Effects of unilateral high-frequency stimulation of the subthalamic nucleus (STN) on c-fos immunostaining. A, B, Photomicrographs illustrating c-fos immunolabeling in the STN on the stimulated (A) and contralateral (B) sides in an hemiparkinsonian rat. Scale bar, 180 μm.C–F, Higher magnification photomicrographs from intact (C, D) and hemiparkinsonian (E, F) rats on the stimulated (C, E) and contralateral (D, F) sides in the same sections. Scale bar, 70 μm. CP, Cerebral peduncle.