Modeling a Neural Oscillator that Paces Heartbeat in the Medicinal Leech

Abstract

Heartbeat in the medicinal leech is paced by a neural oscillator comprising two elemental oscillators whose activity is coordinated by intersegmental coordinating fibers. The elemental oscillators each consist of a bilateral pair of heart interneurons linked by reciprocal inhibitory synapses. The activity cycle of each elemental oscillator consists of alternating bursts of action potentials (plateau/burst phase) and periods of inhibition (inactive phase). Oscillation ensues in the reciprocally inhibitory pairs because each neuron is able to escape from the inhibition of its contralateral partner and thus move on to the plateau/burst phase