Retrograde degeneration in the thalamus following orbital frontal cortex lesions for the 3 cases in Group O. Areas of moderate degeneration are shown in light shading. cim, central intermedial; MD, medial dorsal thalamus; Re, reuniens; VLc, ventral lateral caudal part; VLm, ventral lateral, medial part; VPLo, ventral posterior, lateral oral part; VPLc, ventral posterior, lateral caudal part; VPL, ventral posterior lateral.