Figure 6.1. The brain stem.
The Inferior colliculus and the Superior colliculus are located in the upper part of the brain stem,
close to the Medial geniculate body in the lower part of the Thalamus. The vestibulocochlear nerve
connects the brain stem with the ear. The figure also shows other cranial nerves (yellow).
The pineal body is a gland.^6 The third ventricle is a fluid-filled cavity. The cerebellar peduncles
connect the brain stem with the cerebellum, which is cut off in the figure.
(Brodal 2010:86)
Contributions of the brain stem to consciousness
Damasio argues that ”brains begin building conscious minds not at the level of the cerebral cortex
but rather at the level of the brain stem” (p. 22). He finds evidence that subcortical structures can
create coarse maps, in particular the geniculate bodies in the lower thalamus and the neighboring
superior colliculus in the upper brain stem. Deep layers of the superior colliculus create maps related
to visual, auditory and somatic information, and the superior colliculus displays gamma-range oscilla-
tions, similar to oscillations ascribed to synchronization in the cortex (pp. 68, 83-86, 326).
A special kind of evidence for the contribution of the brain stem to the conscious mind comes
from the study of children born without the cerebal cortex as consequence of a trauma during the
pregnancy period. This deficit is known as hydranencephaly. Such a child possesses an intact brain
6 The pineal gland produces the hormone melatonin, related to the regulation of sleep.