Patients will undergo cognitive testing and electrical stimulation experiments.

Record brain activity during memory encoding

To map thalamocortical and corticothalamic causal effective connectivity, the study team will use the well-known method of repeated single electrical pulse stimulation with intracranial EEG. Study team will measure the amplitude and timing to first peak of cerebro-cerebral evoked potentials (CCEPs).

To map thalamocortical and corticothalamic functional connectivity, he study team will obtain 8 runs of 6mins resting state fMRIs. Study team will measure the correlation of BOLD activity across voxels of interest.

The study team will identify seizure onset zones (SOZs) using the measure of Epileptogenicity Index (EI) applied to data collected through intracranial EEG, and will label the SOZs as medial temporal lobe epilepsy (mTLE) versus nonmedial TLEs.

Seizure propagation to ANT and PLV will be examined through intracranial EEG data within individuals by measuring EI and the propagation latencies from SOZ to ANT and PLV recording sites will be noted.

Successful memory encoding is associated with coordinated activity across hippocampus (HPC) and ANT (i.e., high frequency activity in ANT locked to the phase of hippocampal theta). Using intracranial EEG data, the study team will follow traditional analyses of changes in power in the canonical EEG bands (e.g., 3-7 Hz, theta band, 40-150 Hz, high gamma, etc.) as well as computationally derived aperiodic features of the signal [i.e., using the fitting oscillations & one over f (FOOOF) function]. Response onset latency of neural activity will determine with simultaneous recordings across HPC, ANT, and PLV how each ROI is engaged in time during a given experimental condition (i.e., encoding trials later recalled and trials not later recalled). We will also use validated methods of phase amplitude coupling (PAC) and intersite phase coherence (ISPC) to quantify cross regional relationships.