Involvement of Wulst neurons in hiding reaction of pied flycatcher nestlings with different visual afferentation.

We studied transcriptional activity in the higher avian center visual system (Wulst area) in acoustically guided defensive behavior in visually deprived and non-deprived nestlings to evaluate the effects of visual afferentation on functional involvement of visual structures in acoustically guided defensive behavior. Exclusion of visual afferentation from already formed defensive behavior did not significantly change immunoreactivity of Wulst neurons, which attests to substantial contribution of other, non-visual, activating influences. Limitation of visual afferentation during the formation of defensive behavior decreased immunoreactivity of Wulst neurons. Dendritic sprouting in Wulst neurons of visually deprived nestlings unable to promote the formation of complex interneuronic interactions.