Responses In Ventromedial Prefrontal Cortex Research Articles

Modulation of prefrontal couplings by prior belief-related responses in ventromedial prefrontal cortex.

Humans and other animals can maintain constant payoffs in an uncertain environment by steadily re-evaluating and flexibly adjusting current strategy, which largely depends on the interactions between the prefrontal cortex (PFC) and mediodorsal thalamus (MD). While the ventromedial PFC (vmPFC) represents the level of uncertainty (i.e., prior belief about external states), it remains unclear how the brain recruits the PFC-MD network to re-evaluate decision strategy based on the uncertainty. Here, we leverage non-linear dynamic causal modeling on fMRI data to test how prior belief-dependent activity in vmPFC gates the information flow in the PFC-MD network when individuals switch their decision strategy. We show that the prior belief-related responses in vmPFC had a modulatory influence on the connections from dorsolateral PFC (dlPFC) to both, lateral orbitofrontal (lOFC) and MD. Bayesian parameter averaging revealed that only the connection from the dlPFC to lOFC surpassed the significant threshold, which indicates that the weaker the prior belief, the less was the inhibitory influence of the vmPFC on the strength of effective connections from dlPFC to lOFC. These findings suggest that the vmPFC acts as a gatekeeper for the recruitment of processing resources to re-evaluate the decision strategy in situations of high uncertainty.

Sex differences in emotion- and reward-related neural responses predicting increases in substance use in adolescence

Adolescent substance use is a significant public health problem and there is a need for effective substance use preventions. To develop effective preventions, it is important to identify neurobiological risk factors that predict increases in substance use in adolescence and to understand potential sex differences in risk mechanisms. The present study used functional magnetic resonance imaging and hierarchical linear modeling to examine negative emotion- and reward-related neural responses in early adolescence predicting growth in substance use to middle adolescence in 81 youth, by sex. Adolescent neural responses to negative emotional stimuli and monetary reward receipt were assessed at age 12–14. Adolescents reported on substance use at age 12–14 and at 6 month, and 1, 2, and 3 year follow-ups. Adolescent neural responses did not predict initiation of substance use (yes/no), but, among users, neural responses predicted growth in substance use frequency. For girls, heightened right amygdala responses to negative emotional stimuli in early adolescence predicted growth in substance use frequency through middle adolescence. For boys, blunted left nucleus accumbens and bilateral ventromedial prefrontal cortex responses to monetary reward predicted growth in substance use frequency. Findings suggest different emotion and reward-related predictors of the development of substance use for adolescent girls versus boys.

Negative Urgency and Ventromedial Prefrontal Cortex Responses to Alcohol Cues: fMRI Evidence of Emotion-Based Impulsivity

Recent research has highlighted the role of emotion-based impulsivity (negative and positive urgency personality traits) for alcohol use and abuse, but has yet to examine how these personality traits interact with the brain's motivational systems. Using functional magnetic resonance imaging (fMRI), we tested whether urgency traits and mood induction affected medial prefrontal responses to alcohol odors (AcO). Twenty-seven social drinkers (mean age=25.2, 14 males) had 6 fMRI scans while viewing negative, neutral, or positive mood images (3 mood conditions) during intermittent exposure to AcO and appetitive control (AppCo) aromas. Voxel-wise analyses (p<0.001) confirmed [AcO>AppCo] activation throughout medial prefrontal cortex (mPFC) and ventromedial PFC (vmPFC) regions. Extracted from a priori mPFC and vmPFC regions and analyzed in Odor (AcO, AppCo)×Mood factorial models, AcO activation was greater than AppCo in left vmPFC (p<0.001), left mPFC (p=0.002), and right vmPFC (p=0.01) regions. Mood did not interact significantly with activation, but the covariate of trait negative urgency accounted for significant variance in left vmPFC (p=0.01) and right vmPFC (p=0.01) [AcO>AppCo] activation. Negative urgency also mediated the relationship between vmPFC activation and both (i) subjective craving and (ii) problematic drinking. The trait of negative urgency is associated with neural responses to alcohol cues in the vmPFC, a region involved in reward value and emotion-guided decision-making. This suggests that negative urgency might alter subjective craving and brain regions involved in coding reward value.

Polysubstance dependent patients display a more utilitarian profile in moral decision-making than alcohol-dependent patients, depressive patients and controls

BackgroundAddiction has been shown to be associated with the endorsement of utilitarian moral judgments. Ventro-medial prefrontal cortex (VMPFC) dysfunction may explain these findings. Methods100 subjects were recruited: 25 polysubstance dependent patients, 25 alcohol dependent patients, 25 patients with major depressive disorders, and 25 normal controls. Subjects were assessed with a battery of 24 moral dilemmas: 8 impersonal dilemmas (no physical contact involved); 8 personal pareto (direct action that does not make the harmed individual worse off) and 8 personal non-pareto (direct action that does make the harmed individual worse off). The Iowa Gambling Task was used to document a possible connection between VMPFC dysfunction and responses to the moral dilemmas. ResultsPolysubstance dependent patients endorsed more utilitarian choices than controls on all types of dilemmas and more than depressed patients on impersonal and personal pareto dilemmas. Alcohol dependent patients had intermediate results between polysubstance dependent patients and controls but these differences were not significant. All patients showed significantly poorer performance compared to controls on the Iowa Gambling Task, but there was no significant association between Iowa Gambling Tasks scores and moral dilemma choices. ConclusionPolysubstance dependent patients made more utilitarian choices when responding to moral dilemmas than depressed patients and normal controls, while alcoholic patients showed intermediate results. The absence of correlation between performance on the Iowa Gambling Task and the number of more utilitarian choices indicates that moral dilemma and decision making under uncertainty tap into separate mechanisms.

Endogenous testosterone levels are associated with amygdala and ventromedial prefrontal cortex responses to anger faces in men but not women

Testosterone moderates behavioral and physiological responses to the emotion anger. However, little is known about the effects of testosterone in the human brain in the context of the perception of anger. We used fMRI to measure BOLD responses to anger faces in the amygdala and ventromedial prefrontal cortex (vmPFC) as a function of endogenous testosterone levels in 24 participants (10 men). In one task, participants passively viewed anger faces and neutral faces and in another task, participants engaged in an oddball task while viewing anger and neutral faces. Men's, but not women's, amygdala BOLD response to anger faces was negatively correlated with their endogenous testosterone levels in both tasks. Men's, but not women's, vmPFC BOLD response to anger faces was positively correlated with their endogenous testosterone levels in the passive-viewing task. In men, amygdala and vmPFC BOLD responses to anger faces were negatively associated. Our results extend past research by documenting associations between endogenous testosterone levels and BOLD responses to anger faces in the amygdala and vmPFC in men, and our results also support research that documents negative associations between amygdala and vmPFC activity.

A Double Dissociation of Ventromedial Prefrontal Cortical Responses to Sad and Happy Stimuli in Depressed and Healthy Individuals

The ventromedial prefrontal cortex (VMPFC) is a region implicated in the assessment of the rewarding potential of stimuli and may be dysfunctional in major depressive disorder (MDD). The few studies examining prefrontal cortical responses to emotive stimuli in MDD have indicated increased VMPFC responses to pleasant images but decreased responses to sad mood provocation when compared with healthy individuals. We wished to corroborate these results by examining neural responses to personally relevant happy and sad stimuli in MDD and healthy individuals within the same paradigm. Neural responses to happy and sad emotional stimuli (autobiographical memory prompts and congruent facial expressions) were measured using blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) in MDD (n = 12) and healthy (n = 12) individuals. Increased and decreased responses in VMPFC were observed in MDD and healthy individuals, respectively, to happy stimuli, whereas the pattern was reversed for MDD and healthy individual responses to sad stimuli. These findings were not explained by medication effects in depressed individuals. These findings indicate a double dissociation of the pattern of VMPFC response to happy and sad stimuli in depressed and healthy individuals and suggest abnormal reward processing in MDD.