Figure 9.

CF development and regression in affected SCA1 mice. Normal development of CF/PC synapses is depicted in the top row. At early stages (p7) each PC is innervated by multiple CFs from the inferior olive (IO). As development proceeds (p14) activity of one CF strengthens, its terminals translocate up the proximal dendritic shaft of the PC. At 5 weeks of age, and into the adult, one CF maintains its synapses with the PC dendritic tree segregated from the synaptic territory of parallel fibers. In ATXN1[82Q]-S776 mice development is mostly normal except that translocation of the dominant CF terminals up the PC dendritic tree is delayed and some of its terminals remain on the PC soma (5 weeks). As disease progresses in ATXN1 mice CF terminals regress from the PC dendritic tree (12 week old adult). In ATXN1[30Q]-D776 mice development is more substantially altered. Although one CF seems to be become dominant and translocates its terminals up the PC dendritic tree (p14) subsequent terminal translocation is more severely compromised and pruning of terminals from the PC soma fails to occur (5 weeks). As in ATXN1[82Q]-S776 mice, CF terminals that translocated up the PC dendritic tree regress with age (12 week old adult). DCN, deep cerebellar nuclei.