The term fields of Forel refers to a composite, predominantly white matter substructure of the subthalamus. Defined in the human ( Carpenter-1983 ) and the macaque ( Shantha-1968 ) it consists of field H, field H1 and field H2 . Cells scattered among the fibers of field H constitute the nucleus of field H ( Carpenter-1983 ). In the rat ( Swanson-2004 ) and mouse ( Hof-2000 ) the cellular component predominates; see nucleus of field H.