Cerebellar Involvement in Cognitive Sequencing

Inclusion Criteria:

* 1\) Age 18-50;
* 2\) educational attainment of at least 8 years;
* 3\) capable of giving informed consent;
* 4\) fluent speaker of English by self-report;
* 5\) right handed.

Exclusion Criteria:

* 1\) illicit drug use within 30 days of MRI scanning;
* 2\) neurological or systemic disorder which can cause dementia or cognitive dysfunction;
* 3\) history of an Axis I psychiatric disorder including substance use disorder;
* 4\) history of definite stroke;
* 5\) focal lesion on MRI exam;
* 6\) uncorrected visual deficits by self-report
* 7\) contraindications for MRI scanning
* 8\) use of anxiolytic, antidepressant, neuroleptic, or sedative medication
* 9\) Additional exclusion criteria recommended by Wassermann for TMS neuromodulation, including: History of seizure or a family history of epilepsy, heart disease, intracardiac lines, increased intracranial pressure, history of head trauma, and history of respiratory disease