TY - JOUR T1 - Determinants of Action Potential Propagation in Cerebellar Purkinje Cell Axons JF - The Journal of Neuroscience JO - J. Neurosci. SP - 464 LP - 472 DO - 10.1523/JNEUROSCI.3871-04.2005 VL - 25 IS - 2 AU - Pablo Monsivais AU - Beverley A. Clark AU - Arnd Roth AU - Michael Häusser Y1 - 2005/01/12 UR - http://www.jneurosci.org/content/25/2/464.abstract N2 - Axons have traditionally been viewed as highly faithful transmitters of action potentials. Recently, however, experimental evidence has accumulated to support the idea that under some circumstances axonal propagation may fail. Cerebellar Purkinje neurons fire highfrequency simple spikes, as well as bursts of spikes in response to climbing fiber activation (the “complex spike”). Here we have visualized the axon of individual Purkinje cells to directly investigate the relationship between somatic spikes and axonal spikes using simultaneous somatic whole-cell and cell-attached axonal patch-clamp recordings at 200-800 μm from the soma. We demonstrate that sodium action potentials propagate at frequencies up to ∼260 Hz, higher than simple spike rates normally observed in vivo. Complex spikes, however, did not propagate reliably, with usually only the first and last spikes in the complex spike waveform being propagated. On average, only 1.7 ± 0.2 spikes in the complex spike were propagated during resting firing, with propagation limited to interspike intervals above ∼4 msec. Hyperpolarization improved propagation efficacy without affecting total axonal spike number, whereas strong depolarization could abolish propagation of the complex spike. These findings indicate that the complex spike waveform is not faithfully transmitted to downstream synapses and that propagation of the climbing fiber response may be modulated by background activity. ER -