Moth auditory system
Moth auditory system is a favorite model for neurobiologists. Starting from excellent experiments of Kenneth Roeder and Asher Treat in fifties (Roeder,Treat, 1957; Roeder, 1966), a large amount of data about different moths and their ears has been gathered. Their ears are among the most well-studied in animal kingdom.
Here is a brief description of its morphology and neuronal properties.
Overwhelming majority of research was devoted to the perception of bat cries. The overall sensitivity was measured and the neuronal responses which caused a moth to turn and fly directly away from the source of ultrasound were studied (Roeder and Treat, 1961; Roeder, 1962; Fullard, 1998).
But, from the echolocation point of view, the knowledge of overall sensitivity is far from being enough. Moreover, the existing data on auditory responses recorded from the receptor cell axons gave the moth's ear no chance to be used as a detector of an echo from the nearby objects because of its insufficient temporal resolution.
Nevertheless, assuming that noctuid moth do echolocate, we can list the most important parameters of their auditory system which set the limits for the echolocator. Through our studies, we have determined these parameters one by one. Now it has become clear that the auditory system of noctuid moths is quite sophisticated in function compared to its rather simple structure and that it could be successfully used as an echo detector for the short-range echolocator.
Below the links you can find detailed descriptions of our studies aimed to answer each of the questions.
1. Sensitivity to the short clicks similar to the probing signals of a moth. Sensitivity determines the maximal distance where the obstacle could be reliably detected by means of echolocation.
2. Temporal resolution of an ear, which gives the ability to distinguish between the own click and the following echo. The echo in its turn could consist of several components reflected from objects situated at different distances. Temporal resolution determines the minimal distance at which the echolocator is still effective.
3. Frequency tuning and spectral resolution. The complex temporal structure of an echo could lead to a frequency shift from the initial probing signal spectrum. The auditory system must not be too sensitive to the distortions of that kind.
And, additionally, the function of the mysterious B cell from the ear of a moth was understood - this neuron turned out to play an important role in echolocation.