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Lutz Wiegrebe

Neural basis of auditory object localization and recognition

The mammalian auditory system excels in the segregation and identification of auditory objects from complex auditory scenes. With a combination of psychophysical and computational neurobiological approaches, my group aims to uncover the perceptual potency and the underlying neural principles of auditory object localization and recognition. Our model systems are primarily the echo-imaging of bats and spatial auditory perception in gerbils and humans.

Bats are hearing specialists. Anyone who has monitored bats preying on insects in highly cluttered space readily acknowledges the exceptional capabilities provided by the combination of flight and echolocation. Through the extremely accurate comparison of their ultrasonic emissions with the echoes reflected from objects in their environment, echolocating bats can not only deduct the position of objects in space but also their three-dimensional shape. We have developed an echo-acoustic phantom target technique which allows to present bats with virtual echo-acoustic objects similar to how a computer screen can present visual virtual objects. With this technique we describe and analyze the extraordinary perceptual capabilities of echolocating bats. In close collaboration with the electrophysiology group of Dr. Uwe Firzlaff and Prof. Gerd Schuller, we identify neural correlates of the psychophysical performance in the bats’ auditory brain.

While the gerbil has become a very important animal model for human auditory processing in both in-vivo and in-vitro electrophysiology, relatively little is known whether gerbils recruit similar perceptual strategies to analyze their acoustic environment. In carefully matched experimental paradigms, the human psychophysical performance is compared to the neural representation of the stimuli at different stages of the gerbil auditory system. We also describe the gerbils’ perception both in terms of auditory object localization and categorization and, together with the in-vivo electrophysiological expertise from the Grothe lab, analyze the underlying neural circuitry across the ascending auditory system.

The human psychophysical works is focused on the analysis of complex sounds in terms of periodicity (pitch) and localization. Current projects aim at the localization and spatial segregation of rustling sounds and on blind humans’ capability to orient through the auditory analysis of self generated sounds.