Abstract [This resubmitted project carries on the study of how auditory space is encoded in the barn owl's brain, with the overarching goal of understanding the interplay between midbrain and forebrain neural populations underlying discriminability and stimulus selection through auditory space. Behavioral spatial discrimination assays will be used to test the hypothesis that spatial discriminability is optimized by a built-in representation of natural cue statistics and in vivo recordings through multi-electrode arrays (MEAs) will be conducted in both anesthetized and awake barn owls for investigating activity patterns of midbrain neural populations underlying this effect (Aim 1). Population recordings in the midbrain space map, the hub of the midbrain stimulus selection network, will be used to investigate the interplay of stimulus temporal dynamics and brain oscillations in the coding of salient sounds across space (Aim 2). Simultaneous population recordings over brain regions will be used to investigate the routing of neural activity between midbrain and forebrain underlying sound localization (Aim 3). Recent findings by our group indicating commonalities of coding schemes across birds and mammals, including humans, support the premise that investigating mechanisms underlying discriminability, stimulus selection across space, and population-level midbrain and forebrain routing of activity, important open questions in sound localization, will be of significance across species. The group has recently developed multiunit recordings in awake animals, which will be used towards every specific aim.] Towards Aim 1, we will investigate the relationship between spatial discriminability and a representation of natural statistics of spatial cues, focusing on interaural time difference (ITD), a critical binaural cue for determining the azimuth location of sounds across species. This aim will test a hypothesis, based on premises supported by previous work from our group, that a built-in representation of natural ITD statistics, determined by the acoustical properties of the head, exists in the brain and optimizes sound localization. Behavioral studies will be conducted to assess spatial discriminability across frequency and space. MEAs will be used to record activity of the midbrain map of auditory space and use decoding analyses to investigate properties of population responses supporting the optimized discriminability pattern. [Recordings in awake birds will be used as a control for the effect of anesthesia. Preliminary data show feasibility of recordings in awake animals and a pattern of ITD discriminability across frequency and locations consistent with the hypothesis and properties of midbrain population responses supporting feasibility of this approach.] In Aim 2 we will scrutinize the midbrain stimulus selection network of barn owls on a population scale. Previous work suggested a role of gamma oscillations in stimulus selection and recent studies b...