<Tr> <Td_colspan="2"> Anatomical terms of neuroanatomy (edit on Wikidata) </Td> </Tr> <P> The thalamus (from Greek θάλαμος, "chamber") is the large mass of gray matter in the dorsal part of the diencephalon of the brain with several functions such as relaying of sensory and motor signals to the cerebral cortex, and the regulation of consciousness, sleep, and alertness . </P> <P> It is a midline symmetrical structure of two halves, within the vertebrate brain, situated between the cerebral cortex and the midbrain . The medial surface of the two halves constitute the upper lateral wall of the third ventricle . </P> <P> It is the main product of the embryonic diencephalon, as first assigned by Wilhelm His, Sr. in 1893 . </P>

Which ventricle is located between the two halves of the thalamus