Patients with drug-resistant epilepsy often experience problems with mood, thinking, or behavior that cannot be explained by seizure activity alone. This study will examine how cognitive and mood-related brain regions communicate in patients undergoing routine intracranial electroencephalogram (iEEG) seizure assessment in the Epilepsy Monitoring Unit at the Medical University of South Carolina (MUSC). While the clinical electrodes are in place, we will apply brief single magnetic pulses (single-pulse transcranial magnetic stimulation, or spTMS) to the scalp in specific brain regions and record the brain's electrical response through the existing electrodes; no additional surgery is required. We will compare the responses to stimulation of an emotionally and cognitively relevant region (left dorsolateral prefrontal cortex) with a contrast site (primary motor cortex). We will also investigate whether momentary brain rhythms and seizure-related electrical activity affect responses propagation through the brain. The findings may help identify measurable brain signaling patterns ("biomarkers") to understand how cognitive-emotional brain networks work in people with epilepsy and inform future personalized non-invasive brain stimulation methods for treating neurological and psychiatric disorders.