Abnormal approach-related motivation but spared reinforcement learning in MDD: Evidence from fronto-midline Theta oscillations and frontal Alpha asymmetry.

Major depression is characterized by abnormal reward processing and reinforcement learning (RL). This impairment might stem from deficient motivation processes, in addition to reduced reward sensitivity. In this study, we recorded 64-channel EEG in a large cohort of major depressive disorder (MDD) patients and matched healthy controls (HC) while they performed a standard RL task.

Spared internal but impaired external reward prediction error signals in major depressive disorder during reinforcement learning.

Background: Major depressive disorder (MDD) creates debilitating effects on a wide range of cognitive functions, including reinforcement learning (RL). In this study, we sought to assess whether reward processing as such, or alternatively the complex interplay between motivation and reward might potentially account for the abnormal reward-based learning in MDD.

Methods: A total of 35 treatment resistant MDD patients and 44 age matched healthy controls (HCs) performed a standard probabilistic learning task.

Modulatory effects of happy mood on performance monitoring: Insights from error-related brain potentials.

Goal-adaptive behavior requires the rapid detection of conflicts between actions and intentions or goals. Although many studies have focused in the past on the influence of negative affect on this cognitive control process (and more specifically, on error monitoring), little is known about the possible modulatory effects of positive affect on it. To address this question, we used a standard (positive) mood induction procedure (based on guided imagery) and asked participants to carry out a speeded go/no-go task while high-density electroencephalography was recorded concurrently.

Accelerated intermittent theta burst stimulation treatment in medication-resistant major depression: A fast road to remission?

Although accelerated repetitive Transcranial Magnetic Stimulation (rTMS) paradigms and intermittent Theta-burst Stimulation (iTBS) may have the potency to result in superior clinical outcomes in Treatment Resistant Depression (TRD), accelerated iTBS treatment has not yet been studied. In this registered randomized double-blind sham-controlled crossover study, spread over four successive days, 50 TRD patients received 20 iTBS sessions applied to the left dorsolateral prefrontal cortex (DLPFC). The accelerated iTBS treatment procedure was found to be safe and resulted in immediate statistically significant decreases in depressive symptoms regardless of order/type of stimulation (real/sham).

What is in the feedback? Effect of induced happiness vs. sadness on probabilistic learning with vs. without exploration.

According to dominant neuropsychological theories of affect, emotions signal salience of events and in turn facilitate a wide spectrum of response options or action tendencies. Valence of an emotional experience is pivotal here, as it alters reward and punishment processing, as well as the balance between safety and risk taking, which can be translated into changes in the exploration-exploitation trade-off during reinforcement learning (RL). To test this idea, we compared the behavioral performance of three groups of participants that all completed a variant of a standard probabilistic learning task, but who differed regarding which mood state was actually induced and maintained (happy, sad or neutral).

Effects of positive mood on probabilistic learning: behavioral and electrophysiological correlates.

Whether positive mood can change reinforcement learning or not remains an open question. In this study, we used a probabilistic learning task and explored whether positive mood could alter the way positive versus negative feedback was used to guide learning. This process was characterized both at the behavioral and electro-encephalographic levels.