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Showing papers by "Hermann Wagner published in 1994"


Journal ArticleDOI
TL;DR: In this article, a model for the visual disparity in the barn owl was proposed, based on the representation of interaural time difference, the main cue for encoding sound-source azimuths.
Abstract: Binocular responses have been recorded extra-cellularly at 58 sites in the barn owl's (Tyto alba) visual Wulst. Neurons showed disparity tuning to stimulation with moving bars, moving sinewave gratings and a moving visual-noise stimulus. Responses to sinewave gratings as a function of disparity were cyclic, with the period of a cycle of the response being correlated to one cycle of the stimulus. Cyclic responses were also found when bars or noise were used as a stimulus, but, especially in response to visual noise, one response peak, the main peak, was different from the other peaks, the sidepeaks: usually, the main peak was either higher or narrower or both higher and narrower than the sidepeaks. When the responses to different spatial frequencies were compared, response maxima coincided at the main peak, but not at the other peaks. In analogy to auditory physiology the disparity at which the frequency-independent peak occurs is termed ‘characteristic disparity’. Spatial-frequency tuning revealed broad tuning, ranging from 1 to more than 3 octaves at 50% of the maximal response. Disparity tuning was broad at the onset of the response and sharpened later. The data are discussed within the framework of a model for the neural representation of visual disparity that was derived from a model proposed earlier for the representation of interaural time difference, the main cue for encoding sound-source azimuths in the barn owl.

26 citations


Journal ArticleDOI
TL;DR: This work investigated the level dependence of acoustic motion sensitivity in midbrain neurons with standard extracellular recording techniques and found that cells in the owl's midbrain are indeed able to encode motion direction largely independently of stimulus level.
Abstract: 1. Many neurons in the owl's midbrain are able to discriminate by their responses the motion of an acoustic source in one direction, the preferred direction, from the motion of the source in the op...

20 citations