| Abstract: | Dynamics of neuronal activity in the cingulate gyrus (CG) was investigated during the sleep-wake cycle (SWC) of free-ranging cats. The highest activity rate was found to occur in 65.4% of neurons during active emotional consciousness (EC) and the so-called emotional phase of paradoxical sleep (PS), while firing rate decreased during passive consciousness (PC) and slow-wave sleep (SS). Peak firing rate was observed during SS in 15% of neurons, while divisions of activity between stages of the SWC remained the same in 19.6%. In addition, discharge patterns in 75.2% of neurons changed consistently in step with phase shifts. More particularly, neurons fired during EC and PS with single action potentials with a more or less even time distribution, whereas a burst-phase activity pattern occurred in the course of SS. Firing rate declined (in 42.6% of units) or remained unchanged (in 50.4%) in the majority of CG neurons (even amongst those manifesting highest activity during EC and PS) as episodes of isolated EEG arousal developed (whether in the context of SS or as PS wore off). This would indicate that the CG actually contributes to shaping the behavioral state of consciousness. The CG, therefore, as one of the higher divisions of the limbic system, must play a major part in controlling the basic mechanisms of the SWC, as well as emotionally motivated processes evolving in the cycle.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 21, No. 6, pp. 832–840, November–December, 1989. |
