Attention bias modification through transcranial direct current stimulation (tDCS): A review

Attention bias is a tendency to preferably detect, orient and select emotionally valued stimuli, as compared to neutral stimuli, and plays a crucial role in the psychopathology of various psychiatric disorders. Transcranial direct current stimulation (tDCS) has been applied for the alteration of attention bias in health and disease with different parameters and conditions, but the contribution of these factors to the magnitude and directionality of effects has not previously been comprehensively reviewed. In this review, we aimed to systematically explore the effects of tDCS on attention bias in different tasks, tDCS conditions, and health states. Data were collected in accordance with the PRISMA approach. A literature search identified 22 original experiments that explored the effects of tDCS on attention bias. Determinants of tDCS effects on attention bias were cortical target areas, the specific task under study, stimulation parameters, and the presence of psychopathology. Relevant cortical areas for modification of attention bias via tDCS were the dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC). The observed heterogeneity of the impact of tDCS on the modulation of attention bias can be explained by the area of stimulation, valence of stimuli, task characteristics, and the intensity of stimulation.