Neuronal Circuits That Generate Swimming Movements in Leeches

Wolfgang Otto Friesen

in Handbook of Brain Microcircuits

Published on behalf of Oxford University Press

Published in print August 2010 | ISBN: 9780195389883
Published online September 2012 | e-ISBN: 9780199965137 | DOI:
Neuronal Circuits That Generate Swimming Movements in Leeches

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  • Development of the Nervous System


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Swimming undulations in leeches arise from iterated segmental oscillators that are coupled by intersegmental interactions. Oscillator subunits, comprising individually identified intersegmental interneurons and local inhibitory motoneurons, control the activity of excitatory motoneurons that command body wall tension. Synaptic interactions within ganglia are almost exclusively non-spike-mediated, however intersegmental connections, which together with sensory feedback from segmental muscle tension receptors set rostrocaudal phase lags, are mediated by impulses. The latter have an interganglionic transit time of about 15ms. Overall, swimming in leeches is generated by strong local oscillators linked by individually weak, but in the aggregate strong intersegmental interactions. Driven by an extensive set of multisegmental excitatory interneurons, the system functions as a unit.

Chapter.  2292 words.  Illustrated.

Subjects: Development of the Nervous System

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