Figure 6.

Retrograde labeling. A, Medium-magnification fluorescence micrograph of striatum after injections of rhodamine beads into both SN and GP under the EGFP filter. Eleven fluorescent EGFP–TH⁺ neurons (arrows) are visible. B, Same field as in A but under the rhodamine filter showing numbers fluorescent retrogradely labeled SPNs. C, Merged image of A and B. Note that there is no colocalization of EGFP and rhodamine. D, Rhodamine injection sites in SN and GP for three animals. E, Higher-magnification merged image of the area shown in the white square in C shows that none of the retrogradely labeled neurons express EGFP.