FIGURE 6.

(A,B) Retrograde neuronal labeling in the face and arm regions of the SMA after Fluoro-ruby (FR) injection into the STN. (C,D) Higher-power magnifications of the rectangular areas in (A,B). (E,F) NeuN immunostaining of the face and arm regions of the SMA. Note that the IT injections cause no marked tissue damage. (G) Distribution of FR-positive neurons in the face, arm, and leg regions of the SMA. Note that FR-positive neurons are so few in the arm region where IT injections were made (at two rostrocaudally distinct levels pointed to by arrows), as compared to those in the face and leg regions. Numerals on the abscissa represent the distance from rostrocaudal zero on the stereotaxic frame (equivalent to the interaural line).