D.N. LAPSHIN, D.D. VORONTSOV
DIRECTIONAL AND FREQUENCY CHARACTERISTICS OF AUDITORY NEURONS IN CULEX MALE MOSQUITOES
The paired auditory organ of mosquito, the Johnston's organ (JO),
being the receiver of particle velocity component of sound, is
directional by its structure. However, to date almost no physiological
measurements of its directionality was done. In addition, the recent
finding on the grouping of the JO auditory neurons into the antiphase
pairs demanded confirmation by different methods. Using the vector
superposition of the signals produced by two orthogonally oriented
speakers, we measured the directional characteristics of individual units
as well as their relations in physiologically distinguishable groups – pairs
or triplets. The feedback stimulation method allowed to discriminate
responses of the two simultaneously recorded units, and to show that
they indeed responded in antiphase. Units of different frequency tuning
as well as high-sensitive units (thresholds of 27 dB SPVL and below)
were found in every angular sector of the JO, providing the mosquito
with the ability to produce complex auditory behaviors.
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