| Influence of stimulus level on acoustic motion-direction sensitivity in barn owl midbrain neurons. | |
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MedLine Citation:
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PMID: 8064356 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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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 opposite direction, the null direction. This differential response can be understood by the action of an acoustic motion detector. However, the motion detector would work in an effective way only if the motion direction-sensitive responses of a cell were largely independent of stimulus level. 2. We investigated the level dependence of acoustic motion sensitivity in midbrain neurons with standard extracellular recording techniques. We used an apparent motion paradigm with sounds moving clockwise or counterclockwise in the horizontal plane or stationary sounds for stimulation from free-field speakers. In most cases we added a constant level of background noise to the stimuli having a variable level. Thus we could analyze the responses as a function of the signal-to-noise ratio. 3. Moving and stationary sounds yielded similar response thresholds and similar dynamic ranges. 4. When the background level was changed the response threshold changed accordingly, so that the response threshold always occurred at a constant signal-to-noise ratio independent of background level. 5. The preferred direction of all cells was independent of stimulus level and some 22 percent of the cells showed a directional bias of their response at threshold. In no cell was a change in the preferred direction observed when stimulus level was varied. Typically, however, the motion direction sensitivity, measured by a signed directionality index, was not maximal at threshold. However, the dynamic range, i.e., the range of stimulus levels over which motion direction sensitivity changed, was < or = 20 dB in most cases. Therefore these cells are indeed able to encode motion direction largely independently of stimulus level. 6. We discuss the data within the framework of the acoustic motion detector mentioned above and with respect to earlier reports on acoustic motion sensitivity in the owl and other animals. |
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Authors:
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H Wagner; T Trinath; D Kautz |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of neurophysiology Volume: 71 ISSN: 0022-3077 ISO Abbreviation: J. Neurophysiol. Publication Date: 1994 May |
Date Detail:
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Created Date: 1994-09-20 Completed Date: 1994-09-20 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0375404 Medline TA: J Neurophysiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1907-16 Citation Subset: IM; S |
Affiliation:
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Max-Planck-Institut für biologische Kybernetik, Tübingen, Germany. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Attention / physiology* Auditory Pathways / physiology Birds / physiology* Brain Mapping Evoked Potentials, Auditory / physiology Loudness Perception / physiology* Mesencephalon / physiology* Motion Perception / physiology* Neurons / physiology Orientation / physiology* Predatory Behavior / physiology Sound Localization / physiology* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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