ABSTRACT
The pulvinar and the lateral geniculate nuclei (LGN) make up the visual areas of the thalamus. These two nuclei have very different patterns of connections with the cortex. Retinal signals arrive at the striate cortex primarily through the LGN, so one important function of the LGN is to faithfully relay the crucial properties of these early visual signals. However, the pulvinar appears to play a very different role, and may be important in regulating communications between cortical areas. One reason to suspect this is based simply on its phylogenetics. The pulvinar has increased in size proportionately with increases in mammalian cortex (Armstrong, 1982). In the rat, for example, there is no observable pulvinar, while in humans the pulvinar reaches its largest dimensions (Browne & Simmons, 1984). Such development also suggests that it would be a mistake to dogmatically separate the functions of the “old” subcortex from the “new” cortex; these structures, in the human and other primates at least, appear to have developed together.
