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  • Poster presentation
  • Open Access

Can a central pattern generator produce multiple motor patterns? Modeling scratch rhythms in turtle

BMC Neuroscience201213 (Suppl 1) :P52

  • Published:


  • Animal Model
  • Dynamical System
  • Pattern Generator
  • Knee Extensor
  • Repetitive Behavior
A central pattern generator (CPG) is a population of neurons producing rhythmic or repetitive behavior (i.e. scratching, walking, masticating) without requiring rhythmic input to the population. Turtles are observed to produce several rhythmic motor patterns in response to stimuli, in particular rostral scratch, pocket scratch, caudal scratch, and forward swim (see Figure 1A) [1], [2]. The rostral scratch and pocket scratch rhythms are created through the activity of three motoneurons: Hip Extensor (HE), Knee Extensor (KE) and Hip Flexor (HF). A CPG (see Figure 1B) for rostral scratch and caudal scratch has been proposed, featuring overlapping populations of spinal neurons such that each spinal neuron projects to each motoneuron to produce both scratch rhythms via changing inputs [1]. We implement the CPG as a system of relaxation oscillators. The system successfully reproduces the desired rhythms (see Figure 1C). We also consider a dynamical systems approach to determine the mechanisms underlying rhythm generation, seeking the minimal network necessary to produce both rhythms. Additionally, we numerically explore the role of model parameters and present sufficient conditions on model parameters to produce both rhythms.
Figure 1
Figure 1

A. Example recordings of fictive scratching and fictive swimming [2]; B. The proposed CPG [1]; C. Results of simulation for Rostral (left) and Pocket (right) scratch.

Authors’ Affiliations

Department of Mathematics, University of Pittsburgh, Pittsburgh, PA 15213, USA


  1. Berkowitz A, Stein PSG: Activity of descending propriospinal axons in the turtle hindlimb enlargement during two forms of fictive scratching: phase analyses. J Neurosci. 1994, 14 (8): 5105-5119.PubMedGoogle Scholar
  2. Berkowitz A: Physiology and morphology of shared and specialized spinal interneurons for locomotion and scratching. J Neurophysiol. 2008, 99: 2887-901. 10.1152/jn.90235.2008.View ArticlePubMedGoogle Scholar


© Snyder and Rubin; licensee BioMed Central Ltd. 2012

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.