Abstract
The pleural interneuron PlB is a white neuron in the pleural ganglion of the snail Lymnaea. We test the hypothesis that it inhibits neurons at all levels of the feeding system, using a combination of anatomy, physiology and pharmacology. There is just one PlB in each pleural ganglion. Its axon traverses the pedal and cerebral ganglia, running into the buccal ganglia. It has neuropilar branches in the regions of the cerebral and buccal ganglia where neurons that are active during feeding also branch. Activation of the PlB blocks fictive feeding, whether the feeding rhythm occurs spontaneously or is driven by a modulatory interneuron. The PlB inhibits all the neurons in the feeding network, including protraction and retraction motoneurons, central pattern generator interneurons, buccal modulatory interneurons (SO, OC), and cerebral modulatory interneurons (CV1, CGC). Only the CV1 interneuron shows discrete 1:1 IPSPs; all other effects are slow, smooth hyperpolarizations. All connections persist in Ca2+/Mg2+-rich saline, which reduces polysynaptic effects. The inhibitory effects are mimicked by 0.5 to 100 mumol l(-1) FMRFamide, which the PlB soma contains. We conclude that the PlB inhibits neurons in the feeding system at all levels, probably acting though the peptide transmitter FMRFamide.
| Original language | English |
|---|---|
| Pages (from-to) | 379-390 |
| Number of pages | 12 |
| Journal | Journal of comparative physiology a-Neuroethology sensory neural and behavioral physiology |
| Volume | 190 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - May 2004 |
Keywords
- feeding
- FMRFamide
- pleural interneuron
- pleural ganglion
- pond snail, Lymnaea
- CENTRAL PATTERN GENERATOR
- CEREBRAL GIANT-CELLS
- BODY WITHDRAWAL RESPONSE
- SNAIL LYMNAEA
- POND SNAIL
- MOTOR OUTPUT
- CENTRAL MOTONEURONS
- IDENTIFIED NEURONS
- BUCCAL GANGLIA
- SYSTEM