Changes of neuronal responsiveness in the mediorostral neostriatum/hyperstriatum after auditory filial imprinting in the domestic chick.

Abstract

Auditory filial imprinting in the domestic chick is an established experimental model for investigating basic mechanisms of learning-related synaptic plasticity. In in vivo electrophysiological studies, we analysed whether imprinting alters the responsiveness of neurons to acoustic imprinting stimuli in the mediorostral neostriatum/hyperstriatum ventrale. We compared the response characteristics of neurons in the mediorostral neostriatum/hyperstriatum ventrale in freely behaving or anesthetized acoustically imprinted, non-imprinted (naive controls) and passive control chicks (stimulus-exposed) during presentation of either the imprinting stimulus or an unfamiliar discrimination stimulus. In acoustically imprinted chicks, the multiunit activity in anesthetized chicks and the fast Fourier transform power spectrum in freely behaving chicks in the mediorostral neostriatum/hyperstriatum ventrale were significantly changed during playback of the learned stimulus in comparison to spontaneous activity and compared to the activity during playback of the unfamiliar discrimination stimulus. In anesthetized non-imprinted and passive control chicks, the multiunit activity showed slightly enhanced activity during playback of either the imprinting or the discrimination stimulus in comparison to spontaneous activity. However, in both control groups there were no significant differences between the responses towards the imprinting and the discrimination stimuli. These results indicate that neurons in the mediorostral neostriatum/hyperstriatum ventrale change their responsiveness towards learned, behaviorally relevant stimuli during auditory filial imprinting.