Anhedonia and general distress show dissociable ventromedial prefrontal cortex connectivity in major depressive disorder.

Anhedonia, the reduced ability to experience pleasure in response to otherwise rewarding stimuli, is a core symptom of major depressive disorder (MDD). Although the posterior ventromedial prefrontal cortex (pVMPFC) and its functional connections have been consistently implicated in MDD, their roles in anhedonia remain poorly understood. Furthermore, it is unknown whether anhedonia is primarily associated with intrinsic 'resting-state' pVMPFC functional connectivity or an inability to modulate connectivity in a context-specific manner. To address these gaps, a pVMPFC region of interest was first identified using activation likelihood estimation meta-analysis. pVMPFC connectivity was then examined in relation to anhedonia and general distress symptoms of depression, using both resting-state and task-based functional magnetic resonance imaging involving pleasant music, in current MDD and healthy control groups. In MDD, pVMPFC connectivity was negatively correlated with anhedonia but not general distress during music listening in key reward- and emotion-processing regions, including nucleus accumbens, ventral tegmental area/substantia nigra, orbitofrontal cortex and insula, as well as fronto-temporal regions involved in tracking complex sound sequences, including middle temporal gyrus and inferior frontal gyrus. No such dissociations were observed in the healthy controls, and resting-state pVMPFC connectivity did not dissociate anhedonia from general distress in either group. Our findings demonstrate that anhedonia in MDD is associated with context-specific deficits in pVMPFC connectivity with the mesolimbic reward system when encountering pleasurable stimuli, rather than a static deficit in intrinsic resting-state connectivity. Critically, identification of functional circuits associated with anhedonia better characterizes MDD heterogeneity and may help track of one of its core symptoms.

Posterior versus frontal theta activity indexes approach motivation during affective autobiographical memories.

Research has recently identified a promising neurophysiological marker of approach motivation involving posterior versus frontal (Pz - Fz) electroencephalographic (EEG) theta activity PFTA; Wacker, Chavanon, & Stemmler (Journal of Personality and Social Psychology 91:171-187, 2006). Preliminary evidence indicated that PFTA is modulated by dopaminergic activity, thought to underlie appetitive tendencies, and that it indexes self-reported behavioral activation system (BAS) sensitivity. To date, research has largely relied on resting indices of PFTA and has yet to examine the relationship between PFTA and specific approach-related affective states generated by emotionally salient laboratory tasks. Accordingly, the present study evaluated PFTA both at rest and during an ecologically valid autobiographical memory task in which participants recalled personal life experiences involving a goal-striving, an anxious apprehension, a low-point (i.e., difficult), and a neutral memory while EEG data were recorded. In line with prediction, elevated PFTA was observed during both goal-striving and anxious apprehension autobiographical memories. PFTA was particularly elevated during anxious apprehension memories coded as being high on approach-related tendencies. Elevated PFTA during anxious apprehension is consistent with a growing literature indicating that anxious apprehension is associated with elevated approach- and reward-related brain function. Lastly, elevated resting PFTA was positively correlated with self-reported trait anger, a negatively valenced emotion characterized by approach-related tendencies. These results have implications for (a) enhancing our understanding of the neurophysiology of approach-related emotions, (b) establishing PFTA as an index of appetitive motivational states, and (c) clarifying our understanding of the neurophysiology and approach-related tendencies associated with both anxious apprehension and anger.

Impairment in the achievement domain in bipolar spectrum disorders: role of behavioral approach system hypersensitivity and impulsivity.

AIM: Research indicates that bipolar disorder is characterized by both high levels of impairment and high levels of achievement. A critical, and yet largely unexamined question, is: what psychological mechanisms promote high accomplishment (and low impairment) among bipolar spectrum individuals? The aim of this study was to examine this question. The Authors also conceptually explore how the answer to this question can enhance the development of intervention and prevention strategies for adolescents with a bipolar spectrum condition. METHODS: Academic transcript data were obtained for 120 college students who had either a bipolar spectrum disorder (N=54) or no major psychopathology (N=66). RESULTS: Bipolar spectrum individuals obtained a lower cumulative grade point average (GPA, t=-2.9, P=0.005) and dropped more classes (t=2.1, P=or<0.04) than normal controls. The findings also have relevance to the behavioral approach system (BAS) dysregulation theory of bipolar disorder, as well as research on impulsivity among bipolar individuals. Specifically, follow-up analyses revealed that bipolar individuals exhibiting a combination of high BAS drive and low impulsivity earned higher GPAs than the remaining bipolar individuals. Thus, high BAS sensitivity, when paired with low impulsivity, may not be impairing and may contribute to the high achievement sometimes observed among bipolar individuals. CONCLUSION: Such information is important for the development of prevention and intervention programs designed adolescents that lower risk for bipolar impairment without decreasing achievement.