Fig. 6.

Depolarizing current injection into A3-AO during inhibition elicited by air current stimulation. A: a 1,000-ms stimulus delivered to the cerci during the interchirp interval elicits an IPSP (*) and extends the interval. B: diagram of the putative cricket singing network. When singing, the central pattern generator (CPG) is excited (triangle) by the calling song brain command neuron (CN) and drives the motor neuron network (MN). Air stimulation of the cerci forwards an inhibition (circle) to the CPG. The cercal inhibition does not modulate the activity of the CN (1), but it may alter either the connection between the CN and CPG (2) or the connection between the CPG and MN network (3). C: a 20-ms air stimulus elicits inhibition in the opener interneuron. Injection of 100-ms, +5-nA depolarizing current pulse during the inhibition evokes rhythmic singing motor activity in A3-AO and the mesothoracic motoneurons. Vertical scale bars refer only to intracellular recording of A3-AO. D: application of a 1,000-ms air stimulus and injection of a 500-ms depolarizing current (+5 nA) during the stimulus-evoked IPSP (*) elicits rhythmic singing activity in A3-AO and the motoneurons of the wing nerve. Note that the Meso Nv3A recording also represents breathing motor activity. Vertical scale bars refer only to intracellular recording of A3-AO.