A sequential protocol combining dual neuroanatomical tract-tracing with the visualization of local circuit neurons within the striatum

We describe here an experimental approach designed to aid in the identifica tion of complex brain circuits within the rat corpus striatum. Our aim was to characterize in a single section (i) striatal thalamic afferents, (ii) s triatopallidal projection neurons and (iii) striatal local circuit interneu rons. To this end, we have combined anterograde tracing using biotinylated dextran amine and retrograde neuroanatomical tracing with Fluoro-Gold. This dual tracing protocol was further implemented with the visualization of di fferent subpopulations of striatal interneurons. The subsequent use of thre e different peroxidase substrates enabled us to unequivocally detect struct ures that were labeled within a three-color paradigm. (C) 2001 Elsevier Sci ence B.V. All rights reserved.