Table 2.

Morphological and electrophysiological properties of A4 and A7: criteria for reidentification

Cell nameAxon pathCell size (μm); colorElectrophysiologySpontaneous spike and PSPs activityActivity during avoidance turns induced by LOVN stimulation
RP (mV)SH (mV)SD (mS)
A4i-aCPC40–55;
translucent
−47.3  ± 3.280.6  ± 6.43.42–4 Hz (80%2-a), slow bursting2-b; IPSPs, <6 mV (85%)Only active (up to 14 Hz) to ipsilateral stimulus (note, in contrast, As1–4 are active to bilateral stimuli)
A7i-aCPC35–50;
translucent
−45.9  ± 4.573.4  ± 8.53.6Active at <6 Hz (60%); IPSPs, 1–7 mV (95%)Not active during turns, but active during withdrawal phase that occurs before turns
  • Data are expressed as mean ± SEM.

  • i-aCPC, Ipsilateral anterior cerebropedal connective; LOVN, large oral veil nerves; PSPs, postsynaptical potentials; BWN, body wall nerves; RP, resting potential; SH, spike height; SD, Spike duration at half amplitude.

  • F2-a Percentage of preparations observed.

  • F2-b Slow bursting has been observed previously in swim interneurons As2/3 (Jing and Gillette, 1999, their Table 1). Slow bursting in A4 has similar burst duration (40 sec), period (80–160 sec) with that of As2/3, but typically has higher peak spike frequency (up to 11 Hz).