Blood pressure, pulse, and respiratory changes produced by stimulation of the hippocampus of the monkey

Abstract

Cardiovascular and respiratory changes resulting from systematic stimulation of the hippocampal formation of the monkey were recorded. Stimulation of the anterior portion of the hippocampus resulted in a marked depression or cessation of respiratory excursions, but without apparent changes in respiratory rate. Respiratory changes were minimal to absent when posterior regions of the hippocampus were activated. Anterior hippocampal stimulation resulted in an initial depression of blood pressure accompanied by a small drop in pulse rate, followed by a rise in blood pressure which lasted throughout the period of stimulation and then gradually returned to former levels. The duration of the rise in blood pressure following cessation of stimulation was directly correlated with hippocampal activity. Posterior hippocampal stimulation did not show the secondary rise in pressure, only the depression. Marked pulse changes occurred only when the hippocampal gyrus was secondarily activated or stimulated directly. The neuron pathways which mediated these responses fall into two general groups, the fornix system and a hippocampotemporal system or both. A hypothesis that both systems may be concerned in visceral responses is presented.

Sympathetic-related neurons in the preoptic region of the rat identified by viral transneuronal labeling

“…Ruit and Neafsey (1988) demonstrated that L-glutamate microinjections into the ventral subiculum in rats produced decreases in blood pressure and heart rate (Ruit and Neafsey, 1988). In addition, focal activation of particular subdivisons of the hippocampus in monkeys by electrical stimulation also produces blood pressure changes (Votaw and Lauer, 1963). Apart from these studies, we are not aware of other investigations except for psychology studies related to memory tasks (declarative memories), presumably of hippocampal origin, that produce changes in blood pressure and heart rate (Wright et al, 1998).…”

The hippocampus and motivation.

“…Neuroanatomical (Nauta,19S6;Raisman et al,19,66), neurophysiological (Adey, 1961;Brazier, 1970;Elul, 1964;MacLean, 1959;Votaw & Lauer, 1963), and neurochemical (Purpura, 1959) evidence suggests that the hippocampus has a topical organization. As previously described, Raisman et al (1966) proposed a model in which there are two neuronal systems-one primarily involving anterior CA1 cell fields and the second fields CAS and CA4.…”

“…Similar effects of fornix and entorhinal lesions on learning and retention were reported by Uretsky and McLeary (1969). Differential effects with electrical stimulation of dorsal and ventral regions have been reported on attack behavior (Siegel & Flynn, 1968), and changes in blood pressure have been reported in cats (Andy, Webster, Mukawa, & Bonn, 1961) and monkeys (Votaw & Lauer, 1963). Further, various hippocampal regions in the cat differ in terms of electrical activity (Adey, 1961;MacLean, 19S9).…”