Fig. 7.

Reversal of epileptiform activity recorded in the presence of BDNF and bicuculline. A seizure-like episode was recorded from the granule cell layer (GCL) in the same slice as Figure 6. Note the different time base from Figure 6. After ∼3 min, another seizure-like episode was recorded from the same slice, but in the outer molecular layer (OML). The reversal of the extracellular recordings indicates that the seizure-like events reversed polarity in a similar area as the brief discharges produced by BDNF in the absence of bicuculline (Fig. 3). These data suggest that the site of origin of the spontaneous activity was in the inner/middle molecular layer, consistent with an underlying mechanism related to sprouted mossy fibers.