Feedback signal from motoneurons influences a rhythmic pattern generator

Document Type

Article

Publication Date

9-20-2017

Abstract

Motoneurons are not mere output units of neuronal circuits that control motor behavior but participate in pattern generation. Research on the circuit that controls the crawling motor behavior in leeches indicated that motoneurons participate as modulators of this rhythmic motor pattern. Crawling results from successive bouts of elongation and contraction of the whole leech body. In the isolated segmental ganglia, dopamine can induce a rhythmic antiphasic activity of the motoneurons that control contraction (DE-3 motoneurons) and elongation (CV motoneurons). The study was performed in isolated ganglia where manipulation of the activity of specific motoneurons was performed in the course of fictive crawling (crawling). In this study, the membrane potential of CV was manipulated while crawling was monitored through the rhythmic activity of DE-3. Matching behavioral observations that show that elongation dominates the rhythmic pattern, the electrophysiological activity of CV motoneurons dominates the cycle. Brief excitation of CV motoneurons during crawling episodes resets the rhythmic activity of DE-3, indicating that CV feeds back to the rhythmic pattern generator. CV hyperpolarization accelerated the rhythm to an extent that depended on the magnitude of the cycle period, suggesting that CV exerted a positive feedback on the unit(s) of the pattern generator that controls the elongation phase. A simple computational model was implemented to test the consequences of such feedback. The simulations indicate that the duty cycle of CV depended on the strength of the positive feedback between CV and the pattern generator circuit.

Identifier

85029742216 (Scopus)

Publication Title

Journal of Neuroscience

External Full Text Location

https://doi.org/10.1523/JNEUROSCI.0756-17.2017

e-ISSN

15292401

ISSN

02706474

PubMed ID

28821650

First Page

9149

Last Page

9159

Issue

38

Volume

37

Grant

PICT 2012-2360

Fund Ref

Agencia Nacional de Promoción Científica y Tecnológica

This document is currently not available here.

Share

COinS