ATXN1 and Ataxia: Notably, shrinkage of the ML and the PN dendrites with retraction of CFs are architectural hallmarks of SCA1 (Duvick et al., 2010; Barnes et al., 2011; Ebner et al., 2013; Power et al., 2016) and other ataxias, for example those where calcium signaling proteins (Matsumoto et al., 1996; Empson et al., 2007) and mGluR1 are knocked out (Kano et al., 1997; Ichise et al., 2000).