Figure 5.

Synchronous Purkinje inputs set spike timing of nuclear neurons, in vitro and in vivo. (A) Responses of a whole-cell current-clamped cerebellar nuclear neuron in a mouse cerebellar slice to dynamically clamped (dyn) IPSPs mimicking 40 asynchronous (top) or 20 asynchronous and 20 synchronous Purkinje inputs (bottom). (B) Normalized interspike interval distributions during partially synchronized (50%, i.e., 20 out of 40) dynIPSPs, where the rates of the synchronous input ranged from 50 to 100 Hz. Abscissa tick marks indicate multiples of the interstimulus intervals of the synchronous subpopulation. Bin width, 2 ms. Black: no current injection. Blue: with 200 pA steady current (DC) applied to increase spike probability during inhibition. (C) Responses of an extracellularly recorded cerebellar nuclear neuron in a ketamine-xylazine anesthetized mouse. Upper trace, response of a nuclear neuron to 40-Hz molecular layer stimulation (bar). Inset, recording site in the cerebellar nuclei recovered after focal Alexa 568 injection. Dashed lines demarcate cerebellar folia. Scale bar, 200 μm. (D) Mean normalized interspike interval distributions during molecular layer stimulation from 20 to 100 Hz. Abscissa tick marks indicate multiples of the interstimulus intervals. Red baseline histogram includes intervals before and after stimulation. Bin width, 2 ms. (E) Black: polar histograms of interspike intervals during stimulation across rates (left) or during baseline periods. Red: net vectors of polar histograms. Reprinted from Person and Raman (2012), with permission.