Skip to main content
. Author manuscript; available in PMC: 2012 Dec 1.
Published in final edited form as: J Neural Eng. 2011 Nov 4;8(6):065003. doi: 10.1088/1741-2560/8/6/065003

Figure 1.

Figure 1

Components and basic behavior of the neuro-mechanical model. (A) The two-level spinal CPG (comprised of RG, In, and PF located in the top shaded rectangle) receives tonic supra-spinal drive and generates a basic locomotor rhythm providing alternating activation of flexor and extensor motoneurons (Mn - F and Mn - E). All neurons are represented by spheres (light: excitatory, dark: inhibitory) and motoneurons by diamonds. Excitatory and inhibitory synaptic connections are indicated by arrows and small circles, respectively. The motoneurons activate antagonistic muscles that drive a single-joint limb, and feedback from muscle afferents closes the loop. (B) Sample model activity shows the output of the rhythm generator neurons (RG, top), motoneurons (Mn, middle), and limb angle (bottom). Flexor related activity is plotted with a solid red line, with active phase duration indicated by the segment labeled FL, and extensor related activity is plotted with a dashed blue line, with active phase duration indicated by the segment labeled EXT. Note that flexor and extensor phases are shifted relative to swing and stance phases (SW and ST, bottom). (A) Modified from Markin et al. [14], with permission from the New York Academy of Sciences.