Objectives: Interest in transcranial direct current stimulation (tDCS) in clinical practice has been growing, however, the knowledge about its efficacy and mechanisms of action remains limited. This paper presents a realistic magnetic resonance imaging (MRI)-derived finite element model of currents applied to the human brain during tDCS.
Experimental design: Current density distributions were analyzed in a healthy human head model with varied electrode montages. For each configuration, we calculated the cortical current density distributions. Analogous studies were completed for three pathological models of cortical infarcts.
Principal observations: The current density magnitude maxima injected in the cortex by 1 mA tDCS ranged from 0.77 to 2.00 mA/cm(2). The pathological models revealed that cortical strokes, relative to the non-pathological solutions, can elevate current density maxima and alter their location.
Conclusions: These results may guide optimized tDCS for application in normal subjects and patients with focal brain lesions.