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Learning & Memory

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https://www.readbyqxmd.com/read/28716958/%C3%AE-subunit-containing-gabaa-receptor-prevents-overgeneralization-of-fear-in-adult-mice
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
https://www.readbyqxmd.com/read/28620079/starvation-promotes-odor-feeding-time-associations-in-flies
#8
Nitin Singh Chouhan, Reinhard Wolf, Martin Heisenberg
Starvation causes a motivational state that facilitates diverse behaviors such as feeding, walking, and search. Starved Drosophila can form odor/feeding-time associations but the role of starvation in encoding of "time" is poorly understood. Here we show that the extent of starvation is correlated with the fly's ability to establish odor/feeding-time memories. Prolonged starvation promotes odor/feeding-time associations after just a single cycle of reciprocal training. We also show that starvation is required for acquisition but is dispensable for retrieval of odor/feeding-time memory...
July 2017: Learning & Memory
https://www.readbyqxmd.com/read/28620078/role-of-the-anterior-cingulate-cortex-in-the-retrieval-of-novel-object-recognition-memory-after-a-long-delay
#9
Marie A Pezze, Hayley J Marshall, Kevin Cf Fone, Helen J Cassaday
Previous in vivo electrophysiological studies suggest that the anterior cingulate cortex (ACgx) is an important substrate of novel object recognition (NOR) memory. However, intervention studies are needed to confirm this conclusion and permanent lesion studies cannot distinguish effects on encoding and retrieval. The interval between encoding and retrieval tests may also be a critical determinant of the role of the ACgx. The current series of experiments used micro-infusion of the GABAA receptor agonist, muscimol, into ACgx to reversibly inactivate the area and distinguish its role in encoding and retrieval...
July 2017: Learning & Memory
https://www.readbyqxmd.com/read/28620077/the-influence-of-recollection-and-familiarity-in-the-formation-and-updating-of-associative-representations
#10
Jason D Ozubko, Morris Moscovitch, Gordon Winocur
Prior representations affect future learning. Little is known, however, about the effects of recollective or familiarity-based representations on such learning. We investigate the ability to reuse or reassociate elements from recollection- and familiarity-based associations to form new associations. Past neuropsychological research suggests that hippocampal, and presumably recollective, representations are more flexible than extra-hippocampal, presumably familiarity-based, representations. We therefore hypothesize that the elements of recollective associations, as opposed to familiarity-based representations, may be more easily manipulated and decoupled from each other, and facilitate the formation of new associations...
July 2017: Learning & Memory
https://www.readbyqxmd.com/read/28620076/superior-long-term-synaptic-memory-induced-by-combining-dual-pharmacological-activation-of-pka-and-erk-with-an-enhanced-training-protocol
#11
Rong-Yu Liu, Curtis Neveu, Paul Smolen, Leonard J Cleary, John H Byrne
Developing treatment strategies to enhance memory is an important goal of neuroscience research. Activation of multiple biochemical signaling cascades, such as the protein kinase A (PKA) and extracellular signal-regulated kinase (ERK) pathways, is necessary to induce long-term synaptic facilitation (LTF), a correlate of long-term memory (LTM). Previously, a computational model was developed which correctly predicted a novel enhanced training protocol that augmented LTF by searching for the protocol with maximal overlap of PKA and ERK activation...
July 2017: Learning & Memory
https://www.readbyqxmd.com/read/28620075/experience-dependent-epigenomic-reorganization-in-the-hippocampus
#12
Corey G Duke, Andrew J Kennedy, Cristin F Gavin, Jeremy J Day, J David Sweatt
Using a hippocampus-dependent contextual threat learning and memory task, we report widespread, coordinated DNA methylation changes in CA1 hippocampus of Sprague-Dawley rats specific to threat learning at genes involved in synaptic transmission. Experience-dependent alternations in gene expression and DNA methylation were observed as early as 1 h following memory acquisition and became more pronounced after 24 h. Gene ontology analysis revealed significant enrichment of functional categories related to synaptic transmission in genes that were hypomethylated at 24 h following threat learning...
July 2017: Learning & Memory
https://www.readbyqxmd.com/read/28620074/regulatory-bc1-rna-in-cognitive-control
#13
Anna Iacoangeli, Aderemi Dosunmu, Taesun Eom, Dimitre G Stefanov, Henri Tiedge
Dendritic regulatory BC1 RNA is a non-protein-coding (npc) RNA that operates in the translational control of gene expression. The absence of BC1 RNA in BC1 knockout (KO) animals causes translational dysregulation that entails neuronal phenotypic alterations including prolonged epileptiform discharges, audiogenic seizure activity in vivo, and excessive cortical oscillations in the γ frequency band. Here we asked whether BC1 RNA control is also required for higher brain functions such as learning, memory, or cognition...
July 2017: Learning & Memory
https://www.readbyqxmd.com/read/28507036/medial-prefrontal-cortex-and-dorsomedial-striatum-are-necessary-for-the-trial-unique-delayed-nonmatching-to-location-tunl-task-in-rats-role-of-nmda-receptors
#14
Don A Davies, Jessica L Hurtubise, Quentin Greba, John G Howland
The trial-unique, delayed nonmatching-to-location (TUNL) task is a recently developed behavioral task that measures spatial working memory and a form of pattern separation in touchscreen-equipped operant conditioning chambers. Limited information exists regarding the neurotransmitters and neural substrates involved in the task. The present experiments tested the effects of systemic and intracranial injections of NMDA receptor antagonists on the TUNL task. After training, male Long Evans rats systemically injected with the competitive NMDA receptor antagonist CPP (10 mg/kg) had impaired accuracy regardless of the degree of stimuli separation or length of delay between the sample and test phases...
June 2017: Learning & Memory
https://www.readbyqxmd.com/read/28507035/long-term-sensitization-training-in-aplysia-decreases-the-excitability-of-a-decision-making-neuron-through-a-sodium-dependent-mechanism
#15
John S Hernandez, Marcy L Wainwright, Riccardo Mozzachiodi
In Aplysia, long-term sensitization (LTS) occurs concurrently with a suppression of feeding. At the cellular level, the suppression of feeding is accompanied by decreased excitability of decision-making neuron B51. We examined the contribution of voltage-gated Na(+) and K(+) channels to B51 decreased excitability. In a pharmacologically isolated Na(+) channels environment, LTS training significantly increased B51 firing threshold, compared with untrained controls. Conversely, in a pharmacologically isolated K(+) channels environment, no differences were observed between trained and untrained animals in either amplitude or area of B51 K(+)-dependent depolarizations...
June 2017: Learning & Memory
https://www.readbyqxmd.com/read/28507034/sleep-supports-inhibitory-operant-conditioning-memory-in-aplysia
#16
Albrecht P A Vorster, Jan Born
Sleep supports memory consolidation as shown in mammals and invertebrates such as bees and Drosophila. Here, we show that sleep's memory function is preserved in Aplysia californica with an even simpler nervous system. Animals performed on an inhibitory conditioning task ("learning that a food is inedible") three times, at Training, Retrieval 1, and Retrieval 2, with 17-h intervals between tests. Compared with Wake animals, remaining awake between Training and Retrieval 1, Sleep animals with undisturbed post-training sleep, performed significantly better at Retrieval 1 and 2...
June 2017: Learning & Memory
https://www.readbyqxmd.com/read/28507033/response-specific-sex-difference-in-the-retention-of-fear-extinction
#17
Meagan E Voulo, Ryan G Parsons
Fear conditioning studies in rodents allow us to assess vulnerability factors which might underlie fear-based psychopathology such as post-traumatic stress disorder (PTSD). Despite PTSD being more prevalent in females than males, very few fear conditioning studies in rodents have tested females. Our study assessed fear conditioning and extinction in male and female rats using both fear-potentiated startle and freezing behavior as measures. Rats were trained to fear cues that predicted the occurrence of shock and then subsequently exposed to an extinction training procedure where the cue was presented repeatedly in the absence of shock...
June 2017: Learning & Memory
https://www.readbyqxmd.com/read/28507032/%C3%AE-2-nicotinic-acetylcholine-receptors-influence-hippocampus-dependent-learning-and-memory-in-adolescent-mice
#18
Shahrdad Lotfipour, Celina Mojica, Sakura Nakauchi, Marcela Lipovsek, Sarah Silverstein, Jesse Cushman, James Tirtorahardjo, Andrew Poulos, Ana Belén Elgoyhen, Katumi Sumikawa, Michael S Fanselow, Jim Boulter
The absence of α2* nicotinic acetylcholine receptors (nAChRs) in oriens lacunosum moleculare (OLM) GABAergic interneurons ablate the facilitation of nicotine-induced hippocampal CA1 long-term potentiation and impair memory. The current study delineated whether genetic mutations of α2* nAChRs (Chrna2(L9'S/L9'S) and Chrna2(KO)) influence hippocampus-dependent learning and memory and CA1 synaptic plasticity. We substituted a serine for a leucine (L9'S) in the α2 subunit (encoded by the Chrna2 gene) to make a hypersensitive nAChR...
June 2017: Learning & Memory
https://www.readbyqxmd.com/read/28507031/memory-consolidation-within-the-central-amygdala-is-not-necessary-for-modulation-of-cerebellar-learning
#19
Adam B Steinmetz, Ka H Ng, John H Freeman
Amygdala lesions impair, but do not prevent, acquisition of cerebellum-dependent eyeblink conditioning suggesting that the amygdala modulates cerebellar learning. Two-factor theories of eyeblink conditioning posit that a fast-developing memory within the amygdala facilitates slower-developing memory within the cerebellum. The current study tested this hypothesis by impairing memory consolidation within the amygdala with inhibition of protein synthesis, transcription, and NMDA receptors in rats. Rats given infusions of anisomycin or DRB into the central amygdala (CeA) immediately after each eyeblink conditioning session were severely impaired in contextual and cued fear conditioning, but were completely unimpaired in eyeblink conditioning...
June 2017: Learning & Memory
https://www.readbyqxmd.com/read/28416633/intrusions-in-episodic-memory-reconsolidation-or-interference
#20
Angela Klingmüller, Jeremy B Caplan, Tobias Sommer
It would be profoundly important if reconsolidation research in animals and other memory domains generalized to human episodic memory. A 3-d-list-discrimination procedure, based on free recall of objects, with a contextual reminder cue (the testing room), has been thought to demonstrate reconsolidation of human episodic memory (as noted in a previous study). Our goal was to replicate the central result, a high intrusion rate during recall of the target list, and evaluate the reconsolidation account relative to an alternative account, based on state-dependent learning and interference...
May 2017: Learning & Memory
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