[Responses of pericruciate cortex neurons to stimulation of the hypothalamus and reticular formation].

Neurons of the pericruciate cortex revealed a high degree of reactivity to stimulation of posterior hypothalamus (HP) and mesencephalic reticular formation (RF)--94 and 88% resp., and a marked convergence of upward discharges from HP and RF (73.5%) in anesthetized and immobilized cats. Latency and unit responses (2.4--4.0 msec) suggested a monosynaptic input from the two subcortical structures. Out of the corticofugal neurons activated antidromically, 27% were of the "divergent" type with collaterals in both the HP and RF and, therefore, reacting antidromically to stimulation of these structures. A predominance of cortical antidromic responses to stimulation of HP suggested a greater corticofugal influence on hypothalamic rather than on reticular neurons (84% and 42.3% resp.). Mean latency of antidromic reaction of cortico--hypothalamic neurons was 2.4 +/- 0.2 msec (0.8--6.0 msec), of cortico--reticular neurons--3.2 +/- 0.3 msec (1.0--6.0 msec). The conduction velocity (12.5 m/sec) was the same for both the HP and RF. Characteristics of neuronal organization of hypothalamo--cortical and reticulo--cortical systems of integration are discussed.