5 nA) in the dendrite of the neuron triggered enduring singing activity with the normal chirp pattern. During the first chirps of a singing episode, its overall membrane potential slowly hyperpolarized and after singing stopped it repolarized within 3–5 sec to the resting potential. During singing, the neuron hyperpolarized by 5–10 mV in phase with the opener-motoneuron activity and depolarized by 10–15 mV in phase with the closer motoneurons. Each depolarization gave rise to a burst of 2–4 action potentials starting 9.3 ± 0.9 msec (mean ± SD; N = 1, n = 50) after the beginning of the wing-opener activity and 14.3 ± 0.9 msec (mean ± SD; N = 1, n = 50) before the wing-closer activity, Inhibitors,research,lifescience,medical which

is 4–6 msec earlier than the closer neurons we recorded in the abdominal neuromeres of the Inhibitors,research,lifescience,medical metathoracic ganglion. Discussion The neural basis of cricket singing has been repeatedly the subject of neurobiological studies (reviews: Kutsch and Huber 1989; Elsner 1994; Gerhardt and Huber 2002). Here, we intracellularly recorded and stained interneurons of the singing network and demonstrated

their impact on singing pattern generation by intracellular current injection. Motor pattern of fictive singing After cutting all wing nerves, fictive singing was evoked by microinjection of eserine in the brain neuropiles housing Inhibitors,research,lifescience,medical the dendrites of the descending calling song command neurons (Hedwig 2000). With a syllable cycle of 21–26 Hz and a chirp cycle of 2.3–2.9 Hz, the fictive singing motor pattern precisely matched the temporal characteristics of the natural calling song (Doherty 1985; Verburgt Inhibitors,research,lifescience,medical et al. 2011). Even minute details like the gradual decrease in the instantaneous syllable rate within the chirps and the constant temporal coupling between wing-opener and wing-closer activity (Kutsch 1969) remained unchanged after deafferentation. This clearly demonstrates that in contrast to locomotory pattern generators (Pearson 1995; Ausborn et al. 2007; Büschges and Gruhn 2008), the cricket singing CPG operates independent of sensory feedback

to produce a characteristic and Inhibitors,research,lifescience,medical highly stable motor pattern, as required for species-specific signaling. Also in intact crickets, the circuitry of the singing network dictates the temporal pattern of the calling song, whereas mechanosensory feedback merely adjusts the precise angular position Bumetanide and closing velocity of the Compound Library chemical structure moving wings (Möss 1971; Elliott 1983; Schäffner and Koch 1987) to ensure a proper engaging force for sound production (Elliott and Koch 1983). Organization of the singing network All singing interneurons we identified exhibited characteristic arborizations in the dorsal midline neuropiles of the fused metathoracic and first unfused abdominal ganglion (Fig. 10; Table 1). Likewise, previously identified singing interneurons had dendrites projecting posteriorly along the midline of the metathoracic ganglion complex (Hennig 1990).