First-order projections activated by stimulation of hypothalamic sites eliciting attack and flight in rats

14C-deoxyglucose autoradiographs of attack rats were compared densitometrically with those of control rats whose electrodes were located nearby and elicited nonaggressive behaviors like those that accompanied the attack. Most closely associated with attack was the path from the ventromedial hypothalamus through the ventral supraoptic commissural pathway to the peripeduncular area, subparafascicular nucleus, zona incerta, and cuneiform area. Moderately correlated with attack were 4 visual areas: the dorsal and ventral lateral geniculate nuclei, pretectal area, and superior colliculus. Activity in the periaqueductal gray was unrelated to attack ipsilaterally and only weakly related contralaterally. In an orthogonal analysis, upward-oriented flight thresholds were significantly correlated with medial activation extending anteriorly to the lateral septal nucleus, dorsally to the thalamic paraventricular-parataenial region, and posteriorly to the periaqueductal gray.