This study investigates whether slow-frequency repetitive transcranial magnetic stimulation targeting frontal pole can acutely modulate brain circuits which show abnormal functioning during behavioral flexibility in obsessive-compulsive disorder, as well as performance on a behavioral task.

Inclusion Criteria: OCD group

• current primary diagnosis of obsessive-compulsive disorder and Yale-Brown Obsessive Compulsive Scale total score ≥ 16;
• 18-55 years of age;
• ability to speak, read, write, and understand English sufficiently well to complete study procedures and provide informed consent;
• either no use of psychiatric medication or stable psychiatric medication use for 6 weeks prior to study entry, limited to use of serotonin reuptake inhibitors and PRN use of benzodiazepines (other psychiatric medication use excluded), and
• right-handed.

Inclusion Criteria: Healthy Control group

• 18-55 years of age;
• ability to speak, read, write, and understand English sufficiently well to complete study procedures and provide informed consent;
• right-handed.

Exclusion Criteria: OCD group

• active problematic substance use;
• lifetime psychosis or bipolar mood disorder or OCD beliefs of delusional nature;
• clinically significant hoarding symptoms;
• active suicidal or homicidal ideation;
• significant neurological disease or intracranial pathology;
• use of medications which increase risk for seizures during TMS;
• significant or unstable medical disorders or contraindication to TMS or MRI scan.

Exclusion Criteria: Healthy Control group

• current psychiatric diagnosis;
• lifetime psychosis, bipolar mood disorder, or OCD;
• active suicidal or homicidal ideation;
• significant neurological disease or intracranial pathology;
• use of psychiatric medications;
• use of medications which increase risk for seizures during TMS;
• significant or unstable medical disorders or contraindication to TMS or MRI scan.

Arms denoted as open-label do not include masking