Cerebellar LTD in Alert Mice Figure 2. Relationships between evoked local field potential components and Purkinje cell firing behavior. (A) Recording of spontaneous firing behavior of a Purkinje cell (PC) shows the presence of single spikes (SS) and complex spikes (CS). The presence of a CS followed by a pause in the SS firing (asterisk) identifies this neuron as a PC. (B) Single trials, superimposed (n = 11), show spontaneous firing before the whisker electrical stimulation (Stim) and the temporal reorganization of the firing after the stimulus. SS firing occurred at the low points of the N2 and N3 components and later. The evoked CS occurred at a latency of 9–13 ms after the stimulus onset (arrowhead). The single trace appears in color to facilitate the identification of SS and CS. (C) Histogram (bin size = 1 ms) of a PC recording shows the typical SS (top) and CS (bottom) response to whisker pad electrical stimulation (n = 37). After stimulus onset (arrowhead), the PC showed an initial SS burst at N2–N3 latencies, followed by a CS, followed by a silent period. (D) Superimposition (n = 43) of a PC recording triggered by CS (dotted line) during spontaneous firing. (E) Superimposition (n = 58) of the same PC presented in (C) in response to electrical whisker stimulation (arrowheads). The figure shows that SS and CS waveforms were preserved during whisker stimulation. (F) The SS latency distribution, in response to whisker pad electrical stimulation, combined from 45 PCs. The two major peaks correspond to the occurrence times of the N2 (black bars) and N3 (gray bars) postsynaptic components. Bin sizes are 0.2 ms. (G) Latency of the complex spike (CS) for the same population of PCs. The CS always occurred after SS evoked potentials. Bin sizes are 0.5 ms. doi:10.1371/journal.pone.0036184.g002 PLoS ONE | www.plosone.org 5 April 2012 | Volume 7 | Issue 4 | e36184