The Balance between Negative and Positive Brain System Activity

THE BALANCE BETWEEN NEGATIVE AND POSITIVE BRAIN SYSTEM ACTIVITY EVERETT W. BOVARD* I. Location and Function of Two Systems Preliminary evidence for two brain systems concerned widi autonomic and neuroendocrine function has been considered previously [i]. The first ofthese systems, inhibitory with respect to the neuroendocrine response to stress, appears to be strongly represented in the anterior and lateral hypothalamus; die second, facüitatory with respect to the stress response, is strongly represented in the posterior and medial hypothalamus. Selfstimulation in the first ofthese systems dirough depth electrodes appears to be rewarding for both man and animal, whereas electrical stimulation in the second system has adverse effects. The two hypothalamic zones where these systems are represented have been shown to be reciprocally inhibitory, and the hypodiesis has been advanced [i] diat this is but a special case ofdie general reciprocally inhibitory relationship between these two systems. Additional evidence from work with man and monkeys now provides a more differentiated view ofdie structure and function ofdiese two systems . Inworkwithhumanpatients undergoing neurosurgery, Sem-Jacobsen [2] found diat a positive and a negative system, widi opposite reactions to electrical stimulation, are located close to each odier in die ventromedial frontal lobe, temporal lobe, parietal lobe, hypothalamus, and midbrain, as well as in more midline regions (not specified). Forexample, hefound [3] diatstimulationofthe amygdaloid nucleus of the temporal lobe at one point induced a euphoric reaction in the patient * Department ofAnatomy, Albert Einstein College ofMedicine, New York 61, New York. This work was made possible by support from the National Institute ofMental Health in the form ofa special research fellowship at Montreal Neurological Institute and an inter-disciplinary fellowship at Albert Einstein College ofMedicine. HO Everett W. Bovard · Negative and Positive Brain Systems Perspectives in Biology and Medicine · Autumn 1962 but at a point one-halfmillimeter away, a fear reaction. The responses of both systems appeared to vary together, both being strong or weak in the same region. Patients stimulated with electrodes in the positive system reported feelingsofpleasureandeuphoriaandonoccasionrequestedfurtherstimulation [2]. Whenallowed to stimulate this system intheir ownbrains, the patients did so on occasion to die point ofconvulsion. In recording from positive system sites through the same electrodes used for stimulation, immediately after such stimulation, Sem-Jacobsen found afterdischarge was still taking place in the microregion that had been stimulated. In general, Sem-Jacobsen found feelings ofease and relaxation,joy with smiling, and great satisfaction, respectively, to be elicited from stimulation ofdifferent areas in the positive system. Negative responses could be subdivided into areas resulting in resdessness, anxiety, depression, fright, and horror. To avoid unnecessary discomfort for the patient, die negative system was stimulated very little in diese studies. The relaxing and calming effect ofventromedialfrontallobe stimulation was strong enough to terminate psychotic episodes in less than one minute on several occasions, Sem-Jacobsen found. It should be noted here that, of eighteen patients studied in this series, fifteen had been diagnosed as schizophrenic, one as a psychopath, and two were epileptics. It is interesting to note that when Sem-Jacobsen stimulated two positive areas (ventromedial frontal lobe and central temporal lobe) in rapid succession , he found what he termed a good clinical effect ofsome duration in calming a rather violent manic patient. The effect ofstimulating either one ofthese areas at separate times was in the same direction but ofshorter duration. This suggests that summation ofpositive system responses may take place. Depth electrode studies, also widi mentalpatients, over aperiod ofseven years by Heath [4] and his group at Tulane present a picture roughly similar to that emerging from Sem-Jacobsen's work but differing in detail. Heath found diat patients stimulated in die septal region appeared more alert, spoke more rapidly, and generally reported that diey "felt good." Several asked for more such stimulation. Patients with intractable pain obtained immediate relieffrom such stimulation. 117 In contrast, electrical stimulation of the rostral hypothalamus1 by Heath and his group resulted in marked discomfort, with patients complaining ofanxiety, evidencing rapid heartbeat, and flushing. Stimulation at sites in the caudal hypodialamus and die tegmentum of the midbrain yielded diffuse tension and rage reactions. All stimulation to the amygdala and anterior hippocampus produced emergency reactions ofrage or fear. The differences between these two...