The medial geniculate nucleus is a nucleus of the thalamus that acts as a relay for auditory information. It receives its input from the inferior colliculus and sends information out to the auditory cortex. In neuroanatomy, a nucleus is a central nervous system structure that is composed mainly of gray matter, and which acts as a hub or transit point for electrical signals in a single neural subsystem. ... The thalamus is a part of the brain. ... This article is about compression waves. ... The paired inferior colliculi together with the superior colliculi form the eminences of the corpora quadrigemina. ... The primary auditory cortex the region of the brain which is responsible for processing of auditory (sound) information. ...