Thomas Polak

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According to the Reinforcement Sensitivity Theory (RST), Gray's dimension of impulsivity, reflecting human trait reward sensitivity, determines the extent to which stimuli activate the Behavioural Approach System (BAS). The potential neural underpinnings of the BAS, however, remain poorly understood. In the present study, we examined the association between(More)
The method of vagus somatosensory evoked potentials (VSEP) was introduced to easily measure the activity of vagus brain stem nuclei. In Alzheimer's disease, this measure was characterized by longer latencies as compared to controls while amplitudes did not show statistical significant differences at frontal and central recording sites. Therefore, the(More)
Background. In order to prevent future errors, we constantly control our behavior for discrepancies between the expected (i.e., intended) and the real action outcome and continuously adjust our behavior accordingly. Neurophysiological correlates of this action-monitoring process can be studied with event-related potentials (error-related negativity (ERN)(More)
OBJECTIVES Neurotoxic effects of alcohol consumption are well-known. There is plenty of literature on frontal lobe impairment on the behavioural and structural brain imaging level. However, only few functional imaging studies investigated altered neural patterns and even less abstinence-related neural recovery. METHODS In a cross-sectional design three(More)
It has been shown that applying transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) influences declarative memory processes. This study investigates the efficacy of tDCS on emotional memory consolidation, especially experimental fear conditioning. We applied an auditory fear-conditioning paradigm, in which two(More)
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,(More)
OBJECTIVE Visuospatial deficits are among the first symptoms of Alzheimer disease (AD) and linked to lower activation in the superior parietal cortex as assessed with functional imaging. Near-infrared spectroscopy (NIRS) is an optical method to measure changes in the concentration of oxygenated hemoglobin and deoxygenated hemoglobin in the microvascular(More)
Both functional imaging or EEG studies and studies including neurological patients found the dorsolateral prefrontal cortex (dLPFC) to be an important brain area for the processing of emotion and attention. The aim of the present study was to investigate whether emotion and attention can be modulated through bilateral transcranial direct current stimulation(More)
Alcohol craving has been shown to be an important factor for relapses in alcohol-dependent patients. Furthermore, brain activity in reward-related areas in response to alcohol-related cues is positively related to the amount of post-relapse alcohol consumption. On the other hand, it has been shown that cue-exposure based extinction training (CET) leads to(More)
In Alzheimer's disease (AD), mild functional disturbances should precede gross structural damage and even more clinical symptoms, possibly by decades. Moreover, alterations in the brainstem are supposed to occur earlier as cortical affections. Based on these considerations, we developed a new method aiming at the measurement of vagal brainstem functioning(More)