 Recently, the use of low amplitude direct current stimulation of the human cortex has received attention as a possible for treatment for depression and pain Been et al, 2007. This technique called transcranial direct current stimulation or tDCS involves the placement of two sponge electrodes over separate areas of the scalp. tDCS has been shown to be capable of changing the excitability of the superficial neurons immediately beneath the sponge electrodes. Evidence suggests that anodal stimulation is associated with increased cortical excitability and cathodal stimulation is associated with decreased cortical excitability Been et al, 2007. 