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1.
Nat Commun ; 12(1): 894, 2021 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-33563989

RESUMO

Prefrontal cortex is critical for cognition. Although much is known about the representation of cognitive variables in the prefrontal cortex, much less is known about the spatio-temporal neural dynamics that underlie cognitive operations. In the present study, we examined information timing and flow across the lateral prefrontal cortex (LPFC), while monkeys carried out a two-armed bandit reinforcement learning task in which they had to learn to select rewarding actions or rewarding objects. When we analyzed signals independently within subregions of the LPFC, we found a task-specific, caudo-rostral gradient in the strength and timing of signals related to chosen objects and chosen actions. In addition, when we characterized information flow among subregions, we found that information flow from action to object representations was stronger from the dorsal to ventral LPFC, and information flow from object to action representations was stronger from the ventral to dorsal LPFC. The object to action effects were more pronounced in object blocks, and also reflected learning specifically in these blocks. These results suggest anatomical segregation followed by the rapid integration of information within the LPFC.


Assuntos
Comportamento de Escolha/fisiologia , Córtex Pré-Frontal/fisiologia , Recompensa , Animais , Mapeamento Encefálico , Aprendizagem , Macaca , Modelos Neurológicos , Neurônios/fisiologia , Córtex Pré-Frontal/citologia , Tempo de Reação/fisiologia , Reforço Psicológico
2.
Neuron ; 109(4): 568-570, 2021 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-33600753

RESUMO

In this issue of Neuron, Cross et. al (2021) use a deep reinforcement learning algorithm to understand human neural activation evoked by playing different video games. The results shed light on the neural principles underlying reward-guided decisions in naturalistic domains.


Assuntos
Jogos de Vídeo , Algoritmos , Encéfalo , Humanos , Reforço Psicológico , Recompensa
3.
Nat Commun ; 11(1): 6441, 2020 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-33361766

RESUMO

The learning of motor skills unfolds over multiple timescales, with rapid initial gains in performance followed by a longer period in which the behavior becomes more refined, habitual, and automatized. While recent lesion and inactivation experiments have provided hints about how various brain areas might contribute to such learning, their precise roles and the neural mechanisms underlying them are not well understood. In this work, we propose neural- and circuit-level mechanisms by which motor cortex, thalamus, and striatum support motor learning. In this model, the combination of fast cortical learning and slow subcortical learning gives rise to a covert learning process through which control of behavior is gradually transferred from cortical to subcortical circuits, while protecting learned behaviors that are practiced repeatedly against overwriting by future learning. Together, these results point to a new computational role for thalamus in motor learning and, more broadly, provide a framework for understanding the neural basis of habit formation and the automatization of behavior through practice.


Assuntos
Córtex Cerebral/fisiologia , Aprendizagem , Rememoração Mental/fisiologia , Vias Neurais/fisiologia , Comportamento , Simulação por Computador , Humanos , Modelos Neurológicos , Neurônios/fisiologia , Reforço Psicológico , Análise e Desempenho de Tarefas
4.
PLoS One ; 15(12): e0240070, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33382700

RESUMO

Dietary nitrate lowers blood pressure and improves athletic performance in humans, yet data supporting observations that it may increase cerebral blood flow and improve cognitive performance are mixed. We tested the hypothesis that nitrate and nitrite treatment would improve indicators of learning and cognitive performance in a zebrafish (Danio rerio) model. We utilized targeted and untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to examine the extent to which treatment resulted in changes in nitrate or nitrite concentrations in the brain and altered the brain metabolome. Fish were exposed to sodium nitrate (606.9 mg/L), sodium nitrite (19.5 mg/L), or control water for 2-4 weeks and free swim, startle response, and shuttle box assays were performed. Nitrate and nitrite treatment did not change fish weight, length, predator avoidance, or distance and velocity traveled in an unstressed environment. Nitrate- and nitrite-treated fish initially experienced more negative reinforcement and increased time to decision in the shuttle box assay, which is consistent with a decrease in associative learning or executive function however, over multiple trials, all treatment groups demonstrated behaviors associated with learning. Nitrate and nitrite treatment was associated with mild anxiogenic-like behavior but did not alter epinephrine, norepinephrine or dopamine levels. Targeted metabolomics analysis revealed no significant increase in brain nitrate or nitrite concentrations with treatment. Untargeted metabolomics analysis found 47 metabolites whose abundance was significantly altered in the brain with nitrate and nitrite treatment. Overall, the depletion in brain metabolites is plausibly associated with the regulation of neuronal activity including statistically significant reductions in the inhibitory neurotransmitter γ-aminobutyric acid (GABA; 18-19%), and its precursor, glutamine (17-22%). Nitrate treatment caused significant depletion in the brain concentration of fatty acids including linoleic acid (LA) by 50% and arachidonic acid (ARA) by 80%; nitrite treatment caused depletion of LA by ~90% and ARA by 60%, change which could alter the function of dopaminergic neurons and affect behavior. Nitrate and nitrite treatment did not adversely affect multiple parameters of zebrafish health. It is plausible that indirect NO-mediated mechanisms may be responsible for the nitrate and nitrite-mediated effects on the brain metabolome and behavior in zebrafish.


Assuntos
Aprendizagem por Associação/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Função Executiva/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Nitratos/farmacologia , Nitrito de Sódio/farmacologia , Animais , Ansiedade/induzido quimicamente , Ansiedade/psicologia , Ácido Araquidônico/antagonistas & inibidores , Ácido Araquidônico/metabolismo , Comportamento Animal/efeitos dos fármacos , Tamanho Corporal/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Encéfalo/metabolismo , Dopamina/metabolismo , Epinefrina/metabolismo , Feminino , Glutamina/metabolismo , Ácido Linoleico/antagonistas & inibidores , Ácido Linoleico/metabolismo , Masculino , Metaboloma/fisiologia , Norepinefrina/metabolismo , Reflexo de Sobressalto/efeitos dos fármacos , Reforço Psicológico , Peixe-Zebra/metabolismo , Ácido gama-Aminobutírico/metabolismo
5.
PLoS One ; 15(12): e0225023, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33326450

RESUMO

Dog training methods range broadly from those using mostly positive punishment and negative reinforcement (aversive-based) to those using primarily positive reinforcement (reward-based). Although aversive-based training has been strongly criticized for negatively affecting dog welfare, there is no comprehensive research focusing on companion dogs and mainstream techniques, and most studies rely on owner-reported assessment of training methods and dog behavior. The aim of the present study was to evaluate the effects of aversive- and reward-based training methods on companion dog welfare within and outside the training context. Ninety-two companion dogs were recruited from three reward-based schools (Group Reward, n = 42), and from four aversive-based schools, two using low proportions of aversive-based methods (Group Mixed, n = 22) and two using high proportions of aversive-based methods (Group Aversive, n = 28). For evaluating welfare during training, dogs were video recorded for three sessions and six saliva samples were collected, three at home (baseline levels) and three after training (post-training levels). Video recordings were used to examine the frequency of stress-related behaviors (e.g., lip lick, yawn) and the overall behavioral state of the dog (e.g., tense, relaxed), and saliva samples were analyzed for cortisol concentration. For evaluating welfare outside the training context, dogs participated in a cognitive bias task. Results showed that dogs from Group Aversive displayed more stress-related behaviors, were more frequently in tense and low behavioral states and panted more during training, and exhibited higher post-training increases in cortisol levels than dogs from Group Reward. Additionally, dogs from Group Aversive were more 'pessimistic' in the cognitive bias task than dogs from Group Reward. Dogs from Group Mixed displayed more stress-related behaviors, were more frequently in tense states and panted more during training than dogs from Group Reward. Finally, although Groups Mixed and Aversive did not differ in their performance in the cognitive bias task nor in cortisol levels, the former displayed more stress-related behaviors and was more frequently in tense and low behavioral states. These findings indicate that aversive-based training methods, especially if used in high proportions, compromise the welfare of companion dogs both within and outside the training context.


Assuntos
Animais de Estimação/psicologia , Reforço Psicológico , Afeto/fisiologia , Animais , Comportamento Animal/fisiologia , Condicionamento Psicológico/fisiologia , Cães , Humanos , Hidrocortisona/análise , Masculino , Punição/psicologia , Recompensa , Saliva/química , Estresse Psicológico/metabolismo , Estresse Psicológico/psicologia , Inquéritos e Questionários , Gravação em Vídeo
6.
Brain Nerve ; 72(11): 1275-1282, 2020 Nov.
Artigo em Japonês | MEDLINE | ID: mdl-33191305

RESUMO

In order to analyze the dynamic behavior of neural systems such as oscillations or rhythms, an approach based on the dynamical systems theory may be useful. In the first part of this article, we present an elementary introduction to that approach based on the materials for an author's lecture. In the second part, we introduce our own study related to dopamine and reinforcement learning using that approach, in which we assumed the decay of learned values and propose a possible mechanism of the effects of dopamine depletion on motivation.


Assuntos
Dopamina , Reforço Psicológico , Humanos , Aprendizagem , Motivação
7.
Nat Commun ; 11(1): 5407, 2020 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-33106508

RESUMO

When making decisions, should one exploit known good options or explore potentially better alternatives? Exploration of spatially unstructured options depends on the neocortex, striatum, and amygdala. In natural environments, however, better options often cluster together, forming structured value distributions. The hippocampus binds reward information into allocentric cognitive maps to support navigation and foraging in such spaces. Here we report that human posterior hippocampus (PH) invigorates exploration while anterior hippocampus (AH) supports the transition to exploitation on a reinforcement learning task with a spatially structured reward function. These dynamics depend on differential reinforcement representations in the PH and AH. Whereas local reward prediction error signals are early and phasic in the PH tail, global value maximum signals are delayed and sustained in the AH body. AH compresses reinforcement information across episodes, updating the location and prominence of the value maximum and displaying goal cell-like ramping activity when navigating toward it.


Assuntos
Tomada de Decisões , Hipocampo/fisiologia , Adolescente , Adulto , Comportamento de Escolha , Feminino , Humanos , Aprendizagem , Masculino , Reforço Psicológico , Recompensa , Adulto Jovem
8.
PLoS One ; 15(10): e0239616, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33007023

RESUMO

Foraging animals have to evaluate, compare and select food patches in order to increase their fitness. Understanding what drives foraging decisions requires careful manipulation of the value of alternative options while monitoring animals choices. Value-based decision-making tasks in combination with formal learning models have provided both an experimental and theoretical framework to study foraging decisions in lab settings. While these approaches were successfully used in the past to understand what drives choices in mammals, very little work has been done on fruit flies. This is despite the fact that fruit flies have served as model organism for many complex behavioural paradigms. To fill this gap we developed a single-animal, trial-based decision making task, where freely walking flies experienced optogenetic sugar-receptor neuron stimulation. We controlled the value of available options by manipulating the probabilities of optogenetic stimulation. We show that flies integrate reward history of chosen options and forget value of unchosen options. We further discover that flies assign higher values to rewards experienced early in the behavioural session, consistent with formal reinforcement learning models. Finally, we also show that the probabilistic rewards affect walking trajectories of flies, suggesting that accumulated value is controlling the navigation vector of flies in a graded fashion. These findings establish the fruit fly as a model organism to explore the genetic and circuit basis of reward foraging decisions.


Assuntos
Drosophila melanogaster/fisiologia , Animais , Comportamento Animal/fisiologia , Comportamento de Escolha/fisiologia , Tomada de Decisões/fisiologia , Comportamento Alimentar/fisiologia , Preferências Alimentares/fisiologia , Aprendizagem/fisiologia , Modelos Logísticos , Masculino , Modelos Biológicos , Optogenética , Reforço Psicológico , Recompensa
9.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3086-3089, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018657

RESUMO

Brain-Machine Interface (BMI) provides a promising way to help disabled people restore their motor functions. The patients are able to control the external devices directly from their neural signals by the decoder. Due to various reasons such as mental fatigue and distraction, the distribution of the neural signals might change, which might lead to poor performance for the decoder. In this case, we need to calibrate the parameters before each session, which needs the professionals to label the data and is not convenient for the patient's usage at home. In this paper, we propose a covariant cluster transfer mechanism for the kernel reinforcement learning (RL) algorithm to speed up the adaptation across sessions. The parameters of the decoder will adaptively change according to a reward signal, which could be easily set by the patient. More importantly, we cluster the neural patterns in previous sessions. The cluster represents the conditional distribution from neural patterns to actions. When a distinct neural pattern appears in the new session, the nearest cluster will be transferred. In this way, the knowledge from the old session could be utilized to accelerate the learning in the new session. Our proposed algorithm is tested on the simulated neural data where the neural signal's distribution differs across sessions. Compared with the training from random initialization and a weight transfer policy, our proposed cluster transfer mechanism maintains a significantly higher success rate and a faster adaptation when the conditional distribution from neural signals to actions remains similar.


Assuntos
Interfaces Cérebro-Computador , Algoritmos , Humanos , Aprendizagem , Reforço Psicológico , Recompensa
10.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3351-3354, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018722

RESUMO

Reinforcement learning (RL) algorithm interprets neural signals into movement intentions with the guidance of the reward in Brain-machine interfaces (BMIs). Current RL algorithms generally work for the tasks with immediate rewards delivery, and lack of efficiency in delayed reward task. Prefrontal cortex, including medial prefrontal cortex(mPFC), has been demonstrated to assign credit to intermediate steps, which reinforces preceding action more efficiently. In this paper, we propose to simulate the functionality of mPFC activities as intermediate rewards to train a RL based decoder in a two-step movement task. A support vector machine (SVM) is adopted to verify if the subject expects a reward due to the accomplishment of a subtask from mPFC activity. Then this discrimination result will be utilized to guide the training of the RL decoder for each step respectively. Here, we apply the Sarsa-style attention-gated reinforcement learning (SAGREL) as the decoder to interpret motor cortex(M1) activity to action states. We test on in vivo primary motor cortex (M1) and mPFC data collected from rats, where the rats need to first trigger the start and then press lever for rewards using M1 signals. SAGREL using intermediate rewards from mPFC activities achieves a prediction accuracy of 66.8% ± 2.0.% (mean ± std) %, which is significantly better than the one using the reward by the end of trial (45.9.% ± 1.2%). This reveals the potentials of modelling mPFC activities as intermediate rewards for the delayed reward tasks.


Assuntos
Interfaces Cérebro-Computador , Animais , Aprendizagem , Córtex Pré-Frontal , Ratos , Reforço Psicológico , Recompensa
11.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 5553-5556, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019236

RESUMO

Prolonged influence of negative emotions can result in clinical depression or anxiety, and while many prescribed techniques exist, music therapy approaches, coupled with psychotherapy, have shown to help lower depressive symptoms, supplementing traditional treatment approaches. Identifying the appropriate choice of music, therefore, is of utmost importance. Selecting appropriate playlists, however, are challenged by user feedback that may inadvertently select songs that amplify the negative effects. Therefore, this work uses electroencephalogram (EEG) that automatically identifies the emotional impact of music and trains a reinforcement-learning approach to identify an adaptive personalized playlist of music to lead to improved emotional states. This work uses data from 32 users, collected in the publicly available DEAP dataset, to select songs for users that guide them towards joyful emotional states. Using a domain-specific reward-shaping function, a Q-learning agent is able to correctly guide a majority of users to the target emotional states, represented in a common emotion wheel. The average angular error of all users is 57°, with a standard deviation of 2.8 and the target emotional state is achieved.Clinical relevance- Music therapy for improving clinical depression and anxiety can be supplemented by additional emotion-guided music decisions in remote and personal settings by using automated techniques to capture emotional state and identify music that best guides users to target joyful states.


Assuntos
Música , Eletroencefalografia , Emoções , Humanos , Aprendizagem , Reforço Psicológico
12.
Nat Commun ; 11(1): 4429, 2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32868772

RESUMO

Can humans be trained to make strategic use of latent representations in their own brains? We investigate how human subjects can derive reward-maximizing choices from intrinsic high-dimensional information represented stochastically in neural activity. Reward contingencies are defined in real-time by fMRI multivoxel patterns; optimal action policies thereby depend on multidimensional brain activity taking place below the threshold of consciousness, by design. We find that subjects can solve the task within two hundred trials and errors, as their reinforcement learning processes interact with metacognitive functions (quantified as the meaningfulness of their decision confidence). Computational modelling and multivariate analyses identify a frontostriatal neural mechanism by which the brain may untangle the 'curse of dimensionality': synchronization of confidence representations in prefrontal cortex with reward prediction errors in basal ganglia support exploration of latent task representations. These results may provide an alternative starting point for future investigations into unconscious learning and functions of metacognition.


Assuntos
Encéfalo/fisiologia , Reforço Psicológico , Adulto , Estado de Consciência , Tomada de Decisões , Feminino , Humanos , Aprendizagem , Imagem por Ressonância Magnética/métodos , Masculino , Metacognição/fisiologia , Adulto Jovem
13.
CBE Life Sci Educ ; 19(3): es10, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32870082

RESUMO

To promote undergraduate education reform, teaching professional development (TPD) efforts aim to encourage instructors to adopt evidence-based practices. However, many instructors do not attend TPD. There may be many reasons for this, including low intrinsic motivation to participate in TPD. Psychologists have dealt with motivational barriers in educational contexts using psychosocial interventions, brief activities that draw on a rich history of psychological research to subtly alter key, self-reinforcing psychological processes to yield long-term intrinsic motivation and behavioral changes. Psychosocial interventions, for example, have been used to alter students' noncognitive attitudes and beliefs, such as attributions and mindset, which positively influence students' motivation and academic performance. Here, we propose that insights from research on psychosocial interventions may be leveraged to design interventions that will increase instructors' motivation to participate in TPD, thus enhancing existing pedagogical reform efforts. We discuss psychological principles and "best practices" underlying effective psychosocial interventions that could guide the development of interventions to increase instructors' motivation to attend TPD. We encourage new interdisciplinary research collaborations to explore the potential of these interventions, which could be a new approach to mitigating at least one barrier to undergraduate education reform.


Assuntos
Educação Profissionalizante , Motivação , Ensino/psicologia , Desempenho Acadêmico , Ansiedade/psicologia , Atitude , Humanos , Reforço Psicológico , Estudantes/psicologia
14.
Health Psychol ; 39(11): 966-974, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32955279

RESUMO

Objective: Research concerning trans-disease processes aims to ascertain an underlying mechanism of several seemingly dissonant behaviors, pathological conditions, or both. The theory of reinforcer pathology posits that excessive delay discounting and the maladaptive overvaluation of a particular commodity underlie a variety of dysfunctional health behavior ranging from substance abuse to overeating and financial responsibility. The present study extends recent health behavior research by examining the extent delay discounting and food valuation correlate with engagement in a latent factor model of health and financial behaviors among healthy-weight participants and participants with obesity using the Health Behaviors Questionnaire. Method: A total of 700 participants (n = 340, body mass index [BMI] < 30; n = 360, BMI > 30 kg/m2) were recruited using Amazon Mechanical Turk. Participants completed a monetary delay discounting assessment, the Health Behaviors Questionnaire, and 2 measures of food valuation: Behavioral economic demand and the Power of Food Scale (PFS). Results: Utilizing structural equation modeling, both delay discounting and food valuation significantly correlated with engagement in health and financial behavior for both groups. The comparison of latent factors between groups indicated that participants with obesity were less likely to engage in multiple health behaviors and that these differences can be partially attributed to differences in delay discounting and food valuation. Conclusion: These results replicate previous research and further support the role of delay discounting as a trans-disease process. Given these results, trans-disease interventions, such as episodic future thinking, designed to specifically target reinforcer pathology may have a profound effect on overall functioning. (PsycInfo Database Record (c) 2020 APA, all rights reserved).


Assuntos
Comportamentos Relacionados com a Saúde/fisiologia , Obesidade/psicologia , Reforço Psicológico , Adulto , Feminino , Humanos , Masculino
15.
Proc Natl Acad Sci U S A ; 117(36): 22522-22531, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32839338

RESUMO

A long-lasting challenge in neuroscience has been to find a set of principles that could be used to organize the brain into distinct areas with specific functions. Recent studies have proposed the orderly progression in the time constants of neural dynamics as an organizational principle of cortical computations. However, relationships between these timescales and their dependence on response properties of individual neurons are unknown, making it impossible to determine how mechanisms underlying such a computational principle are related to other aspects of neural processing. Here, we developed a comprehensive method to simultaneously estimate multiple timescales in neuronal dynamics and integration of task-relevant signals along with selectivity to those signals. By applying our method to neural and behavioral data during a dynamic decision-making task, we found that most neurons exhibited multiple timescales in their response, which consistently increased from parietal to prefrontal and cingulate cortex. While predicting rates of behavioral adjustments, these timescales were not correlated across individual neurons in any cortical area, resulting in independent parallel hierarchies of timescales. Additionally, none of these timescales depended on selectivity to task-relevant signals. Our results not only suggest the existence of multiple canonical mechanisms for increasing timescales of neural dynamics across cortex but also point to additional mechanisms that allow decorrelation of these timescales to enable more flexibility.


Assuntos
Córtex Cerebral , Rede Nervosa/fisiologia , Neurônios/fisiologia , Animais , Córtex Cerebral/citologia , Córtex Cerebral/fisiologia , Comportamento de Escolha/fisiologia , Feminino , Macaca , Masculino , Rede Nervosa/citologia , Reforço Psicológico , Recompensa
16.
Br J Anaesth ; 125(4): 596-604, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32819621

RESUMO

BACKGROUND: A novel G-protein signalling-biased mu opioid peptide (MOP) receptor agonist, PZM21, was recently developed with a distinct chemical structure. It is a potent Gi/o activator with minimal ß-arrestin-2 recruitment. Despite intriguing activity in rodent models, PZM21 function in non-human primates is unknown. The aim of this study was to investigate PZM21 actions after systemic or intrathecal administration in primates. METHODS: Antinociceptive, reinforcing, and pruritic effects of PZM21 were compared with those of the clinically used MOP receptor agonists oxycodone and morphine in assays of acute thermal nociception, capsaicin-induced thermal allodynia, itch scratching responses, and drug self-administration in gonadally intact, adult rhesus macaques (10 males, six females). RESULTS: After subcutaneous administration, PZM21 (1.0-6.0 mg kg-1) and oxycodone (0.1-0.6 mg kg-1) induced dose-dependent thermal antinociceptive effects (P<0.05); PZM21 was 10 times less potent than oxycodone. PZM21 exerted oxycodone-like reinforcing effects and strength as determined by two operant schedules of reinforcement in the intravenous drug self-administration assay. After intrathecal administration, PZM21 (0.03-0.3 mg) dose-dependently attenuated capsaicin-induced thermal allodynia (P<0.05). Although intrathecal PZM21 and morphine induced MOP receptor-mediated antiallodynic effects, both compounds induced robust, long-lasting itch scratching. CONCLUSIONS: PZM21 induced antinociceptive, reinforcing, and pruritic effects similar to clinically used MOP receptor agonists in primates. Although structure-based discovery of PZM21 identified a novel avenue for studying G-protein signalling-biased ligands, biasing an agonist towards G-protein signalling pathways did not determine or alter reinforcing (i.e. abuse potential) or pruritic effects of MOP receptor agonists in a translationally relevant non-human primate model.


Assuntos
Analgésicos/farmacologia , Prurido/induzido quimicamente , Receptores Opioides mu/agonistas , Reforço Psicológico , Tiofenos/farmacologia , Ureia/análogos & derivados , Animais , Relação Dose-Resposta a Droga , Feminino , Macaca mulatta , Masculino , Ureia/farmacologia
17.
J Pharmacol Sci ; 144(2): 89-93, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32763057

RESUMO

l-3,4-dihydroxyphenylalanine (l-DOPA) is a candidate neurotransmitter. l-DOPA is released by nicotine through nicotinic receptors. Recently, G-protein coupled receptor GPR143, was identified as a receptor for l-DOPA. In this study, genetic association studies between GPR143 genetic polymorphisms and smoking behaviors revealed that the single-nucleotide polymorphism rs6640499, in the GPR143 gene, was associated with traits of smoking behaviors in Japanese individuals. In Gpr143 gene-deficient mice, nicotine-induced hypolocomotion and rewarding effect were attenuated compared to those in wild-type mice. Our findings suggest the involvement of GPR143 in the smoking behaviors.


Assuntos
Proteínas do Olho/genética , Deleção de Genes , Estudos de Associação Genética , Glicoproteínas de Membrana/genética , Nicotina/efeitos adversos , Polimorfismo de Nucleotídeo Único , Receptores Acoplados a Proteínas-G/genética , Receptores de Neurotransmissores/genética , Reforço Psicológico , Transtornos Relacionados ao Uso de Substâncias/genética , Animais , Grupo com Ancestrais do Continente Asiático , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Índice de Gravidade de Doença
18.
PLoS One ; 15(7): e0236178, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32716945

RESUMO

Despite active research on trading systems based on reinforcement learning, the development and performance of research methods require improvements. This study proposes a new action-specialized expert ensemble method consisting of action-specialized expert models designed specifically for each reinforcement learning action: buy, hold, and sell. Models are constructed by examining and defining different reward values that correlate with each action under specific conditions, and investment behavior is reflected with each expert model. To verify the performance of this technique, profits of the proposed system are compared to those of single trading and common ensemble systems. To verify robustness and account for the extension of discrete action space, we compared and analyzed changes in profits of the three actions to our model's results. Furthermore, we checked for sensitivity with three different reward functions: profit, Sharpe ratio, and Sortino ratio. All experiments were conducted with S&P500, Hang Seng Index, and Eurostoxx50 data. The model was 39.1% and 21.6% more efficient than single and common ensemble models, respectively. Considering the extended discrete action space, the 3-action space was extended to 11- and 21-action spaces, and the cumulative returns increased by 427.2% and 856.7%, respectively. Results on reward functions indicated that our models are well trained; results of the Sharpe and Sortino ratios were better than the implementation of profit only, as in the single-model cases. The Sortino ratio was slightly better than the Sharpe ratio.


Assuntos
Algoritmos , Comércio , Aprendizado Profundo , Bases de Dados como Assunto , Investimentos em Saúde , Modelos Econômicos , Redes Neurais de Computação , Reforço Psicológico , Fatores de Tempo
19.
PLoS One ; 15(7): e0236088, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32692764

RESUMO

Interrogative suggestibility, as measured with Gudjonsson Suggestibility Scales, consists of an individual's tendency to yield to misleading questions (Yield) and to change answers after negative feedback (Shift). This study aimed to determine whether reinforced self-affirmation (RSA), a technique that aims to boost self-confidence in order to increase the tendency to rely on one's own memory instead of external cues, can reduce interrogative suggestibility. RSA consists of self-affirmation induced by means of writing down one's greatest achievements in life and of manipulated positive feedback. The efficacy of two kinds of positive feedback was explored. Shift was reduced by positive feedback relating both to memory and to the feeling that a person is very independent in their judgements, while only feedback related to memory reduced Yield. The results are discussed in terms of the different mechanisms underlying Yield and Shift. Inducing independence of judgements might not have been effective in the case of Yield because to some extent it taps opinions but not the quality of a cognitive process such as memory. An individual may believe in their own opinions and views but still be unsure about the quality of their own memory.


Assuntos
Retroalimentação Psicológica/fisiologia , Julgamento , Memória/fisiologia , Reforço Psicológico , Autoimagem , Sugestão , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
20.
Nat Hum Behav ; 4(10): 1053-1066, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32632333

RESUMO

Distinct model-free and model-based learning processes are thought to drive both typical and dysfunctional behaviours. Data from two-stage decision tasks have seemingly shown that human behaviour is driven by both processes operating in parallel. However, in this study, we show that more detailed task instructions lead participants to make primarily model-based choices that have little, if any, simple model-free influence. We also demonstrate that behaviour in the two-stage task may falsely appear to be driven by a combination of simple model-free and model-based learning if purely model-based agents form inaccurate models of the task because of misconceptions. Furthermore, we report evidence that many participants do misconceive the task in important ways. Overall, we argue that humans formulate a wide variety of learning models. Consequently, the simple dichotomy of model-free versus model-based learning is inadequate to explain behaviour in the two-stage task and connections between reward learning, habit formation and compulsivity.


Assuntos
Modelos Estatísticos , Aprendizagem por Probabilidade , Recompensa , Análise e Desempenho de Tarefas , Pensamento/fisiologia , Adulto , Comportamento de Escolha/fisiologia , Objetivos , Hábitos , Humanos , Modelos Psicológicos , Reforço Psicológico , Adulto Jovem
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