Selective processing of calling songs by auditory interneurons in the female cricket, Gryllus pennsylvanicus: possible roles in behavior

Female crickets (Gryllus pennsylvanicus), caught in the field as nymphs, responded as adults in the laboratory with selective phonotaxis to model calling songs (CSs) that reproduced the dominant carrier frequencies and syllable periods (SPs) characteristic of the male's natural calling song. Extracellular recordings demonstrated two types of auditory interneurons in the female's cervical connectives that were very similar to the AN1 and AN2 neurons previously described in other gryllid species. The AN2 neuron responded to model CSs with a phasically encoded immediate response, and a more tonically encoded prolonged response. AN2's immediate response exhibited SP-dependent decreases (termed decrement) in its responses to sequential syllables of the CS that were greatest to CSs with the shortest SPs and diminished as SPs were lengthened, resulting in an SP-dependent habituation. Picrotoxin application transformed this SP-dependent habituation by AN2 to SP-selective responses in which the degree of decrement was greatest to SPs that were most phonotactically attractive. AN2's prolonged response was most sensitive to 5 kHz CSs and correlated with the carrier frequency tuning for the thresholds of phonotaxis by females. Thus, in females, AN2's immediate (in the presence of picrotoxin) and prolonged responses were selectively tuned to the SPs and carrier frequencies of the male's calls that were most attractive behaviorally. AN1's responses at threshold were also tuned to the dominant carrier frequencies of the male's CS.     

Phonotaxis in flying crickets

The effects of two-tone stimuli on the high frequency bat-avoidance steering behavior of flying crickets (Teleogryllus oceanicus) were studied during tethered flight. Similarly, the effects of two-tone stimuli on the ultrasound sensitive auditory interneuron, Int-1, which elicits this behavior, were studied using intracellular staining and recording techniques. When a low frequency tone (3-8 kHz) was presented simultaneously with an aversive high frequency tone (in a two-tone stimulus paradigm), the high frequency avoidance steering behavior was suppressed. Suppression was optimal when the low frequency tone was between 4 and 5 kHz and about 10-15 dB louder than the high frequency tone (Figs. 2, 3). Best suppression occurred when the low frequency tone-pulse just preceded or overlapped the high frequency tone-pulse, indicating that the suppressive effects of 5 kHz could last for up to 70 ms (Fig. 4). The threshold for avoidance of the bat-like stimulus was elevated when model bat biosonar (30 kHz) was presented while the animal was performing positive phonotaxis toward 5 kHz model calling song, but only if the calling song intensity was relatively high (greater than 70-80 dB SPL) (Fig. 1). However, avoidance steering could always be elicited as long as the calling song was not more than 10 dB louder than the ultrasound (Fig. 1). This suppressive effect did not require performance of positive phonotaxis to the calling song (Fig. 2) and was probably due to the persistence of the suppressive effects of the 5 kHz model calling song (Fig. 4). The requirement for relatively high intensities of calling song suggest that the suppression of bat-avoidance by the calling song is not likely to be of great significance in nature. The high frequency harmonics of the male cricket's natural calling song overlap the lower frequency range used by insectivorous bats (10-20 kHz) and are loud enough to elicit avoidance behavior in a flying female as she closely approaches a singing male (Fig. 5). The high frequency 'harmonics' of a model calling song were aversive even if presented with a normally attractive temporal pattern (pulse repetition rate of 16 pps) (Fig. 6A). When the 5 kHz 'fundamental' was added to one of the high frequency 'harmonics', in a two-tone stimulus paradigm, this complex model calling song was attractive; the high frequency 'harmonic' no longer elicited the avoidance behavior (Fig. 6) and the animals steered toward the model CS. Thus, addition of 5 kHz to a high frequency harmonic of the calling song 'masked' the aversive nature of this stimulus.(ABSTRACT TRUNCATED AT 400 WORDS)     

Acoustic communication in Okanagana rimosa (Say) (Homoptera: Cicadidae)

The cicada Okanagana rimosa (Say) has an acoustic communication system with three types of loud timbal sounds: (i) A calling song lasting several seconds to about 1 min which consists of a sequence of chirps at a repetition rate of 83 chirps per second. Each chirp of about 6 ms duration contains 4-5 pulses. The sound level of the calling song is 87-90 dB SPL at a distance of 15 cm. (ii) An amplitude modulated courtship song with increasing amplitude and repetition rate of chirps and pulses. (iii) A protest squawk with irregular chirp and pulse structure. The spectra of all three types are similar and show main energy peaks at 8-10 kHz. Only males sing, and calling song production is influenced by the songs of other males, resulting in an almost continuous sound in dense populations. In such populations, the calling songs overlap and the temporal structure of individual songs is obscured within the habitat. The calling song of the broadly sympatric, closely related species O. canadensis (Provander) is similar in frequency content, but distinct in the temporal pattern (24 chirps per second, 24 ms chirp duration, eight pulses per chirp) which is likely important for species separation in sympatric populations. The hearing threshold of the auditory nerve is similar for females and males of O. rimosa and most sensitive at 4-5 kHz. Experiments in the field show that female phonotaxis of O. rimosa depends on parameters of the calling song. Most females are attracted to calling song models with a 9 kHz carrier frequency (peak frequency of the calling song), but not to models with a 5 kHz carrier frequency (minimum hearing threshold). Phonotaxis depends on temporal parameters of the conspecific song, especially chirp repetition rate. Calling song production is influenced by environmental factors, and likelihood to sing increases with temperature and brightness of the sky. Correspondingly, females perform phonotaxis most often during sunny conditions with temperatures above 22 degrees C. Non-mated and mated females are attracted by the acoustic signals, and the percentage of mated females performing phonotaxis increases during the season.     

Response properties of the prothoracic AN2 auditory interneurone to model calling songs in the cricket Gryllus bimaculatus

Sound processing properties for calling song (CS) models, as described for the prothoracic L3 auditory neurone in Acheta domesticus, are investigated for the homologous auditory neurone 2 (AN2) in female Gryllus bimaculatus De Geer. AN2 of G. bimaculatus responds selectively to the syllable period (SP) of models of a male CS. The selectiveness of this response parallels the selectivity of phonotaxis females perform in response to the same SPs. Both, the responses of AN2 and female behaviour show clear interindividual variability. The SP‐selective responses of AN2 result from an SP‐dependent reduction in the spiking to subsequent syllables of the model CSs, measured as the percentage decrement. This SP‐dependent response does not primarily result from inbuilt properties of the AN2 membrane. Rather, it is dependent on inhibitory input to the AN2. However, clear inhibitory postsynaptic potentials in dendritic recordings of the AN2 are not encountered. This immediate response of AN2 to CSs is followed by an increased rate of tonic firing between stimulus CSs, which is termed the prolonged response, and is dependent on the carrier frequencies that make up the male CSs. With stimulation on the contralateral side of the soma of AN2s, more than 50% of AN2s exhibit a prolonged response. However, with stimulation from the ipsilateral side of the soma, most AN2s exhibit a prolonged response. The prolonged response of AN2 at 5 kHz may be even more sensitive than the immediate response. Thus, the AN2 neurone could provide a basis for phonotaxis that is selective for both the SPs and the carrier frequencies of potentially attractive calling songs.     

Temporal pattern changes in the calling song of the katydidMygalopsis marki Bailey in response to conspecific song (Orthoptera: Tettigoniidae)

Males of Mygalopsis markiBailey (Tettigoniidae: Orthoptera) alter the temporal structure of their song in response to other competing males. The song of males calling in aggregations has a high variance in the number of syllables per chirp, with short intervals between each chirp. In contrast, the temporal pattern of the song of isolated males is more evenly spaced, with an increase in length of the interchirp intervals and low variance in the number of syllables per chirp. In order to simulate a calling male moving closer to a male in an aggregation, a playback technique was adopted whereby the recorded calling song of a male was presented to itself via a loudspeaker in increments of 2dB. The change in song pattern of the resident male involved a reduction in the number of syllables per chirp and an increase in the interchirp interval, with the number of chirps per second remaining constant. This reduction in the output of the song, instead of not calling as a result of an acoustic contest, may still allow males to continue calling for females.     

Frequency and temporal pattern-dependent phonotaxis of crickets (Teleogryllus oceanicus) during tethered flight and compensated walking

Summary Phonotactic responses ofTeleogryllus oceanicus were studied with two methods. Tethered crickets were stimulated with sound while they performed stationary flight, and steering responses were indicated by abdominal movements. Walking crickets tracked a sound source while their translational movements were compensated by a spherical treadmill, and their walking direction and velocity were recorded.During both flight and walking, crickets attempted to locomote towards the sound source when a song model with 5 kHz carrier frequency was broadcast (positive phonotactic response) and away from the source when a song model with 33 kHz carrier frequency was used (negative phonotactic response) (Figs. 2, 4).One-eared crickets attempted, while flying, to steer towards the side of the remaining ear when stimulated with the 5 kHz model, and away from that side in response to the 33 kHz model (Fig. 3). While walking, one-eared crickets circled towards and away from the intact side in response to the 5 kHz and 33 kHz models, respectively (Fig. 6).Positive and negative responses differed in their temporal pattern requirements. Phonotactic responses were not elicited when a non-calling song pattern (2 pulses/s) was played with a carrier frequency appropriate for positive phonotactic responses (5 kHz), but this pattern did elicit negative responses with 33 kHz carrier frequency (Figs. 7–10). When an intermediate carrier frequency, 15 kHz, was used, the response type (positive or negative) depended on the stimulus temporal pattern; the calling song pattern elicited primarily positive responses, while the non-calling song pattern elicited negative responses (Figs. 11, 12, 14, 15). A curious phenomenon was often observed in the flight steering responses; while most responses to 15 kHz song pattern were primarily positive, they often had an initial negative component which was supplanted by the positive component of the response after approximately 2–5 s (Figs. 11, 12).In recent experiments onGryllus campestris, Thorson et al. (1982) described frequency-dependent errors in phonotactic direction (anomalous phonotaxis) and showed how such errors might arise from the frequency-dependent directional properties of the cricket's auditory apparatus. Our findings, particularly the dependence of response type on temporal pattern when 15 kHz carrier frequency was used, argue that frequency-dependent directional properties alone cannot account for positive and negative phonotaxis inT. oceanicus. Rather, these represent qualitatively different attempts to locomote towards and away from the sound source, respectively.We discuss the possibility that central integration of these opposing tendencies might contribute to anomalous phonotaxis.     

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's 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's 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's prolonged response, on average, best matched the same females phonotactic threshold. The prolonged response was stimulated by inputs from both ears while L3's immediate response was driven only from its axon-ipsilateral ear. The prolonged response was not selective for either the CS's syllable period or chirp rate.     

Phonotaxis in flying crickets

The steering responses of three species of field crickets, Teleogryllus oceanicus, T. commodus, and Gryllus bimaculatus, were characterized during tethered flight using single tone-pulses (rather than model calling song) presented at carrier frequencies from 3-100 kHz. This range of frequencies encompasses the natural songs of crickets (4-20 kHz, Fig. 1) as well as the echolocation cries of insectivorous bats (12-100 kHz). The single-pulse stimulus paradigm was necessary to assess the aversive nature of high carrier frequencies without introducing complications due to the attractive properties of repeated pulse stimuli such as model calling songs. Unlike the natural calling song, single tone-pulses were not attractive and did not elicit positive phonotactic steering even when presented at the calling song carrier frequency (Figs. 2, 3, and 9). In addition to temporal pattern, phonotactic steering was sensitive to carrier frequency as well as sound intensity. Three discrete flight steering behaviors positive phonotaxis, negative phonotaxis and evasion, were elicited by appropriate combinations of frequency, temporal pattern and sound intensity (Fig. 12). Positive phonotactic steering required a model calling song temporal pattern, was tuned to 5 kHz and was restricted to frequencies below 9 kHz. Negative phonotactic steering, similar to the 'early warning' bat-avoidance behavior of moths, was produced by low intensity (55 dB SPL) tone-pulses at frequencies between 12 and 100 kHz (Figs. 2, 3, and 9). In contrast to model calling song, single tone-pulses of high intensity 5-10 kHz elicited negative phonotactic steering; low intensity ultrasound (20-100 kHz) produced only negative phonotactic steering, regardless of pulse repetition pattern. 'Evasive', side-to-side steering, similar to the 'last-chance' bat-evasion behavior of moths was produced in response to high intensity (greater than 90 dB) ultrasound (20-100 kHz). Since the demonstration of negative phonotactic steering did not require the use of a calling song temporal pattern, avoidance of ultrasound cannot be the result of systematic errors in localizing an inherently attractive stimulus when presented at high carrier frequencies. Unlike attraction to model calling song, the ultrasound-mediated steering responses were of short latency (25-35 ms) and were produced in an open loop manner (Fig. 4), both properties of escape behaviors.(ABSTRACT TRUNCATED AT 400 WORDS)     

Auditory pattern recognition and steering in the cricket Teleogryllus oceanicus

Male crickets Teleogryllus oceanicus (Le Guillou) produce a complex species‐specific calling song with phrases combining groups of single pulses (chirps) and groups of double‐pulses (trills) to attract females, which fly or walk towards singing males. In open‐loop trackball experiments, phonotactic steering responses to normal calling song phrases consisting of chirps and trills are strongest, suggesting that both components are necessary for maximal attractiveness. Sequences of just chirps or trills are less effective in eliciting phonotactic walking and steering. Split‐song paradigms are used to analyze the steering behaviour underlying orientation in more detail. The females' phonotactic steering reflects the alternating acoustic pattern of the split‐song paradigm. Analysis with high temporal resolution demonstrate, that even when the calling song is presented only from one side, the steering velocity and lateral deviation towards the song is modulated by steering events to single‐sound pulses. Therefore, pattern recognition, which integrates the structure of the song, appears not to be directly involved in the rapid steering response. This organization of phonotactic behaviour with a parallel processing of pattern recognition and steering is similar to other cricket species and may allow T. oceanicus females to steer transiently towards distorted song patterns as they occur in natural habitats.     

Auditory behaviour of a parasitoid fly (Emblemasoma auditrix, Sarcophagidae, Diptera)

Females of the parasitoid fly Emblemasoma auditrix find their host cicada (Okanagana rimosa) by its acoustic signals. In laboratory experiments, fly phonotaxis had a mean threshold of about 66 dB SPL when tested with the cicada calling song. Flies exhibited a frequency dependent phonotaxis when testing to song models with different carrier frequencies (pulses of 6 ms duration and a repetition rate of 80 pulses s(-1)). However, the phonotactic threshold was rather broadly tuned in the range from 5 kHz to 11 kHz. Phonotaxis was also dependent on the temporal parameters of the song models: repetition rates of 60 pulses s(-1) and 80 pulses s and pulse durations of 5-7 ms resulted in the highest percentages of phonotaxis performing animals coupled with the lowest threshold values. Thus, parasitoid phonotaxis is adapted especially to the temporal parameters of the calling song of the host. Choice experiments revealed a preference of a song model with 9 kHz carrier frequency (peak energy of the host song) compared with 5 kHz carrier frequency (electrophysiologically determined best hearing frequency). However, this preference changed with the relative sound pressure level of both signals. When presented simultaneously, E. auditrix preferred 5-kHz signals, if they were 5 dB SPL louder than the 9-kHz signal.     

Behavioral response ofGraminella nigrifrons (Homoptera: Cicadellidae) to experimentally manipulated vibrational signals

Mate recognition for the leafhopper Graminella nigrifrons(Forbes) occurs when a male spontaneously emits a multisectional vibrational calling song to which females respond by emitting simple pulses. Significant differences were found among males in the duration, number of chirps, and chirp rate within sections of the song and the total song. Repeatability (proportion of total variation due to differences among males) of call features ranged from very low (0.04 for total chirps in song) to high (0.67 for section 3 chirp rate). However, song modification and playback experiments revealed that the variation in the measured song features was not important in determining whether a female will respond. Rather, female response depended only on the presence of two of the three types of pulses which comprise a chirp. These essential pulses were found within chirps of all call sections that contain chirps. Manipulation of chirp rates from 0.58 to 2.70 times the normal rate did not affect female response, nor did changing the period of silence between the essential pulse types from 0.25 to 1.75 times the normal period. These results suggest that components of the male calling song function in mate recognition but are not used by females to discriminate among conspecific males.     

Frequency as a releaser in the courtship song of two crickets,Gryllus bimaculatus (de Geer) and Teleogryllus oceanicus: a neuroethological analysis

1. The courtship behavior of male field crickets, Gryllus bimaculatus (De Geer) and Teleogryllus oceanicus, is a complex, multimodal behavioral act that involves acoustic signals (a courtship song; Fig. 1A,B). The dominant frequency is 4.5 kHz for T. oceanicus song (Fig. 1A) and 13.5 kHz for G. bimaculatus (Fig. IB).
2. When courting males are deprived of their courtship song by wing amputation, their courtship success declines markedly but is restored when courting is accompanied by tape-recordings of their courtship songs or a synthetic courtship song with only the dominant frequency of the natural song; other naturally occurring frequency components are ineffective for restoring mating success (Figs. 4, 5).
3. It has been suggested that an identified auditory interneuron, AN2, plays a critical role in courtship success. Chronic recordings of AN2 in an intact, tethered female show that AN2's response to the natural courtship song and synthesized songs at 4.5 and 13.5 kHz is similar in T. oceanicus. By contrast, in G. bimaculatus, AN2's response to the natural courtship song and synthesized song at 13.5 kHz, but not at 4.5 kHz, is similar (Figs. 2,3).
4. In behavioral experiments, playback of a 30 kHz synthetic courtship song in G. bimaculatus does not restore courtship success, yet this same stimulus elicits as strong a response from AN2 as does the normal courtship song (Fig. 6). Thus, contrary to earlier work by others, we conclude AN2 is not, by itself, a critical neural link in the courtship behavior of these two species of crickets.

     

Processing of Song Signals in the Cricket and its Hormonal Control

SYNOPSIS. Phonotaxis by female crickets to the calling songof males, is an important model for investigating the neuralbasis of auditory behavior. Recent advances make it possibleto explain some components of this behavior and its hormonalcontrol, at the level of identified neurons and molecular expressionwithin those neurons Tonotopically arranged afferents from the cricket's ear, projectto local and intersegmental prothoracic interneurons. Bilateralprocessing of signals and some temporal-pattern specific processingoccurs in the prothoracic ganglion and influences acoustic informationthat is sent to the brain via ascending interneurons that aredemonstrably involved in phonotaxis. High, low and band- passinterneurons in the brain continue temporal pattern processingwhich matches the selectivity of phonotaxis and may be filtersfor recognition of the calling song. Neurons descending fromthe brain and prothoracic ganglion, direct multimodal signals(including auditory) to more posterior regions, possibly theleg motor neurons that are responsible for phonotaxis Age-related changes or artificially induced changes in JuvenileHormone III levels regulate the threshold for phonotaxis inAcheta domesticus, by varying the threshold of LI, a prothoracicascending interneuron that is necessary for phonotaxis to lowintensity calling songs. Results from in situ hybridizationsuggest that this might be accomplished, in part, by controllingthe levels of nicotinic acetylcholine receptor-like mRNA expressedin LI, presumably by increasing its neurotransmitter receptordensity. L3 is a prothoracic ascending interneuron that exhibitsbandselective response properties to the syllable period ofthe calling song. L3's response is age and JHIII related, andis correlated to phonotactic selectivity. These changes in L3might be accomplished, at least in part by JHIII regulatingthe expression of nicotinic acetylcholine receptor-like mRNAin L3     

Auditory interneurons in locusts produce directional head and abdomen movements

Locusts (Locusta migratoria) were stimulated with pulses of pure tones of frequencies between 5 kHz and 25 kHz. Interneurons responding to these stimuli (auditory interneurons) were recorded intracellularly and identified by dye injection. Their output functions were investigated by injection of depolarizing current during simultaneous registration of components of flight steering behavior of the animals, i.e. movements of the head and the abdomen and flight activity. Three different types of effects were found, corresponding to 3 functional classes of interneurons:

Response of the cercus-to-giant interneuron system in crickets to species-specific song

Summary In addition to their high frequency stridulatory sound, crickets (Gryllus campestris) also produce low frequency airborne vibrations resulting from the strokes of the crickets' wings closing and opening during stridulation. Giant interneurons of the ventral cord, which receive inputs from cereal hairs, respond to these low frequencly components of cricket song up to a distance of some ten cm. The discharges are correlated to the time course of the acoustic stimulation, therefore allowing the transmission of the time patterns (syllables, chirps) of calling song, rivalry song and even courtship song. With simultaneous recording from both sides of the abdominal nerve cord, synchronous or alternating discharges can be detected, correlated either with syllables or intervals. The response mode depends on the position of the two individuals in relation to each other. Recording directly from singing males demonstrates interneuron response to selfgenerated signals, too. A possible communicative function of the system is discussed.Supported by the Deutsche Forschungsgemeinschaft as part of the program Neurale Mechanismen des Verhaltens (Da 61/8, 61/9)We thank Dr. F. Huber and Dr. H. Scharstein for helpful comments.     

Responses and song pattern copying of Omega-type I-neurons in the cricket,Gryllus bimaculatus,at different prothoracic temperatures

Summary Omega-type I-neurons (ON/1) (Fig. 1A) were recorded intracellularly with the prothoracic ganglion kept at temperatures of either 8–9°, or 20–22° or 30–33 °C and the forelegs with the tympanal organs kept at ambient temperature (20–22 °C). The neurons were stimulated with synthetic calling songs (5 kHz carrier frequency) with syllable periods (SP in ms) varying between 20 and 100, presented at sound intensities between 40 and 80 dB SPL. The amplitude and duration of spikes as well as response latency decreased at higher temperatures (Figs. 1 B, 2, 6). At lower prothoracic temperatures (8–9 °C) the neuron's responses to songs with short SP (20 ms) failed to copy single syllables, or with moderate SP (40 ms) copied the syllable with low signal to noise ratio (Fig. 3). The auditory threshold of the ON/1 type neuron, when tested with the song model, was temperature-dependent. At 9° and 20 °C it was between 40 and 50 dB SPL and at 33 °C it was less than 40 dB SPL (Fig. 4). For each SP, the slope of the intensity-response function was positively correlated with temperature, however, at low prothoracic temperatures the slope was lower for songs with shorter SPs (Fig. 5). The poor copying of the syllabic structure of the songs with short SPs at low prothoracic temperatures finds a behavioral correlate because females when tested for phonotaxis on a walking compensator responded best to songs with longer SPs at a similar temperature.Abbreviations epsps excitatory postsynaptic potentials - ON/1 omega-type I-neuron - SP syllable period - SPL sound pressure level     

Sexual differences in cricket calling song recognition

Summary Phonotactic behavior was studied in male crickets,Teleogryllus oceanicus. Tethered flying males were presented with electronically synthesized calling song models in a two-choice phonotaxis assay, and their song preferences were determined and compared with previous findings for females.Males are poorer at discriminating between songs than females; they do not display choice behavior as frequently as females, and the choices they do make are not as consistent as those of females (Figs. 3, 4). T. oceanicus calling song is composed of rhythmically different chirp and trill sections. The selectivity of males for these two components differs from that of females. Females prefer chirp to trill, but the opposite is true for males (Fig. 5B-F). Males are similar to females in that they prefer either a conspecific song model or its separate components to a heterospecific model (Fig. 5A, G, H).Behavioral and neural implications of these findings are discussed.     

Female recognition of trills in the male calling song of the field cricket,<Emphasis Type="Italic"> Teleogryllus taiwanemma</Emphasis>

The calling song of the field cricket, Teleogryllus taiwanemma, is usually considered to consist of sequences of separate chirps. However, sometimes it comprises a phrase of several chirps in a row, with one long chirp (chirp) and a few short chirps (trills). In this study, I compared the phrase containing only chirps with that containing both chirps and trills by analyzing male songs and conducting playback experiments of male songs to females. The song analyses showed significant differences between chirps and trills for all song parameters except bandwidth. To test whether female preference differed with respect to the two phrases, I performed two-speaker playback experiments. When the same numbers of phrases were presented per unit time, females preferred the song with trills to that without trills. This result may reflect female preference for songs with greater sound density. In subsequent playback experiments, I equalized the total sound duration per unit time (duty cycle) in songs with and without trills. The numbers of females that preferred songs with and without trills did not differ significantly. This suggests that trills can attract females like chirps do, even though the two sounds have different components.     

Sound localisation in crickets

Intracellular recordings were made in the brain of the cricket Gryllus bimaculatus from an ascending auditory interneuron (AN1). Acoustic stimuli with calling song temporal pattern were delivered via earphones in a preparation with the acoustic trachea cut (attenuation of crossing sound > 30 dB). The input-output function of this cell was then determined by recording its responses to stimulation of the ipsilateral ear alone, of the contralateral ear alone and to stimulation of both ears simultaneously with the same or different carrier frequencies and intensities.This interneuron was excited by the ear ipsilateral to its axon and dendritic field and unresponsive to stimuli presented to the axon-contralateral ear alone. However, in binaural stimulation experiments, the response to a constant ipsilateral stimulus was progressively reduced as the intensity of a simultaneous contralateral stimulus was increased, above a threshold intensity.Tuning curves for threshold of this inhibition, determined in binaural stimulation experiments, indicated significant inhibition in the range 3–20 kHz with lowest threshold at 4–5 kHz. The inhibition was unaffected by sectioning of the contralateral circumoesophageal or neck connective, indicating that the inhibitory influence crosses the midline at the level of the prothoracic ganglion. Intracellular recordings from AN1 in the prothoracic ganglion confirmed that it was indeed neurally inhibited by inputs from the contralateral ear.Tuning curves for excitation of an omega neuron (ON1) by the ear ipsilateral to its soma and also the tuning of inhibition of ON1 by its contralateral ON1 partner, closely match the tuning of inhibition of AN1 and to a lesser extent, of AN2. This was taken as evidence that each AN1 is inhibited by the contralateral ON1. The significance of this interaction for directional hearing and phonotaxis is discussed.Abbreviations AP/CHP action potentials per chirp - AN1, AN2 ascending auditory interneurons 1, 2 - ON1 omega neuron 1 - ipsi ipsilateral contra contralateral - PTG prothoracic ganglion loc lateral ocellar nerve - On optic nerve an antennal nerve - coc circum-oesophageal connective so sound off     

Temperature coupling in cricket acoustic communication

Summary Temperature effects on calling song production and recognition were investigated in the North American field cricket, Gryllus firmus. Temporal parameters of field-recorded G. firmus calling song are strongly affected by temperature. Chirp rate and syllable rate increase, by factors of 4 and 2, respectively, as linear functions of temperature over the range in which these animals sing in the field (12°–30 °C). Temperature affects syllable duration to a lesser extent, and does not influence calling song carrier frequency. Female phonotactic preference, measured on a spherical treadmill in the laboratory, also changes with temperature such that warmer females prefer songs with faster chirp and syllable rates. Best phonotaxis, measured as accuracy of orientation to the sound source, and highest walking velocity, occur in response to temperature-matched songs at 15°, 21°, and 30 °C. Experiments under semi-natural conditions in an outdoor arena revealed that females perform phonotaxis at temperatures as low as 13 °C. Taken together, the song and phonotaxis data demonstrate that this communication system is temperature coupled. A strategy is outlined by which temperature coupling may be exploited to test hypotheses about the organization of neural networks subserving song recognition.Abbreviations CP chirp period - SP syllable period - SD syllable duration