Measuring Plasticity in SFC/dACC Following Theta-Burst-Stimulation Using TMS

Overview

This is a study to determine whether particular forms of brain-stimulation, applied to superior frontal cortex/preSMA can affect cognition and associated frontal theta oscillations. To perform this study, the investigators first measure brain activity and cognitive performance using "BrainE", a cognitive task platform that assesses cognition on sustained attention, response inhibition, working memory, interference processing and emotion processing assessments. Next, the investigators apply brain-stimulation over a mid-frontal region associated with these tasks (mid-line frontal activity overlying superior frontal cortex/pre-SMA area). Finally, human subjects perform the "BrainE" task assessments again immediately after the brain-stimulation. The investigators compare the effects of brain stimulation on average frontal activity evoked across the cognitive tasks, and on the cognitive performance averaged across tasks. The investigators primarily compare the effects of two types of brain-stimulation against each other: intermittent Theta-Burst Stimulation (a protocol designed to excite brain activity) and continuous Theta-Burst-Stimulation (a stimulation protocol designed to inhibit brain activity).

1. Brain/Behavior Recordings: to measure brain activity as described above, the investigators first ask subjects to engage in a cognitive assessment set while measuring EEG activity. For this study, the assessment set consists of the following tasks: (1) sustained attention; (2) response inhibition; (2) visuo-spatial working-memory; (3) Flanker interference processing, and (4) emotional interference processing. This battery takes about 30 minutes to complete. 24 channel EEG recordings are performed simultaneous to the cognitive tasks. Subjects perform the "BrainE" cognitive assessment, then receive brain-stimulation, and will then immediately be tested on the BrainE assessment again. 2. Brain-Stimulation: Each subject will be asked to come in twice for this study, separated by 1 week. On week one they will receive one stimulation protocol, and on the subsequent week they will receive the other (order determined randomly for each subject). The intermittent Theta-Burst-Stimulation protocol (iTBS) consists of a similar burst pattern (3 stimulation pulses 20ms apart; each burst applied every 200ms). However, after 10 bursts (2 seconds of stimulation) there is a pause for 8 seconds. 200 bursts are still applied, however due to the inter-burst intervals, this paradigm takes 200 seconds. The continuous Theta-Burst-Stimulation protocol (cTBS) consists of a burst of three stimulation pulses, applied 20ms apart; with each burst occurring every 200ms. Thus, every second participants receive 5 bursts. This continues for 40 seconds, such that participants in total receive 200 bursts or 600 pulses.