Simulated responses of cerebellar Purkinje cells are independent of the dendritic location of granule cell synaptic inputs.
Cerebellar Purkinje cell responses to granule cell synaptic inputs were examined with a computer model including active dendritic conductances. Dendritic P-type Ca2+ channels amplified postsynaptic responses when the model was firing at a physiological rate. Small synchronous excitatory inputs applied distally on the large dendritic tree resulted in somatic responses of similar size to those generated by more proximal inputs. In contrast, in a passive model the somatic postsynaptic potentials to distal inputs were 76% smaller. The model predicts that the somatic firing response of Purkinje cells is relatively insensitive to the exact dendritic location of synaptic inputs. We describe a mechanism of Ca2+-mediated synaptic amplification, based on the subspiking threshold recruitment of P-type Ca2+ channels in the dendritic branches surrounding the input site.
De Schutter
E
E
Division of Biology 216-76, California Institute of Technology, Pasadena 91125.
Bower
J M
JM
D000818:Animals; D002118:Calcium / Q000378:metabolism; D003198:Computer Simulation; D003712:Dendrites / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D009457:Neuroglia / Q000502:physiology*; D011689:Purkinje Cells / Q000502:physiology* / Q000648:ultrastructure; D013569:Synapses / Q000502:physiology*; D013570:Synaptic Membranes / Q000502:physiology
D002118:Calcium