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Learning & Memory

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https://www.readbyqxmd.com/read/28814475/developmental-pathway-genes-and-neural-plasticity-underlying-emotional-learning-and-stress-related-disorders
#1
Marissa E Maheu, Kerry J Ressler
The manipulation of neural plasticity as a means of intervening in the onset and progression of stress-related disorders retains its appeal for many researchers, despite our limited success in translating such interventions from the laboratory to the clinic. Given the challenges of identifying individual genetic variants that confer increased risk for illnesses like depression and post-traumatic stress disorder, some have turned their attention instead to focusing on so-called "master regulators" of plasticity that may provide a means of controlling these potentially impaired processes in psychiatric illnesses...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814474/role-of-the-bed-nucleus-of-the-stria-terminalis-in-aversive-learning-and-memory
#2
Travis D Goode, Stephen Maren
Surviving threats in the environment requires brain circuits for detecting (or anticipating) danger and for coordinating appropriate defensive responses (e.g., increased cardiac output, stress hormone release, and freezing behavior). The bed nucleus of the stria terminalis (BNST) is a critical interface between the "affective forebrain"-including the amygdala, ventral hippocampus, and medial prefrontal cortex-and the hypothalamic and brainstem areas that have been implicated in neuroendocrine, autonomic, and behavioral responses to actual or anticipated threats...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814473/breaking-boundaries-optimizing-reconsolidation-based-interventions-for-strong-and-old-memories
#3
James W B Elsey, Merel Kindt
Recent research has demonstrated that consolidated memories can enter a temporary labile state after reactivation, requiring restabilization in order to persist. This process, known as reconsolidation, potentially allows for the modification and disruption of memory. Much interest in reconsolidation stems from the possibility that maladaptive memory traces-a core feature of several psychiatric conditions-could be tackled by disrupting their reconsolidation. However, research has indicated a range of supposed boundary conditions on the induction of reconsolidation...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814472/neurobiology-of-fear-and-specific-phobias
#4
René Garcia
Fear, which can be expressed innately or after conditioning, is triggered when a danger or a stimulus predicting immediate danger is perceived. Its role is to prepare the body to face this danger. However, dysfunction in fear processing can lead to psychiatric disorders in which fear outweighs the danger or possibility of harm. Although recognized as highly debilitating, pathological fear remains insufficiently treated, indicating the importance of research on fear processing. The neurobiological basis of normal and pathological fear reactions is reviewed in this article...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814471/novelty-and-fear-conditioning-induced-gene-expression-in-high-and-low-states-of-anxiety
#5
Melanie P Donley, Jeffrey B Rosen
Emotional states influence how stimuli are interpreted. High anxiety states in humans lead to more negative, threatening interpretations of novel information, typically accompanied by activation of the amygdala. We developed a handling protocol that induces long-lasting high and low anxiety-like states in rats to explore the role of state anxiety on brain activation during exposure to a novel environment and fear conditioning. In situ hybridization of the inducible transcription factor Egr-1 found increased gene expression in the lateral nucleus of the amygdala (LA) following exposure to a novel environment and contextual fear conditioning in high anxiety-like rats...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814470/a-dangerous-context-changes-the-way-that-rats-learn-about-and-discriminate-between-innocuous-events-in-sensory-preconditioning
#6
Nathan M Holmes, R Frederick Westbrook
Four experiments used a sensory preconditioning protocol to examine how a dangerous context influences learning about innocuous events. In Experiments 1, 2, and 3, rats were exposed to presentations of a tone followed immediately or 20-sec later by presentations of a light. These tone-light pairings occurred in a context that was either familiar and safe, or equally familiar but dangerous, that is, it was a context in which rats had been exposed to footshock. Rats were next exposed to parings of the light and shock and then tested with the tone (and light)...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814469/characterization-of-the-amplificatory-effect-of-norepinephrine-in-the-acquisition-of-pavlovian-threat-associations
#7
Lorenzo Díaz-Mataix, Walter T Piper, Hillary C Schiff, Clark H Roberts, Vincent D Campese, Robert M Sears, Joseph E LeDoux
The creation of auditory threat Pavlovian memory requires an initial learning stage in which a neutral conditioned stimulus (CS), such as a tone, is paired with an aversive one (US), such as a shock. In this phase, the CS acquires the capacity of predicting the occurrence of the US and therefore elicits conditioned defense responses. Norepinephrine (NE), through β-adrenergic receptors in the amygdala, enhances threat memory by facilitating the acquisition of the CS-US association, but the nature of this effect has not been described...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814468/persistent-effects-of-acute-stress-on-fear-and-drug-seeking-in-a-novel-model-of-the-comorbidity-between-post-traumatic-stress-disorder-and-addiction
#8
Christie L Pizzimenti, Tom M Navis, K Matthew Lattal
Even following long periods of abstinence, individuals with anxiety disorders have high rates of relapse to drugs of abuse. Although many current models of relapse demonstrate effects of acute stress on drug-seeking, most of these studies examine stressful experiences that occur in close temporal and physical proximity to the reinstatement test. Here, we assess the effects of a stressful experience in one context on fear and drug-seeking in a different context. We adapt the stress-enhanced fear learning procedure to examine impacts on drug-seeking long after the stressful experience occurred...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814467/input-from-the-medial-geniculate-nucleus-modulates-amygdala-encoding-of-fear-memory-discrimination
#9
Nicole C Ferrara, Patrick K Cullen, Shane P Pullins, Elena K Rotondo, Fred J Helmstetter
Generalization of fear can involve abnormal responding to cues that signal safety and is common in people diagnosed with post-traumatic stress disorder. Differential auditory fear conditioning can be used as a tool to measure changes in fear discrimination and generalization. Most prior work in this area has focused on elevated amygdala activity as a critical component underlying generalization. The amygdala receives input from auditory cortex as well as the medial geniculate nucleus (MgN) of the thalamus, and these synapses undergo plastic changes in response to fear conditioning and are major contributors to the formation of memory related to both safe and threatening cues...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814466/interaction-of-induced-anxiety-and-verbal-working-memory-influence-of-trait-anxiety
#10
Nilam Patel, Catherine Stoodley, Daniel S Pine, Christian Grillon, Monique Ernst
This study examines the influence of trait anxiety on working memory (WM) in safety and threat. Interactions between experimentally induced anxiety and WM performance (on different cognitive loads) have been reported in healthy, nonanxious subjects. Differences in trait anxiety may moderate these interactions. Accordingly, these interactions may be potentiated by high trait anxiety (HTA), or show a resilient pattern that protects cognitive performance. HTA and low trait anxiety (LTA) were defined by a median split of scores on the trait component of the state-trait anxiety inventory...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814465/the-ventromedial-prefrontal-cortex-in-a-model-of-traumatic-stress-fear-inhibition-or-contextual-processing
#11
Zachary T Pennington, Austin S Anderson, Michael S Fanselow
The ventromedial prefrontal cortex (vmPFC) has consistently appeared altered in post-traumatic stress disorder (PTSD). Although the vmPFC is thought to support the extinction of learned fear responses, several findings support a broader role for this structure in the regulation of fear. To further characterize the relationship between vmPFC dysfunction and responses to traumatic stress, we examined the effects of pretraining vmPFC lesions on trauma reactivity and enhanced fear learning in a rodent model of PTSD...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814464/on-the-transition-from-reconsolidation-to-extinction-of-contextual-fear-memories
#12
Lindsey F Cassini, Charlotte R Flavell, Olavo B Amaral, Jonathan L C Lee
Retrieval of an associative memory can lead to different phenomena. Brief reexposure sessions tend to trigger reconsolidation, whereas more extended ones trigger extinction. In appetitive and fear cued Pavlovian memories, an intermediate "null point" period has been observed where neither process seems to be engaged. Here we investigated whether this phenomenon extends to contextual fear memory. Adult rats were subjected to a contextual fear conditioning paradigm, reexposed to the context 2 d later for 3, 5, 10, 20, or 30 min, with immediate injections of MK-801 or saline following reexposure, and tested on the following day...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28814463/neurobiological-correlates-of-state-dependent-context-fear
#13
Mariah A A Meyer, Kevin A Corcoran, Helen J Chen, Sonia Gallego, Guanguan Li, Veda V Tiruveedhula, James M Cook, Jelena Radulovic
Retrieval of fear memories can be state-dependent, meaning that they are best retrieved if the brain states at encoding and retrieval are similar. Such states can be induced by activating extrasynaptic γ-aminobutyric acid type A receptors (GABAAR) with the broad α-subunit activator gaboxadol. However, the circuit mechanisms and specific subunits underlying gaboxadol's effects are not well understood. Here we show that gaboxadol induces profound changes of local and network oscillatory activity, indicative of discoordinated hippocampal-cortical activity, that were accompanied by robust and long-lasting state-dependent conditioned fear...
September 2017: Learning & Memory
https://www.readbyqxmd.com/read/28716958/%C3%AE-subunit-containing-gabaa-receptor-prevents-overgeneralization-of-fear-in-adult-mice
#14
Wen-Hua Zhang, Jin Zhou, Han-Qing Pan, Xiao-Yang Wang, Wei-Zhu Liu, Jun-Yu Zhang, Xiao-Ping Yin, Bing-Xing Pan
The role of δ subunit-containing GABAA receptor (GABAA(δ)R) in fear generalization is uncertain. Here, by using mice with or without genetic deletion of GABAA(δ)R and using protocols in which the conditioned tone stimuli were cross presented with different nonconditioned stimuli, we observed that when the two tone stimuli were largely similar, both genotypes froze similarly to either of them. However, when they differed markedly, the knockout mice froze much more than their wild-type littermates to the nonconditioned but not conditioned stimuli...
August 2017: Learning & Memory
https://www.readbyqxmd.com/read/28716957/ampa-receptors-control-fear-extinction-through-an-arc-dependent-mechanism
#15
Simon Trent, Philip Barnes, Jeremy Hall, Kerrie L Thomas
Activity-regulated cytoskeleton-associated protein (Arc) supports fear memory through synaptic plasticity events requiring actin cytoskeleton rearrangements. We have previously shown that reducing hippocampal Arc levels through antisense knockdown leads to the premature extinction of contextual fear. Here we show that the AMPA receptor antagonist CNQX elevates hippocampal Arc levels during extinction and blocks extinction that can be rescued by reducing Arc. Increasing Arc levels with CNQX also overcomes the actin-destabilizing properties of cytochalasin D and promotes extinction...
August 2017: Learning & Memory
https://www.readbyqxmd.com/read/28716956/a-comparison-of-behavioral-and-pharmacological-interventions-to-attenuate-reactivated-fear-memories
#16
Roque I Ferrer Monti, Joaquín M Alfei, Matías Mugnaini, Adrián M Bueno, Tom Beckers, Gonzalo P Urcelay, Victor A Molina
Two experiments using rats in a contextual fear memory preparation compared two approaches to reduce conditioned fear: (1) pharmacological reconsolidation blockade and (2) reactivation-plus-extinction training. In Experiment 1, we explored different combinations of reactivation-plus-extinction parameters to reduce conditioned fear and attenuate reacquisition. In Experiment 2, memory reactivation was followed by extinction training or administration of midazolam (MDZ) (vs. vehicle) to reduce conditioned fear and attenuate spontaneous recovery...
August 2017: Learning & Memory
https://www.readbyqxmd.com/read/28716955/acute-exercise-enhances-the-consolidation-of-fear-extinction-memory-and-reduces-conditioned-fear-relapse-in-a-sex-dependent-manner
#17
Courtney A Bouchet, Brian A Lloyd, Esteban C Loetz, Caroline E Farmer, Mykola Ostrovskyy, Natalie Haddad, Rebecca M Foright, Benjamin N Greenwood
Fear extinction-based exposure therapy is the most common behavioral therapy for anxiety and trauma-related disorders, but fear extinction memories are labile and fear tends to return even after successful extinction. The relapse of fear contributes to the poor long-term efficacy of exposure therapy. A single session of voluntary exercise can enhance the acquisition and consolidation of fear extinction in male rats, but the effects of exercise on relapse of fear after extinction are not well understood. Here, we characterized the effects of 2 h of voluntary exercise during the consolidation phase of contextual or auditory fear extinction learning on long-term fear extinction memory and renewal in adult, male and female, Long-Evans rats...
August 2017: Learning & Memory
https://www.readbyqxmd.com/read/28716954/synaptically-driven-phosphorylation-of-ribosomal-protein-s6-is-differentially-regulated-at-active-synapses-versus-dendrites-and-cell-bodies-by-mapk-and-pi3k-mtor-signaling-pathways
#18
Patricia Salgado Pirbhoy, Shannon Farris, Oswald Steward
High-frequency stimulation of the medial perforant path triggers robust phosphorylation of ribosomal protein S6 (rpS6) in activated dendritic domains and granule cell bodies. Here we dissect the signaling pathways responsible for synaptically driven rpS6 phosphorylation in the dentate gyrus using pharmacological agents to inhibit PI3-kinase/mTOR and MAPK/ERK-dependent kinases. Using phospho-specific antibodies for rpS6 at different sites (ser235/236 versus ser240/244), we show that delivery of the PI3-kinase inhibitor, wortmannin, decreased rpS6 phosphorylation throughout the somatodendritic compartment (granule cell layer, inner molecular layer, outer molecular layer), especially in granule cell bodies while sparing phosphorylation at activated synapses (middle molecular layer)...
August 2017: Learning & Memory
https://www.readbyqxmd.com/read/28716953/a-novel-in-vitro-analog-expressing-learning-induced-cellular-correlates-in-distinct-neural-circuits
#19
Harris A Weisz, Marcy L Wainwright, Riccardo Mozzachiodi
When presented with noxious stimuli, Aplysia exhibits concurrent sensitization of defensive responses, such as the tail-induced siphon withdrawal reflex (TSWR) and suppression of feeding. At the cellular level, sensitization of the TSWR is accompanied by an increase in the excitability of the tail sensory neurons (TSNs) that elicit the reflex, whereas feeding suppression is accompanied by decreased excitability of B51, a decision-making neuron in the feeding neural circuit. The goal of this study was to develop an in vitro analog coexpressing the above cellular correlates...
August 2017: Learning & Memory
https://www.readbyqxmd.com/read/28716952/differential-involvement-of-the-medial-prefrontal-cortex-across-variants-of-contextual-fear-conditioning
#20
Nicholas A Heroux, Patrese A Robinson-Drummer, Hollie R Sanders, Jeffrey B Rosen, Mark E Stanton
The context preexposure facilitation effect (CPFE) is a contextual fear conditioning paradigm in which learning about the context, acquiring the context-shock association, and retrieving/expressing contextual fear are temporally dissociated into three distinct phases. In contrast, learning about the context and the context-shock association happens concurrently in standard contextual fear conditioning (sCFC). By infusing the GABAA receptor agonist muscimol into medial prefrontal cortex (mPFC) in adolescent Long-Evans rats, the current set of experiments examined the functional role of the mPFC in each phase of the CPFE and sCFC...
August 2017: Learning & Memory
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