OBJECTIVES

The main objective of the study is to gather insight into the neural mechanisms underlying epileptic seizures by recording both multi-unit and single-unit activity and test the excitability of the neurons using microstimulation in the SOZ.

We are planning on performing inter-ictal acute microelectrode recordings and microstimulation along a path leading to the SOZ as identified by standard sEEG methods, as a step preceding surgical resection of the epileptogenic tissue in patients with intractable temporal lobe epilepsy. The electrodes will be guided using standard stereotactic equipment, allowing for precise 3-D localization of the recorded sites. Recordings containing local field potentials, single-units, as well as high-frequency background (multi-unit) activity will be performed before, during and after applying electrical stimulation. The parameters of the stimulation (frequency, amplitude) will be varied in order to test various possible mechanisms ranging from direct neuronal excitation (Filali et al 2004), expected at low frequencies, to depolarization block (Beurrier et al 2001, Bikson et al 2003), expected at higher frequencies. These investigations will allow characterization of the excitability of the single neurons in the epileptogenic foci with possible applications to deconstructing collective oscillations through deep brain stimulation (Hodaie et al 2002).

.