RESUMEN
Studies of subjective well-being have conventionally relied upon self-report, which directs subjects' attention to their emotional experiences. This method presumes that attention itself does not influence emotional processes, which could bias sampling. We tested whether attention influences experienced utility (the moment-by-moment experience of pleasure) by using functional magnetic resonance imaging (fMRI) to measure the activity of brain systems thought to represent hedonic value while manipulating attentional load. Subjects received appetitive or aversive solutions orally while alternatively executing a low or high attentional load task. Brain regions associated with hedonic processing, including the ventral striatum, showed a response to both juice and quinine. This response decreased during the high-load task relative to the low-load task. Thus, attentional allocation may influence experienced utility by modulating (either directly or indirectly) the activity of brain mechanisms thought to represent hedonic value.
Asunto(s)
Atención/fisiología , Encéfalo/fisiología , Jugos de Frutas y Vegetales , Quinina/administración & dosificación , Administración Oral , Adolescente , Adulto , Analgésicos no Narcóticos/administración & dosificación , Análisis de Varianza , Atención/efectos de los fármacos , Encéfalo/anatomía & histología , Encéfalo/efectos de los fármacos , Mapeo Encefálico , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Desempeño Psicomotor/efectos de los fármacos , Desempeño Psicomotor/fisiología , Tiempo de Reacción/efectos de los fármacos , Tiempo de Reacción/fisiología , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Anticipating the location of a temporarily obscured target-what Piaget (the construction of reality in the child. Basic Books, New York, 1954) called "object permanence"-is a critical skill, especially in hunters of mobile prey. Previous research with bottlenose dolphins found they could predict the location of a target that had been visibly displaced into an opaque container, but not one that was first placed in an opaque container and then invisibly displaced to another container. We tested whether, by altering the task to involve occlusion rather than containment, these animals could show more advanced object permanence skills. We projected dynamic visual displays at an underwater-viewing window and videotaped the animals' head moves while observing these displays. In Experiment 1, the animals observed a small black disk moving behind occluders that shifted in size, ultimately forming one large occluder. Nine out of ten subjects "tracked" the presumed movement of the disk behind this occluder on their first trial-and in a statistically significant number of subsequent trials-confirming their visible displacement abilities. In Experiment 2, we tested their invisible displacement abilities. The disk first disappeared behind a pair of moving occluders, which then moved behind a stationary occluder. The moving occluders then reappeared and separated, revealing that the disk was no longer behind them. The subjects subsequently looked to the correct stationary occluder on eight of their ten first trials, and in a statistically significant number of subsequent trials. Thus, by altering the stimuli to be more ecologically valid, we were able to show that the dolphins could indeed succeed at an invisible displacement task.
Asunto(s)
Delfín Mular/psicología , Cognición , Percepción Visual , Animales , Femenino , Masculino , Movimiento (Física) , Percepción de Movimiento , Estimulación LuminosaRESUMEN
Rats emit 50kHz ultrasonic vocalizations (USVs) in situations of increased motivation, such as during the anticipation of palatable food or drugs of abuse. Whether the same holds true for the anticipation of alcohol intake remains unknown. Alcohol drinking in a nondependent state is thought to be mediated by its rewarding effects (positive reinforcement), whereas drinking in the dependent state is motivated by alcohol's stress-relieving effects (negative reinforcement). Here, we measured context-elicited 50kHz USVs in alcohol-dependent (alcohol vapor-exposed) and nondependent rats immediately before operant alcohol self-administration sessions. Dependent rats showed escalated levels of alcohol intake compared with nondependent rats. Overall, dependent and nondependent rats showed similar levels of anticipatory 50kHz USVs. However, the number of anticipatory USVs was positively correlated with alcohol intake in dependent rats but not nondependent rats. Additionally, dependent rats with higher alcohol intake displayed increased anticipatory 50kHz USVs compared with rats that had lower alcohol intake, whereas no difference was observed between rats with high and low alcohol intake in the nondependent group. Increased 50kHz USVs were specific for the anticipation of alcohol self-administration and did not generalize to a novel environment. These findings suggest that anticipatory 50kHz USVs may be an indicator of context-elicited negative reinforcement learning.
Asunto(s)
Consumo de Bebidas Alcohólicas/fisiopatología , Alcoholismo/fisiopatología , Etanol/envenenamiento , Ultrasonido , Vocalización Animal , Animales , Masculino , Ratas , Ratas Wistar , Refuerzo en Psicología , Recompensa , Autoadministración , Espectrografía del Sonido/métodosRESUMEN
RATIONALE: Fifty kilohertz ultrasonic vocalizations (USVs) have been sometimes shown to reflect positive affective-like states in rats. Rewarding events, such as access to palatable food or drugs of abuse, increase the number of anticipatory 50-kHz USVs. However, little is known about the predictability of USVs, subtypes of USVs involved, and underlying neurobiological mechanisms. OBJECTIVES: We examined whether cue-induced anticipatory 50-kHz USVs predict palatable food intake and tested the effects of dopamine D1 and µ-opioid receptor antagonism on anticipatory USVs. MATERIALS: Food-restricted rats received repeated sessions of a 2-min cue light immediately followed by a 5-min access to palatable food. Ultrasonic vocalizations were recorded during cue presentation. After 24 pairing sessions, the rats were pretreated with the D1 receptor antagonist SCH 23390 (5, 10, and 20 µg/kg) and µ-opioid receptor antagonist naltrexone (0.03, 0.06, 0.13, 0.25, 0.5, and 1 mg/kg) in a Latin-square design, and USVs were recorded during cue presentation. RESULTS: Rats emitted 50-kHz USVs during cue presentation, and the number of USVs increased across sessions with robust and stable interindividual differences. Escalation in USVs was subtype-dependent, with nontrill calls significantly increasing over time. Palatable food intake was positively correlated with anticipatory 50-kHz USVs. Moreover, anticipatory USVs were dose-dependently prevented by antagonism of D1 and µ-opioid receptors. CONCLUSIONS: These findings demonstrate that anticipatory 50-kHz USVs represent a stable phenotype of increased motivation for food, and dopamine and opioid systems appear to mediate anticipatory 50-kHz USVs.
Asunto(s)
Benzazepinas/farmacología , Señales (Psicología) , Conducta Alimentaria/efectos de los fármacos , Naltrexona/farmacología , Receptores de Dopamina D1/antagonistas & inhibidores , Receptores Opioides mu/antagonistas & inhibidores , Vocalización Animal/efectos de los fármacos , Animales , Alimentos , Masculino , Ratas , Ratas WistarRESUMEN
Drug addiction has been conceptualized as a chronically relapsing disorder of compulsive drug seeking and taking that progresses through three stages: binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. Drug addiction impacts multiple motivational mechanisms and can be conceptualized as a disorder that progresses from positive reinforcement (binge/intoxication stage) to negative reinforcement (withdrawal/negative affect stage). The construct of negative reinforcement is defined as drug taking that alleviates a negative emotional state. Our hypothesis is that the negative emotional state that drives such negative reinforcement is derived from dysregulation of key neurochemical elements involved in the brain stress systems within the frontal cortex, ventral striatum, and extended amygdala. Specific neurochemical elements in these structures include not only recruitment of the classic stress axis mediated by corticotropin-releasing factor (CRF) in the extended amygdala as previously hypothesized but also recruitment of dynorphin-κ opioid aversive systems in the ventral striatum and extended amygdala. Additionally, we hypothesized that these brain stress systems may be engaged in the frontal cortex early in the addiction process. Excessive drug taking engages activation of CRF not only in the extended amygdala, accompanied by anxiety-like states, but also in the medial prefrontal cortex, accompanied by deficits in executive function that may facilitate the transition to compulsive-like responding. Excessive activation of the nucleus accumbens via the release of mesocorticolimbic dopamine or activation of opioid receptors has long been hypothesized to subsequently activate the dynorphin-κ opioid system, which in turn can decrease dopaminergic activity in the mesocorticolimbic dopamine system. Blockade of the κ opioid system can also block anxiety-like and reward deficits associated with withdrawal from drugs of abuse and block the development of compulsive-like responding during extended access to drugs of abuse, suggesting another powerful brain stress/anti-reward system that contributes to compulsive drug seeking. Thus, brain stress response systems are hypothesized to be activated by acute excessive drug intake, to be sensitized during repeated withdrawal, to persist into protracted abstinence, and to contribute to the development and persistence of addiction. The recruitment of anti-reward systems provides a powerful neurochemical basis for the negative emotional states that are responsible for the dark side of addiction. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.