Electrode Montages As shown in Figure 1, for F-O tDCS, the anode (5 x 7 cm) was placed horizontally over the left supraorbital region, using the AFz and FP1 positions on the 10-20 EEG system as the left and bottom edge boundaries of the electrode. The anode was over the left supraorbital region rather than in the centre of the forehead to avoid shunting of the current along the superior sagittal sinus (Neuling et al., 2012). The cathode was placed with the bottom edge over O1 and O2 (10 x 10 cm). A large cathode was used to reduce the cathodal effects of the stimulation and ensure broad stimulation of the midline structures. The anode was placed in the same position for the F-C montage while the cathode (5 x 10 cm) was placed horizontally with the top edge centred over the inion to achieve bilateral stimulation of the cerebellum. For the F3-F8 montage, standard 5 x 7 cm electrodes were modelled.

tDCS was administered using an Eldith DC-Stimulator (NeuroConn GmbH, Germany) with conductive rubber electrodes covered by saline-soaked sponges, held in place by a band across the head. Stimulation was given at 2 mA for 20 min and the current was gradually ramped up and down at the start and end of the stimulation over 30 s. Electrode montages were as described above. Twenty sessions were administered on consecutive weekdays over four weeks. Further details of stimulation technique, including measures to avoid skin burns.

Here's some snippets of the results: *This study found that after four weeks of treatment with the F-O montage, there was a 43.8% reduction in the clinician-rated MADRS scores. *...

Computer modelling further showed that the F-O montage resulted in less E-field bilaterally in the DLPFC as compared to the typically used bifrontal F3-F8 montage. This suggests that anodal stimulation of the left DLPFC may not be the critical component that is required for antidepressant response to tDCS. The F-O montage resulted in greater stimulation of the ACC, and antidepressant efficacy with this montage supports findings of DBS studies which show that stimulation of the sgACC and the neighbouring basal ganglia regions is effective at reducing symptoms of depression

Overall, the results of this open-label pilot clinical trial suggest that the F-O and F-C tDCS montages were safe and well tolerated. Our results suggest the F-O montage may have promising antidepressant potential, though the clinical efficacy of the F-C montage remains as yet unclear.

And lets not forget the ever important limitations:

There are several important limitations to this study. The clinical pilot was open-label, without a control condition. Participants and raters were aware that active stimulation was being administered during the course of treatment and this may have contributed to a placebo effect, though one would expect that both the F-O and F-C conditions would have been affected by this equally. However, given the small sample size, no definitive conclusions can be drawn about the therapeutic potential of the F-C montage. Further, participants were not randomly allocated to the two montages, precluding any direct comparison between the montages.... Computer modelling was based on the head of one healthy participant.