Fig. 1. Synchronization of field potential and intracellular activities during paroxysmal fast runs.

A. Simultaneous depth-EEG and quadruple intracellular recordings. The electrodes were equally distributed from anterior to posterior parts of suprasylvian gyrus. The intra-cell 1 was in the anterior part of area 5 and the intra-cell 4 was in the posterior part of area 21. Encircled fragments are expanded below as indicated by arrows. Small deflections seen in expanded periods of intracellular recordings are attributed to capacitive coupling. B. Fifteen consecutive segments taken during the first and the second fast run (from panel A) for each cell are color coded for their membrane potential (see calibration bar). The segments were selected as following: the maximum of field potential depth negativity is taken as zero time and from this time point, a segment of ± 200 ms was extracted in each intracellular recording. Note that in both periods, the first maximum of depolarization in neuron 1 and 2 preceded the maximum in the field potential, the neuron 3 slightly preceded the field potential during the first shown period and followed the field during the second period, and finally the neuron 4 followed the field with constant delay during the first period and showed “patchy” pattern during the second period, during which, some cycles had similar delays, the next group of cycles was either not involved in the activity or had another delay in respect to the field. Vertical black lines indicate the maximum of depth negativity. Vertical dashed blue lines indicate the onset of the depolarized component of fast run being electrode Intra-cell 2 during the first fast run episode (left) and electrode Intra-cell 1 during the second one (right). C. Summary data showing histograms of distribution of seizures duration, individual fast run duration, and the number of fast runs per seizure.