A Soterix Clinical Trials Direct Current Stimulator will apply 20 minutes of up to 4.0mA direct current through two biocarbon rubber electrodes covered with at least 5mm-thick conductive electrode paste buffer, and placed over the optimized locations based on the international 10-20 system by using a combination of 10-20 EEG cap measurement and a stereotactic neuronavigation system. Stereotactic neuronavigation will be used as needed and may not be used on all participants.

Sham stimulation is performed with the same device and all procedures will be identical except for the duration of stimulation. Participants will receive 30 seconds of up to 4 mA of direct current stimulation at the beginning of the session. Participants habituate to the sensation of tDCS within 30-60 seconds of stimulation. This procedure provides the same sensation of tDCS without the full duration of stimulation, making it a highly effective sham procedure.

During tDCS, a weak electrical current is applied to the scalp that penetrates skin, bone, CSF and the meninges to stimulate underlying cortical and subcortical tissue

Change in working memory performance on the N back working memory MRI task from baseline to post test will be assessed. Post test will occur approximately two weeks following baseline.

The N-back working memory task will be completed during the MRI scan at both baseline and post test assessments. Working memory performance will be defined as a composite of reaction time and accuracy for two back trials. Specifically Target Accuracy percent correct and average correct target reaction time in milliseconds. Percent changes were calculated for Target Accuracy and Reaction Time in the form of (post test-pre test)/pre test. Since the direction of improvement is opposite for the two variables (i.e. higher Accuracy is better and lower Reaction Time is better), the reaction time percent change was multiplied by -1 to ensure a larger number indicated improved performance. To create a composite these two percent changes (Target Accuracy and Reaction Time) were averaged into a single value.

A Soterix Clinical Trials Direct Current Stimulator will apply 20 minutes of up to 4.0mA direct current through two biocarbon rubber electrodes covered with at least 5mm-thick conductive electrode paste buffer, and placed over the optimized locations based on the international 10-20 system by using a combination of 10-20 EEG cap measurement and a stereotactic neuronavigation system. Stereotactic neuronavigation will be used as needed and may not be used on all participants.

tDCS: During tDCS, a weak electrical current is applied to the scalp that penetrates skin, bone, CSF and the meninges to stimulate underlying cortical and subcortical tissue

cognitive training: Cognitive Training (CT) will involve up to 10 hours of training over 2-weeks (10 days). CT employs a PositScience BrainHQ suite via its researcher portal. These tasks are web-based and multi-platform (i.e., Windows, Mac). Participants will be randomly assigned to training on 4 tasks focusing on working memory or 4 tasks focusing on attention/speed of processing.

Change in working memory performance on the N back working memory MRI task from baseline to post test will be assessed. Post test will occur approximately two weeks following baseline.

The N-back working memory task will be completed during the MRI scan at both baseline and post test assessments. Working memory performance will be defined as a composite of reaction time and accuracy for two back trials. Specifically Target Accuracy percent correct and average correct target reaction time in milliseconds. Percent changes were calculated for Target Accuracy and Reaction Time in the form of (post test-pre test)/pre test. Since the direction of improvement is opposite for the two variables (i.e. higher Accuracy is better and lower Reaction Time is better), the reaction time percent change was multiplied by -1 to ensure a larger number indicated improved performance. To create a composite these two percent changes (Target Accuracy and Reaction Time) were averaged into a single value.

A Soterix Clinical Trials Direct Current Stimulator will apply 20 minutes of up to 4.0mA direct current through two biocarbon rubber electrodes covered with at least 5mm-thick conductive electrode paste buffer, and placed over the optimized locations based on the international 10-20 system by using a combination of 10-20 EEG cap measurement and a stereotactic neuronavigation system. Stereotactic neuronavigation will be used as needed and may not be used on all participants.

tDCS: During tDCS, a weak electrical current is applied to the scalp that penetrates skin, bone, CSF and the meninges to stimulate underlying cortical and subcortical tissue

cognitive training: Cognitive Training (CT) will involve up to 10 hours of training over 2-weeks (10 days). CT employs a PositScience BrainHQ suite via its researcher portal. These tasks are web-based and multi-platform (i.e., Windows, Mac). Participants will be randomly assigned to training on 4 tasks focusing on working memory or 4 tasks focusing on attention/speed of processing.