Feeding CPG in Aplysia directly controls two distinct outputs of a compartmentalized interneuron that functions as a CPG element.
In the context of motor program generation in Aplysia, we characterize several functional aspects of intraneuronal compartmentalization in an interganglionic interneuron, CBI-5/6. CBI-5/6 was shown previously to have a cerebral compartment (CC) that includes a soma that does not generate full-size action potentials and a buccal compartment (BC) that does. We find that the synaptic connections made by the BC of CBI-5/6 in the buccal ganglion counter the activity of protraction-phase neurons and reinforce the activity of retraction-phase neurons. In buccal motor programs, the BC of CBI-5/6 fires phasically, and its premature activation can phase advance protraction termination and retraction initiation. Thus the BC of CBI-5/6 can act as an element of the central pattern generator (CPG). During protraction, the CC of CBI-5/6 receives direct excitatory inputs from the CPG elements, B34 and B63, and during retraction, it receives antidromically propagating action potentials that originate in the BC of CBI-5/6. Consequently, in its CC, CBI-5/6 receives depolarizing inputs during both protraction and retraction, and these depolarizations can be transmitted via electrical coupling to other neurons. In contrast, in its BC, CBI-5/6 uses spike-dependent synaptic transmission. Thus the CPG directly and differentially controls the program phases in which the two compartments of CBI-5/6 may transmit information to its targets.
Sasaki
Kosei
K
Department of Neuroscience, Mount Sinai School of Medicine, New York, NY 10029, USA.
Due
Michael R
MR
Jing
Jian
J
Weiss
Klaudiusz R
KR
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001048:Aplysia / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D004594:Electrophysiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D017952:Ganglia, Invertebrate / Q000502:physiology; D007323:Instinct; D007395:Interneurons / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione