Interaction between CPG and Cerebral Cortex Based on Neural Mass Model

The central pattern generator(CPG) is used to control robot very well. But the adjustment of CPG parameters and it's interaction with the external inputs are still open problems. Based on biological knowledge, the central nervous system rules the switch of the CPG modes. In this paper we focus on the coupling relationship between the cerebral cortex and the CPG and establish the mathematical model to analyze their interaction mechanism. Firstly, we propose the model of the interaction between the neural mass model(NMM) and the CPG, which describes the relationship between the cerebral cortex and the CPG. Then the period doubling and the phase diagrams are used to describe changes in system behavior and the interaction mechanism. Through analysis on dynamic characteristics of the new model, we find that many modes described in state equilibrium points in the cerebral cortex correspond to the locomotion patterns and the change of state equilibrium points in the cerebral cortex leads to the change of gait patterns. The mode in the cerebral cortex relies not only on the excitatory input from other cortical areas, but also on the external input of CPG. And the results can explain the biological phenomenon that the increasing electrical stimulation would lead to a gait switch in a decerebrated animal.