Modulating Brain Activity to Improve Goal-directed Physical Activity in Older Adults

tDCS will be delivered via six gel electrodes with placement and current parameters optimized based on a standard brain to maximize the average normal component of the generated electric field over the left dlPFC. Current delivered by anyone electrode will never exceed 2.0 mA; the total amount of current from all electrodes will not exceed 4 mA. Each 20-minute session will begin and end with a 60-second ramp up/down of current amplitude to maximize comfort.

An 'active' sham will be used in which very low-level currents are transferred between the same electrodes used in the active condition throughout the 20-minute session. However, currents will be designed to mimic the cutaneous sensations induced by tDCS yet not significantly influence cortical tissue.

Study staff will complete face-to-face and telephone counseling sessions with each participant, tailored to their state of readiness to increase physical activity levels. The participant will be provided with a goal to increase their average daily step count by 20% from baseline. The staff member will review the participant's stated barriers to exercise and provide them with a list of strategies they may use to augment their step counts throughout each day. Bi-weekly face-to-face counseling sessions will then be completed to review and discuss activity performance and answer any questions the participant may have regarding their efforts to increase physical activity.