Early visual experience shapes the representation of auditory space in theforebrain gaze fields of the barn owl

Auditory spatial information is processed in parallel forebrain and midbrai n pathways. Sensory experience early in life has been shown to exert a powe rful influence on the representation of auditory space in the midbrain spac e-processing pathway. The goal of this study was to determine whether early experience also shapes the representation of auditory space in the forebra in. Owls were raised wearing prismatic spectacles that shifted the visual field in the horizontal plane. This manipulation altered the relationship betwee n interaural time differences (ITDs), the principal cue used for azimuthal localization, and locations of auditory stimuli in the Visual field. Extrac ellular recordings were used to characterize ITD tuning in the auditory arc histriatum (AAr), a subdivision of the forebrain gaze fields, in normal and prism-reared owls. Prism rearing altered the representation of ITD in the AAr. In prism-reared owls, unit tuning for ITD was shifted in the adaptive direction, according to the direction of the optical displacement imposed by the spectacles. Ch anges in ITD tuning involved the acquisition of unit responses to adaptive ITD values and, to a lesser extent, the elimination of responses to nonadap tive (previously normal) ITD values. Shifts in ITD tuning in the AAr were s imilar to shifts in ITD tuning observed in the optic tectum of the same owl s. This experience-based adjustment of binaural tuning in the AAr helps to mai ntain mutual registry between the forebrain and midbrain representations of auditory space and may help to ensure consistent behavioral responses to a uditory stimuli.