In learning groups, contrary to our expectation of deficient striatal activation associated with HD mutation, c-Fos-expressing cell counts in the DMS were, in general, greater in R6/1 mice (genotype effect: F1,38) = 4.11, p = 0.0497), and more particularly at pre-symptomatic 2 months of age (p<0.01, Fig 3G). The gene discussed is FOS; the disease is Huntington disease.