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1.
Bratisl Lek Listy ; 120(12): 894-898, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31855047

RESUMO

OBJECTIVES: Central systolic blood pressure (CSBP) is the pressure in the root of aorta, which directly influences organs such as brain, heart and kidneys and is related to organ damage. Its value increases with the aortic stiffness. The aim of this study was to analyze the relationships of CSBP to aortic stiffness parameters. METHODS: Central blood pressure (BP) and related parameters were measured by Arteriograph, working based on oscillometric principle, using pulse wave analysis (PWA) approach. We examined 123 patients (69 females, 54 males) with a primary hypertension. RESULTS: Using a linear correlation analysis, we found that CSBP was correlated to aortic pulse wave velocity (PWV), aortic and brachial pulse pressure (PP), aortic augmentation index, return time of reflected pressure wave (RT) and aortic and brachial augmentation indexes. Multivariate analysis defines the aortic pulse pressure (PPao) as the most powerful parameter influencing CSBP. By an individual analysis of BP in each patient separately, we defined two different types of central hemodynamics; those with a higher CSBP than brachial SBP occur in stiffer aorta. CONCLUSION: The CSBP increases with aortic PP, the most powerful stiffness parameter of aorta. Higher CSBP than brachial SBP usually accompanies a stiffer aorta (Tab. 5, Ref. 19).


Assuntos
Pressão Sanguínea/fisiologia , Análise de Onda de Pulso/métodos , Rigidez Vascular , Pressão Arterial , Determinação da Pressão Arterial , Feminino , Humanos , Masculino
2.
Nat Commun ; 10(1): 2554, 2019 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-31186425

RESUMO

Representations of our future environment are essential for planning and decision making. Previous research in humans has demonstrated that the hippocampus is a critical region for forming and retrieving associations, while the medial orbitofrontal cortex (OFC) is an important region for representing information about recent states. However, it is not clear how the brain acquires predictive representations during goal-directed learning. Here, we show using fMRI that while participants learned to find rewards in multiple different Y-maze environments, hippocampal activity was highest during initial exposure and then decayed across the remaining repetitions of each maze, consistent with a role in rapid encoding. Importantly, multivariate patterns in the OFC-VPFC came to represent predictive information about upcoming states approximately 30 s in the future. Our findings provide a mechanism by which the brain can build models of the world that span long-timescales to make predictions.


Assuntos
Aprendizagem em Labirinto/fisiologia , Córtex Pré-Frontal/fisiologia , Recompensa , Adulto , Feminino , Previsões , Hipocampo/fisiologia , Humanos , Imagem por Ressonância Magnética , Masculino
3.
Nat Commun ; 9(1): 4886, 2018 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-30459310

RESUMO

Many decisions are based on an internal model of the world. Yet, how such a model is constructed from experience and represented in memory remains unknown. We test the hypothesis that reward shapes memory for sequences of events by retroactively prioritizing memory for objects as a function of their distance from reward. Human participants encountered neutral objects while exploring a series of mazes for reward. Across six data sets, we find that reward systematically modulates memory for neutral objects, retroactively prioritizing memory for objects closest to the reward. This effect of reward on memory emerges only after a 24-hour delay and is stronger for mazes followed by a longer rest interval, suggesting a role for post-reward replay and overnight consolidation, as predicted by neurobiological data in animals. These findings demonstrate that reward retroactively prioritizes memory along a sequential gradient, consistent with the role of memory in supporting adaptive decision-making.


Assuntos
Memória/fisiologia , Tempo de Reação/fisiologia , Recompensa , Adolescente , Adulto , Feminino , Humanos , Modelos Logísticos , Masculino , Estimulação Luminosa , Adulto Jovem
4.
J Neurosci ; 38(35): 7649-7666, 2018 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-30061189

RESUMO

Over the past few decades, neuroscience research has illuminated the neural mechanisms supporting learning from reward feedback. Learning paradigms are increasingly being extended to study mood and psychiatric disorders as well as addiction. However, one potentially critical characteristic that this research ignores is the effect of time on learning: human feedback learning paradigms are usually conducted in a single rapidly paced session, whereas learning experiences in ecologically relevant circumstances and in animal research are almost always separated by longer periods of time. In our experiments, we examined reward learning in short condensed sessions distributed across weeks versus learning completed in a single "massed" session in male and female participants. As expected, we found that after equal amounts of training, accuracy was matched between the spaced and massed conditions. However, in a 3-week follow-up, we found that participants exhibited significantly greater memory for the value of spaced-trained stimuli. Supporting a role for short-term memory in massed learning, we found a significant positive correlation between initial learning and working memory capacity. Neurally, we found that patterns of activity in the medial temporal lobe and prefrontal cortex showed stronger discrimination of spaced- versus massed-trained reward values. Further, patterns in the striatum discriminated between spaced- and massed-trained stimuli overall. Our results indicate that single-session learning tasks engage partially distinct learning mechanisms from distributed training. Our studies begin to address a large gap in our knowledge of human learning from reinforcement, with potential implications for our understanding of mood disorders and addiction.SIGNIFICANCE STATEMENT Humans and animals learn to associate predictive value with stimuli and actions, and these values then guide future behavior. Such reinforcement-based learning often happens over long time periods, in contrast to most studies of reward-based learning in humans. In experiments that tested the effect of spacing on learning, we found that associations learned in a single massed session were correlated with short-term memory and significantly decayed over time, whereas associations learned in short massed sessions over weeks were well maintained. Additionally, patterns of activity in the medial temporal lobe and prefrontal cortex discriminated the values of stimuli learned over weeks but not minutes. These results highlight the importance of studying learning over time, with potential applications to drug addiction and psychiatry.


Assuntos
Mapeamento Encefálico , Condicionamento Operante/fisiologia , Córtex Pré-Frontal/fisiologia , Recompensa , Lobo Temporal/fisiologia , Adolescente , Adulto , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Neuroimagem , Estimulação Luminosa , Fatores de Tempo , Adulto Jovem
5.
Comput Biol Med ; 102: 221-226, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-29739614

RESUMO

A large amount of digital image material is routinely captured during esophagogastroduodenoscopies but, for the most part, is not used for confirming the diagnosis process of celiac disease which is primarily based on histological examination of biopsies. Recently, considerable effort has been undertaken to make use of image material by developing semi- or fully-automated systems to improve the diagnostic workup. Recently, focus was especially laid on developing state-of-the-art deep learning architectures, exploiting the endoscopist's expert knowledge and on making systems fully automated and thereby completely observer independent. In this work, we summarize recent trends in the field of computer-aided celiac disease diagnosis based on upper endoscopy and discuss about recent progress, remaining challenges, limitations currently prohibiting a deployment in clinical practice and future efforts to tackle them.


Assuntos
Doença Celíaca/diagnóstico por imagem , Aprendizado Profundo , Diagnóstico por Computador/métodos , Endoscopia , Processamento de Imagem Assistida por Computador/métodos , Algoritmos , Automação , Biópsia , Tomada de Decisões , Duodeno/diagnóstico por imagem , Gastroscopia , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Aprendizado de Máquina , Variações Dependentes do Observador , Reconhecimento Automatizado de Padrão
6.
Clin Oral Investig ; 21(5): 1559-1564, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27743214

RESUMO

OBJECTIVES: The ultrasonic NO PAIN technology (Electro Medical Systems, Nyon, CH) promises minimal pain during debridement due to linear oscillating action combined with a sinusoidal power output and feedback control. The aim of the present study was to measure pain perception on a visual analogue scale (VAS) during supportive periodontal therapy including debridement of hypersensitive teeth. Two ultrasonic scalers were used, one with and one without NO PAIN technology. MATERIAL AND METHODS: In a randomized-controlled clinical study with split-mouth design, 100 hypersensitive teeth matched for air blast hypersensitivity were either treated with the ultrasonic device Piezon Master 700 or the Mini Piezon (both EMS, Nyon, CH). Pain perception during debridement was assessed by a VAS (range 0-10). RESULTS: The average VAS for the test device Piezon Master 700 with NO PAIN technology was 3.16 ± 2.10, and for the control device Mini Piezon without NO PAIN technology 3.40 ± 2.59 (p = 0.490). Placing an arbitrary threshold at the VAS score of 3 for significant pain experience, 60 % of the subjects experienced no significant pain with either instrument. CONCLUSION: No statistically significant difference in perceived pain between the instruments used was found. CLINICAL RELEVANCE: Both ultrasonic devices showed very small pain intensities during debridement of highly hypersensitive teeth and can therefore be recommended for supportive periodontal therapy.


Assuntos
Desbridamento/instrumentação , Raspagem Dentária/instrumentação , Sensibilidade da Dentina/complicações , Percepção da Dor , Terapia por Ultrassom/instrumentação , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor
7.
J Cogn Neurosci ; 28(9): 1270-82, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27167401

RESUMO

Neuroscientific studies of social cognition typically employ paradigms in which perceivers draw single-shot inferences about the internal states of strangers. Real-world social inference features much different parameters: People often encounter and learn about particular social targets (e.g., friends) over time and receive feedback about whether their inferences are correct or incorrect. Here, we examined this process and, more broadly, the intersection between social cognition and reinforcement learning. Perceivers were scanned using fMRI while repeatedly encountering three social targets who produced conflicting visual and verbal emotional cues. Perceivers guessed how targets felt and received feedback about whether they had guessed correctly. Visual cues reliably predicted one target's emotion, verbal cues predicted a second target's emotion, and neither reliably predicted the third target's emotion. Perceivers successfully used this information to update their judgments over time. Furthermore, trial-by-trial learning signals-estimated using two reinforcement learning models-tracked activity in ventral striatum and ventromedial pFC, structures associated with reinforcement learning, and regions associated with updating social impressions, including TPJ. These data suggest that learning about others' emotions, like other forms of feedback learning, relies on domain-general reinforcement mechanisms as well as domain-specific social information processing.


Assuntos
Encéfalo/fisiologia , Retroalimentação Psicológica/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Percepção Social , Percepção da Fala/fisiologia , Mapeamento Encefálico , Sinais (Psicologia) , Emoções , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Modelos Psicológicos , Testes Neuropsicológicos , Adulto Jovem
8.
J Neurosci ; 36(10): 2868-80, 2016 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-26961943

RESUMO

Rewarding experiences exert a strong influence on later decision making. While decades of neuroscience research have shown how reinforcement gradually shapes preferences, decisions are often influenced by single past experiences. Surprisingly, relatively little is known about the influence of single learning episodes. Although recent work has proposed a role for episodes in decision making, it is largely unknown whether and how episodic experiences contribute to value-based decision making and how the values of single episodes are represented in the brain. In multiple behavioral experiments and an fMRI experiment, we tested whether and how rewarding episodes could support later decision making. Participants experienced episodes of high reward or low reward in conjunction with incidental, trial-unique neutral pictures. In a surprise test phase, we found that participants could indeed remember the associated level of reward, as evidenced by accurate source memory for value and preferences to re-engage with rewarded objects. Further, in a separate experiment, we found that high-reward objects shown as primes before a gambling task increased financial risk taking. Neurally, re-exposure to objects in the test phase led to significant reactivation of reward-related patterns. Importantly, individual variability in the strength of reactivation predicted value memory performance. Our results provide a novel demonstration that affect-related neural patterns are reactivated during later experience. Reactivation of value information represents a mechanism by which memory can guide decision making.


Assuntos
Encéfalo/fisiologia , Tomada de Decisões/fisiologia , Memória/fisiologia , Recompensa , Adulto , Encéfalo/irrigação sanguínea , Sinais (Psicologia) , Retroalimentação Psicológica , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imagem por Ressonância Magnética , Masculino , Oxigênio/sangue , Dor/psicologia , Tempo de Reação/fisiologia , Assunção de Riscos , Estatísticas não Paramétricas , Adulto Jovem
9.
Oral Oncol ; 51(3): 247-53, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25532817

RESUMO

OBJECTIVES: We aimed to determine the prognostic significance of receptor activator of nuclear factor kappa-B ligand (RANKL), RANK and osteoprotegerin (OPG) in patients with oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: The protein expression of RANKL, RANK and OPG was assessed by immunohistochemistry on pretreatment biopsies of 93 patients with locally advanced OSCC who received preoperative chemoradiotherapy (CRT). The primary endpoint was cancer-specific survival. Secondary endpoints were correlation of biomarkers with bone invasion and pathological tumor response. Kaplan-Meier curves and Cox regression models were used for survival analyses. RESULTS: A significantly higher OPG expression was demonstrated in patients with malignant bone invasion and non-responders to CRT as compared to patients without bone invasion and responders (p=0.032 and p=0.033, respectively). Multivariate analysis revealed that higher OPG expression was independently associated with shorter cancer-specific survival (p=0.04). The expression status of RANKL and RANK was not significantly related to clinicopathological characteristics and had no impact on survival of OSCC patients. CONCLUSION: Upregulation of OPG expression is associated with bone invasion, poor pathological tumor regression to neoadjuvant CRT, and worse long-term cancer-specific survival in patients with locally advanced OSCC. Our results indicate that OPG may be a novel prognostic biomarker in oral cancer.


Assuntos
Neoplasias Ósseas/patologia , Carcinoma de Células Escamosas/patologia , Neoplasias Bucais/patologia , Osteoprotegerina/metabolismo , Ligante RANK/metabolismo , Biomarcadores Tumorais/metabolismo , Neoplasias Ósseas/metabolismo , Neoplasias Ósseas/terapia , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/terapia , Feminino , Humanos , Masculino , Neoplasias Bucais/metabolismo , Neoplasias Bucais/terapia , Prognóstico , Análise de Sobrevida
10.
J Neurosci ; 34(45): 14901-12, 2014 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-25378157

RESUMO

Learning is essential for adaptive decision making. The striatum and its dopaminergic inputs are known to support incremental reward-based learning, while the hippocampus is known to support encoding of single events (episodic memory). Although traditionally studied separately, in even simple experiences, these two types of learning are likely to co-occur and may interact. Here we sought to understand the nature of this interaction by examining how incremental reward learning is related to concurrent episodic memory encoding. During the experiment, human participants made choices between two options (colored squares), each associated with a drifting probability of reward, with the goal of earning as much money as possible. Incidental, trial-unique object pictures, unrelated to the choice, were overlaid on each option. The next day, participants were given a surprise memory test for these pictures. We found that better episodic memory was related to a decreased influence of recent reward experience on choice, both within and across participants. fMRI analyses further revealed that during learning the canonical striatal reward prediction error signal was significantly weaker when episodic memory was stronger. This decrease in reward prediction error signals in the striatum was associated with enhanced functional connectivity between the hippocampus and striatum at the time of choice. Our results suggest a mechanism by which memory encoding may compete for striatal processing and provide insight into how interactions between different forms of learning guide reward-based decision making.


Assuntos
Aprendizagem por Associação , Corpo Estriado/fisiologia , Memória Episódica , Recompensa , Adolescente , Adulto , Comportamento de Escolha , Feminino , Hipocampo/fisiologia , Humanos , Masculino
11.
Nat Neurosci ; 17(11): 1607-12, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25282614

RESUMO

Pain is a primary driver of learning and motivated action. It is also a target of learning, as nociceptive brain responses are shaped by learning processes. We combined an instrumental pain avoidance task with an axiomatic approach to assessing fMRI signals related to prediction errors (PEs), which drive reinforcement-based learning. We found that pain PEs were encoded in the periaqueductal gray (PAG), a structure important for pain control and learning in animal models. Axiomatic tests combined with dynamic causal modeling suggested that ventromedial prefrontal cortex, supported by putamen, provides an expected value-related input to the PAG, which then conveys PE signals to prefrontal regions important for behavioral regulation, including orbitofrontal, anterior mid-cingulate and dorsomedial prefrontal cortices. Thus, pain-related learning involves distinct neural circuitry, with implications for behavior and pain dynamics.


Assuntos
Comportamento , Mapeamento Encefálico , Aprendizagem/fisiologia , Dor/fisiopatologia , Substância Cinzenta Periaquedutal/fisiologia , Córtex Pré-Frontal/fisiologia , Adolescente , Adulto , Comportamento/fisiologia , Feminino , Giro do Cíngulo/fisiologia , Giro do Cíngulo/fisiopatologia , Humanos , Imagem por Ressonância Magnética , Masculino , Manejo da Dor , Substância Cinzenta Periaquedutal/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Adulto Jovem
12.
J Neurosci ; 34(34): 11297-303, 2014 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-25143610

RESUMO

An important aspect of adaptive learning is the ability to flexibly use past experiences to guide new decisions. When facing a new decision, some people automatically leverage previously learned associations, while others do not. This variability in transfer of learning across individuals has been demonstrated repeatedly and has important implications for understanding adaptive behavior, yet the source of these individual differences remains poorly understood. In particular, it is unknown why such variability in transfer emerges even among homogeneous groups of young healthy participants who do not vary on other learning-related measures. Here we hypothesized that individual differences in the transfer of learning could be related to relatively stable differences in intrinsic brain connectivity, which could constrain how individuals learn. To test this, we obtained a behavioral measure of memory-based transfer outside of the scanner and on a separate day acquired resting-state functional MRI images in 42 participants. We then analyzed connectivity across independent component analysis-derived brain networks during rest, and tested whether intrinsic connectivity in learning-related networks was associated with transfer. We found that individual differences in transfer were related to intrinsic connectivity between the hippocampus and the ventromedial prefrontal cortex, and between these regions and large-scale functional brain networks. Together, the findings demonstrate a novel role for intrinsic brain dynamics in flexible learning-guided behavior, both within a set of functionally specific regions known to be important for learning, as well as between these regions and the default and frontoparietal networks, which are thought to serve more general cognitive functions.


Assuntos
Hipocampo/fisiologia , Vias Neurais/fisiologia , Córtex Pré-Frontal/fisiologia , /fisiologia , Adolescente , Adulto , Aprendizagem por Associação , Mapeamento Encefálico , Tomada de Decisões , Feminino , Jogos Experimentais , Hipocampo/irrigação sanguínea , Humanos , Processamento de Imagem Assistida por Computador , Individualidade , Imagem por Ressonância Magnética , Masculino , Vias Neurais/irrigação sanguínea , Oxigênio/sangue , Córtex Pré-Frontal/irrigação sanguínea , Recompensa , Adulto Jovem
14.
Science ; 338(6104): 270-3, 2012 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-23066083

RESUMO

Every day people make new choices between alternatives that they have never directly experienced. Yet, such decisions are often made rapidly and confidently. Here, we show that the hippocampus, traditionally known for its role in building long-term declarative memories, enables the spread of value across memories, thereby guiding decisions between new choice options. Using functional brain imaging in humans, we discovered that giving people monetary rewards led to activation of a preestablished network of memories, spreading the positive value of reward to nonrewarded items stored in memory. Later, people were biased to choose these nonrewarded items. This decision bias was predicted by activity in the hippocampus, reactivation of associated memories, and connectivity between memory and reward regions in the brain. These findings explain how choices among new alternatives emerge automatically from the associative mechanisms by which the brain builds memories. Further, our findings demonstrate a previously unknown role for the hippocampus in value-based decisions.


Assuntos
Associação , Tomada de Decisões/fisiologia , Hipocampo/fisiologia , Memória/fisiologia , Recompensa , Adolescente , Adulto , Feminino , Humanos , Neuroimagem , Valores Sociais , Adulto Jovem
15.
Eur J Neurosci ; 35(7): 1092-104, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22487039

RESUMO

Research in decision-making has focused on the role of dopamine and its striatal targets in guiding choices via learned stimulus-reward or stimulus-response associations, behavior that is well described by reinforcement learning theories. However, basic reinforcement learning is relatively limited in scope and does not explain how learning about stimulus regularities or relations may guide decision-making. A candidate mechanism for this type of learning comes from the domain of memory, which has highlighted a role for the hippocampus in learning of stimulus-stimulus relations, typically dissociated from the role of the striatum in stimulus-response learning. Here, we used functional magnetic resonance imaging and computational model-based analyses to examine the joint contributions of these mechanisms to reinforcement learning. Humans performed a reinforcement learning task with added relational structure, modeled after tasks used to isolate hippocampal contributions to memory. On each trial participants chose one of four options, but the reward probabilities for pairs of options were correlated across trials. This (uninstructed) relationship between pairs of options potentially enabled an observer to learn about option values based on experience with the other options and to generalize across them. We observed blood oxygen level-dependent (BOLD) activity related to learning in the striatum and also in the hippocampus. By comparing a basic reinforcement learning model to one augmented to allow feedback to generalize between correlated options, we tested whether choice behavior and BOLD activity were influenced by the opportunity to generalize across correlated options. Although such generalization goes beyond standard computational accounts of reinforcement learning and striatal BOLD, both choices and striatal BOLD activity were better explained by the augmented model. Consistent with the hypothesized role for the hippocampus in this generalization, functional connectivity between the ventral striatum and hippocampus was modulated, across participants, by the ability of the augmented model to capture participants' choice. Our results thus point toward an interactive model in which striatal reinforcement learning systems may employ relational representations typically associated with the hippocampus.


Assuntos
/fisiologia , Aprendizagem/fisiologia , Recompensa , Adolescente , Adulto , Gânglios da Base/fisiologia , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos , Desempenho Psicomotor/fisiologia , Adulto Jovem
16.
Eur J Neurol ; 17(6): 852-60, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-20100231

RESUMO

BACKGROUND AND PURPOSE: When to start disease-modifying treatment (DMT) in patients with a clinically isolated syndrome (CIS) requires individual weighing of benefits versus possible burden of side effects and costs. How this occurs in a routine setting is barely known. The aim of the study was to investigate the decision-making process regarding immediate or later DMT and the ensuing impact on CIS patients in Austria. METHODS: Demographic and (para) clinical characteristics of 296 CIS patients were recorded in 29 multiple sclerosis (MS) centres, and the patients' overall condition was rated on a visual analogue scale (VAS). Clinical follow-up and VAS ratings were repeated at 6-month intervals over 2 years. The decision for initiation of DMT was at the physician's and patient's discretion. RESULTS: In 29% of patients, DMT was started within 3 months and this decision was independently associated with a T2-lesion number >or=9 on MRI and a worse VAS rating by the physician. DMT initiation in the subsequent 6 months was additionally associated with the presence of oligoclonal bands and rarely occurred thereafter. Adapted to the clinical course, later treatment was associated with the highest rate of conversion to clinically definite MS and greatest disability after 2 years whilst never treated patients fared best. Patient VAS ratings significantly improved during follow-up independently of treatment decisions. CONCLUSION: The management of Austrian CIS patients relies strongly on MRI findings and the physicians' interpretation of the patients' overall situation which, after 2 years, depends primarily on the course of the disease.


Assuntos
Doenças Desmielinizantes/tratamento farmacológico , Fatores Imunológicos/uso terapêutico , Padrões de Prática Médica/estatística & dados numéricos , Adulto , Áustria , Encéfalo/patologia , Tomada de Decisões , Doenças Desmielinizantes/patologia , Progressão da Doença , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla/patologia , Medição da Dor
17.
Soc Cogn Affect Neurosci ; 4(4): 409-16, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19843618

RESUMO

A reward or punishment can seem better or worse depending on what else might have happened. Little is known, however, about how neural representations of an anticipated incentive might be influenced by the available alternatives. We used event-related FMRI to investigate the activation in the nucleus accumbens (NAcc), while we varied the available alternative incentives in a monetary incentive delay task. Some task blocks included only uncertain gains and losses; others included the same uncertain gains and losses intermixed with certain gains and losses. The availability of certain gains and losses increased NAcc activation for uncertain losses and decreased the difference between uncertain gains and losses. We suggest that this pattern of activation can result from reference point changes across blocks, and that the worst available loss may serve as an important anchor for NAcc activation. These findings imply that NAcc activation represents anticipated incentive value relative to the current context of available alternative gains and losses.


Assuntos
Tomada de Decisões/fisiologia , Motivação/fisiologia , Núcleo Accumbens/fisiologia , Recompensa , Adolescente , Adulto , Análise de Variância , Mapeamento Encefálico , Sinais (Psicologia) , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imagem por Ressonância Magnética , Masculino , Núcleo Accumbens/irrigação sanguínea , Oxigênio/sangue , Tempo de Reação/fisiologia , Esquema de Reforço , Fatores de Tempo , Adulto Jovem
18.
Soc Cogn Affect Neurosci ; 4(1): 85-92, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19047075

RESUMO

Despite increases in the human life span, people have not increased their rate of saving. In a phenomenon known as 'temporal discounting', people value immediate gains over future gains. According to a future self-continuity hypothesis, individuals perceive and treat the future self differently from the present self, and so might fail to save for their future. Neuroimaging offers a novel means of testing this hypothesis, since previous research indicates that self- vs other-judgments elicit activation in the rostral anterior cingulate (rACC). Using event-related functional magnetic resonance imaging, we predicted and found not only individual differences in rACC activation while rating the current vs future self, but also that individual differences in current vs future self activation predicted temporal discounting assessed behaviorally a week after scanning. In addition to supporting the future self-continuity hypothesis, these findings hold implications for significant financial decisions, such as choosing whether to save for the future or spend in the present.


Assuntos
Comportamento Impulsivo/economia , Comportamento Impulsivo/psicologia , Autoimagem , Adolescente , Córtex Cerebral/fisiologia , Feminino , Previsões , Giro do Cíngulo/fisiologia , Humanos , Individualidade , Imagem por Ressonância Magnética , Masculino , Tempo de Reação/fisiologia , Recompensa , Adulto Jovem
19.
Neuron ; 58(5): 814-22, 2008 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-18549791

RESUMO

The "endowment effect" refers to the tendency to place greater value on items that one owns-an anomaly that violates the reference-independence assumption of rational choice theories. We investigated neural antecedents of the endowment effect in an event-related functional magnetic resonance imaging (fMRI) study. During scanning, 24 subjects considered six products paired with 18 different prices under buying, choosing, or selling conditions. Subjects showed greater nucleus accumbens (NAcc) activation for preferred products across buy and sell conditions combined, but greater mesial prefrontal cortex (MPFC) activation in response to low prices when buying versus selling. During selling, right insular activation for preferred products predicted individual differences in susceptibility to the endowment effect. These findings are consistent with a reference-dependent account in which ownership increases value by enhancing the salience of the possible loss of preferred products.


Assuntos
Mapeamento Encefálico , Encéfalo/fisiologia , Tomada de Decisões/fisiologia , Administração Financeira , Encéfalo/anatomia & histologia , Encéfalo/irrigação sanguínea , Feminino , Lateralidade Funcional , Humanos , Processamento de Imagem Assistida por Computador/métodos , Individualidade , Imagem por Ressonância Magnética/métodos , Masculino , Oxigênio/sangue , Recompensa , Análise e Desempenho de Tarefas
20.
Neuroreport ; 19(5): 509-13, 2008 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-18388729

RESUMO

In functional magnetic resonance imaging research, nucleus accumbens (NAcc) activation spontaneously increases before financial risk taking. As anticipation of diverse rewards can increase NAcc activation, even incidental reward cues may influence financial risk taking. Using event-related functional magnetic resonance imaging, we predicted and found that anticipation of viewing rewarding stimuli (erotic pictures for 15 heterosexual men) increased financial risk taking, and that this effect was partially mediated by increases in NAcc activation. These results are consistent with the notion that incidental reward cues influence financial risk taking by altering anticipatory affect, and so identify a neuropsychological mechanism that may underlie effective emotional appeals in financial, marketing, and political domains.


Assuntos
Sinais (Psicologia) , Economia , Núcleo Accumbens/fisiologia , Recompensa , Assunção de Riscos , Adolescente , Adulto , Mapeamento Encefálico , Humanos , Processamento de Imagem Assistida por Computador , Imagem por Ressonância Magnética/métodos , Masculino , Núcleo Accumbens/irrigação sanguínea , Oxigênio/sangue , Análise de Regressão
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