Centromedian nucleus

In the anatomy of the brain, the centromedian nucleus, also known as the centrum medianum, (CM or Cm-Pf) is a part of the intralaminar nucleus (ILN) of the thalamus. There are two centromedian nuclei arranged bilaterally.

It contains about 2000 neurons per cubic millimetre and has a volume of about 300 cubic millimetres with 600,000 neurons in total.

Input and output
It sends nerve fibres to the caudate, putamen and collateral fibres to the cerebral cortex. It receives nerve fibres from the cerebral cortex, vestibular nuclei, globus pallidus, superior colliculus, reticular formation, and spinothalamic tract.

Function
Its physiological role involves attention and arousal, including control of the level of cortical activity. Some frequencies of extracellular electrical stimulation of the centromedian nucleus can cause absence seizures (temporary loss of consciousness) although electrical stimulation can be of therapeutic use in intractable epilepsy and Tourette's syndrome. General anaesthetics specifically suppress activity in the ILN, including the centromedian nucleus. Complete bilateral lesions of the centromedian nucleus can lead to states normally associated with brain death such as coma, death, persistent vegetative state, forms of mutism and severe delirium. Unilateral lesions can lead to unilateral thalamic neglect.

Furthermore, it has been suggested, yet still controversial, that the human consciousness resides fully or at least mainly in the centromedian nucleus.