Figure 3. Photomicrograph in high magnification and low magnification (upper right) through peri-aqueductal gray matter (A), parabrachial nucleus (B), and locus coeruleus (C) showing Fos-IR neurons. AQ, cerebral aqueduct; scp, superior cerebellar peduncle; sctv, ventral spinocerebellar peduncle; V4, fourth ventricle.