Dynamics of calcium and its roles in the dendrite of the cerebellar Purkinje cell.

The calcium ion (Ca2+) serves as an important cellular messenger with spatio-temporally highly dynamic patterns. Not only Ca2+ entering from the plasma membrane but also Ca2+ released from intracellular store sites play crucial roles in neurons as well as in other cell types. The cerebellar Purkinje cell shows a variety of spatio-temporal Ca2+ dynamics in its rich arborization, and the Ca2+ release mechanism mediated by IP3 receptors and ryanodine receptors has been shown to be crucial for the induction of long-term depression, a form of synaptic plasticity, in this neuron. Purkinje cells in a model mouse line of human neurodegenerative disease, spinocerebellar ataxia type 1, showed abnormal Ca2+ release properties, which indicated tight regulation of Ca2+ dynamics in the wild type Purkinje cell. Quantitative analysis of the complex Ca2+ dynamics in the Purkinje cell dendrite is still in progress to elucidate the link between external stimuli and the resultant biochemical changes.