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Neurobiology of Learning and Memory

N Müller, S Campbell, M Nonaka, T M Rost, G Pipa, B N Konrad, A Steiger, M Czisch, G Fernández, M Dresler, L Genzel
Variance in spatial abilities are thought to be determined by in utero levels of testosterone and oestrogen, measurable in adults by the length ratio of the 2nd and 4th digit (2D:4D). We confirmed the relationship between 2D:4D and spatial performance using rats in two different tasks (paired-associate task and watermaze) and replicated this in humans. We further clarified anatomical and functional brain correlates of the association between 2D:4D and spatial performance in humans.
April 21, 2018: Neurobiology of Learning and Memory
Liyu Li, Xiaoli Gao, Qiang Zhou
Impairment in fear extinction is widely viewed as a major contributor to, or even an underlying mechanism of, the pathogenesis of anxiety disorders and PTSD. Children with traumatic experience have a higher risk for developing anxiety disorders and PTSD in the adult. Little is known about the nature of fear memory extinction and its underlying mechanism during this period. Here we showed that while renewal of fear memory is context-specific in adult mice, it is absent in infant mice (P17). Using local injection of GABAa receptor antagonist picrotoxin, we found that there is no functional connectivity between infralimbic prefrontal cortex and hippocampus in P17 mice, while prefrontal cortex projection to amygdala is functioning...
April 20, 2018: Neurobiology of Learning and Memory
Ivan Skelin, Scott Kilianski, Bruce L McNaughton
Memory consolidation is a gradual process through which episodic memories become incorporated into long-term 'semantic' representations. It likely involves reactivation of neural activity encoding the recent experience during non-REM sleep. A critical prerequisite for memory consolidation is precise coordination of reactivation events between the hippocampus and cortical/subcortical structures, facilitated by the coupling of local field potential (LFP) oscillations (slow oscillations, sleep spindles and sharp wave/ripples) between these structures...
April 13, 2018: Neurobiology of Learning and Memory
Dana M Leidl, Belinda P P Lay, Cassandra Chakouch, R Frederick Westbrook, Nathan M Holmes
The present series of experiments pursued our recent findings that consolidation of a second-order fear memory requires neuronal activity, but not de novo protein synthesis, in the basolateral amygdala complex (BLA). It used a modified second-order conditioning protocol in which rats were exposed to S1-shock pairings in stage 1 and pairings of the serial S2-S1 compound and shock in stage 2. Experiment 1 showed that responding (freezing) to S2 in this protocol is conditional on its compounding with S1 in stage 2 (Experiment 1), and therefore, the result of associative formation...
April 12, 2018: Neurobiology of Learning and Memory
Vassilios Papaleonidopoulos, Costas Papatheodoropoulos
The hippocampus is a functionally heterogeneous structure with the cognitive and emotional signal processing ascribed to the dorsal (DH) and the ventral hippocampus (VH) respectively. However, the underlying mechanisms are poorly understood. Noradrenaline is released in hippocampus during emotional arousal modulating synaptic plasticity and memory consolidation through activation of β adrenergic receptors (β-ARs). Using recordings of field excitatory postsynaptic potentials from the CA1 field of adult rat hippocampal slices we demonstrate that long-term potentiation (LTP) induced either by theta-burst stimulation (TBS) that mimics a physiological firing pattern of hippocampal neurons or by high-frequency stimulation is remarkably more sensitive to β-AR activation in VH than in DH...
April 10, 2018: Neurobiology of Learning and Memory
Rose Chesworth, Laura H Corbit
A critical barrier to recovery from alcohol addiction is relapse propensity. Alcohol cues can trigger relapse, and pharmacologically facilitating processes such as extinction, which decreases cue associations, may help prevent relapse. The noradrenergic system mediates extinction learning for alcohol; however, the neural locus of this effect is unknown. This study sought to determine whether the basolateral amygdala (BLA), a region critical for fear extinction, also mediates extinction of alcohol seeking. Hooded Wistar rats (N = 12-15 per experiment) were implanted with bilateral cannula targeting the BLA and trained to lever press for 10% ethanol during auditory or visual cues...
April 9, 2018: Neurobiology of Learning and Memory
James E Delorme, Varna Kodoth, Sara J Aton
Sleep loss affects many aspects of cognition, and memory consolidation processes occurring in the hippocampus seem particularly vulnerable to sleep loss. The immediate-early gene Arc plays an essential role in both synaptic plasticity and memory formation, and its expression is altered by sleep. Here, using a variety of techniques, we have characterized the effects of brief (3-h) periods of sleep vs. sleep deprivation (SD) on the expression of Arc mRNA and Arc protein in the mouse hippocampus and cortex. By comparing the relative abundance of mature Arc mRNA with unspliced pre-mRNA, we see evidence that during SD, increases in Arc across the cortex, but not hippocampus, reflect de novo transcription...
April 7, 2018: Neurobiology of Learning and Memory
James W Grau, Yung-Jen Huang
Evidence is reviewed that behavioral training and neural injury can engage metaplastic processes that regulate adaptive potential. This issue is explored within a model system that examines how training affects the capacity to learn within the lower (lumbosacral) spinal cord. Response-contingent (controllable) stimulation applied caudal to a spinal transection induces a behavioral modification indicative of learning. This behavioral change is not observed in animals that receive stimulation in an uncontrollable manner...
April 7, 2018: Neurobiology of Learning and Memory
Walter Magerl, Niels Hansen, Rolf-Detlef Treede, Thomas Klein
The human pain system can be bidirectionally modulated by high-frequency (HFS; 100Hz) and low-frequency (LFS; 1Hz) electrical stimulation of nociceptors leading to long-term potentiation or depression of pain perception (pain-LTP or pain-LTD). Here we show that priming a test site by very low-frequency stimulation (VLFS; 0.05Hz) prevented pain-LTP probably by elevating the threshold (set point) for pain-LTP induction. Conversely, prior HFS-induced pain-LTP was substantially reversed by subsequent VLFS, suggesting that preceding HFS had primed the human nociceptive system for pain-LTD induction by VLFS...
April 6, 2018: Neurobiology of Learning and Memory
Alejandro Rivera-Olvera, Janikua Nelson-Mora, María E Gonsebatt, Martha L Escobar
Accumulating evidence indicates that homeostatic plasticity mechanisms dynamically adjust synaptic strength to promote stability that is crucial for memory storage. Our previous studies have shown that prior training in conditioned taste aversion (CTA) prevents the subsequent induction of long-term potentiation (LTP) in the projection from the basolateral nucleus of the amygdala (Bla) to the insular cortex (IC) in vivo. We have also reported that induction of LTP in the Bla-IC pathway modifies the CTA extinction...
April 6, 2018: Neurobiology of Learning and Memory
Bruno Popik, Ana Paula Crestani, Mateus Oliveira Silva, Jorge Alberto Quillfeldt, Lucas de Oliveira Alvares
It has been proposed that long-lasting changes in dendritic spines provide a physical correlate for memory formation and maintenance. Spine size and shape are highly plastic, controlled by actin polymerization/depolymerization cycles. This actin dynamics are regulated by proteins such as calpain, a calcium-dependent cysteine protease that cleaves the structural cytoskeleton proteins and other targets involved in synaptic plasticity. Here, we tested whether the pharmacological inhibition of calpain in the dorsal hippocampus affects memory consolidation, retrieval and reconsolidation in rats trained in contextual fear conditioning...
April 6, 2018: Neurobiology of Learning and Memory
Maryna Pilkiw, Kaori Takehara-Nishiuchi
Many cognitive processes, such episodic memory and decision making, rely on the ability to form associations between two events that occur separately in time. The formation of such temporal associations depends on neural representations of three types of information: what has been presented (trace holding), what will follow (temporal expectation), and when the following event will occur (explicit timing). The present review seeks to link these representations with firing patterns of single neurons recorded while rodents and non-human primates associate stimuli, outcomes, and motor responses over time intervals...
March 31, 2018: Neurobiology of Learning and Memory
Susanne Vogel, Lars Schwabe
Learning by explicit instruction is a highly efficient way to instantaneously learn new behaviors and to overcome potentially harmful learning by trial-and-error. Despite the importance of instructed learning for education, influences on the efficacy of an instruction are currently unknown. Decades of research, however, showed that stress is a powerful modulator of learning and memory, including the acquisition of stimulus-response (S-R) associations. Moreover, brain areas critical for instructed learning are a major target of hormones and neurotransmitters released during stress...
March 31, 2018: Neurobiology of Learning and Memory
S L B Oliveira, M G M Oliveira, D C Hipolide
Sleep deprivation is known to affect memory formation, but how it interacts with different memory systems is not completely understood. Adenosine, a homeostatic regulator of sleep that has an increased extracellular concentration during sleep deprivation, is one of the neuromodulators that may be involved in this interaction. The A1 adenosine receptor is involved in both sleep regulation and memory formation. Among other pathways, the A1 receptor decreases cAMP levels in the cytosol and thus also regulates protein kinase A (PKA) and exchange protein activated by cAMP (EPAC) activity...
March 31, 2018: Neurobiology of Learning and Memory
Margaret K Tanner, Holly S Hake, Courtney A Bouchet, Benjamin N Greenwood
Extinction-based exposure therapy is the most common behavioral therapy for anxiety and trauma-related disorders, but fear tends to resurface even after successful extinction. Identification of novel strategies to enhance fear extinction and reduce fear relapse is of paramount importance to mental health. Exercise can enhance cognitive function, but it is not yet well understood whether exercise can be an effective augmentation strategy for fear extinction. In the current review, we present the current state of knowledge on the effects of exercise on fear extinction...
March 31, 2018: Neurobiology of Learning and Memory
Patricia Sampedro-Piquero, Román D Moreno-Fernández, M Carmen Mañas-Padilla, Sara Gil-Rodríguez, Ana Luisa Gavito, Francisco J Pavón, Carmen Pedraza, María García-Fernández, David Ladrón de Guevara-Miranda, Luis J Santín, Estela Castilla-Ortega
Learning experiences are potent modulators of adult hippocampal neurogenesis (AHN). However, the vast majority of findings on the learning-induced regulation of AHN derive from aversively-motivated tasks, mainly the water maze paradigm, in which stress is a confounding factor that affects the AHN outcome. Currently, little is known regarding the effect of appetitively-motivated training on AHN. Hence we studied how spatial learning to find food rewards in a hole-board maze modulates AHN (cell proliferation and immature neurons) and AHN-related hippocampal neuroplasticity markers (BDNF, IGF-II and CREB phosphorylation) in mice...
March 30, 2018: Neurobiology of Learning and Memory
Richard A Inman, John M Pearce
In a discrimination based on magnitude, the same stimulus is presented at two different magnitudes and an outcome, such as food, is signalled by one magnitude but not the other. The review presented in the first part of the article shows that, in general, such a discrimination is acquired more readily when the outcome is signalled by the larger rather than the smaller of the two magnitudes. This asymmetry is observed with magnitudes based on sound, odour, temporal duration, quantity, and physical length. The second part of the article, explores the implications of this pattern of results for the theory of discrimination learning presented by Pearce (1994)...
March 26, 2018: Neurobiology of Learning and Memory
Gideon Rothschild
Our everyday lives present us with a continuous stream of multi-modal sensory inputs. While most of this information is soon forgotten, sensory information associated with salient experiences can leave long-lasting memories in our minds. Extensive human and animal research has established that the hippocampus is critically involved in this process of memory formation and consolidation. However, the underlying mechanistic details are still only partially understood. Specifically, the hippocampus has often been suggested to encode information during experience, temporarily store it, and gradually transfer this information to the cortex during sleep...
March 24, 2018: Neurobiology of Learning and Memory
Frank Raven, Peter Meerlo, Eddy A Van der Zee, Ted Abel, Robbert Havekes
Sleep and sleep loss have a profound impact on hippocampal function, leading to memory impairments. Modifications in the strength of synaptic connections directly influences neuronal communication, which is vital for normal brain function, as well as the processing and storage of information. In a recently published study, we found that as little as five hours of sleep deprivation impaired hippocampus-dependent memory consolidation, which was accompanied by a reduction in dendritic spine numbers in hippocampal area CA1...
March 24, 2018: Neurobiology of Learning and Memory
Fiona C Baker, Negin Sattari, Massimiliano de Zambotti, Aimee Goldstone, William A Alaynick, Sara C Mednick
Age and sex are two of the three major risk factors for Alzheimer's disease (ApoE-e4 allele is the third), with women having a two-fold greater risk for Alzheimer's disease after the age of 75 years. Sex differences have been shown across a wide range of cognitive skills in young and older adults, and evidence supports a role for sex steroids, especially estradiol, in protecting against the development of cognitive decline in women. Sleep may also be a protective factor against age-related cognitive decline, since specific electrophysiological sleep events (e...
March 21, 2018: Neurobiology of Learning and Memory
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