Schalllokalisation bei der Schleiereule in virtueller Umgebung
Final Report Abstract
It was the scientific goal of the project to increase the understanding of the mechanisms underlying sound localization in the barn owl. The first question to be examined was whether the barn owl ear functions as a pressure difference receiver. In this project we collaborated with Jakob Christensen-Dalsgaard and Ole Larsen form Odense University (Denmark) and collected data with laser Doppler vibrometry in a free-field setting. The data published showed that the large interaural canal in the barn owl allowed significant sound transmission at low frequencies. The sound transmission induced considerable eardrum directionality in a narrow frequency band from 1.5 to 3.5 kHz. This is below the frequency range used by the barn owl for locating prey, but may conceivably be used for locating conspecific callers. We complemented earlier research on adaptation on the neurophysiological level with a behavioral study. We started from the observation that barn owls do not immediately approach a source after they hear a sound, but wait for a second sound before they strike. This represents a gain in striking behavior by avoiding responses to random incidents. However, the first stimulus is also expected to change the threshold for perceiving the subsequent second sound, thus possibly introducing some costs. We mimicked this situation in a behavioral double-stimulus paradigm utilizing saccadic head turns of owls. The first stimulus served as an adapter, was presented in frontal space, and did not elicit a head turn. The second stimulus, emitted from a peripheral source, elicited the head turn. The time interval between both stimuli was varied. Data obtained with double stimulation were compared with data collected with a single stimulus from the same positions as the second stimulus in the double-stimulus paradigm. Sound-localization performance was quantified by the response latency, accuracy, and precision of the head turns. Response latency was increased with double stimuli, while accuracy and precision were decreased. The effect depended on the interstimulus interval. These results suggest that waiting for a second stimulus may indeed impose costs on sound localization by adaptation and this reduces the gain obtained by waiting for a second stimulus.
Publications
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(2013) Investigating adaptation in the barn owl with a double-stimulus paradigm: a behavioral approach. ARO2013 abstract #517
Kettler L, Brill S, Zähringer D, Wagner H
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(2013) Investigating adaptation in the barn owl with a double-stimulus paradigm: a behavioral approach. Göttingen Neuroscience meeting 2013 abstract #T18-9C
Kettler L, Brill S, Zähringer D, Wagner H
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(2013) Neuroethology of prey capture in the barn owl (Tyto alba L.) Journal of Physiology-Paris, Vol. 107. 2013, Issues 1–2, pp. 51–61.
Wagner, H, Kettler L, Orlowski J, Tellers P
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(2014) Influence of double stimulation on sound-localization behavior in barn owls. J Comp Physiol A200: 1033-1044.
Kettler L, Wagner H
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(2014) Spectral and Temporal Integration in the Auditory System of Barn Owls. ARO2014 abstract #100
Kettler L
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(2015) Do owls use ILDs to disambiguate the sound source on the horizontal plane? ARO2015 abstract #444
Kettler L, Griebel H, Wagner H
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(2016) Low frequency eardrum directionality in the barn owl induced by sound transmission through the interaural canal. Biological Cybernetics, Vol. 110. 2016, Issue 4, pp 333–343.
Kettler L, Christensen-Dalsgaard J, Larsen ON, Wagner H
