Anatomy embroiders function in Purkinje cells

The anatomy of the human cerebellar Purkinje cell, as captured by Ramón y Cajal in a drawing, inspired the spectacular cover embroidery by Lisa Stoneman (Roanoke College, Roanoke, VA, USA) in the October issue of The Lancet Neurology. 1 Like contemporary confocal microscopy images do, this anatomical representation also raises fascinating questions about the function served by the complex array of dendrites in this cell type. Each Purkinje cell, in rodents, receives about 174 000 synaptic inputs from the parallel fibre axons of the far tinier cerebellar granule cells, along with a single powerful input from the climbing fibre arising from the inferior olivary nucleus. 2 Even though a large fraction of those synapses can become inactive with learning, 3 it is remarkable that the information processed from such a large number of inputs, which are even more numerous in human beings, is ultimately channelled down a single inhibitory axon to the deep cerebellar nuclei, as denoted by the label a in Cajal's original 1894 drawing (appendix).