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Neurobiology of Learning and Memory

Enmanuelle Pardilla-Delgado, Jessica D Payne
While the influence of sleep on memory has a long history, sleep's role in the formation of false memories is less clear. Moreover, virtually nothing is known about the development of false memories beyond delays of about 12 hours. Here, for the first time, we assess post-sleep development of true and false memories across longer delay intervals of 24 and 48 hours. Although technically a false memory, remembering information that is related to the theme, or gist, of an experience can be considered an adaptive process...
November 26, 2016: Neurobiology of Learning and Memory
Jörg Neubert, Katja Hillbrandt, Mathias Weymar, Alfons O Hamm, Julia Wendt
Inhibitory learning is an important factor for decreasing fear expression. We investigated conditioned inhibition of learned fear responses using conditioned excitors and inhibitors differing in fear-relevance in a sample of 48 healthy female students. To study the effect of stimulus fear-relevance, we used the fear potentiated startle paradigm in an AX+/BX- discrimination learning task with fear-relevant (spider) vs. fear-irrelevant (butterfly) pictures as CS+ (A) and CS- (B), respectively. We found that, during acquisition, participants with elevated fear of spiders showed stronger fear potentiated startle to AX+ compared to BX- when the inhibitor (B) was fear-irrelevant (butterfly) using both median split as well as correlational analyses...
November 26, 2016: Neurobiology of Learning and Memory
Diane J Kim, Nathan St Louis, Ralph A Molaro, Glenn T Hudson, Robert C Chorley, Brenda J Anderson
Psychological stressors elicit the anticipation of homeostatic challenge, whereas physical stressors are direct threats to homeostasis. Many rodent models of stress include both types of stressors, yet deficits, like those reported for working memory, are often attributed to psychological stress. To empirically test whether intermittent psychological stressors, such as repeated threats, are solely sufficient to impair spatial working memory, we developed a novel rodent model of stress that is restricted to the anticipation of threat, and free of direct physical challenge...
November 21, 2016: Neurobiology of Learning and Memory
Shira Meir Drexler, Oliver T Wolf
Glucocorticoids are secreted following exposure to stressful events. Their modulating role on memory reconsolidation, a post-retrieval process of re-stabilization, has been investigated only recently, at times with conflicting results. The goal of this review is twofold. First, to establish the modulating role of glucocorticoids on memory reconsolidation. Second, to point the potential factors and confounds that might explain the seemingly paradoxical findings. Here we review recent pharmacological studies, conducted in rodents and humans, which suggest a critical role of glucocorticoids in this post-retrieval process...
November 18, 2016: Neurobiology of Learning and Memory
Melanie M Pina, Christopher L Cunningham
Abstinent alcohol-dependent individuals experience an enduring sensitivity to cue-induced craving and relapse to drinking. There is considerable evidence indicating that structures within the midbrain and extended amygdala are involved in this process. Individually, the ventral tegmental area (VTA) and the bed nucleus of the stria terminalis (BNST) have been shown to modulate cue-induced ethanol-seeking behavior. It is hypothesized that cue-induced seeking is communicated through a direct projection from the BNST to VTA...
November 17, 2016: Neurobiology of Learning and Memory
Felix W Moll, Andreas Nieder
Single neuron activity in the corvid nidopallium caudolaterale (NCL), the supposed avian functional analog of the prefrontal cortex, represents associations of auditory with visual stimuli. This is of high adaptive value for songbirds that need to rely on audio-visual associations to communicate, find a mate or escape predators. However, it remains unclear whether NCL neurons can represent cross-modal associations in a modality invariant, abstract fashion. To dissociate between modality-dependent and modality-invariant NCL activity, we trained two crows to match auditory sample cues with visual test stimuli, and vice versa, across a temporal memory delay...
November 15, 2016: Neurobiology of Learning and Memory
Heidi C Meyer, David J Bucci
During adolescence, individuals experience a broad range of dynamic environments as they strive to establish independence. Learning to respond appropriately in both new and previously encountered environments requires that an individual identify and learn the meaning of cues indicating that a behavior is appropriate, or alternatively, that it should be altered or inhibited. Although the ability to regulate goal-directed behavior continues to develop across adolescence, the specific circumstances under which adolescents experience difficulty with inhibitory control remain unclear...
November 15, 2016: Neurobiology of Learning and Memory
Jakke Tamminen, Matthew A Lambon Ralph, Penelope A Lewis
Recent memories are spontaneously reactivated during sleep, leading to their gradual strengthening. Whether reactivation also mediates the integration of new memories with existing knowledge is unknown. We used targeted memory reactivation (TMR) during slow-wave sleep (SWS) to selectively cue reactivation of newly learned spoken words. While integration of new words into their phonological neighbourhood was observed in both cued and uncued words after sleep, TMR-triggered integration was predicted by the time spent in rapid eye movement (REM) sleep...
November 15, 2016: Neurobiology of Learning and Memory
Andrés Molero-Chamizo
The amygdala is one of the structures involved in the acquisition of conditioned taste aversion (CTA). Nevertheless, the specific roles that the nuclei of this structure play in CTA learning are controversial. Electrolytic lesions applied to the basolateral nucleus of the amygdala can eliminate or reduce the acquisition of this learning. This effect has been attributed to the involvement of fibers that pass through this nucleus and connect with other structures that are critical for CTA. Excitotoxic lesions may allow a clearer insight as to the potential involvement of this nucleus in the acquisition of CTA...
November 12, 2016: Neurobiology of Learning and Memory
Wen-Yu Tzeng, Chian-Fang G Cherng, Lung Yu, Ching-Yi Wang
The presence of companions renders decreases in cocaine-stimulated dopamine release in the nucleus accumbens and cocaine-induced conditioned place preference (CPP) magnitude. Limbic systems are widely believed to underlie the modulation of accumbal dopamine release and cocaine conditioning. Thus, this study aimed to assess whether intact basolateral nucleus of amygdala (BLA), dorsal hippocampus (DH), and dorsolateral striatum (DLS) is required for the companions-exerted suppressive effect on the cocaine-induced CPP...
November 11, 2016: Neurobiology of Learning and Memory
D Lana, J Di Russo, T Mello, G L Wenk, M G Giovannini
The present study was aimed at establishing whether the mTOR pathway and its downstream effector p70S6K in CA3 pyramidal neurons are under the modulation of the cholinergic input to trigger the formation of long term memories, similar to what we demonstrated in CA1 hippocampus. We performed in vivo behavioral experiments using the step down inhibitory avoidance test in adult Wistar rats to evaluate memory formation under different conditions. We examined the effects of rapamycin, an inhibitor of mTORC1 formation, scopolamine, a muscarinic receptor antagonist or mecamylamine, a nicotinic receptor antagonist, on short and long term memory formation and on the functionality of the mTOR pathway...
November 10, 2016: Neurobiology of Learning and Memory
Amber B Dunbar, Jane R Taylor
Interfering with memory reconsolidation has valuable potential to be used as a treatment for maladaptive memories and psychiatric disorders. Numerous studies suggest that reconsolidation-based therapies may benefit psychiatric populations, but much remains unanswered. After reviewing the literature in clinical and healthy human populations, we discuss some of the major limitations to reconsolidation studies and clinical application. Finally, we provide recommendations for developing improved reconsolidation-based treatments, namely exploiting known boundary conditions and focusing on a novel unconditioned stimulus-retrieval paradigm...
November 9, 2016: Neurobiology of Learning and Memory
Jacek Debiec, Regina M Sullivan
What an animal needs to learn to survive is altered dramatically as they change from dependence on the parent for protection to independence and reliance on self-defense. This transition occurs in most altricial animals, but our understanding of the behavioral neurobiology has mostly relied on the infant rat. The transformation from dependence to independence occurs over three weeks in pups and is accompanied by complex changes in responses to both natural and learned threats and the supporting neural circuitry...
November 4, 2016: Neurobiology of Learning and Memory
Jee Hyun Kim, Christina J Perry, Despina E Ganella, Heather B Madsen
Remembering and forgetting are fundamental features of an organism. Extinction is a type of forgetting where there is a decrease in the significance and/or the meaning of an associative memory when elements of that memory no longer predict one another. The neural mechanisms underlying extinction of fear memories have been extensively studied in the laboratory because extinction processes are clinically relevant to exposure therapies that treat anxiety disorders. However, only in the last decade have we begun to unveil the similarities and differences in plasticity underlying extinction across development...
November 4, 2016: Neurobiology of Learning and Memory
Laurie L Wellman, Mairen E Fitzpatrick, Olga Y Hallum, Amy M Sutton, Brook L Williams, Larry D Sanford
Fear conditioning associated with inescapable shock training (ST) and fearful context re-exposure (CR) alone can produce significant behavioral fear, a stress response and alterations in subsequent REM sleep. These alterations may vary among animals and are mediated by the basolateral nucleus of the amygdala (BLA). Here, we used the GABAA agonist, muscimol (Mus), to inactivate BLA prior to CR and examined the effects on sleep, freezing and stress-induced hyperthermia (SIH). Wistar rats (n=28) were implanted with electrodes for recording sleep, data loggers for recording core body temperature, and with cannulae aimed bilaterally into BLA...
November 3, 2016: Neurobiology of Learning and Memory
David Clewett, Michiko Sakaki, Shawn Nielsen, Giselle Petzinger, Mara Mather
Arousal's selective effects on cognition go beyond the simple enhancement of emotional stimuli, sometimes enhancing and other times impairing processing of proximal neutral information. Past work shows that arousal impairs encoding of subsequent neutral stimuli regardless of their top-down priority via the engagement of β-adrenoreceptors. In contrast, retrograde amnesia induced by emotional arousal can flip to enhancement when preceding neutral items are prioritized in top-down attention. Whether β-adrenoreceptors also contribute to this retrograde memory enhancement of goal-relevant neutral stimuli is unclear...
November 2, 2016: Neurobiology of Learning and Memory
Kathryn D Baker, Rick Richardson
Adolescents, both humans and rodents, exhibit a marked impairment in extinction of fear relative to younger and older groups which could be caused by a failure to efficiently recruit NMDA receptors (NMDARs) in adolescence. It is well-established that systemic administration of NMDAR antagonists (e.g., MK801) before extinction training impairs the retention of extinction in adult and juvenile rodents, but it is unknown whether this is also the case for adolescents. Therefore, in the present study we investigated the effect of pharmacologically manipulating the NMDAR on extinction retention in adolescent rats...
November 1, 2016: Neurobiology of Learning and Memory
Abbi R Hernandez, Jordan E Reasor, Leah M Truckenbrod, Katelyn N Lubke, Sarah A Johnson, Jennifer L Bizon, Andrew P Maurer, Sara N Burke
The ability to use information from the physical world to update behavioral strategies is critical for survival across species. The prefrontal cortex (PFC) supports behavioral flexibility; however, exactly how this brain structure interacts with sensory association cortical areas to facilitate the adaptation of response selection remains unknown. Given the role of the perirhinal cortex (PER) in higher-order perception and associative memory, the current study evaluated whether PFC-PER circuits are critical for the ability to perform biconditional object discriminations when the rule for selecting the rewarded object shifted depending on the animal's spatial location in a 2-arm maze...
November 1, 2016: Neurobiology of Learning and Memory
Luis Fernando Cobar, Li Yuan, Ayumu Tashiro
Place cells show location-specific firing patterns according to an animal's position in an environment and are thought to contribute to the spatial representation required for self-navigation. Decades of study have extensively characterized the properties of place cells and suggested the involvement of long-term potentiation (LTP), a long-lasting synaptic strengthening, in place cell activity. Here, we review the basic characteristics of place cell activity and the findings that support the idea that LTP contributes to the formation, maintenance, and plasticity of place cell activity...
October 26, 2016: Neurobiology of Learning and Memory
Maile A Henson, Charles J Tucker, Meilan Zhao, Serena M Dudek
Activity-dependent pruning of synaptic contacts plays a critical role in shaping neuronal circuitry in response to the environment during postnatal brain development. Although there is compelling evidence that shrinkage of dendritic spines coincides with synaptic long-term depression (LTD), and that LTD is accompanied by synapse loss, whether NMDA receptor (NMDAR)-dependent LTD is a required step in the progression toward synapse pruning is still unknown. Using repeated applications of NMDA to induce LTD in dissociated rat neuronal cultures, we found that synapse density, as measured by colocalization of fluorescent markers for pre- and postsynaptic structures, was decreased irrespective of the presynaptic marker used, post-treatment recovery time, and the dendritic location of synapses...
October 26, 2016: Neurobiology of Learning and Memory
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