Our finding of both significant volume reduction and altered DTI measurements in the ventral striatum and GP of HD rats is particularly interesting in light of earlier reported accumulation of huntingtin aggregates in the same regions (Nguyen et al. 2006; Petrasch-Parwez et al. 2007), and lends support to the notion that limbic systems may be affected in HD rats. This evidence concerns the gene HTT and Huntington disease.