Development of neuronal responsiveness in the mediorostral neostriatum/hyperstriatum ventrale during auditory filial imprinting in domestic chicks

Chronic electrophysiological recordings of slow field potentials from tone- imprinted chicks show significantly enhanced fast Fourier transform (FFT) p ower during playback of rhythmic 400-Hz imprinting tone stimuli in the pres ence of a surrogate mother. The FFT power was already significantly higher during the very first imprinting session, when the chick was exposed to the imprinting tone stimuli in the presence of the surrogate mother compared t o spontaneous activity (EEG recordings). During discrimination tests, where individual chicks were exposed to the imprinting tone stimuli in alternati on to rhythmic 700-Hz tone stimuli (discrimination tone stimuli), the FFT p ower was significantly higher during playback of the imprinting tone stimul i than the FFT power during playback of the discrimination tone stimuli. Ch icks which were imprinted in the absence of the surrogate mother also show enhanced FFT power in the course of the imprinting sessions; however, in co ntrast to the first group, they did not show significant differences in the FFT power during playback of either the imprinting or discrimination tone stimuli in the discrimination tests. Our results suggest that the high FFT power of a potential imprinting stimulus or situation, which is expressed i n newborn (still naive) chicks, is maintained only when the chicks form an association between the tone stimuli and a positive emotional situation (re presented by the surrogate mother), (C) 2000 Academic Press.