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

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, September 30, 2009, 29(39):12355-12367; doi:10.1523/JNEUROSCI.3079-09.2009

This Article Full Text 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 Citation Map 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 Google Scholar Articles by DeLong, N. D. Articles by Nusbaum, M. P. PubMed PubMed Citation Articles by DeLong, N. D. Articles by Nusbaum, M. P.

 Previous Article

Behavioral/Systems/Cognitive
Parallel Regulation of a Modulator-Activated Current via Distinct Dynamics Underlies Comodulation of Motor Circuit Output

Nicholas D. DeLong, ^* Matthew S. Kirby, ^* Dawn M. Blitz, and Michael P. Nusbaum

Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6074

Correspondence should be addressed to Dr. Michael P. Nusbaum, Department of Neuroscience, 215 Stemmler Hall, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6074. Email: nusbaum{at}mail.med.upenn.edu

The cellular mechanisms underlying comodulation of neuronal networks are not elucidated in most systems. We are addressing this issue by determining the mechanism by which a peptide hormone, crustacean cardioactive peptide (CCAP), modulates the biphasic (protraction/retraction) gastric mill (chewing) rhythm driven by the projection neuron MCN1 in the crab stomatogastric ganglion. MCN1 activates this rhythm by slow peptidergic (CabTRP Ia) and fast GABAergic excitation of the reciprocally inhibitory central pattern generator neurons LG (protraction) and Int1 (retraction), respectively. MCN1 synaptic transmission is limited to the retraction phase, because LG inhibits MCN1 during protraction. Bath-applied CCAP also excites both LG and Int1, but selectively prolongs protraction. Here, we use computational modeling and dynamic-clamp manipulations to establish that CCAP prolongs the gastric mill protractor (LG) phase and maintains the retractor (Int1) phase duration by activating the same modulator-activated inward current (I_MI) in LG as MCN1-released CabTRP Ia. However, the CCAP-activated current (I_MI-CCAP) and MCN1-activated current (I_MI-MCN1) exhibit distinct time courses in LG during protraction. This distinction results from I_MI-CCAP being regulated only by postsynaptic voltage, whereas I_MI-MCN1 is also regulated by LG presynaptic inhibition of MCN1. Hence, without CCAP, retraction and protraction duration are determined by the time course of I_MI-MCN1 buildup and feedback inhibition-mediated decay, respectively, in LG. With I_MI-CCAP continually present, the impact of the feedback inhibition is reduced, prolonging protraction and maintaining retraction duration. Thus, comodulation of rhythmic motor activity can result from convergent activation, via distinct dynamics, of a single voltage-dependent current.

---

Received June 29, 2009; revised Aug. 4, 2009; accepted Aug. 24, 2009.

Correspondence should be addressed to Dr. Michael P. Nusbaum, Department of Neuroscience, 215 Stemmler Hall, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6074. Email: nusbaum{at}mail.med.upenn.edu

This article has been cited by other articles:

				N. D. DeLong and M. P. Nusbaum Hormonal Modulation of Sensorimotor Integration J. Neurosci., February 17, 2010; 30(7): 2418 - 2427. [Abstract] [Full Text] [PDF]

				N. D. DeLong, M. P. Beenhakker, and M. P. Nusbaum Presynaptic Inhibition Selectively Weakens Peptidergic Cotransmission in a Small Motor System J Neurophysiol, December 1, 2009; 102(6): 3492 - 3504. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help