Changes in the firing pattern distribution, e.g. in SCA2 and SCA323,24, altered action potential frequency, e.g. in SCA2, SCA3, and SCA57,23,24, or a higher action potential irregularity, as described in SCA2 and episodic ataxia type 223,24 show the pathophysiological heterogeneity of hereditary ataxias. This evidence concerns the gene ATXN3 and hereditary ataxia.