Electrical lesions. Histological verification of electrode locations A/B show Nissl stained 42 μm frontal sections. (A) Two lesions (L1/L2) caused by repeated electrical stimulation through chronically implanted electrodes placed into vocally active sites within the PAG. AQ, aqueduct; B, boundary between PAG and surrounding tissue. (B) Electrically induced lesion (L) 400 μm below the location of the iontophoresis probes in the PLA. Due to the 400 μm offset of the lesion below the PLA the function of the PLA during further experiments was not influenced. CER, cerebellum; LL, lateral lemniscus; 4V, 4th ventricle.