I am planning to conduct a study to compare between two different tDCS montages over two different cortical areas, and the study will be controlled using sham group. What would be the tDCS montage for the sham group?
Ideally, the sham stimulation montage will be the same as the real stimulation. However, for sham tDCS, there will be an initial ramp of current, but then the current will drop to zero for the duration of the stimulation. At the end of the stimulation, there will be another current ramp. The aim of this is to produce a similar tingling sensation associated with real tDCS, without stimulating the brain region below the electrodes for more than 1 min.
Usually the montage is the same but in the sham tDCS the current used to be emanated only during the first 20s and the last 10s of stimulation for emulated the same sensation of active stimulation.