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

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 will first measure brain activity/cognitive performance using "BrainE", a rapid series of cognitive tests measuring sustained attention, behavioral inhibition, working memory and interference/distractor processing. Next, the investigators will apply brain-stimulation over a mid-frontal region most strongly associated with these tasks (mid-line frontal activity overlying superior frontal cortex/pre-SMA area). Finally, human subjects will perform BrainE assessments again immediately after the brain-stimulation. The investigators will compare the effects of brain stimulation on frontal activity evoked on the cognitive tasks, and on behavioral performance across these tasks. The investigators will further compare two types of brain-stimulation against each other: continuous Theta-Burst-Stimulation (a stimulation protocol designed to inhibit brain activity) and intermittent Theta-Burst Stimulation (a protocol designed to excite brain activity).

1. Brain/Behavior Recordings: to measure brain activity as described above, the investigators will first ask subjects to engage in a cognitive battery while measuring EEG activity. For this study, the battery consists of the following tasks: (1) a go/no-go task to study sustained attention and behavioral inhibition; (2) a visuo-spatial working-memory task; (3) a Flanker interference task and (4) a emotional-distractor task. A breath monitoring task is also included as a measure of internal attention/distraction. This battery takes about 30 minutes to complete. 24 channel EEG recordings will be performed during this task. Subjects will perform BrainE, will receive brain-stimulation, and will then immediately be tested on the BrainE tasks 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 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. 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.