A circuit for detection of interaural time differences in the nucleus laminaris of turtles.
| Autor: | Willis KL; University of Maryland, Department of Biology, Center for Comparative and Evolutionary Biology of Hearing, Neuroscience and Cognitive Science Graduate Program, College Park, MD 20742, USA kwillis@ou.edu., Carr CE; University of Maryland, Department of Biology, Center for Comparative and Evolutionary Biology of Hearing, Neuroscience and Cognitive Science Graduate Program, College Park, MD 20742, USA. |
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| Jazyk: | angličtina |
| Zdroj: | The Journal of experimental biology [J Exp Biol] 2017 Nov 15; Vol. 220 (Pt 22), pp. 4270-4281. Date of Electronic Publication: 2017 Sep 25. |
| DOI: | 10.1242/jeb.164145 |
| Abstrakt: | The physiological hearing range of turtles is approximately 50-1000 Hz, as determined by cochlear microphonics ( Wever and Vernon, 1956a). These low frequencies can constrain sound localization, particularly in red-eared slider turtles, which are freshwater turtles with small heads and isolated middle ears. To determine if these turtles were sensitive to interaural time differences (ITDs), we investigated the connections and physiology of their auditory brainstem nuclei. Tract tracing experiments showed that cranial nerve VIII bifurcated to terminate in the first-order nucleus magnocellularis (NM) and nucleus angularis (NA), and the NM projected bilaterally to the nucleus laminaris (NL). As the NL received inputs from each side, we developed an isolated head preparation to examine responses to binaural auditory stimulation. Magnocellularis and laminaris units responded to frequencies from 100 to 600 Hz, and phase-locked reliably to the auditory stimulus. Responses from the NL were binaural, and sensitive to ITD. Measures of characteristic delay revealed best ITDs around ±200 μs, and NL neurons typically had characteristic phases close to 0, consistent with binaural excitation. Thus, turtles encode ITDs within their physiological range, and their auditory brainstem nuclei have similar connections and cell types to other reptiles. Competing Interests: Competing interestsThe authors declare no competing or financial interests. (© 2017. Published by The Company of Biologists Ltd.) |
| Databáze: | MEDLINE |
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