Synaptic Specializations Support Frequency-Independent Purkinje Cell Output from the Cerebellar Cortex

Publication date: 20 December 2016
Source:Cell Reports, Volume 17, Issue 12
Author(s): Josef Turecek, Skyler L. Jackman, Wade G. Regehr
The output of the cerebellar cortex is conveyed to the deep cerebellar nuclei (DCN) by Purkinje cells (PCs). Here, we characterize the properties of the PC-DCN synapse in juvenile and adult mice and find that prolonged high-frequency stimulation leads to steady-state responses that become increasingly frequency independent within the physiological firing range of PCs in older animals, resulting in a linear relationship between charge transfer and activation frequency. We used a low-affinity antagonist to show that GABAA-receptor saturation occurs at this synapse but does not underlie frequency-invariant transmission. We propose that PC-DCN synapses have two components of release: one prominent early in trains and another specialized to maintain transmission during prolonged activation. Short-term facilitation offsets partial vesicle depletion to produce frequency-independent transmission.

Graphical abstract

Teaser

Turecek et al. show that, at synapses between Purkinje cells and deep cerebellar nuclear neurons, synaptic transmission is frequency invariant. This frequency invariance is generated by a balance between short-term depression and facilitation.


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