Analogue signaling of somato-dendritic synaptic activity to axon enhances GABA release in young cerebellar molecular layer interneurons

Analogue signaling is the phenomenon by which subthreshold activity in the dendrites and soma of neurons is transmitted down the axon. Although it has been demonstrated in many different preparations, the extent and physiological role of analogue signaling for subthreshold, somatodendritic spontaneous activity have not been studied in detail. In order to address this we performed simultaneous, whole-cell recordings of the soma and axon of young cerebellar interneurons. We show that the somatodendritic spontaneous glutamatergic events are transmitted down the axon for significant distances and produce a measurable change in the voltage of the axonal varicosities. By combining electrophysiological recordings in the culture preparation and in slices, we further show that the analogously transmitted EPSPs can affect GABA release significantly, and that this effect is not due to a modification in the axonal AP shape or amplitude.