Plurisegmental neurones of the cricket Gryllus campestris L. that discharge in the rhythm of its own song

Male crickets (Gryllus campestris L.) mounted so that their wings and abdomen could move freely were induced to stridulate by brain lesion. During the song the activity of single neurones was recorded extracellularly in a cervical connective. Nine distinct spike patterns were observed. Patterns I and II tend to copy the chirp as a whole rather than the onset of the syllables (the recorded potentials of the wing-opener muscle M99 marked the syllable onset). The other patterns reflect the syllabic structure. Each, in its own way, marks the various syllables with different numbers of spikes. The delay of the spike response is different for each pattern. Some patterns, but not others, also reflect the beginning or end of the song, or the abdominal expiratory activity. One neurone also responds in correlation with muscle discharges typical of the courtship song. In some of the patterns it is evident that there is a stronger correlation with the closer muscle (M90) discharge than with the opener muscle discharge. Activation by auditory self-stimulation by way of the tympanal organs can be ruled out for all patterns. It is possible that patterns I–V are induced by afferent activity coupled to the wing movement. Patterns VI–VIII are probably copies of motor signals ascending from the thoracic song-pattern generators to the head ganglia. It is evident that the head ganglia have detailed information as to the motor output for stridulation and abdominal expiration.