Short-term synaptic enhancement modulates ingestion motor programs of aplysia.
Activity-dependent synaptic plasticity regulates the flow of information in neuronal networks and has important implications for the expression of behavior. We find a functional role for short-term synaptic enhancement (STE) such as facilitation, augmentation, and post-tetanic potentiation at central synapses in the sea slug Aplysia californica. Consummatory feeding in Aplysia such as rhythmic biting is controlled by command-like cerebral-buccal interneurons (CBIs) that drive rhythmic motor output in the buccal ganglia. CBI interneuron-2 (CBI-2) makes monosynaptic connections onto buccal neurons, including premotor neurons B31/32 and B34 and motor neurons B61/62. Stimulating CBI-2 at a physiological firing frequency of 10 Hz for 30 sec causes these synapses to increase their EPSP amplitude by approximately 200%. This STE persists for nearly 2 min, during which time there is an increased cycle frequency of rhythmic ingestion buccal motor programs (iBMPs) elicited by CBI-2. This increase does not occur if the contralateral CBI-2 is trained and the test is performed with the ipsilateral CBI-2; therefore, the effect on motor programs only occurs in CBI-2 pathways in which STE is elicited. Furthermore, we find that STE elicited at CBI-2 buccal synapses permits iBMPs to be initiated at lower firing frequencies. Thus, STE of CBI-2 synapses appears to contribute to the initiation or modulation, or both, of buccal motor programs for rhythmic ingestion in Aplysia.
Sánchez
J A
JA
Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri 65211, USA.
Kirk
M D
MD
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001048:Aplysia; D001522:Behavior, Animal / Q000502:physiology; D002413:Cations, Divalent / Q000378:metabolism; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology*; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000502:physiology; D066298:In Vitro Techniques; D007395:Interneurons / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D010507:Periodicity; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
D002413:Cations, Divalent