Neuroscience 2004 Abstract
| Presentation Number: | 657.3 |
|---|---|
| Abstract Title: | Hormonal modulation of neuronal circuit modulation. |
| Authors: |
Kirby, M. S.*1
; Nusbaum, M. P.1
1Dept Neurosci, Univ. of Pennsylvania, Philadelphia, PA |
| Primary Theme and Topics |
Motor Systems - Pattern Generation and Locomotion |
| Secondary Theme and Topics | Motor Systems<br />- Invertebrate Motor Systems |
| Session: |
657. Modulation of Small Circuit Dynamics Poster |
| Presentation Time: | Tuesday, October 26, 2004 10:00 AM-11:00 AM |
| Location: | San Diego Convention Center - Hall A-H, Board # GG16 |
| Keywords: | stomatogastric ganglion, gastric mill rhythm, hormonal modulation, metamodulation |
We aim to determine how the actions of circulating hormones modify the influence of modulatory projection neurons on a small motor circuit. To this end we are studying how the hormone crustacean cardioactive peptide (CCAP) alters the gastric mill (chewing) rhythm (GMR) elicited by the projection neurons MCN1 and CPN2 in the stomatogastric ganglion (STG) of the crab Cancer borealis. Selective stimulation of MCN1 and co-activation of MCN1 and CPN2 elicit distinct GMRs. CCAP application directly excites a subset of gastric mill neurons but it does not activate the GMR. However, CCAP (threshold <0.1 nM) lowers the minimum MCN1 firing rate needed for GMR activation. When the MCN1 firing rate is held constant, CCAP appears to slow the rhythm by prolonging the protractor phase of the MCN1-elicited GMR (Kirby & Nusbaum, SFN 2003). Here we show that CCAP also alters the MCN1/CPN2-elicited GMR and it does so in a manner comparable to its actions on the MCN1-elicited GMR. We also show that there is not a strict correlation between whether a gastric mill neuron is a direct CCAP target and whether the activity of that neuron is altered by CCAP application during the GMR. For example, most but not all direct CCAP targets show CCAP-altered activity during the GMR, and some non-targets exhibit altered GMR activity during CCAP application. CCAP also directly modulates the pyloric circuit (Weimann et al., 1997, J Neurosci), and the pyloric rhythm regulates the speed of the GMR (Bartos et al., 1999, J Neurosci). Consequently, CCAP might alter the GMR only indirectly, by altering pyloric rhythmic activity. We show that CCAP modulation of the gastric mill circuit persists in the absence of pyloric rhythmic activity. Thus, hormonal modulation can alter neuronal modulation of circuit activity.
Supported by NIH NS29436 (MPN), NSF DGE9616278 (MSK).
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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