It is widely accepted that the electrical activity of motoneurons that drive locomotion in the stick insect are controlled by two separate mechanisms: (i) the frequency of the activity through the central pattern generator, which provides the rhythm of movement during locomotion and (ii) the ‘magnitude’ through circuits distinct from the earlier one. In this study, we show a possible way of how this control mechanism might be implemented in the nervous system of the stick insect by means of a network model. To do this, we had to define the ‘magnitude’ of the neuronal activity more precisely as the average number of spikes per unit time. The model was constructed on the basis of relevant electrophysiological and morphological data. However, only their integration in the model led to the novel properties that enable the network quickly to adapt the motoneuronal activity to central commands or sensory signals by changing both the firing pattern and intensity of the motoneuron discharges. The network would thus act as the controlling network for each of the muscle pairs that move the individual joints in each of the legs. Our model may contribute to a better understanding of the mechanisms that underlie the fast adaptive control of locomotion in this, and possibly in other types of locomotor systems.
Emmy Noether Research Group of Computational Biology, Department of Animal Physiology, Institute of Zoology, University of Cologne, Cologne, Germany
Correspondence to Silvia Daun-Gruhn, PhD, Emmy Noether Research Group of Computational Biology, Department of Animal Physiology, Institute of Zoology, University of Cologne, Cologne, Zülpicher Street 47b, Köln D-50674, Germany Tel: +49 221 4703829; fax: +49 221 4704889; e-mail: firstname.lastname@example.org
Received September 1, 2011
Accepted September 4, 2011