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https://www.readbyqxmd.com/read/28098430/behavioral-and-electrophysiological-alterations-for-reinforcement-learning-in-manic-and-euthymic-patients-with-bipolar-disorder
#1
Vin Ryu, Ra Yeon Ha, Su Jin Lee, Kyooseob Ha, Hyun-Sang Cho
AIMS: Bipolar disorder is characterized by behavioral changes such as risk-taking and increasing goal-directed activities, which may result from altered reward processing. Patients with bipolar disorder show impaired reward learning in situations that require the integration of reinforced feedback over time. In this study, we examined the behavioral and electrophysiological characteristics of reward learning in manic and euthymic patients with bipolar disorder using a probabilistic reward task...
January 18, 2017: CNS Neuroscience & Therapeutics
https://www.readbyqxmd.com/read/28098244/stochastic-evolution-in-populations-of-ideas
#2
Robin Nicole, Peter Sollich, Tobias Galla
It is known that learning of players who interact in a repeated game can be interpreted as an evolutionary process in a population of ideas. These analogies have so far mostly been established in deterministic models, and memory loss in learning has been seen to act similarly to mutation in evolution. We here propose a representation of reinforcement learning as a stochastic process in finite 'populations of ideas'. The resulting birth-death dynamics has absorbing states and allows for the extinction or fixation of ideas, marking a key difference to mutation-selection processes in finite populations...
January 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28097374/effects-of-5-ht1a-5-ht2a-and-5-ht2c-receptor-agonists-and-antagonists-on-responding-for-a-conditioned-reinforcer-and-its-enhancement-by-methylphenidate
#3
Paul J Fletcher, Fiona D Zeeb, Caleb J Browne, Guy A Higgins, Ashlie D Soko
OBJECTIVES: These experiments examined the effects of selective 5-HT1A, 5-HT2A and 5-HT2C receptor ligands on responding for a conditioned reinforcer (CRf). Effects of these ligands were measured under basal conditions and following elevated dopamine (DA) activity produced by the DA reuptake inhibitor methylphenidate. METHODS: Water-restricted rats learned to associate a conditioned stimulus (CS) with water in operant chambers. Subsequently, two response levers were made available; responding on one lever delivered the CS (now a CRf), while responding on the second lever had no consequences...
January 18, 2017: Psychopharmacology
https://www.readbyqxmd.com/read/28095201/multisensory-bayesian-inference-depends-on-synapse-maturation-during-training-theoretical-analysis-and-neural-modeling-implementation
#4
Mauro Ursino, Cristiano Cuppini, Elisa Magosso
Recent theoretical and experimental studies suggest that in multisensory conditions, the brain performs a near-optimal Bayesian estimate of external events, giving more weight to the more reliable stimuli. However, the neural mechanisms responsible for this behavior, and its progressive maturation in a multisensory environment, are still insufficiently understood. The aim of this letter is to analyze this problem with a neural network model of audiovisual integration, based on probabilistic population coding-the idea that a population of neurons can encode probability functions to perform Bayesian inference...
January 17, 2017: Neural Computation
https://www.readbyqxmd.com/read/28095003/cocaine-addiction-as-a-homeostatic-reinforcement-learning-disorder
#5
Mehdi Keramati, Audrey Durand, Paul Girardeau, Boris Gutkin, Serge H Ahmed
Drug addiction implicates both reward learning and homeostatic regulation mechanisms of the brain. This has stimulated 2 partially successful theoretical perspectives on addiction. Many important aspects of addiction, however, remain to be explained within a single, unified framework that integrates the 2 mechanisms. Building upon a recently developed homeostatic reinforcement learning theory, the authors focus on a key transition stage of addiction that is well modeled in animals, escalation of drug use, and propose a computational theory of cocaine addiction where cocaine reinforces behavior due to its rapid homeostatic corrective effect, whereas its chronic use induces slow and long-lasting changes in homeostatic setpoint...
January 16, 2017: Psychological Review
https://www.readbyqxmd.com/read/28092578/experienced-gray-wolf-optimization-through-reinforcement-learning-and-neural-networks
#6
E Emary, Hossam M Zawbaa, Crina Grosan
In this paper, a variant of gray wolf optimization (GWO) that uses reinforcement learning principles combined with neural networks to enhance the performance is proposed. The aim is to overcome, by reinforced learning, the common challenge of setting the right parameters for the algorithm. In GWO, a single parameter is used to control the exploration/exploitation rate, which influences the performance of the algorithm. Rather than using a global way to change this parameter for all the agents, we use reinforcement learning to set it on an individual basis...
January 10, 2017: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/28092323/brain-substrates-of-reward-processing-and-the-%C3%AE-opioid-receptor-a-pathway-into-pain
#7
Frauke Nees, Susanne Becker, Sabina Millenet, Tobias Banaschewski, Luise Poustka, Arun Bokde, Uli Bromberg, Christian Büchel, Patricia J Conrod, Sylvane Desrivières, Vincent Frouin, Jürgen Gallinat, Hugh Garavan, Andreas Heinz, Bernd Ittermann, Jean-Luc Martinot, Dimitri Papadopoulos Orfanos, Tomáš Paus, Michael N Smolka, Henrik Walter, Rob Whelan, Gunter Schumann, Herta Flor
The processing of reward and reinforcement learning seems to be important determinants of pain chronicity. However, reward processing is already altered early in life and if this is related to the development of pain symptoms later on is not known. The aim of this study was first to examine whether behavioural and brain-related indicators of reward processing at the age of 14 to 15 years are significant predictors of pain complaints 2 years later, at 16 to 17 years. Second, we investigated the contribution of genetic variations in the opioidergic system, which is linked to the processing of both, reward and pain, to this prediction...
February 2017: Pain
https://www.readbyqxmd.com/read/28091572/a-computational-psychiatry-approach-identifies-how-alpha-2a-noradrenergic-agonist-guanfacine-affects-feature-based-reinforcement-learning-in-the-macaque
#8
S A Hassani, M Oemisch, M Balcarras, S Westendorff, S Ardid, M A van der Meer, P Tiesinga, T Womelsdorf
Noradrenaline is believed to support cognitive flexibility through the alpha 2A noradrenergic receptor (a2A-NAR) acting in prefrontal cortex. Enhanced flexibility has been inferred from improved working memory with the a2A-NA agonist Guanfacine. But it has been unclear whether Guanfacine improves specific attention and learning mechanisms beyond working memory, and whether the drug effects can be formalized computationally to allow single subject predictions. We tested and confirmed these suggestions in a case study with a healthy nonhuman primate performing a feature-based reversal learning task evaluating performance using Bayesian and Reinforcement learning models...
January 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28088350/the-emotive-nature-of-conflict-monitoring-in-the-medial-prefrontal-cortex
#9
Blair Saunders, Hause Lin, Marina Milyavskaya, Michael Inzlicht
The detection of conflict between incompatible impulses, thoughts, and actions is a ubiquitous source of motivation across theories of goal-directed action. In this overview, we explore the hypothesis that conflict is emotive, integrating perspectives from affective science and cognitive neuroscience. Initially, we review evidence suggesting that the mental and biological processes that monitor for information processing conflict-particularly those generated by the anterior midcingulate cortex-track the affective significance of conflict and use this signal to motivate increased control...
January 11, 2017: International Journal of Psychophysiology
https://www.readbyqxmd.com/read/28080112/beyond-trial-by-trial-adaptation-a-quantification-of-the-time-scale-of-cognitive-control
#10
Bart Aben, Tom Verguts, Eva Van den Bussche
The idea that adaptation to stimulus or response conflict can operate over different time scales takes a prominent position in various theories and models of cognitive control. The mechanisms underlying temporal variations in control are nevertheless poorly understood, which is partly due to a lack of appropriate empirical measures. Inspired by reinforcement learning models, we developed a method to quantify the time scale of control behaviorally, by computing trial-by-trial effects that go beyond the preceding trial...
January 12, 2017: Journal of Experimental Psychology. Human Perception and Performance
https://www.readbyqxmd.com/read/28077716/the-attraction-effect-modulates-reward-prediction-errors-and-intertemporal-choices
#11
Sebastian Gluth, Jared M Hotaling, Jörg Rieskamp
: Classical economic theory contends that the utility of a choice option should be independent of other options. This view is challenged by the attraction effect, in which the relative preference between two options is altered by the addition of a third, asymmetrically dominated option. Here, we leveraged the attraction effect in the context of intertemporal choices to test whether both decisions and reward prediction errors (RPE) in the absence of choice violate the independence of irrelevant alternatives principle...
January 11, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28074855/mir-218-targets-mecp2-and-inhibits-heroin-seeking-behavior
#12
Biao Yan, Zhaoyang Hu, Wenqing Yao, Qiumin Le, Bo Xu, Xing Liu, Lan Ma
MicroRNAs (miRNAs) are a class of evolutionarily conserved, 18-25 nucleotide non-coding sequences that post-transcriptionally regulate gene expression. Recent studies implicated their roles in the regulation of neuronal functions, such as learning, cognition and memory formation. Here we report that miR-218 inhibits heroin-induced behavioral plasticity. First, network propagation-based method was used to predict candidate miRNAs that played potential key roles in regulating drug addiction-related genes. Microarray screening was also carried out to identify miRNAs responding to chronic heroin administration in the nucleus accumbens (NAc)...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28071747/deficits-in-reinforcement-learning-but-no-link-to-apathy-in-patients-with-schizophrenia
#13
Matthias N Hartmann-Riemer, Steffen Aschenbrenner, Magdalena Bossert, Celina Westermann, Erich Seifritz, Philippe N Tobler, Matthias Weisbrod, Stefan Kaiser
Negative symptoms in schizophrenia have been linked to selective reinforcement learning deficits in the context of gains combined with intact loss-avoidance learning. Fundamental mechanisms of reinforcement learning and choice are prediction error signaling and the precise representation of reward value for future decisions. It is unclear which of these mechanisms contribute to the impairments in learning from positive outcomes observed in schizophrenia. A recent study suggested that patients with severe apathy symptoms show deficits in the representation of expected value...
January 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28071646/reinforcement-learning-accounts-for-moody-conditional-cooperation-behavior-experimental-results
#14
Yutaka Horita, Masanori Takezawa, Keigo Inukai, Toshimasa Kita, Naoki Masuda
In social dilemma games, human participants often show conditional cooperation (CC) behavior or its variant called moody conditional cooperation (MCC), with which they basically tend to cooperate when many other peers have previously cooperated. Recent computational studies showed that CC and MCC behavioral patterns could be explained by reinforcement learning. In the present study, we use a repeated multiplayer prisoner's dilemma game and the repeated public goods game played by human participants to examine whether MCC is observed across different types of game and the possibility that reinforcement learning explains observed behavior...
January 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28069437/indispensable-role-of-the-voltage-gated-calcium-channels-in-the-procognitive-effects-of-angiotensin-iv
#15
Jan Józef Braszko
BACKGROUND: Voltage-gated calcium channels (VGCCs) play a major role in brain functioning, including that of cognition-related structures such as cerebral cortex and hippocampus. Cellular mechanisms underlying learning and memory enhancing effect of the neuropeptide angiotensin IV (Ang IV) have been linked to VGCCs but only in respect of its long-term potentiation (LTP)-inducing effect. OBJECTIVE: To assess behaviorally effects of L- and T-type VGCCs blocking drugs in low, behaviorally inactive, doses on Ang IV facilitation of recall of aversively (foot-shock) and appetitively (curiosity for novelty) motivated behaviors...
January 6, 2017: Brain Research Bulletin
https://www.readbyqxmd.com/read/28065844/effects-of-the-chronic-restraint-stress-induced-depression-on-reward-related-learning-in-rats
#16
Pan Xu, Kezhu Wang, Cong Lu, Liming Dong, Yixi Chen, Qiong Wang, Zhe Shi, Yanyan Yang, Shanguang Chen, Xinmin Liu
Chronic mild or unpredictability stress produces a persistent depressive-like state. The main symptoms of depression include weight loss, despair, anhedonia, diminished motivation and mild cognition impairment, which could influence the ability of reward-related learning. In the present study, we aimed to evaluate the effects of chronic restraint stress on the performance of reward-related learning of rats. We used the exposure of repeated restraint stress (6h/day, for 28days) to induce depression-like behavior in rats...
January 5, 2017: Behavioural Brain Research
https://www.readbyqxmd.com/read/28065344/abai-s-moc-assessment-of-knowledge-program-matures-adding-value-with-continuous-learning-and-assessment
#17
REVIEW
David I Bernstein, Stephen I Wasserman, William P Thompson, Theodore M Freeman
Rapid changes in modern medicine along with advances in the science of learning and memory have necessitated a shift in the way physician knowledge is assessed. Physician recertification beyond initial certification has historically consisted of retaining large amounts of knowledge over a long time span. The adult learning theory has shown that the maintenance and improvement of our knowledge base is more effective by being exposed to new concepts at regular intervals throughout one's career and reinforcing these concepts on an ongoing basis...
January 2017: Journal of Allergy and Clinical Immunology in Practice
https://www.readbyqxmd.com/read/28065182/increased-fronto-striatal-reward-prediction-errors-moderate-decision-making-in-obsessive-compulsive-disorder
#18
T U Hauser, R Iannaccone, R J Dolan, J Ball, J Hättenschwiler, R Drechsler, M Rufer, D Brandeis, S Walitza, S Brem
BACKGROUND: Obsessive-compulsive disorder (OCD) has been linked to functional abnormalities in fronto-striatal networks as well as impairments in decision making and learning. Little is known about the neurocognitive mechanisms causing these decision-making and learning deficits in OCD, and how they relate to dysfunction in fronto-striatal networks. METHOD: We investigated neural mechanisms of decision making in OCD patients, including early and late onset of disorder, in terms of reward prediction errors (RPEs) using functional magnetic resonance imaging...
January 9, 2017: Psychological Medicine
https://www.readbyqxmd.com/read/28057502/variations-of-the-morris-water-maze-task-to-comparatively-assess-human-and-rodent-place-navigation
#19
Robby Schoenfeld, Thomas Schiffelholz, Christian Beyer, Bernd Leplow, Nigel Foreman
Performance in the Morris water maze has been widely used in routine behavioural studies of rodents. Since the advent of computer-based virtual environments, adaptations of the water maze have become available for human research. Despite decades of comparative neuroscience, formal comparisons of human and animal place navigation performance are rarely. We studied 36 subjects, 18 young male mice in a Morris water maze and 18 male students in a virtual version. Quantitative measures (escape latencies, distances and platform crossings) indicated no discernable differences between human and rodent performance, reinforcing the task's general validity and its implied cross-species comparability...
January 2, 2017: Neurobiology of Learning and Memory
https://www.readbyqxmd.com/read/28048913/mo-de-bra-02-simac-a-simulation-tool-for-teaching-linear-accelerator-physics
#20
M Carlone, N Harnett, W Harris, B Norrlinger, M MacPherson, M Lamey, R Anderson, M Oldham
PURPOSE: The first goal of this work is to develop software that can simulate the physics of linear accelerators (linac). The second goal is to show that this simulation tool is effective in teaching linac physics to medical physicists and linac service engineers. METHODS: Linacs were modeled using analytical expressions that can correctly describe the physical response of a linac to parameter changes in real time. These expressions were programmed with a graphical user interface in order to produce an environment similar to that of linac service mode...
June 2016: Medical Physics
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