Meckenhäuser Gundula, Krämer Stefanie, Farkhooi Farzad, Ronacher Bernhard, Nawrot Martin P
Neuroinformatics and Theoretical Neuroscience, Department of Biology, Chemistry and Pharmacy, Institute of Biology, Freie Universität Berlin Berlin, Germany.
Behavioural Physiology Group, Department of Biology, Humboldt-Universität zu Berlin Berlin, Germany.
Front Syst Neurosci. 2014 Dec 19;8:183. doi: 10.3389/fnsys.2014.00183. eCollection 2014.
Acoustic communication plays a key role for mate attraction in grasshoppers. Males use songs to advertise themselves to females. Females evaluate the song pattern, a repetitive structure of sound syllables separated by short pauses, to recognize a conspecific male and as proxy to its fitness. In their natural habitat females often receive songs with degraded temporal structure. Perturbations may, for example, result from the overlap with other songs. We studied the response behavior of females to songs that show different signal degradations. A perturbation of an otherwise attractive song at later positions in the syllable diminished the behavioral response, whereas the same perturbation at the onset of a syllable did not affect song attractiveness. We applied naïve Bayes classifiers to the spike trains of identified neurons in the auditory pathway to explore how sensory evidence about the acoustic stimulus and its attractiveness is represented in the neuronal responses. We find that populations of three or more neurons were sufficient to reliably decode the acoustic stimulus and to predict its behavioral relevance from the single-trial integrated firing rate. A simple model of decision making simulates the female response behavior. It computes for each syllable the likelihood for the presence of an attractive song pattern as evidenced by the population firing rate. Integration across syllables allows the likelihood to reach a decision threshold and to elicit the behavioral response. The close match between model performance and animal behavior shows that a spike rate code is sufficient to enable song pattern recognition.
声学通讯在蚱蜢的配偶吸引中起着关键作用。雄性通过歌声向雌性宣传自己。雌性通过评估歌曲模式（一种由短暂停顿隔开的重复声音音节结构）来识别同种雄性，并以此作为其健康状况的指标。在它们的自然栖息地中，雌性经常接收到时间结构退化的歌曲。例如，干扰可能是由于与其他歌曲重叠造成的。我们研究了雌性对显示不同信号退化的歌曲的反应行为。在音节后期位置对原本有吸引力的歌曲进行干扰会降低行为反应，而在音节开始时进行相同的干扰则不会影响歌曲的吸引力。我们将朴素贝叶斯分类器应用于听觉通路中已识别神经元的尖峰序列，以探索关于声学刺激及其吸引力的感官证据在神经元反应中是如何呈现的。我们发现，三个或更多神经元的群体足以可靠地解码声学刺激，并根据单次试验的整合放电率预测其行为相关性。一个简单的决策模型模拟了雌性的反应行为。它根据群体放电率计算每个音节出现有吸引力歌曲模式的可能性。跨音节的整合使可能性达到决策阈值并引发行为反应。模型性能与动物行为之间的紧密匹配表明，放电率编码足以实现歌曲模式识别。
