HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 91/6/2874    most recent 00028.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science 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 ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Crow, T. Articles by Tian, L.-M. Search for Related Content PubMed PubMed Citation Articles by Crow, T. Articles by Tian, L.-M.

Statocyst Hair Cell Activation of Identified Interneurons and Foot Contraction Motor Neurons in Hermissenda

Department of Neurobiology and Anatomy, University of Texas Medical School, Houston, Texas 77030

Submitted 9 January 2004; accepted in final form 19 February 2004

Pavlovian conditioning of Hermissenda produces both light-elicited inhibition of normal positive phototactic behavior and conditioned stimulus (CS)-elicited foot-shortening. Rotation, the unconditioned stimulus (US) elicits foot-shortening and reduced forward ciliary locomotion. The neural circuit supporting ciliary locomotion and its modulation by light is known in some detail. However, the neural circuits responsible for rotation-elicited foot-shortening and reduced forward ciliary locomotion are not known. Here we describe components of the neural circuit in Hermissenda that produce anterior foot contraction and ciliary activation mediated by statocyst hair cells. We have characterized in semi-intact preparations newly identified pedal ventral contraction motor neurons (VCMNs) and interneurons (I_b). Type I_b interneurons receive polysynaptic input from statocyst hair cells and project directly to VCMNs and cilia-activating motor neurons. Depolarization of VCMNs with extrinsic current in normal artificial seawater (ASW) and high-divalent cation ASW, and under conditions where central synaptic transmission was suppressed with 5 mM Ni²⁺ ASW, elicited a contraction of the ipsilateral anterior foot measured from videotape recordings. Mechanical displacement of the statocyst or depolarization of identified statocyst hair cells with extrinsic current elicited spikes and complex excitatory postsynaptic potentials (EPSPs) in type I_b interneurons and complex EPSPs and spikes recorded in VCMNs. Type I_b interneurons are electrically coupled and project to VCMNs and VP1 cilia-activating motor neurons located in the contralateral pedal ganglia. The results indicate that statocyst hair-cell-mediated anterior foot contraction and graviceptive ciliary locomotion involve different interneuronal circuit components from the circuit previously identified as supporting light modulated ciliary locomotion.

This article has been cited by other articles:

				C. R. Butson and G. A. Clark Random Noise Paradoxically Improves Light-Intensity Encoding in Hermissenda Photoreceptor Network J Neurophysiol, January 1, 2008; 99(1): 146 - 154. [Abstract] [Full Text] [PDF]

				A. Korngreen Noise in the Foreground. Focus on "A Method to Estimate Synaptic Conductances From Membrane Potential Fluctuations" J Neurophysiol, June 1, 2004; 91(6): 2400 - 2400. [Full Text] [PDF]