The recent discovery that familial hemiplegic migraine, episodic ataxia type 2, and spinocerebellar ataxia type 6 are allelic disorders caused by different mutations in CACNA1A, a calcium-channel-encoding gene, adds to a growing list of channelopathies causing paroxysmal neurologic disturbance and progressive neurodegeneration. Calcium channelopathies in the central nervous system provide a model to study the important roles that calcium channels play in neuronal function.