Parallel fibre receptive fields of Purkinje cells and interneurons are climbing fibre-specific

In cats decerebrated at the intercollicular level, the cutaneous parallel fibre receptive fields of Purkinje cells, molecular layer interneurons and Golgi cells in the cerebellar C3 zone were delineated by natural stimulation of the skin during extracellular unitary recordings. The locations of these receptive fields were compared with the climbing fibre receptive field of the local Purkinje cell and with the receptive fields of other neurons located along a beam of parallel fibres. The parallel fibre receptive fields of these neurons were highly specific to the local climbing fibre receptive field. In Purkinje cells, the parallel fibre receptive fields were located outside the climbing fibre receptive field of the same cell. In contrast, the parallel fibre receptive fields of interneurons were similar to the receptive field of the locally terminating climbing fibres. In both types of neurons, the parallel fibre receptive fields were small and had distinct borders. The location on the skin of the parallel fibre receptive fields differed conspicuously between neighbouring Purkinje cells and between neighbouring interneurons along a beam as well as between Purkinje cells and interneurons in the same electrode tracks. The remarkable specificity between the parallel fibre receptive fields in Purkinje cells and interneurons and the receptive field of the local climbing fibre is most easily explained by different forms of parallel fibre synaptic plasticity.