RESUMEN
Patients with depression show an enhanced preoccupation with negative expectations and are often unable to look forward to positive events. Here we studied anticipatory emotional processes in unmedicated depressed patients using functional magnetic resonance imaging. Consistent with a negative processing bias, we hypothesized enhanced responses to negative and attenuated responses to positive expectancy cues in brain areas associated with emotional expectancy. Participants comprised 19 drug-free depressed patients and 19 matched healthy control subjects who viewed affective photographs. Pictures were preceded by an expectancy cue which signaled the emotional valence of the upcoming picture in half of the trials. Depressed patients showed attenuated blood-oxygen-level-dependent responses in the left lateral prefrontal cortex (inferior frontal gyrus, Brodmann area 44) during positive expectancy and-contrary to our hypothesis-in the right lateral orbitofrontal cortex (middle frontal gyrus, Brodmann area 47) during negative expectancy. This attenuation was specific for the anticipation (as opposed to the perception) of emotional pictures and correlated with a clinical measure of depressive symptoms. The observed attenuation suggests emotion-context insensitivity rather than a negative processing bias during anticipatory emotional processes in depression. This hyporeactivity may contribute to clinical features like anergia, apathy, and loss of motivation in the context of both positive and negative incentives.
Asunto(s)
Mapeo Encefálico , Encéfalo/irrigación sanguínea , Trastorno Depresivo Mayor/patología , Trastorno Depresivo Mayor/fisiopatología , Emociones/fisiología , Imagen por Resonancia Magnética , Adulto , Análisis de Varianza , Atención/fisiología , Encéfalo/patología , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Persona de Mediana Edad , Escalas de Valoración PsiquiátricaRESUMEN
OBJECTIVE: Increased responsiveness to appetitive and reduced responsiveness to aversive anticipatory cues may be associated with dysfunction of the brain reward system in mania. Here we studied neural correlates of gain and loss expectation in mania using functional magnetic resonance imaging (fMRI). METHOD: Fifteen manic patients and 26 matched healthy control individuals performed a monetary incentive delay task, during which subjects anticipated to win or lose a varying amount of money. Varying both magnitude and valence (win, loss) of anticipatory cues allowed us to isolate the effects of magnitude, valence and expected value (magnitude-by-valence interaction). RESULTS: Response times and total gain amount did not differ significantly between groups. FMRI data indicated that the ventral striatum responded according to cued incentive magnitude in both groups, and this effect did not significantly differ between groups. However, a significant group difference was observed for expected value representation in the left lateral orbitofrontal cortex (OFC; BA 11 and 47). In this region, patients showed increasing BOLD responses during expectation of increasing gain and decreasing responses during expectation of increasing loss, while healthy subjects tended to show the inverse effect. In seven patients retested after remission OFC responses adapted to the response pattern of healthy controls. CONCLUSIONS: The observed alterations are consistent with a state-related affective processing bias during the expectation of gains and losses which may contribute to clinical features of mania, such as the enhanced motivation for seeking rewards and the underestimation of risks and potential punishments.
Asunto(s)
Trastorno Bipolar/fisiopatología , Cognición/fisiología , Función Ejecutiva/fisiología , Lóbulo Frontal/fisiopatología , Adulto , Trastorno Bipolar/tratamiento farmacológico , Encéfalo/fisiología , Mapeo Encefálico , Estudios de Casos y Controles , Señales (Psicología) , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Pruebas Neuropsicológicas , Tiempo de Reacción , RecompensaRESUMEN
OBJECTIVES: The present study in hypomanic and manic patients explored how amygdala responses to affective stimuli depend on the valence of the stimuli presented. METHODS: We compared 10 patients with 10 matched healthy control subjects. We measured blood oxygen level-dependent (BOLD) responses in the amygdala while subjects passively viewed photographs taken from the International Affective Picture System. After the fMRI session, subjects saw the pictures again and subjectively rated the emotional valence and intensity of each picture. RESULTS: Compared to healthy individuals, hypomanic or manic patients showed higher valence ratings in positive pictures and associated larger BOLD responses in the left amygdala during positive versus neutral picture viewing. This enhanced amygdala activation was correlated with Young Mania Rating Scale scores and with euphoric as opposed to irritable symptom presentation. CONCLUSIONS: Increased valence ratings and amygdala responses to positive affective stimuli may reflect a positive processing bias contributing to elevated mood states characteristic for euphoric mania.