Orbital cortical influences on cardiovascular dynamics and myocardial structure in conscious monkeys.

The posterior orbital cortex of the frontal lobes in conscious monkeys was stimulated electrically to study the influence of this structure on cardiovascular hemodynamics and cardiac morphology. Stimulating electrodes, cardiac output flow probes, and arterial blood pressure transducers were chronically implanted by aseptic procedures into eight Macaca fascicularis monkeys. Cardiovascular changes induced by stimulating the orbital cortex included both biphasic and unidirectional alterations in cardiac output, blood pressure, heart rate, stroke volume, and total systemic resistance. Electrode position and the rate (Hz) of applied stimulation were the primary determinants of the direction and magnitude of the response. All animals stimulated demonstrated acute, discrete interventricular septal myocytolysis, characteristic of early ischemic lesions. Since the orbital cortex is a part of the limbic system, changes induced by its stimulation suggest a pathophysiological mechanism whereby emotional expression may effect dynamic shifts in cardiovascular functions and may thus induce permanent and manifest myocardial lesions.