QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

This Article Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Boyan, G. S. Search for Related Content PubMed PubMed Citation Articles by Boyan, G. S.

 Previous Article  |  Next Article 

Journal of Neuroscience, Vol 8, 2748-2757, Copyright © 1988 by Society for Neuroscience

ARTICLE

Presynaptic inhibition of identified wind-sensitive afferents in the cercal system of the locust

GS Boyan
Molecular Neurobiology Group, Research School of Biological Sciences, Australian National University, Canberra City.

The paired cerci located at the tip of the locust abdomen bear a large number of wind-sensitive filiform hairs, each of which sends an axon via the cercal nerve into the terminal ganglion of the CNS. The filiform afferents fire bursts of action potentials when their hairs are displaced by wind or mechanical stimuli. Filiform axon terminals in the CNS are depolarized concomitantly with the discharge of another type of unit (a primary afferent-depolarizing, or PAD, unit) recorded in the cercal nerve. The instantaneous spike frequency of PAD unit discharges matches the evoked depolarization very closely, and during such depolarizations spike amplitudes in the filiform afferent terminals are reduced by up to 55%. Depolarizing current pulses injected into the axonal terminals of an identified filiform afferent evoke spikes that are blocked by the PAD unit, probably via an intercalated interneuron. The PAD unit makes a monosynaptic connection with only one of the 4 giant interneurons (GIN 2) on each side of the terminal ganglion, and indirect connections with 2 others. Depolarizing current pulses injected into the neuropilar segments of GINs evoke fewer spikes when the PAD unit is active, consistent with the PAD unit's mediation of conductance changes in postsynaptic cells. Iontophoretic injection of Lucifer yellow shows the PAD unit to be an afferent with axon terminals overlapping those of filiform afferents and posteriorly directed branches of interneurons such as GIN 2 in the CNS. Passive movements of a cercus, monitored with a position transducer, show that the PAD unit fires discrete bursts during cercal displacement. The PAD unit most probably has its soma and dendrites in tissue spanning the cercal base. By responding to cercal movements sufficient to also activate filiform hairs, and by mediating conductance changes in both the presynaptic terminals of filiform afferents and the postsynaptic membranes of interneurons, the PAD unit desensitizes a pathway to movement-generated afferent input, and ensures that the locust remains sensitive to external wind stimuli.

This article has been cited by other articles:

				M. Gebhardt and H.-W. Honegger Physiological characterisation of antennal mechanosensory descending interneurons in an insect (Gryllus bimaculatus, Gryllus campestris) brain J. Exp. Biol., January 7, 2001; 204(13): 2265 - 2275. [Abstract] [Full Text] [PDF]

				M. Wachowiak and L. B. Cohen Presynaptic Inhibition of Primary Olfactory Afferents Mediated by Different Mechanisms in Lobster and Turtle J. Neurosci., October 15, 1999; 19(20): 8808 - 8817. [Abstract] [Full Text] [PDF]

				A. R. Marchand, W.J.P. Barnes, and D. Cattaert Primary Afferent Depolarizations of Sensory Origin Within Contact-Sensitive Mechanoreceptive Afferents of a Crayfish Leg J Neurophysiol, June 1, 1997; 77(6): 3340 - 3354. [Abstract] [Full Text] [PDF]

				D. L. Ray and D. Cattaert Neural Mechanisms of Reflex Reversal in Coxo-Basipodite Depressor Motor Neurons of the Crayfish J Neurophysiol, April 1, 1997; 77(4): 1963 - 1978. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help