Experiments on alert rabbits have revealed a definite but dissimilar correspondence of amplitude-temporal dynamics of evoked potentials, neuroronal spike activity in the visual (VC) and the sensorimotor (SC) areas of the cerebral cortex and movements appearing in response to photic flashes, the conditioned signal (CS) of a defensive reflex. VC reaction to the CS sets in in 15 to 20 msec. During the subsequent 20 to 40 msec, there is intensive VC activation and involvement in the reaction of most of the responding elements in the SC. Subsequently, the activation in VC weakens and increases in the SC. Against this background, movements in response to the CS appear with a latency of 60 to 120 msec. The probability of movements in response to photic flashes decreases in the case of distinct phasic reactions to the CS in the period of deep inhibition and intensive postinhibitory activation of VC units. The data obtained imply that the SC neurones play a decisive role in the achievements of the defensive movement to the CS. As to the detection of the very fact of visual stimulation and to the modulation function and correction of the movement, they are provided for both by SC and VC neurones.