Fig. 1.

Purkinje cells recorded in slices are bistable. (A) Three representative sweeps (10-s duration) from a Purkinje cell recorded under current clamp in control conditions. The cell spontaneously alternates between a depolarized membrane potential (up state) where it fires action potentials and a hyperpolarized membrane potential where it is silent (down state). Note the deep hyperpolarization following the transitions from up to down states. Action potentials are truncated to show membrane potential. (B) Three representative sweeps of a Purkinje cell recorded in cell-attached configuration under control conditions. Upward deflections from baseline are extracellularly recorded spontaneous action potentials and are presumed to occur during up states of the Purkinje cell. (C) Raster plot of intracellularly recorded action potentials from all of the sweeps recorded from the cell shown in A. (D) Raster plot of all of the extracellularly recorded action potentials from the cell shown in B. (E) Histograms of the action potential frequency per 200-ms bins throughout all of the recordings of all of the bistable cells recorded under whole-cell conditions (n = 11). Note the large peak representing the amount of time spent in the down state at 0 Hz and the mean firing frequency of around 15 Hz in the up state. (F) Same as E but for all bistable cells recorded in cell-attached recordings (n = 5).