Microelectrostimulation of the Rat Lateral Orbital Cortex Causes Specific Reactions of the Circulation and Respiration

It has been established that the areas of the autonomic prefrontal cortex, located on the medial and lateral surfaces of the cerebral hemispheres, are elements of the central autonomic network and take part in the control of respiratory and circulatory functions. The results of morphological studies indicate that the cortical area on the orbital and frontal surfaces of the hemisphere forms direct connections with the autonomic cortex and other structures of the central autonomic network. These data suggest the involvement of the orbitofrontal cortex in the control of autonomic functions. The purpose of this study was a direct experimental verification of the hypothesis about the possible involvement of the lateral orbital cortex in the control of respiratory and circulatory functions. For this purpose, in acute experiments on laboratory rats anesthetized with urethane, the reactions of the circulatory and respiratory systems to local microelectrostimulation of the lateral orbital and medial prefrontal (infralimbic) cortex by series of rectangular current pulses were recorded. The experiments showed that stimulation of each of the indicated cortical areas of the same experimental animal caused specific reactions of the respiratory system, which manifested themselves in characteristic changes in the volume-time parameters of external respiration. The circulatory system responded to stimulation of the studied areas of the cortex by a gradual decrease in blood pressure against the background of continued stimulation, and depressor responses to stimulation of the infralimbic and lateral orbital cortex differed in amplitude and temporal course. The results obtained confirmed the hypothesis of the possible involvement of the lateral orbital cortex in the control of respiratory and circulatory functions. It is possible that the lateral orbital cortex realizes its influence on the functions of respiration and circulation by interacting with the visceromotor infralimbic cortex; this assumption requires experimental verification.