[Activation of tectofugal visual system of the pied flycatcher nestlings at early developmental stages of feeding behavior guided by diffuse photosensitivity].

Immunohistochemical detection of c-Fos in serial frontal sections of the brain of Pied flycatcher nestlings was used to map the sensory structures involved in early forms of feeding behavior. The c-Fos content was quantitatively analyzed in the higher structures of thalamofugal (Wulst area) and tectofugal (entopallium) visual pathways during visually-guided feeding behavior in 6-day-old nestlings at the stage of diffuse photosensitivity. Induction of c-Fos was not observed in the Wulst area which is known to be involved in the feeding integration in adult bifoveal birds. Induction of c-Fos was detected in the ventral area of entopallium containing neurons that are, according to literature, sensitive to a luminosity change. In the entopallium of 6-day-old nestlings, asymmetry in the evoked c-Fos expression was observed, probably reflecting the asymmetry of the visual projections originating in the embryonic period.