When making decisions, individuals evaluate several possible outcomes of their choice; however, some display heightened reward sensitivity, despite the potential for future negative consequences, which can lead one to make risky choices. Rewards are processed in the mesolimbic dopamine reward system, and this system is in part modulated by genetic polymorphisms that are associated with dopamine transmission. The current study tested if genetic polymorphisms that are associated with enhanced dopamine neurotransmission will be more neurally reward sensitive, score higher on self-reported impulsivity, and make riskier choices. In a sample of 85 participants, five genetic polymorphisms were genotyped and used to create a genetic risk score that represented dopamine transmission efficiency. Two groups (high and low efficiency) were created via median split and then compared on neural reward sensitivity (assessed by event-related potentials, specifically, the medial-frontal negativity [MFN] and the error-related negativity), impulsivity (assessed via self-report), and risky choice (measured using the Balloon Analogue Risk Task and self-report measures). Results indicated that individuals with higher levels of dopamine displayed a less negative MFN and more drinking behaviors than those with lower levels of dopamine. These results suggest that individuals with higher levels of dopamine are less sensitive to punishments, which could lead them to make riskier choices.

Made available in DSpace on 2016-03-15T19:40:17Z (GMT). No. of bitstreams: 1 Gabriel Gaudencio do Rego.pdf: 1139897 bytes, checksum: b56f45681ad1b3adb1fbebc620c7562a (MD5) Previous issue date: 2014-08-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Games are useful tools to simulate social interactions of cooperation or competition and can be applied in conjunction with behavioral and electrophysiological techniques, such as Event Related Potentials (ERP) analysis. The Ultimatum Game (UG) is a well-studied game which can be used to investigate how individuals react to injustice. An initial value is divided between a proponent, who suggests a division rate of this value, and a respondent, who may accept or reject it. If the respondent accepts, both players gain the proposed value, and if he or she rejects, they gain nothing. The behavioral and electrophysiological results have demonstrated typical reactions in the game. The Medial Frontal Negativity (MFN), a component associated with the automatic processing of negative social feedback, and the P300, associated with attention and memory process, are two components commonly observed during UG. While the interaction between volunteers and proponents with typical development is well described, the interaction between volunteers and proponents with Down syndrome is still unknown. This research aimed to investigate differences in the behavioral data, MFN and P300 in participants playing the UG with a typical proposer and Down proposer. 32 subjects participated in the experiment. Scales of social desirability, moral identity, self-esteem and an implicit association test about Down syndrome were applied. The results showed similar behavioral patterns among proponents and previous data described in the literature. Regarding ERPs, the MFN was not detected and there was greater amplitude of P200 component for proposals of the Down. There was also greater amplitude of P300 for fair proposals of the typical proponent compared to the fair proposals of the Down, and of these two compared to unfair proposals of both. The amplitude of the P300 for proposals of typical was negatively correlated with self-esteem scores. Together, the results suggest that the presence of a player with Down syndrome might influence the perception and expectation of the participants about the game, and this effect could be extended to the interaction with the typical proponent. The absence of MFN suggests that participants do not perceived the unfair proposals as a social negative outcome and P300 suggests that the interaction with the typical proposer was more relevant to the participants. Moreover, this relevance was modulated due to personal characteristics of self-esteem. Further studies are suggested in this area to confirm the hypotheses suggested in the present research. / Os jogos simulam situações sociais relativamente simples de cooperação ou competição e podem ser aplicados conjuntamente às técnicas de pesquisa comportamentais e eletrofisiológicas como a análise de potenciais relacionados a eventos (ERP). Um jogo muito estudado é o Ultimatum Game (UG), que pode ser utilizado para investigar como indivíduos reagem à injustiça. Um valor inicial é dividido entre um propositor, que sugere uma divisão do valor, e um respondente que pode aceitar ou rejeitar. Caso este aceite os dois ganham o valor proposto, caso rejeite ninguém ganha. Os resultados comportamentais e eletrofisiológicos têm demonstrado reações comuns no jogo. Os ERPs mais comuns é o MFN, associado ao processamento automático de feedbacks sociais negativos, e o P300, associado a processos atencionais e de memorização. Enquanto a interação entre sujeitos de pesquisa com propositores de desenvolvimento típico já é bem conhecida, o efeito desta interação com propositores com síndrome de Down ainda é desconhecido. O presente buscou investigar diferenças no padrão comportamental, de MFN e P300 em participantes jogando UG com propositor típico e com Down. 32 sujeitos participaram do experimento. Foram aplicadas escalas de desejabilidade social, identidade moral, de autoestima e um teste de atitudes implícitas frente às pessoas com Down. Os resultados demonstraram padrões comportamentais semelhantes entres os propositores e a literatura. Quanto aos ERPs, o MFN não foi detectado e houve presença de componente P200 para propostas de Down. Houve também maior amplitude de P300 para propostas justas do típico em comparação as justas do Down e destes dois em comparação às propostas injustas de ambos. A amplitude do P300 para propostas do típico apresentaram correlação negativa com escalas de autoestima. Os resultados sugerem que a presença de um jogador com síndrome de Down influenciou a percepção e expectativa dos participantes quanto ao jogo, e que este efeito pode ter se estendido para a interação com o propositor típico. A ausência de MFN sugere que não houve processamento das propostas injustas como respostas sociais negativas e o P300 sugere que a interação com o propositor foi de maior relevância para os participantes. Além disto, esta relevância foi modulada em razão de características pessoais de autoestima. São sugeridos novos estudos no tema para confirmar as hipóteses aqui apresentadas.