A new model of the spinal locomotor networks of a salamander and its properties
A salamander is an ideal animal for studying the spinal locomotor network mechanism of vertebrates from an evolutionary perspective since it represents the transition from an aquatic to a terrestrial animal. However, little is known about the spinal locomotor network of a salamander. A spinal locomotor network model is a useful tool for exploring the working mechanism of the spinal networks of salamanders. A new spinal locomotor network model for a salamander is built for a three-dimensional (3D) biomechanical model of the salamander using a novel locomotion-controlled neural network model. Based on recent experimental data on the spinal circuitry and observational results of gaits of vertebrates, we assume that different interneuron sets recruited for mediating the frequency of spinal circuits are also related to the generation of different gaits. The spinal locomotor networks of salamanders are divided into low-frequency networks for walking and high-frequency networks for swimming. Additionally, a new topological structure between the body networks and limb networks is built, which only uses the body networks to coordinate the motion of limbs. There are no direct synaptic connections among limb networks. These techniques differ from existing salamander spinal locomotor network models. A simulation is performed and analyzed to validate the properties of the new spinal locomotor networks of salamanders. The simulation results show that the new spinal locomotor networks can generate a forward walking gait, a backward walking gait, a swimming gait, and a turning gait during swimming and walking. These gaits can be switched smoothly by changing external inputs from the brainstem. These properties are consistent with those of a real salamander. However, it is still difficult for the new spinal locomotor networks to generate highly efficient turning during walking, 3D swimming, nonrhythmic movements, and so on. New experimental data are required for further validation.
KeywordsSalamander Spinal locomotor networks Locomotion-controlled neural networks (LCNNs) Biomechanical model Gait transition
This work is supported in part by the National Natural Science Foundation of China under Grant 61105110 and 11573011, the Natural Science Foundation of the Jiangsu Higher Education Institutions of China under Grant 14KJB510004, the Jiangsu Overseas Research and Training Program for University Prominent Young and Middle-aged Teachers and President, the Lianyungang “521” Project, and the Six Talent Peaks Project in Jiangsu Province.
- Bolt JR (1977) Dissorophoid relationships and ontogeny and the origin of Lissamphibia. J Paleontol 51:235–249Google Scholar
- Knüsel J, Bicanski A, Ryczko D, Cabelguen J-M, Ijspeert AJ (2013) A salamander’s flexible spinal network for locomotion, modeled at two levels of abstraction. Integr Comp Biol 53(3):1–14Google Scholar
- Liu Q, Wang JZ (2018) Modeling and analysis of a new locomotion control neural network. Biol Cybern. https://doi.org/10.1007/s00422-018-0758-x