Plewnia, C. | bioRxiv Science

bioRxiv2021

Dynamic DNA methylation changes in the COMT gene promoter region in response to mental stress and its modulation by transcranial direct current stimulation

Changes in epigenetic modifications present a mechanism how environmental factors like the experience of stress can alter gene regulation. While stress-related disorders have consistently been associated with differential DNA methylation, little is known about the time scale in which these alterations emerge. We investigated dynamic DNA methylation changes in whole blood of 42 healthy male individuals in response to a stressful cognitive task, its association with concentration changes in cortisol and its modulation by transcranial direct current stimulation (tDCS). We observed a continuous increase in COMT promotor DNA methylation which correlated with higher saliva cortisol levels and was still detectable one week later. However, this lasting effect was suppressed by concurrent activity-enhancing anodal tDCS to the dorsolateral prefrontal cortex. Our findings support the significance of gene-specific DNA methylation in whole blood as potential biomarkers for stress-related disorders. Moreover, they suggest alternative molecular mechanisms possibly involved in lasting behavioral effects of tDCS.

neuroscience↗

bioRxiv2020

Neural signatures of performance feedback in the paced auditory serial addition task (PASAT): an ERP study

Due to its importance for successful human behavior, research into cognitive control functioning has gained increasing interest. The paced auditory serial addition task (PASAT) has been used to test and train this fundamental function. It is a challenging task, requiring a high cognitive load in a stressful and frustrating environment. Its underlying neural mechanisms, however, are still unclear. To explore the neural signatures of the PASAT and their link to ongoing cognitive processing, feedback locked event-related potentials were derived from healthy participants during an adaptive 2-back version of the PASAT. Larger neural activation after negative feedback was found for feedback related negativity (FRN), P300 and late positive potential (LPP). In early stages of feedback processing (FRN), a larger difference between positive and negative feedback responses was associated with poorer overall performance, whereas this association was inverted for the later stages (P300 and LPP). This indicates stage-dependent associations of neural activation after negative information and cognitive functioning. Conceivably, increased early responses to negative feedback signify distraction whereas higher activity at later stages reflect cognitive control processes to preserve ongoing performance.

neuroscience↗