Alcohol dependence decreases functional activation of the caudate nucleus during model-based decision processes

BACKGROUND

Impaired decision making, a key characteristic of alcohol dependence (AD), manifests in continuous alcohol consumption despite severe negative consequences. The neural basis of this impairment in individuals with AD and differences with known neural decision mechanisms among healthy subjects are not fully understood. In particular, it is unclear whether the choice behavior among individuals with AD is based on a general impairment of decision mechanisms or is mainly explained by altered value attribution, with an overly high subjective value attributed to alcohol-related stimuli.

METHODS

Here, we use a functional magnetic resonance imaging (fMRI) monetary reward task to compare the neural processes of model-based decision making and value computation between AD individuals (n = 32) and healthy controls (n = 32). During fMRI, participants evaluated monetary offers with respect to dynamically changing constraints and different levels of uncertainty.

RESULTS

Individuals with AD showed lower activation associated with model-based decision processes in the caudate nucleus than controls, but there were no group differences in value-related neural activity or task performance.

CONCLUSIONS

Our findings highlight the role of the caudate nucleus in impaired model-based decisions of alcohol-dependent individuals.

Dynamic Computation of Value Signals via a Common Neural Network in Multi-Attribute Decision-Making

Studies in decision neuroscience have identified robust neural representations for the value of choice options. However, overall values often depend on multiple attributes, and it is not well understood how the brain evaluates different attributes and integrates them to combined values. In particular, it is not clear whether attribute values are computed in distinct attribute-specific regions or within the general valuation network known to process overall values. Here, we used an fMRI choice task in which abstract stimuli had to be evaluated based on variations of the attributes color and motion. The behavioral data showed that participants responded faster when overall values were high and attribute value differences were low. On the neural level, we did not find that attribute values were systematically represented in areas V4 and V5, even though these regions are associated with attribute-specific processing of color and motion, respectively. Instead, attribute values were associated with activity in the posterior cingulate cortex, ventral striatum, and posterior inferior temporal gyrus. Further, overall values were represented in dorsolateral and ventromedial prefrontal cortex, and attribute value differences in dorsomedial prefrontal cortex, which suggests that these regions play a key role for the neural integration of attribute values.

Individual differences in self-reported self-control predict successful emotion regulation

Both self-control and emotion regulation enable individuals to adapt to external circumstances and social contexts, and both are assumed to rely on the overlapping neural resources. Here, we tested whether high self-reported self-control is related to successful emotion regulation on the behavioral and neural level. One hundred eight participants completed three self-control questionnaires and regulated their negative emotions during functional magnetic resonance imaging using reappraisal (distancing). Trait self-control correlated positively with successful emotion regulation both subjectively and neurally, as indicated by online ratings of negative emotions and functional connectivity strength between the amygdala and prefrontal areas, respectively. This stronger overall connectivity of the left amygdala was related to more successful subjective emotion regulation. Comparing amygdala activity over time showed that high self-controllers successfully maintained down-regulation of the left amygdala over time, while low self-controllers failed to down-regulate towards the end of the experiment. This indicates that high self-controllers are better at maintaining a motivated state supporting emotion regulation over time. Our results support assumptions concerning a close relation of self-control and emotion regulation as two domains of behavioral control. They further indicate that individual differences in functional connectivity between task-related brain areas directly relate to differences in trait self-control.

The suggestible brain: posthypnotic effects on value-based decision-making

Hypnosis can affect perception, motor function and memory. However, so far no study using neuroimaging has investigated whether hypnosis can influence reward processing and decision-making. Here, we assessed whether posthypnotic suggestions can diminish the attractiveness of unhealthy food and whether this is more effective than diminishing attractiveness by one's own effort via autosuggestion. In total, 16 participants were hypnotized and 16 others were instructed to associate a color cue (blue or green) with disgust regarding specific snacks (sweet or salty). Afterwards, participants bid for snack items shown on an either blue or green background during functional magnetic resonance imaging measurement. Both hypnosis and autosuggestion successfully devalued snacks. This was indicated by participants' decision-making, their self-report and by decreased blood oxygen level-dependent signal in the ventromedial prefrontal cortex (vmPFC), a region known to represent value. Different vmPFC subregions coded for cue and snack type. The cue had significantly stronger effects on vmPFC after hypnosis than after autosuggestion, indicating that hypnosis was more effective in genuinely reducing value. Supporting previous findings, the precuneus was involved in the hypnotic effects by encoding whether a snack was sweet or salty during hypnotic cue presentation. Our results demonstrate that posthypnotic suggestions can influence valuation and decision-making.