ATXN1 and Machado-Joseph disease: In addition to SCA1, SCA-2, SCA-3/Machado-Joseph disease, SCA-6, SCA-7, and SCA-17, all of which are “polyglutamine diseases,” exhibit changes that affect a reciprocal circuitry between the cerebellar cortex, the Lat, and the IO, unlike other forms of SCA in which no clear signs of CN involvement has been detected.