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Learning & Memory

Rafi U Haque, Cecelia M Manzanares, Lavonda N Brown, Alvince L Pongos, James J Lah, Gari D Clifford, Allan I Levey
The entorhinal-hippocampal circuit is one of the earliest sites of cortical pathology in Alzheimer's disease (AD). Visuospatial memory paradigms that are mediated by the entorhinal-hippocampal circuit may offer a means to detect memory impairment during the early stages of AD. In this study, we developed a 4-min visuospatial memory paradigm called VisMET (Visuospatial Memory Eye-Tracking Task) that passively assesses memory using eye movements rather than explicit memory judgements. We had 296 control or memory-impaired participants view a set of images followed by a modified version of the images with either an object removed, or a new object added...
March 2019: Learning & Memory
Matthew B Broschard, Jangjin Kim, Bradley C Love, Edward A Wasserman, John H Freeman
A prominent theory of category learning, COVIS, posits that new categories are learned with either a declarative or procedural system, depending on the task. The declarative system uses the prefrontal cortex (PFC) to learn rule-based (RB) category tasks in which there is one relevant sensory dimension that can be used to establish a rule for solving the task, whereas the procedural system uses corticostriatal circuits for information integration (II) tasks in which there are multiple relevant dimensions, precluding use of explicit rules...
March 2019: Learning & Memory
Edwin W Wong, Stephen D Glasgow, Lianne J Trigiani, Daryan Chitsaz, Vladimir Rymar, Abbas Sadikot, Edward S Ruthazer, Edith Hamel, Timothy E Kennedy
Netrin-1 was initially characterized as an axon guidance molecule that is essential for normal embryonic neural development; however, many types of neurons continue to express netrin-1 in the postnatal and adult mammalian brain. Netrin-1 and the netrin receptor DCC are both enriched at synapses. In the adult hippocampus, activity-dependent secretion of netrin-1 by neurons potentiates glutamatergic synapse function, and is critical for long-term potentiation, an experimental cellular model of learning and memory...
March 2019: Learning & Memory
Mateo Leganes-Fonteneau, Kyriaki Nikolaou, Ryan Scott, Theodora Duka
Stimuli conditioned with a substance can generate drug-approach behaviors due to their acquired motivational properties. According to implicit theories of addiction, these stimuli can decrease cognitive control automatically. The present study ( n = 49) examined whether reward-associated stimuli can interfere with cognitive processes in the absence of knowledge about stimulus-outcome contingencies. Conditioned stimuli (CS) were paired with high-reward (HR) or low-reward (LR) probabilities of monetary reward using a Pavlovian learning task...
March 2019: Learning & Memory
Carlos Alexandre Gomes, Axel Mecklinger, Hubert Zimmer
Recognition memory judgments can be influenced by a variety of signals including fluency. Here, we investigated whether the neural correlates of memory illusions (i.e., misattribution of fluency to prior study) can be modulated by fluency context. Using a masked priming/recognition memory paradigm, we found memory illusions for low confidence decisions. When fluency varied randomly across trials, we found reductions in perirhinal cortex (PrC) activity for primed trials, as well as a (pre)cuneus-PrC (BA 35) connectivity...
February 2019: Learning & Memory
Qizong Yang, Igor Antonov, David Castillejos, Anagha Nagaraj, Caleb Bostwick, Andrea Kohn, Leonid L Moroz, Robert D Hawkins
No abstract text is available yet for this article.
February 2019: Learning & Memory
Arne Ilse, Virginia Prameswari, Evelyn Kahl, Markus Fendt
Trait anxiety is considered to be a risk factor for anxiety disorders. The aim of the present study was to investigate how trait anxiety affects associative learning during and after an aversive event in laboratory rats. For this, rats were first submitted to a light-dark box test, followed by relief, safety, and fear learning. Our data demonstrate that all types of learning were affected by trait anxiety, both on a group and on an individual level. Whereas high levels of anxiety impaired relief and safety learning, fear learning was more pronounced...
February 2019: Learning & Memory
Michael Wolter, Ethan Huff, Talia Speigel, Boyer D Winters, Francesco Leri
To test the hypothesis that drugs of abuse and their conditioned stimuli (CSs) enhance memory consolidation, the effects of post-training exposure to cocaine and nicotine were compared to the effects of post-training exposure to contextual stimuli that were paired with the effects of these drugs. Using the object recognition (OR) task, it was first demonstrated that both 10 and 20 mg/kg cocaine, and 0.2 and 0.4 mg/kg nicotine, enhanced recognition memory when administered immediately after, but not 6 h after the sample phase...
February 2019: Learning & Memory
Christian J Merz, Oliver T Wolf
The immediate extinction deficit describes a higher return of fear when extinction takes place immediately after fear acquisition compared to a delayed extinction design. One explanation for this phenomenon encompasses the remaining emotional arousal evoked by fear acquisition to be still present during immediate, but not delayed extinction. In the present study, the predictive learning task, a learning task not involving arousal or stress, was used testing the hypothesis that no immediate extinction deficit should occur in this neutral task...
February 2019: Learning & Memory
Nathan J Brandwein, Peter V Nguyen
Beta-adrenergic receptor (β-AR) activation by norepinephrine (NE) enhances memory and stabilizes long-term potentiation (LTP), a form of synaptic plasticity believed to underlie some forms of hippocampal memory. LTP can occur at multiple synaptic pathways as a result of strong stimulation to one pathway preceding milder stimulation of an adjacent, independent pathway. Synaptic tagging allows LTP to be transferred, or captured, at heterosynaptic pathways. Previous research has shown that β-AR activation promotes heterosynaptic LTP by engaging various signaling cascades...
February 2019: Learning & Memory
Patrick T Piantadosi, Abby G Lieberman, Charles L Pickens, Hadley C Bergstrom, Andrew Holmes
Cognitive flexibility refers to various processes which enable behaviors to be modified on the basis of a change in the contingencies between stimuli or responses and their associated outcomes. Reversal learning is a form of cognitive flexibility which measures the ability to adjust responding based on a switch in the stimulus-outcome contingencies of, typically two, perceptually distinct stimuli. Reversal tasks have provided valuable insight into the neural basis of cognitive flexibility, implicating brain regions including the lateral orbitofrontal cortex (lOFC) and dorsomedial prefrontal cortex (dmPFC)...
January 2019: Learning & Memory
McKenna E Williams, Lisa V Graves, Shannon Yandall DeJesus, Heather M Holden, Nicole E DeFord, Paul E Gilbert
Spatial memory impairment is well documented in old age; however, less is known about spatial memory during middle age. We examined the performance of healthy young, middle-aged, and older adults on a spatial memory task with varying levels of spatial similarity (distance). On low similarity trials, young adults significantly outperformed middle-aged adults, who significantly outperformed older adults ( P s < 0.05). On high similarity trials, young adults significantly outperformed middle-aged and older adults ( P s < 0...
January 2019: Learning & Memory
Mariët van Buuren, Isabella C Wagner, Guillén Fernández
Intrinsic network interactions may underlie individual differences in the ability to remember. The default mode network (DMN) comprises subnetworks implicated in memory, and interactions between the DMN and frontoparietal network (FPN) were shown to support mnemonic processing. However, it is unclear if such interactions during resting-state predict episodic memory ability. We investigated whether intrinsic network interactions within and between the DMN and FPN are related to individual differences in memory performance...
January 2019: Learning & Memory
Jacqueline M Barker, Kathleen G Bryant, L Judson Chandler
The loss of behavioral flexibility is common across a number of neuropsychiatric illnesses. This may be in part due to the loss of the ability to detect or use changes in action-outcome contingencies to guide behavior. There is growing evidence that the ventral hippocampus plays a critical role in the regulation of flexible behavior and reward-related decision making. Here, we investigated the role of glutamatergic projections from the ventral hippocampus in the expression of contingency-mediated reward seeking...
January 2019: Learning & Memory
Sho Araiba, Nicole El Massioui, Bruce L Brown, Valérie Doyère
This study demonstrates that overtraining in temporal discrimination modifies temporal stimulus control in a bisection task and produces habitual responding, as evidenced through insensitivity to food devaluation. Rats were trained or overtrained in a 2- versus 8-sec temporal discrimination task, with each duration associated with a lever (left or right) and food (grain or sucrose). Overtraining produced a leftward shift in the bisection point. Devaluation treatment induced a differential loss of responding depending on stimulus duration (short versus long) and the level of training (training versus overtraining)...
December 2018: Learning & Memory
Qizong Yang, Igor Antonov, David Castillejos, Anagha Nagaraj, Caleb Bostwick, Andrea Kohn, Leonid Moroz, Robert D Hawkins
Long-term but not short-term memory and synaptic plasticity in many brain areas require neurotrophin signaling, transcription, and epigenetic mechanisms including DNA methylation. However, it has been difficult to relate these cellular mechanisms directly to behavior because of the immense complexity of the mammalian brain. To address that problem, we and others have examined numerically simpler systems such as the hermaphroditic marine mollusk Aplysia californica. As a further simplification, we have used a semi-intact preparation of the Aplysia siphon withdrawal reflex in which it is possible to relate cellular plasticity directly to behavioral learning...
December 2018: Learning & Memory
Tony J Cunningham, Stephanie L Leal, Michael A Yassa, Jessica D Payne
Stress influences how we remember emotional events and how these events shape future behaviors. However, the impact of stress on memory specificity for emotional events has yet to be examined. To this end, the present study utilized a mnemonic discrimination task that taxes hippocampal pattern separation, the process of distinguishing between overlapping experiences, thereby allowing us to better understand the mechanisms by which stress affects gist versus detail memory of emotional events. Participants encoded scenes composed of negative or neutral objects placed on neutral backgrounds and then underwent a psychosocial stressor or matched control task...
December 2018: Learning & Memory
Wenxi Zhou, Haoyu Chen, Jiongjiong Yang
How to improve our episodic memory is an important issue in the field of memory. In the present study, we used a discriminative learning paradigm that was similar to a paradigm used in animal studies. In Experiment 1, a picture (e.g., a dog) was either paired with an identical picture, with a similar picture of the same concept (e.g., another dog), or with a picture of a different concept (e.g., a cat). Then, after intervals of 10 min, 1 d, and 1 wk, participants were asked to perform a 2-alternative forced-choice (2AFC) task to discriminate between a repeated and a similar picture, followed by the contextual judgment...
December 2018: Learning & Memory
Veronica L Flores, Tamar Parmet, Narendra Mukherjee, Sacha Nelson, Donald B Katz, David Levitan
The strength of learned associations between pairs of stimuli is affected by multiple factors, the most extensively studied of which is prior experience with the stimuli themselves. In contrast, little data is available regarding how experience with "incidental" stimuli (independent of any conditioning situation) impacts later learning. This lack of research is striking given the importance of incidental experience to survival. We have recently begun to fill this void using conditioned taste aversion (CTA), wherein an animal learns to avoid a taste that has been associated with malaise...
November 2018: Learning & Memory
Sarah E Bae, Rick Richardson
Recent studies have shown that exposure to a novel environment may stabilize the persistence of weak memories, a phenomenon often attributed to a process referred to as "behavioral tagging." While this phenomenon has been repeatedly demonstrated in adult animals, no studies to date have examined whether it occurs in infant animals, which is surprising given that infants exhibit an impaired ability to form long-term memories (LTMs). In the present study, infant (i.e., postnatal day (P) 17) rats were placed in a context and repeatedly shocked...
November 2018: Learning & Memory
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