Personalized Theta-burst Stimulation for Long-lasting Changes in Approach/Avoidance Behavior

This is a double-blinded, counterbalanced crossover study in healthy adults. Volunteers will participate in four TBS-EEG sessions. In each, the investigators will first conduct the approach/avoidance test with EEG. The TBS pulse intensity will be defined according to the resting motor threshold (rMT). After the approach/avoidance test, one of four conditions will be delivered in a randomized order: 1. Verum: personalized closed-loop TBS-EEG stimulation over the left DLPFC at a suprathreshold pulse intensity (up to 120% rMT); 2. Spatial control: personalized TBS stimulation over the functionally irrelevant postcentral gyrus, 3. Temporal control: conventional (non-personalized) TBS with random parameters but the same number of pulses over conventionally defined DLPFC. 4. Dose control: similar to verum but at a subthreshold pulse intensity (up to 80% rMT). At every session, 1,800 pulses will be applied. Following the stimulation, the participant will repeat the approach/avoidance test with EEG.

Inclusion criteria

• Participants must be legal adults between the ages of 18 to 65;
• Able and willing to complete study procedures and tasks.

Exclusion criteria

• History or evidence of chronic neurological or mental disorder;
• Chronic condition that requires pharmacological treatment over the course of study participation;
• Pregnancy or breastfeeding;
• History or evidence of alcohol or drug addiction;
• Contraindications for transcranial magnetic stimulation (history of seizures, metallic or electric implant in the head/neck area);
• Contraindications for magnetic resonance imaging at 3 Tesla (non-compatible implants, metallic foreign bodies, insulin pump, pacemaker).