Assessment of tDCS-Induced Neuronal Responses in Multiple Sclerosis (MS) With Advanced MRI

All participants including healthy controls and MS patients will be given approximately 15 minutes of active tDCS during MRI. The simultaneous tDCS will be performed up to 2 mA dose intensity to determine CMRO2 changes from when the tDCS is on to when the tDCS is off. The stimulation consists of 15-min up to 2 mA tDCS using 5x5 cm electrode sponges with \~30s ramp-up and ramp-down periods.

"While the first tDCS session will be performed at clinic under the full supervision, remaining sessions 2-20 (\~ 1 month) will be completed at home with remote monitoring by the study technician. Participants in the HC subgroup who opt-in to the additional 15 minutes of imaging +tDCS may complete the first session remotely.~For at-home tDCS administration, participants will be given the specially-designed tDCS device and headset, study laptop computer for secure video monitoring with study technician (must have internet access) and access to the cognitive training program, a detailed reference manual, and a training video. The device will produce up to 2.0 mA stimulation for around 20 minutes, and will not operate without the correct headset placement. The device will also automatically abort the session if optimal conditions are not maintained. It reports and records a completion code for each session."

Participants in the healthy control subgroup who are willing may have an additional 15 minutes of imaging combined with 10 minutes of simultaneous tDCS of up to 4.0mA added at the end of their baseline scan. In this case, after the initial imaging and tDCS portion is complete, the participant will remain on the scanner for an additional 15 minutes during which brain imaging will continue and will be combined with 10 minutes of simultaneous tDCS up to 4.0mA. This will be a one-time add-on and will not be required at follow-up.