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Humboldt-Universitaet zu Berlin - Collaborative Research Center for Theoretical Biology

Processing of highly relevant acoustic signals by a sensory system – physiological basis and evolutionary constraints of neuronal feature extraction

How can a relatively small nervous system process and discriminate fine temporal patterns of acoustic signals, and how can it attain a high overall reliability in spite of its unreliable components? We investigate these questions using the acoustic communication of grasshoppers as a model system. In this system, the processing of sensory inputs and the behavioural output are directly connected since the processing of communication signals (“songs”) serves to initiate the meeting of sexual partners and reproduction. A particularly relevant property of this system in the context of the goals of this SFB is its remarkable robustness against various kinds of signal degradation as well as against a “time warp” of the signals. Such temporal compressions or expansions of the signals occur regularly if the temperature of these heterothermic animals changes, and may impede signal recognition.

For the next funding period, we plan to strengthen the link between signal processing and behaviour and hence focus on properties of grasshopper songs that are particularly attractive, i.e. those properties where acoustic pattern recognition has immediate behavioural consequences. (i) On the behavioural level, we aim at identifying the song features that mediate song attractiveness. We will ask whether specific song features can be related to certain morphological characteristics and perhaps signal the condition of a male. We will also test the hypothesis that behaviourally attractive properties convey a particular robustness against ambient noise. (ii) On the neuronal and modelling level, we will ask how song attractiveness is encoded in the auditory pathway, how it can be read out from the spike trains of auditory neurones, and how properties of the neuronal machinery may have evolved to support the extraction of this information. These questions will be tackled in a tight combination of neurophysiological recordings, modelling approaches, and behavioural experiments. We will exploit a particular advantage of our model system: its potential to directly check hypotheses derived from modelling and electrophysiology in the behaving animal. With these approaches we aim at bridging the gaps between neuronal signal processing, sexual selection, and sensory ecology.

description of the 1st period german version
description of the 2nd period