Role of intrinsic properties in Drosophila motoneuron recruitment during fictive crawling.
Motoneurons in most organisms conserve a division into low-threshold and high-threshold types that are responsible for generating powerful and precise movements. Drosophila 1b and 1s motoneurons may be analogous to low-threshold and high-threshold neurons, respectively, based on data obtained at the neuromuscular junction, although there is little information available on intrinsic properties or recruitment during behavior. Therefore in situ whole cell patch-clamp recordings were used to compare parameters of 1b and 1s motoneurons in Drosophila larvae. We find that resting membrane potential, voltage threshold, and delay-to-spike distinguish 1b from 1s motoneurons. The longer delay-to-spike in 1s motoneurons is a result of the shal-encoded A-type K(+) current. Functional differences between 1b and 1s motoneurons are behaviorally relevant because a higher threshold and longer delay-to-spike are observed in MNISN-1s in pairwise whole cell recordings of synaptically evoked activity during bouts of fictive locomotion.
Schaefer
Jennifer E
JE
University of Arizona, Department of Neuroscience, PO Box 210077, Tucson, AZ 85721-0077, USA.
Worrell
Jason W
JW
Levine
Richard B
RB
D000818:Animals; D004331:Drosophila melanogaster; D055785:Gene Knockdown Techniques; D008564:Membrane Potentials / Q000502:physiology; D009043:Motor Activity / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*; D011999:Recruitment, Neurophysiological / Q000502:physiology*