Modulating Default Mode Network Function: A Transcranial Direct Current Stimulation (TDCS) Pilot Study

In this study the investigators are examining the effects of weak electrical stimulation on brain activity as measured by functional magnetic resonance imaging (fMRI). MRI is a widely used method to obtain high resolution brain pictures that are routinely used for diagnostic and clinical purposes. The electrical stimulation is applied on the scalp with a non-FDA approved method called tDCS (transcranial Direct Current Stimulation), typically equivalent to what a 6V battery would produce (and up to no more than 15V). To compare, an AA battery delivers current at 1.5 volt. While almost unnoticeable to the participants, these currents can still temporarily affect brain activity without causing adverse effects. This stimulation would be applied while the participants are in the MRI scanner so that the brain activity can be measured. The participants will have the opportunity to have a test session with the stimulation outside the scanner to get familiar with it.