Although the cerebral cortex is usually thought of as a likely substra
te for psychiatric disease, the close relationship of thalamus to cort
ex, both structurally and functionally, argues for much closer conside
ration of this structure in both research and clinical settings. Four
thalamic nuclei with widely differing functions are considered in term
s of the specific roles they appear to play in central nervous system
activity and their possible roles in psychiatric disease. These nuclei
include the ventrobasal complex, the nucleus reticularis thalami, the
mediodorsal nucleus, and the dorsal thalamic system with special refe
rence to the habenula.