The gigantocellular nucleus, as the name indicates, is mainly composed of the so called giant neuronal cells.

This nucleus has been known to innervate the caudal hypoglossal nucleus

Hypoglossal nucleus

The hypoglossal nucleus is a cranial nerve nucleus, and it extends the length of the medulla, and being a motor nucleus, is close to the midline...

, and responds to glutamateric stimuli.

The gigantocellular nucleus excites the hypoglossal nucleus, and can play a role in the actions of the said nerve.

This nucleus receives connections from the periaqueductal gray

Periaqueductal gray

Periaqueductal gray is the gray matter located around the cerebral aqueduct within the tegmentum of the midbrain. It plays a role in the descending modulation of pain and in defensive behaviour...

, the paraventricular hypothalamic nucleus, central nucleus of the amygdala, lateral hypothalamic area, and parvocellular reticular nucleus

Parvocellular reticular nucleus

The parvocellular reticular nucleus is part of the brain located dorsolateral to the nucleus reticularis pontis caudalis.The dorsal portion of the reticular nucleus has been shown to innervate the mesencephalic trigeminal nucleus and its surrounding area....

.

Retrograde studies have shown that the deep mesencephalic reticular formation and oral pontine reticular nucleus

Oral pontine reticular nucleus

The oral pontine reticular nucleus is delineated from its caudal brother, with which it shares its first three names.This nucleus tapers into the lower mesencephalic reticular formation and contains sporadic giant cells....

 project to the nucleus gigantocellularis.

The dorsal rostral section of the nucleus reticularis gigantocellularis is also involved mediating in expiration

Exhalation

Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....

 (or out-breathing) along with the parvocellular nucleus.