[Discharges in the white rami communicantes evoked by stimulation of different fields of the limbic system].

Electrical responses to stimulation of different areas of the cingulate gyrus were studied in L2-L3 white rami in anesthetized and immobilized cats. The stimulation evoked a sympathetic discharge mostly consisting of a wave with a mean latency of 71.2 +/- 2.3 ms. In a few cases, the main wave was preceded by a short-latency component. Thresholds for eliciting sympathetic discharges were lower in case of stimulation of the ventral region of area 25 in comparison to those of the dorsal region of the same area. A comparative study showed that the lowest were the thresholds of hypothalamic evoked discharges, somewhat higher were the thresholds of amygdala stimulation and the highest were those of the cingulate cortex evoked discharges. In experiments with simultaneous recording of arterial pressure and cingulo-sympathetic discharges, after 10-sec period of tetanic (100/sec) stimulation of the limbic cortex, the early components were facilitated while the late component of the cingulo-sympathetic discharges was depressed. The duration of this inhibition corresponded to the period of pressure reaction and, therefore, was of a baroreceptor origin. Possible mechanisms of cingulate cortex regulation of the activity of sympathetic preganglionic neurons, are discussed.