General description technique/protocol: The distribution of neurons that project to the PMd was examined by using CTb as a retrograde tracer. As shown in Figure 1, in three experiments, the deposit of tracer appeared to be fairly confined to the PMd. The photomicrograph of a representative CTb injection site in the PMd (experiment CTb/CC#6) is shown in Figure 2, and the distribution of retrogradely labeled neurons from this experiment is illustrated schematically in Figure 3. The results of this experiment are described in detail because the injection site was entirely confined to the PMd and, at the same time, produced a robust retrograde labeling. Furthermore, the pattern of retrograde labeling in this experiment was representative of that seen in each of the other experiments with deposits centered in the PMd. |