HTR1A and sudden infant death syndrome: Our major findings are as follows: (1) there is a developmental decrease in 125I-epibatidine binding with age in 5 sites within the rostral and mid medulla; (2) there is a decrease in 125I-epibatidine binding in the PoO, a critical component of the cholinergic ascending arousal system of the rostral pons, in SIDS compared to post-KCOD controls; and (3) smoking affected 125I-epibatidine binding in 3 rostral medullary sites that contain 5-HT neurons and that have been shown to be abnormal in SIDS infants when examined for the serotonin receptor 1A (5-HT1A) (16, 49).