PRIME: PReservIng Memory in Epilepsy

Inclusion Criteria:

• Patients with a presumptive diagnosis of EPH determined by the group of clinicianswho participate in patient management conference.

• Ability to comply with test directions and provide informed consent or assent to thestudy, i.e. cognitively able to participate in studies [typically intelligencequotient (IQ) of 65 or above].

• Relatively preserved verbal memory - as determined via formal neuropsychologicalevaluation performed by the neuropsychologist. The values must within 1.5 standarddeviation (SD) of the mean for verbal memory

• Proficient in English, as all of our tasks and consent forms will be in English andthe inclusion of non-English speakers will introduce another confound in this smallsample size and preclude grouped analysis

• Age 18 - 65 years (we expect the trial to take 5 years and wish to target patientswith minimal medical co-morbidities)

• Must have a minimum of 2 seizures of any type per month - this is essential to beable to detect the impact of neuromodulation on the epilepsy over relatively shortintervals of time. Patients with secondary generalized seizures may also be enrolledso long as they have a maximum of 20 generalized seizures in the past 12 months (prior to enrollment), or an average of no more than 3 generalized seizures permonth.

Exclusion Criteria:

• Impaired reading and cognitive functions (more than 3 standard deviations below themean, usually an IQ < 60), as determined by preoperative neuropsychological testing.

• Patients with gross structural abnormalities (hamartomata, tumors, vascularmalformations, diffuse malformations of cortical development) in the brain thatraise the possibility of dual pathology resulting in the epilepsy and by derivation,a larger epilepsy network.

• Patients with neurological conditions such as recent history (within past 5 years)of a stroke, encephalitis and meningitis. Any patient with a current diagnosis ofthese conditions will also be excluded.

• Patients with any episodes of status epilepticus in the past 12 months prior toenrollment.

• Patients with uncontrolled prominent psychiatric comorbidity that will precludetheir meaningful participation.

• Patients with a Beck Depression Inventory II score at baseline examination greaterthan or equal to 29 (i.e., severe depression).

• Patients who have attempted suicide in the past 12 months.

• Patients with memory impairment due to other neurological conditions such asdementia and Parkinson's disease.

• Patients who are unable to speak or comprehend English. The inclusion of multiplelanguages will make task development and grouped comparisons of neuro-psychologydata difficult.

• Patients with cardiac pacemakers, intracranial aneurysm clips, or other potentiallymobile implanted metallic devices that are deemed MRI incompatible by themanufactures. The absence of high resolution structural imaging precludesappropriate targeting of the regions of interest.

• Profound hippocampal sclerosis with prominent atrophy of the majority of thehippocampus (equivalent to ILAE type III).

• Prior brain surgery for any reason or failed prior brain neuromodulation [priorvagus nerve stimulation (VNS) therapy is acceptable so long as it is held constantfor the duration of the trial].

• History of or current non-epileptic spells (will confound accuracy of seizuredetection with ANT Percept PC and the precision of the estimate of theneuromodulation effect).

• Patients who are pregnant. All female participants of childbearing potential will becounselled prior to enrollment regarding the unknown risks of treatment on a fetusand the importance of using contraception while they are a subject in this study. Ifa female participant becomes pregnant during the study, they will returned toFDA-approved ANT stimulation parameters (standard of care).