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Pedal-Buccal Projection Neurons (P-BPNs) are myomodulin peptide-containing neurons in the central nervous system of Aplysia californica

Basic information

The P-BPNs project from the pedal ganglia to the buccal ganglion. Two particular peptides of the myomodulin (MM) family, MMc and MMe, have been found in cell bodies located in the pedal ganglion. These MM peptides are traced from the pedal ganglia to identify the pedal-buccal projecting neurons.

Figure 1. Summary schematic of pedal, cerebral, and buccal ganglia (Robie 2003)



The cell bodies of the P-BPNs appear as a cluster on the ventral surface of each pedal ganglion. These neurons project axons to the buccal ganglia via the Cerebro-buccal connective (CBC). The P-BPN cell bodies range in size from 40-100 micrometers in diameter.

Figure 2. A.Cerebrobuccal connective backfill traces P-BPNs B.Staining for MMG2-DPs in same ganglion C1.Carboxyfluoroscein injection of projections to CBC C2.Extracellular recording of a P-BPN C3.CBC stained for MMG2-DPs. (Proekt 2005)


  • The P-BPNs exhibit an average resting membrane potential of -44.2mV. Excitatory synapses onto the P-BPNs by the central-pedal regulator (C-PR) neuron, cause repeated firing. Given the input from the C-PR and the synaptic connection to the buccal nerves, the suggested role of the P-BPNs is that of a simple connector involved in both the appetitive and consummatory phases of Aplysia feeding behavior.
  • Firing action potentials from individual P-BPNs reveals impulses in each of the buccal nerves, with the exception of the esophageal nerve.
  • The neurons also project beyond the buccal ganglion to the buccal musculature, but there is not sufficient evidence to merit classification as an interneuron. The P-BPNs are extrinsic to the motor functions of the buccal musculature, having no direct neuromodulatory participation.


  1. Proekt A, Vilim FS, Alexeeva V, Brezina V, Friedman A, Jing J, Li L, Zhurov Y, Sweedler JV, Weiss KR. Identification of a new neuropeptide precursor reveals a novel source of extrinsic modulation in the feeding system of Aplysia. J Neurosci. 2005 Oct 19;25(42):9637-48. PMID: 16237168
  2. Robie A, Diaz-Rios M, Miller MW. A population of pedal-buccal projection neurons associated with appetitive components of Aplysia feeding behavior. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 189 (2003):231-244. PMID: 12664099