| Autor: |
Francisco García-Rosales, Manfred Kössl, M. Jerome Beetz, Julio C. Hechavarría, Sebastian Kordes |
| Rok vydání: |
2017 |
| Předmět: |
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| Zdroj: |
eneuro. 4:ENEURO.0314-17.2017 |
| ISSN: |
2373-2822 |
| Popis: |
For the purpose of orientation, echolocating bats emit highly repetitive and spatially directed sonar calls. Echoes arising from call reflections are used to create an acoustic image of the environment. The inferior colliculus (IC) represents an important auditory stage for initial processing of echolocation signals. The present study addresses the following questions: i) How does the temporal context of an echolocation sequence mimicking an approach flight of an animal affect neuronal processing of distance information to echo delays? ii) How does the IC process complex echolocation sequences containing echo information from multiple objects (multi-object sequence)? Here we conducted neurophysiological recordings from the IC of ketamine-anaesthetized bats of the species Carollia perspicillata and compared the results from the IC with the ones from the auditory cortex. Neuronal responses to an echolocation sequence was suppressed when compared to the responses to temporally isolated and randomized segments of the sequence. The neuronal suppression was weaker in the IC than in the AC. In contrast to the cortex, the time course of the acoustic events is reflected by IC activity. In the IC, suppression sharpens the neuronal tuning to specific call-echo elements and increases the signal-to-noise ratio in the units’ responses. When presenting multiple-object sequences, despite collicular suppression, the neurons responded to each object-specific echo. The latter allows parallel processing of multiple echolocation streams at the IC level. Altogether, our data suggests that temporally-precise neuronal responses in the IC could allow fast and parallel processing of multiple acoustic streams. Significance Statement High stimulus rates usually result in a reduction of neuronal responses that can be described as suppression or adaptation. It remains unclear how neuronal suppression influences sensory processing in animals that rely on high stimulus rates, as it is the case of bats. The present study investigates how natural echolocation sequences are processed in the bat’s inferior colliculus. We report that collicular suppression enhances the signal-to-noise ratio of the spiking activity without degrading the temporal processing of echolocation sequences. Collicular suppression allows for a high tracking ability of the stimulus envelope and for the parallel processing of multiple auditory streams. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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