Correlate of Surface Electroencephalogram (EEG) With Implanted EEG Recordings (ECOG)

Inclusion Criteria:

* Male or Female subjects 18 years of age or older.
* English or Spanish Speaking
* Subjects who have been previously diagnosed with intractable epilepsy and require implantation of invasive electrophysiological recordings as part of their routine clinical presurgical workup.

Exclusion Criteria:

* Patients with skin abnormalities at the planned application sites that would interfere with sensor or electrode applications.
* Patients with pre-existing conditions and/or co-morbidities that would prohibit them from participating in the study due to unacceptable risks to their health and well-being, as determined by the Principal Investigator (PI).
* Patients who the PI deems ineligible at the PI's discretion
* Pregnant patients