Transcranial direct-current stimulation enhances Pavlovian tendencies during intermittent loss of control.

Introduction: Pavlovian bias is an innate motivational tendency to approach rewards and remain passive in the face of punishment. The relative reliance on Pavlovian valuation has been found to increase when the perceived control over environmental reinforcers is compromised, leading to behavior resembling learned helplessness (LH). Methods: Sixty healthy young adults underwent a Go-NoGo reinforcement learning task and received anodal high-definition transcranial direct current stimulation (HD-tDCS) over the medial prefrontal/dorsal anterior cingulate cortex in our randomized, double-blind, sham- controlled study. Furthermore, we evaluated changes in cue-locked mid-frontal theta power derived from simultaneous electroencephalography (EEG). We hypothesized that active stimulation would reduce Pavlovian bias during manipulation of outcome controllability, and the effect would be accompanied by stronger mid-frontal theta activity, representing arbitration between choice strategies in favor of instrumental relative to Pavlovian valuation. Results: We found a progressive decrease in Pavlovian bias during and after loss of control over feedback. Active HD-tDCS counteracted this effect while not affecting the mid-frontal theta signal. Discussion: The results were at odds with our hypotheses but also with previous findings reporting LH-like patterns during and after loss of control without brain stimulation. The discrepancy may be related to different protocols for the controllability manipulation. We argue that the subjective evaluation of task controllability is crucial in mediating the balance between Pavlovian and instrumental valuation during reinforcement learning and that the medial prefrontal/dorsal anterior cingulate cortex is a key region in this respect. These findings have implications for understanding the behavioral and neural underpinnings of LH in humans.

Male depression syndrome is characterized by pronounced Cluster B personality traits.

BACKGROUND: Male depression syndrome (Male-DS) refers to alternative depression symptoms related to the male sex, such as externalizing behaviors, emotional suppression, substance misuse, and risk-seeking. Although these symptoms contribute to gender bias in the diagnosis of depression, Male-DS can be found in both sexes. In this cross-sectional study, we analyzed associations between Male-DS and clinical personality accentuations. METHODS: We compared clinical personality accentuations between 78 depressed patients with high Male-DS scores (46% women; mean age ± standard error of the mean: 36.5 ± 1.6 years) and 76 depressed patients with low Male-DS scores (43% women; age 44.8 ± 1.7 years). We also explored differences between the two patient groups and 176 healthy controls (51% women; age 37.2 ± 1.0 years). RESULTS: Depressed patients with high Male-DS scores showed stronger borderline (partial η2 0.121), impulsive (0.112), and antisocial (0.078) personality accentuations than those with low Male-DS scores after Bonferroni adjustment and controlling for sex, depression severity, and age. Relative to healthy controls, patients with high Male-DS values scored higher in all personality dimensions except for the narcissistic dimension. Patients with low Male-DS values scored higher in all Cluster A and C dimensions and the impulsive and borderline dimensions, but their scores were lower in the narcissistic dimension. LIMITATIONS: Cross-sectional design and focus on in-patients. CONCLUSIONS: We found pronounced Cluster B personality in patients with high Male-DS scores versus patients with low scores. Further prospective research is needed to verify that Cluster B personality traits represent a pre-morbid risk factor for Male-DS.