An approach bias for alcohol stimuli (i.e. faster approach than avoidance reactions) might facilitate relapses in alcohol dependence. Neurobiological models suggest hypersensitivity in the reward system [inter alia nucleus accumbens and orbitofrontal cortex (OFC)] to cause pathologically enhanced approach impulses towards alcohol stimuli. At the same time, in alcohol dependence, these structures are only insufficiently controlled by a hypoactive dorsolateral prefrontal cortex (DLPFC). The present study investigated the cortical aspects of this model with functional near-infrared spectroscopy in 21 alcohol-dependent in-patients and 21 healthy controls (HC; comparable in age, gender and education) during performance of the Approach-Avoidance Task (AAT) for the first time. Complementing previous findings, in reaction times (RTs), patients showed stronger approach preferences for alcohol than non-alcohol stimuli. For non-alcohol stimuli, patients even displayed avoidance preferences. The reversed pattern was found in HC. Group differences in activity of the OFC were identical to those in RTs, revealing patients to assign higher subjective value to approaching alcohol stimuli. In both groups, regulatory activity in the right DLPFC was stronger during avoiding than approaching alcohol pictures. Probable awareness of the behavioural hypotheses due to explicit task instructions and patients' deficient prefrontal function might account for this equally aligned pattern. Results are discussed with regard to recent findings revealing a reduced behavioural approach bias and risk for relapse by applying a retraining version of the AAT. Functional measurements might serve as a method for monitoring the corresponding neurobiological changes and-possibly-predicting the success of such a training.

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Over the past decades, functional near-infrared spectroscopy (fNIRS) has become a valuable tool in the online assessment of brain function in psychological and neuropsychiatric research. Recently, fNIRS has also been employed in the context of neurofeedback (NF), with pilot studies indicating that hemodynamic responses can be deliberately regulated and that neuroplastic changes occur over the course of several training sessions. This review article provides a comprehensive overview of the recent implementation and development of fNIRS as an NF tool; specifically, we will outline initial studies in healthy participants as well as children and adults with attention deficit hyperactivity disorder and describe new protocols aimed at reducing auditory verbal hallucinations (schizophrenic patients) and anxiety symptoms (patients with social anxiety disorder), respectively. Finally, we will discuss recent methodological developments and concerns as well as potential future perspectives. We conclude that fNIRS is a useful tool for conducting NF, especially in terms of multi-session training. However, methodological details need to be considered when designing fNIRS-based NF studies, and future protocols should aim at training broader network structures and implementing implicit training protocols. Finally, future studies should focus not only on (clinical) effects of fNIRS-based NF, but also on the underlying mechanisms and activity changes in extended brain networks.

As hypothesized, we found reduced Pe amplitudes, but also reduced ERN values, in ADHD patients. Importantly, theses differences as well as the deficits in behavioural performance were mainly detectable in the younger subsample, but not in the elderly subsample. Our results indicate that adult ADHD patients are characterized by deficits in error processing, which vanish with age.

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