[Comparative characteristics of hypothalamo-cortical and reticulo-cortical evoked potentials].

In anesthetized and immobilized cats, single shock stimulation of the postero-lateral hypothalamus (Hp) and mesencephalic RF elicited positive-negative evoked potentials in gyrus sigm. anterior (GSA) with a latency of 0.8--2.5 msec and 1.0--3.0 msec for hypothalamo-cortical (HC) and reticulo-cortical (RC) EPs respectively. In gyr. suprasylv. ant. (GSSA) HC and RC EPS with initial negative wave were recorded with a latency of 1.0--3.5 and 0.5--4.0 msec resp. The HC and RC EPs followed frequency of stimulation up to 40/sec and were capable of obvious postetanic potentiation. Paired stimuli revealed that the main positive wave of HC and RC EPs appeared in GSA at an interval of 5--10 msec. In GSSA the surface negative potential appeared at an interval of 10 msec. Full recovery occurred at an interval of 150--200 msec. A biphasic change of excitability of cortical neurons occurred in response to conditioning stimuli. Comparative study of recovery cycles of HC EP to paired stimuli of Hp or mesencephalic RF in one case and of conditioning stimulation of the RF and testing stimulation of Hp in other, suggest predominance of "convergent" cortical neurons with polysensory input from Hp and RF. The characteristics of functional organization of hypothalamo-cortical system of integration are discussed.