[Formation of visual evoked potentials and development of visually guided behavior in the Ficedula hypoleuca nestling].

Age dynamics of evoked potentials (EPs) of Wulst area of the dorsal hyperstriatum (functional analogue of mammalian visual cortex) was investigated in 2-7 days old nestlings. EPs in response to light stimuli, with the duration and intensity imitating natural alimentary signals for 5-7 days-old nestlings, were recorded parallel with the behaviour. It was found that the development of the visual system in precocious nestlings became completed in postembryonal ontogenesis. The most essential changes in the parameters of visual EPs occur between 2.5 and 4 days of nest life. By the end of the 4-th day the EPs parameters resemble those of the definite EPs. During the same period the visually directed form of the alimentary behaviour appears for the first time. Both the visual EPs and the visually directed alimentary behaviour first appear in the ontogenesis in response to the second component of two-fold luminosity change--the natural signal of alimentary behaviour.