Figure 1.

Anatomical locations of the putative action-selection systems. (a) The relative locations of major nuclei and structures including the basal ganglia (hashed) and the mRF shown in a cartoon sagittal section of rat brain. The dashed lines show the location of the three most common decerebration lines—all the brain rostral to the line is removed, leaving hindbrain and spinal cord intact. GP, globus pallidus; SN, substantia nigra; STN, subthalamic nucleus; SC, superior colliculus. (b) Principal reticular formation nuclei and fields in a schematic horizontal section from spinal cord to decerebration line 1 in (a). The main components of the putative brainstem action-selection system are in the medial RF.