SOME FUNCTIONAL CONNECTIONS BETWEEN HYPOTHALAMUS AND MEDULLA

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Abstract
Hypothalamic and anterior midbrain stimulation was performed in cats anesthetized with nembutal. Carotid blood pressure, respiration, and recurrently elicited kneejerk were recorded. Hypothalamic stimulation frequently resulted in enhancement of all 3 recorded functions. Such enhancement was diminished or abolished to the same degree for all 3 recorded functions by subsequent lesions placed in the lateral reticular formation of the medulla ipsilateral to the hypothalamic stimulation site. Enhancement of hypothalamically elicited effects was obtained following lesions placed in the medial inhibitory reticular formation. Simultaneous stimulation of the posterior hypothalamus and the medial reticulum of the bulb caused an inhibition of the hypothalamically induced hypertension equivalent to stimulation of the medial inhibitory reticulum alone. These results indicate that stimulation of the hypothalamic facilitatory areas result in enhancement of somatic reflexia, blood pressure, and respiration, and that these effects are mediated by the lateral facilitatory reticular formation of the brainstem but are opposed by activation of the medial inhibitory reticulum of the bulb.