The Developmental Profile of Seizure Genesis in the Inferior Collicular Cortex of the Rat: Relevance to Human Neonatal Seizures

Abstract

The ontogeny of seizure genesis within the inferior collicular cortex was characterized in rats ranging in age from 3 days old to adult. Brief electrical stimulation of the right inferior collicular cortex in 30-day-old rats evoked poststimulus wild running behavior that coincided with afterdischarge activity in the inferior collicular cortex but not in the adjacent occipital cortex. Similar electrical stimulation in 16-day-old rats produced poststimulus wild running and jumping behaviors, which also coincided with afterdischarge in the inferior collicular cortex. In 10- and 5-day-old rats, electrical stimulation of the inferior collicular cortex produced poststimulus locomotion and coincident afterdischarge activity, but unlike older rats the locomotor behaviors consisted of forelimb paddling, hindlimb treading, and rolling/curling movements of the torso. Identical behaviors can be electrically elicited in 3-day-old rats. Although many of the seizure characteristics appear to be similar among the different age groups, 5-day-old rats were more sensitive to low frequency stimulation than 16-day-old rats, who in turn were more sensitive than adult rats. Thus, the inferior collicular cortex is capable of generating seizure activity in rats as young as 3 days of age, providing a focal model of neonatal seizure genesis.