TABLE 1.

Nuclei in Core Lesion in Reticular Formation in SIDS

Nucleus	Difference in 5-HT1A Binding	Serotonin Neurons Present	Key Function
Raphe obscurus	+	+	Modulation of multiple brainstem reflexes (28)
Paragigantocellularis lateralis	+	+	Neurons expressing 5-HT1A autoreceptors modulate sleep state. Inhibition of 5-HT neurons in the LPGi leads to sleep fragmentation and decreases in REM sleep in piglets. The LPGi receives inputs from many sites in the caudal brainstem, and projects to the spinal cord and to the more rostral areas important for arousal and vigilance (29).
Gigantocellularis	+	+	Critically important for CNS arousal and behavioral responsiveness in postnatal mouse pups. Development of electrophysiological properties of gigantocellularis neurons correlate with increased CNS arousal (30).
Arcuate nucleus	+	+	Putative respiratory chemosensitive fields of ventral medulla in cat (31). A subpopulation of serotonergic neurons exist within the arcuate nucleus (32).
Intermediate reticular zone	+	+	5-HT and catecholamine neurons are intermingled. The IRt brackets the line separating alar and basal visceral plates in embryo and is thought to be involved, via catecholamine activity, in control of sympathetic cardiovascular outflow, cardiorespiratory interactions, and reflex control of vasopressin (33)

The nuclei of the core lesion in SIDS demonstrated in Figure 2.

Abbreviations: LPGi, paragigantocellularis lateralis; CNS, central nervous system; IRt, intermediate reticular zone.