C-PR neuron of Aplysia has differential effects on "Feeding" cerebral interneurons, including myomodulin-positive CBI-12.
Head lifting and other aspects of the appetitive central motive state that precedes consummatory feeding movements in Aplysia is promoted by excitation of the C-PR neuron. Food stimuli activate C-PR as well as a small population of cerebral-buccal interneurons (CBIs). We wished to determine if firing of C-PR produced differential effects on the various CBIs or perhaps affected all the CBIs uniformly as might be expected for a neuron involved in producing a broad undifferentiated arousal state. We found that when C-PR was fired, it produced a wide variety of effects on various CBIs. Firing of C-PR evoked excitatory input to a newly identified CBI (CBI-12) the soma of which is located in the M cluster near the previously identified CBI-2. CBI-12 shares certain properties with CBI-2, including a similar morphology and a capacity to drive rhythmic activity of the buccal-ganglion. Unlike CBI-2, CBI-12 exhibits myomodulin immunoreactivity. Furthermore when C-PR is fired, CBI-12 receives a polysynaptic voltage-dependent slow excitation, whereas, CBI-2 receives relatively little input. C-PR also polysynaptically excites other CBIs including CBI-1 and CBI-8/9 but produces inhibition in CBI-3. In addition, firing of C-PR inhibits plateau potentials in CBI-5/6. The data suggest that activity of C-PR may promote the activity of one subset of cerebral-buccal interneurons, perhaps those involved in ingestive behaviors that occur during the head-up posture. C-PR also inhibits some cerebral-buccal interneurons that may be involved in behaviors in which C-PR activity is not required or may even interfere with other feeding behaviors such as rejection or grazing, that occur with the head down.
Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York 10029, USA.
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Hurwitz
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Perrins
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Xin
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Weiss
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Kupfermann
D000818:Animals; D001048:Aplysia; D048429:Cell Size / Q000502:physiology; D002490:Central Nervous System / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology*; D017952:Ganglia, Invertebrate / Q000502:physiology; D066298:In Vitro Techniques; D007395:Interneurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009479:Neuropeptides / Q000378:metabolism*; D018408:Patch-Clamp Techniques
D009479:Neuropeptides; C053302:myomodulin