The L3 Neuron and an Associated Prothoracic Network are Involved in Calling Song Recognition by Female Crickets

In young virgin Acheta domesticus females, the spiking response of the prothoracic L3 auditory interneuron discriminates between calling songs (CSs) with phonotactically attractive and unattractive syllable periods (SPs), which parallels phonotactic discrimination. Presentation of a CS with an originally attractive SP, but with the intensity modulated so as to minimize L3\u27s selective response, results in a CS with little phonotactic attractiveness. Conversely, a CS with an originally unattractive SP becomes much more attractive when the CS is intensity modulated in ways that duplicate L3\u27s selective response. L3\u27s discriminatory response to CS SP deteriorates with age, in parallel with decreased phonotactic selectiveness (females, older than 14 days, typically are unselective for CS SPs). SP-selective processing, which was not apparent in these old L3s, is immediately restored by removing the contralateral ear. SP-specific information is resident in a network of neurons within the prothoracic ganglion that results in the SP selective responses of the L3 neuron in young females. Changes in the SP-selective responses of the L3 neuron are highly correlated with corresponding changes in the female\u27s phonotactically selective behavior

Prolonged Response to Calling Songs by the L3 Auditory Interneuron in Female Crickets (Acheta domesticus): Possible Roles in Regulating Phonotactic Threshold and Selectiveness for Call Carrier Frequency

L3, an auditory interneuron in the prothoracic ganglion of female crickets (Acheta domesticus) exhibited two kinds of responses to models of the male\u27s calling song (CS): a previously described, phasically encoded immediate response; a more tonically encoded prolonged response. The onset of the prolonged response required 3-8 sec of stimulation to reach its maximum spiking rate and 6-20 sec to decay once the calling song ceased. It did not encode the syllables of the chirp. The prolonged response was sharply selective for the 4-5 kHz carrier frequency of the male\u27s calling songs and its threshold tuning matched the threshold tuning of phonotaxis, while the immediate response of the same neuron was broadly tuned to a wide range of carrier frequencies. The thresholds for the prolonged response covaried with the changing phonotactic thresholds of 2- and 5-day-old females. Treatment of females with juvenile hormone reduced the thresholds for both phonotaxis and the prolonged response by equivalent amounts. Of the 3 types of responses to CSs provided by the ascending L1 and L3 auditory interneurons, the threshold for L3\u27s prolonged response, on average, best matched the same females phonotactic threshold. The prolonged response was stimulated by inputs from both ears while L3\u27s immediate response was driven only from its axon-ipsilateral ear. The prolonged response was not selective for either the CS\u27s syllable period or chirp rate. © 2003 Wiley-Liss, Inc