinction of the updated memory but the retrosplenial cortex is no longer required for retrieval. These results suggest that updating procedures could be used to force a complex, poorly defined memory circuit to rely on a better-defined neural circuit that may be more amenable to behavioral or pharmacological manipulation. This is the first evidence that exposure to new information can fundamentally reorganize the neural circuit supporting an existing memory.
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Affiliation(s)
- Janine L Kwapis
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Timothy J Jarome
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Nicole C Ferrara
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Fred J Helmstetter
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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20
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Involvement of the prelimbic cortex in contextual fear conditioning with temporal and spatial discontinuity. Neurobiol Learn Mem 2017; 144:1-10. [PMID: 28577998 DOI: 10.1016/j.nlm.2017.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 05/02/2017] [Accepted: 05/04/2017] [Indexed: 12/12/2022]
Abstract
Time plays an important role in conditioning, it is not only possible to associate stimuli with events that overlap, as in delay fear conditioning, but it is also possible to associate stimuli that are discontinuous in time, as shown in trace conditioning for a discrete stimuli. The environment itself can be a powerful conditioned stimulus (CS) and be associated to unconditioned stimulus (US). Thus, the aim of the present study was to determine the parameters in which contextual fear conditioning occurs by the maintenance of a contextual representation over short and long time intervals. The results showed that a contextual representation can be maintained and associated after 5s, even in the absence of a 15s re-exposure to the training context before US delivery. The same effect was not observed with a 24h interval of discontinuity. Furthermore, optimal conditioned response with a 5s interval is produced only when the contexts (of pre-exposure and shock) match. As the pre-limbic cortex (PL) is necessary for the maintenance of a continuous representation of a stimulus, the involvement of the PL in this temporal and contextual processing was investigated. The reversible inactivation of the PL by muscimol infusion impaired the acquisition of contextual fear conditioning with a 5s interval, but not with a 24h interval, and did not impair delay fear conditioning. The data provided evidence that short and long intervals of discontinuity have different mechanisms, thus contributing to a better understanding of PL involvement in contextual fear conditioning and providing a model that considers both temporal and contextual factors in fear conditioning.
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21
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Koh MT, Shao Y, Sherwood A, Smith DR. Impaired hippocampal-dependent memory and reduced parvalbumin-positive interneurons in a ketamine mouse model of schizophrenia. Schizophr Res 2016; 171:187-94. [PMID: 26811256 PMCID: PMC4762714 DOI: 10.1016/j.schres.2016.01.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 01/09/2016] [Accepted: 01/11/2016] [Indexed: 01/23/2023]
Abstract
The hippocampus of patients with schizophrenia displays aberrant excess neuronal activity which affects cognitive function. Animal models of the illness have recapitulated the overactivity in the hippocampus, with a corresponding regionally localized reduction of inhibitory interneurons, consistent with that observed in patients. To better understand whether cognitive function is similarly affected in these models of hippocampal overactivity, we tested a ketamine mouse model of schizophrenia for cognitive performance in hippocampal- and medial prefrontal cortex (mPFC)-dependent tasks. We found that adult mice exposed to ketamine during adolescence were impaired on a trace fear conditioning protocol that relies on the integrity of the hippocampus. Conversely, the performance of the mice was normal on a delayed response task that is sensitive to mPFC damage. We confirmed that ketamine-exposed mice had reduced parvalbumin-positive interneurons in the hippocampus, specifically in the CA1, but not in the mPFC in keeping with the behavioral findings. These results strengthened the utility of the ketamine model for preclinical investigations of hippocampal overactivity in schizophrenia.
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Affiliation(s)
- Ming Teng Koh
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA.
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22
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Kim N, Kong MS, Jo KI, Kim EJ, Choi JS. Increased tone-offset response in the lateral nucleus of the amygdala underlies trace fear conditioning. Neurobiol Learn Mem 2015; 126:7-17. [PMID: 26524504 DOI: 10.1016/j.nlm.2015.10.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Revised: 10/19/2015] [Accepted: 10/21/2015] [Indexed: 10/22/2022]
Abstract
Accumulating evidence suggests that the lateral nucleus of the amygdala (LA) stores associative memory in the form of enhanced neural response to the sensory input following classical fear conditioning in which the conditioned stimulus (CS) and the unconditioned stimulus (US) are presented in a temporally continuous manner. However, little is known about the role of the LA in trace fear conditioning where the CS and the US are separated by a temporal gap. Single-unit recordings of LA neurons before and after trace fear conditioning revealed that the short-latency activity to the CS offset, but not that to the onset, increased significantly and accompanied the conditioned fear response. The increased short-latency activity was evident in two aspects: the number of offset-responsive neurons was increased and the latency of the neuronal response to the CS offset was shortened. On the contrary, changes in the firing rate to either the onset or the offset were negligible following unpaired presentations of the CS and US. In sum, our results suggest that increased synaptic efficacy in the CS offset pathway in the LA might underlie the association between temporally distant stimuli in trace fear conditioning.
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Affiliation(s)
- Namsoo Kim
- Department of Psychology, Korea University, 5-1, Anam-dong, Seongbuk-gu, Seoul, Republic of Korea; Department of Psychology and Neuroscience, Duke University, Durham, NC, USA
| | - Mi-Seon Kong
- Department of Psychology, Korea University, 5-1, Anam-dong, Seongbuk-gu, Seoul, Republic of Korea; Department of Psychology, University of Washington, Seattle, WA, USA
| | - Kyeong Im Jo
- Department of Psychology, Korea University, 5-1, Anam-dong, Seongbuk-gu, Seoul, Republic of Korea
| | - Eun Joo Kim
- Department of Psychology, Korea University, 5-1, Anam-dong, Seongbuk-gu, Seoul, Republic of Korea; Department of Psychology, University of Washington, Seattle, WA, USA
| | - June-Seek Choi
- Department of Psychology, Korea University, 5-1, Anam-dong, Seongbuk-gu, Seoul, Republic of Korea.
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23
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Gilmartin MR, Balderston NL, Helmstetter FJ. Prefrontal cortical regulation of fear learning. Trends Neurosci 2014; 37:455-64. [PMID: 24929864 PMCID: PMC4119830 DOI: 10.1016/j.tins.2014.05.004] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/07/2014] [Accepted: 05/13/2014] [Indexed: 11/29/2022]
Abstract
The prefrontal cortex regulates the expression of fear based on previously learned information. Recently, this brain area has emerged as being crucial in the initial formation of fear memories, providing new avenues to study the neurobiology underlying aberrant learning in anxiety disorders. Here we review the circumstances under which the prefrontal cortex is recruited in the formation of memory, highlighting relevant work in laboratory animals and human subjects. We propose that the prefrontal cortex facilitates fear memory through the integration of sensory and emotional signals and through the coordination of memory storage in an amygdala-based network.
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Affiliation(s)
- Marieke R Gilmartin
- Department of Psychology, University of Wisconsin-Milwaukee, 2441 E. Hartford Ave., Milwaukee, WI 53211, USA; Department of Biomedical Sciences, Marquette University, 561 N 15th Street, Milwaukee, WI 53233, USA.
| | - Nicholas L Balderston
- Department of Psychology, University of Wisconsin-Milwaukee, 2441 E. Hartford Ave., Milwaukee, WI 53211, USA
| | - Fred J Helmstetter
- Department of Psychology, University of Wisconsin-Milwaukee, 2441 E. Hartford Ave., Milwaukee, WI 53211, USA
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24
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Raybuck JD, Lattal KM. Bridging the interval: theory and neurobiology of trace conditioning. Behav Processes 2014; 101:103-11. [PMID: 24036411 PMCID: PMC3943893 DOI: 10.1016/j.beproc.2013.08.016] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/25/2013] [Accepted: 08/09/2013] [Indexed: 12/26/2022]
Abstract
An early finding in the behavioral analysis of learning was that conditioned responding weakens as the conditioned stimulus (CS) and unconditioned stimulus (US) are separated in time. This "trace" conditioning effect has been the focus of years of research in associative learning. Theoretical accounts of trace conditioning have focused on mechanisms that allow associative learning to occur across long intervals between the CS and US. These accounts have emphasized degraded contingency effects, timing mechanisms, and inhibitory learning. More recently, study of the neurobiology of trace conditioning has shown that even a short interval between the CS and US alters the circuitry recruited for learning. Here, we review some of the theoretical and neurobiological mechanisms underlying trace conditioning with an emphasis on recent studies of trace fear conditioning. Findings across many studies have implications not just for how we think about time and conditioning, but also for how we conceptualize fear conditioning in general, suggesting that circuitry beyond the usual suspects needs to be incorporated into current thinking about fear, learning, and anxiety.
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Affiliation(s)
- Jonathan D Raybuck
- Department of Behavioral Neuroscience, Oregon Health & Science University, United States.
| | - K Matthew Lattal
- Department of Behavioral Neuroscience, Oregon Health & Science University, United States.
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25
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Chau LS, Prakapenka A, Fleming SA, Davis AS, Galvez R. Elevated Arc/Arg 3.1 protein expression in the basolateral amygdala following auditory trace-cued fear conditioning. Neurobiol Learn Mem 2013; 106:127-33. [DOI: 10.1016/j.nlm.2013.07.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 06/28/2013] [Accepted: 07/11/2013] [Indexed: 01/09/2023]
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26
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Reis DS, Jarome TJ, Helmstetter FJ. Memory formation for trace fear conditioning requires ubiquitin-proteasome mediated protein degradation in the prefrontal cortex. Front Behav Neurosci 2013; 7:150. [PMID: 24167477 PMCID: PMC3805936 DOI: 10.3389/fnbeh.2013.00150] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/02/2013] [Indexed: 11/13/2022] Open
Abstract
The cellular mechanisms supporting plasticity during memory consolidation have been a subject of considerable interest. De novo protein and mRNA synthesis in several brain areas are critical, and more recently protein degradation, mediated by the ubiquitin-proteasome system (UPS), has been shown to be important. Previous work clearly establishes a relationship between protein synthesis and protein degradation in the amygdala, but it is unclear whether cortical mechanisms of memory consolidation are similar to those in the amygdala. Recent work demonstrating a critical role for prefrontal cortex (PFC) in the acquisition and consolidation of fear memory allows us to address this question. Here we use a PFC-dependent fear conditioning protocol to determine whether UPS mediated protein degradation is necessary for memory consolidation in PFC. Groups of rats were trained with auditory delay or trace fear conditioning and sacrificed 60 min after training. PFC tissue was then analyzed to quantify the amount of polyubiquibated protein. Other animals were trained with similar procedures but were infused with either a proteasome inhibitor (clasto-lactacystin β-lactone) or a translation inhibitor (anisomycin) in the PFC immediately after training. Our results show increased UPS-mediated protein degradation in the PFC following trace but not delay fear conditioning. Additionally, post-training proteasome or translation inhibition significantly impaired trace but not delay fear memory when tested the next day. Our results further support the idea that the PFC is critical for trace but not delay fear conditioning and highlight the role of UPS-mediated degradation as critical for synaptic plasticity.
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Affiliation(s)
- David S Reis
- Department of Psychology, University of Wisconsin-Milwaukee Milwaukee, WI, USA
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27
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Extinguishing trace fear engages the retrosplenial cortex rather than the amygdala. Neurobiol Learn Mem 2013; 113:41-54. [PMID: 24055593 DOI: 10.1016/j.nlm.2013.09.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/28/2013] [Accepted: 09/10/2013] [Indexed: 12/26/2022]
Abstract
Extinction learning underlies the treatment for a variety of anxiety disorders. Most of what is known about the neurobiology of extinction is based on standard "delay" fear conditioning, in which awareness is not required for learning. Little is known about how complex, explicit associations extinguish, however. "Trace" conditioning is considered to be a rodent model of explicit fear because it relies on both the cortex and hippocampus and requires explicit contingency awareness in humans. Here, we explore the neural circuit supporting trace fear extinction in order to better understand how complex memories extinguish. We first show that the amygdala is selectively involved in delay fear extinction; blocking intra-amygdala glutamate receptors disrupted delay, but not trace extinction. Further, ERK phosphorylation was increased in the amygdala after delay, but not trace extinction. We then identify the retrosplenial cortex (RSC) as a key structure supporting trace extinction. ERK phosphorylation was selectively increased in the RSC following trace extinction and blocking intra-RSC NMDA receptors impaired trace, but not delay extinction. These findings indicate that delay and trace extinction require different neural circuits; delay extinction requires plasticity in the amygdala whereas trace extinction requires the RSC. Anxiety disorders linked to explicit memory may therefore depend on cortical processes that have not been traditionally targeted by extinction studies based on delay fear.
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28
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Gilmartin MR, Miyawaki H, Helmstetter FJ, Diba K. Prefrontal activity links nonoverlapping events in memory. J Neurosci 2013; 33:10910-4. [PMID: 23804110 PMCID: PMC3693060 DOI: 10.1523/jneurosci.0144-13.2013] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 05/23/2013] [Accepted: 05/30/2013] [Indexed: 01/05/2023] Open
Abstract
The medial prefrontal cortex (mPFC) plays an important role in memory. By maintaining a working memory buffer, neurons in prelimbic (PL) mPFC may selectively contribute to learning associations between stimuli that are separated in time, as in trace fear conditioning (TFC). Until now, evidence for this bridging role was largely descriptive. Here we used optogenetics to silence neurons in the PL mPFC of rats during learning in TFC. Memory formation was prevented when mPFC was silenced specifically during the interval separating the cue and shock. Our results provide support for a working memory function for these cells and indicate that associating two noncontiguous stimuli requires bridging activity in PL mPFC.
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Affiliation(s)
- Marieke R Gilmartin
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA.
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29
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NR2A- and NR2B-containing NMDA receptors in the prelimbic medial prefrontal cortex differentially mediate trace, delay, and contextual fear conditioning. Learn Mem 2013; 20:290-4. [PMID: 23676200 DOI: 10.1101/lm.030510.113] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Activation of N-methyl-D-aspartate receptors (NMDAR) in the prelimbic medial prefrontal cortex (PL mPFC) is necessary for the acquisition of both trace and contextual fear memories, but it is not known how specific NR2 subunits support each association. The NR2B subunit confers unique properties to the NMDAR and may differentially regulate these two fear memories. Here we show that NR2A-containing NMDARs mediate trace, delay, and contextual fear memories, but NR2B-containing NMDARs are required only for trace conditioning, consistent with a role for PL mPFC in working memory.
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30
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Baysinger AN, Kent BA, Brown TH. Muscarinic receptors in amygdala control trace fear conditioning. PLoS One 2012; 7:e45720. [PMID: 23029199 PMCID: PMC3448705 DOI: 10.1371/journal.pone.0045720] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 08/24/2012] [Indexed: 11/18/2022] Open
Abstract
Intelligent behavior requires transient memory, which entails the ability to retain information over short time periods. A newly-emerging hypothesis posits that endogenous persistent firing (EPF) is the neurophysiological foundation for aspects or types of transient memory. EPF is enabled by the activation of muscarinic acetylcholine receptors (mAChRs) and is triggered by suprathreshold stimulation. EPF occurs in several brain regions, including the lateral amygdala (LA). The present study examined the role of amygdalar mAChRs in trace fear conditioning, a paradigm that requires transient memory. If mAChR-dependent EPF selectively supports transient memory, then blocking amygdalar mAChRs should impair trace conditioning, while sparing delay and context conditioning, which presumably do not rely upon transient memory. To test the EPF hypothesis, LA was bilaterally infused, prior to trace or delay conditioning, with either a mAChR antagonist (scopolamine) or saline. Computerized video analysis quantified the amount of freezing elicited by the cue and by the training context. Scopolamine infusion profoundly reduced freezing in the trace conditioning group but had no significant effect on delay or context conditioning. This pattern of results was uniquely anticipated by the EPF hypothesis. The present findings are discussed in terms of a systems-level theory of how EPF in LA and several other brain regions might help support trace fear conditioning.
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Affiliation(s)
- Amber N. Baysinger
- Department of Psychology, Yale University, New Haven, Connecticut, United States of America
| | - Brianne A. Kent
- Department of Psychology, Yale University, New Haven, Connecticut, United States of America
| | - Thomas H. Brown
- Department of Psychology, Yale University, New Haven, Connecticut, United States of America
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, United States of America
- * E-mail: .
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31
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Hunt PS. Supplemental choline during the periweaning period protects against trace conditioning impairments attributable to post-training ethanol exposure in adolescent rats. Behav Neurosci 2012; 126:593-8. [PMID: 22687150 DOI: 10.1037/a0028878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Supplemental choline during early stages of development can result in long-lasting improvements to memory function. In addition, pre- or postnatal choline has been shown to be protective against some of the adverse effects of early alcohol exposure. The present experiment examined whether supplemental choline given to rats would protect against the effects of posttraining alcohol administration on trace fear conditioning. Posttraining alcohol exposure in adolescent rats results in poor performance in this hippocampus-dependent task, although delay conditioning is unaffected. Here, rats were given an s.c. injection of either saline or choline chloride daily on postnatal days (PD) 15-26. On PD 30 subjects were trained in a trace fear conditioning procedure. For the next 3 days animals were administered 2.5 g/kg ethanol or water control, and conditional stimulus (CS)-elicited freezing was measured on PD 34. Results indicated that posttraining alcohol disrupted the expression of trace conditioning and that supplemental choline on PD 15-26 was protective against this effect. That is, choline-treated animals subsequently given posttraining ethanol performed as well as animals not given ethanol. These results indicate that supplemental choline given during the periweaning period protects against ethanol-induced impairments in a hippocampus-dependent learning task. Findings contribute to the growing literature showing improvements in learning and memory in subjects given extra dietary choline during critical periods of brain development.
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Affiliation(s)
- Pamela S Hunt
- Department of Psychology, College of William & Mary, Williamsburg, VA 23187-8795, USA.
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32
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Hayes DJ, Northoff G. Common brain activations for painful and non-painful aversive stimuli. BMC Neurosci 2012; 13:60. [PMID: 22676259 PMCID: PMC3464596 DOI: 10.1186/1471-2202-13-60] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 04/18/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Identification of potentially harmful stimuli is necessary for the well-being and self-preservation of all organisms. However, the neural substrates involved in the processing of aversive stimuli are not well understood. For instance, painful and non-painful aversive stimuli are largely thought to activate different neural networks. However, it is presently unclear whether there is a common aversion-related network of brain regions responsible for the basic processing of aversive stimuli. To help clarify this issue, this report used a cross-species translational approach in humans (i.e. meta-analysis) and rodents (i.e. systematic review of functional neuroanatomy). RESULTS Animal and human data combined to show a core aversion-related network, consisting of similar cortical (i.e. MCC, PCC, AI, DMPFC, RTG, SMA, VLOFC; see results section or abbreviation section for full names) and subcortical (i.e. Amyg, BNST, DS, Hab, Hipp/Parahipp, Hyp, NAc, NTS, PAG, PBN, raphe, septal nuclei, Thal, LC, midbrain) regions. In addition, a number of regions appeared to be more involved in pain-related (e.g. sensory cortex) or non-pain-related (e.g. amygdala) aversive processing. CONCLUSIONS This investigation suggests that aversive processing, at the most basic level, relies on similar neural substrates, and that differential responses may be due, in part, to the recruitment of additional structures as well as the spatio-temporal dynamic activity of the network. This network perspective may provide a clearer understanding of why components of this circuit appear dysfunctional in some psychiatric and pain-related disorders.
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Affiliation(s)
- Dave J Hayes
- Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa, 1145 Carling Avenue, Ottawa, K1Z 7K4, Canada
| | - Georg Northoff
- Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa, 1145 Carling Avenue, Ottawa, K1Z 7K4, Canada
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Photoperiod alters fear responses and basolateral amygdala neuronal spine density in white-footed mice (Peromyscus leucopus). Behav Brain Res 2012; 233:345-50. [PMID: 22652395 DOI: 10.1016/j.bbr.2012.05.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 04/23/2012] [Accepted: 05/18/2012] [Indexed: 11/20/2022]
Abstract
Photoperiodism is a biological phenomenon in which environmental day length is monitored to ascertain time of year to engage in seasonally appropriate adaptations. This trait is common among organisms living outside of the tropics. White-footed mice (Peromyscus leucopus) are small photoperiodic rodents which display a suite of adaptive responses to short day lengths, including reduced hippocampal volume, impairments in hippocampal-mediated memory, and enhanced hypothalamic-pituitary-adrenal axis reactivity. Because these photoperiodic changes in brain and behavior mirror some of the etiology of post-traumatic stress disorder (PTSD), we hypothesized that photoperiod may also alter fear memory and neuronal morphology within the hippocampus-basolateral amygdala-prefrontal cortex fear circuit. Ten weeks of exposure to short days increased fear memory in an auditory-cued fear conditioning test. Short days also increased dendritic spine density of the neurons of the basolateral amygdala, without affecting morphology of pyramidal neurons within the infralimbic region of the medial prefrontal cortex. Taken together, photoperiodic phenotypic changes in brain morphology and physiology induced by a single environmental factor, exposure to short day lengths, affect responses to fearful stimuli in white-footed mice. These results have potential implications for understanding seasonal changes in fear responsiveness, as well as for expanding translational animal models for studying gene-environment interactions underlying psychiatric diseases, such as PTSD.
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Maiya R, Kharazia V, Lasek AW, Heberlein U. Lmo4 in the basolateral complex of the amygdala modulates fear learning. PLoS One 2012; 7:e34559. [PMID: 22509321 PMCID: PMC3317997 DOI: 10.1371/journal.pone.0034559] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 03/02/2012] [Indexed: 01/03/2023] Open
Abstract
Pavlovian fear conditioning is an associative learning paradigm in which mice learn to associate a neutral conditioned stimulus with an aversive unconditioned stimulus. In this study, we demonstrate a novel role for the transcriptional regulator Lmo4 in fear learning. LMO4 is predominantly expressed in pyramidal projection neurons of the basolateral complex of the amygdala (BLC). Mice heterozygous for a genetrap insertion in the Lmo4 locus (Lmo4gt/+), which express 50% less Lmo4 than their wild type (WT) counterparts display enhanced freezing to both the context and the cue in which they received the aversive stimulus. Small-hairpin RNA-mediated knockdown of Lmo4 in the BLC, but not the dentate gyrus region of the hippocampus recapitulated this enhanced conditioning phenotype, suggesting an adult- and brain region-specific role for Lmo4 in fear learning. Immunohistochemical analyses revealed an increase in the number of c-Fos positive puncta in the BLC of Lmo4gt/+ mice in comparison to their WT counterparts after fear conditioning. Lastly, we measured anxiety-like behavior in Lmo4gt/+ mice and in mice with BLC-specific downregulation of Lmo4 using the elevated plus maze, open field, and light/dark box tests. Global or BLC-specific knockdown of Lmo4 did not significantly affect anxiety-like behavior. These results suggest a selective role for LMO4 in the BLC in modulating learned but not unlearned fear.
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Affiliation(s)
- Rajani Maiya
- Ernest Gallo Clinic and Research Center, Emeryville, California, United States of America.
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Trace and contextual fear conditioning are impaired following unilateral microinjection of muscimol in the ventral hippocampus or amygdala, but not the medial prefrontal cortex. Neurobiol Learn Mem 2012; 97:452-64. [PMID: 22469748 DOI: 10.1016/j.nlm.2012.03.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/21/2012] [Accepted: 03/18/2012] [Indexed: 11/23/2022]
Abstract
Trace fear conditioning, in which a brief empty "trace interval" occurs between presentation of the CS and UCS, differs from standard delay conditioning in that contributions from both the hippocampus and prelimbic medial prefrontal cortex (PL mPFC) are required to form a normal long term memory. Little is currently known about how the PL interacts with various temporal lobe structures to support learning across this temporal gap between stimuli. We temporarily inactivated PL along with either ventral hippocampus or amygdala in a disconnection design to determine if these structures functionally interact to acquire trace fear conditioning. Disconnection (contralateral injections) of the PL with either the ventral hippocampus or amygdala impaired trace fear conditioning; however, ipsilateral control rats were also impaired. Follow-up experiments examined the effects of unilateral inactivation of the PL, ventral hippocampus, or amygdala during conditioning. The results of this study demonstrate that unilateral inactivation of the ventral hippocampus or amygdala impairs memory, while bilateral inactivation of the PL is required to produce a deficit. Memory deficits after unilateral inactivation of the ventral hippocampus or amygdala prevent us from determining whether the mPFC functionally interacts with the medial temporal lobe using a disconnection approach. Nonetheless, our findings suggest that the trace fear network is more integrated than previously thought.
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