[Evoked cortical potentials to simple and complex visual signals in children].

The analysis of steadily recorded components of evoked potentials (EP) in different areas of cerebral cortex during tachistoscopic presentation of a homogeneous square, checker-board pattern and schematic drawings of human faces (face-pattern) of 6 degrees size was performed in children aged from 6,5 to 7 years. During contour detection, characterized by significant EP differences between responses to a checker-board pattern and a homogeneous square, the most pronounced changes were observed in the visual projection area of the cortex. Reaction to a complex visual stimulus, characterized by differences of EP to fase and checker-board patterns, had maximal manifestation in the temporo-parieto-occipital area. The changes observed during both operations were noted for EP components appearing up to 250 msec following stimulation. It is suggested that they are connected with the activity of cortical receptive fields. The data obtained are discussed on the basis of hypothesis of a difference between cortical mechanisms of single operations involved in visual perception.