Fig. 8

Computational model of VNS-evoked muscle contractions. A Modeled force from VNS pulse (dashed line) and pulses (solid line). Model output was quantified by the force-time integral (gray area). Simulation parameters used are from (Ding et al. 2003). B Responses to constant frequency VNS in vivo (solid line), model using (Ding et al. 2003) parameters (dotted line), and model using PSO-identified parameters (dashed line). C-E Model of force production using Ding 2003 parameters (grey) and PSO-identified parameters (black) overlaid on force measurements from different types of skeletal muscle motor units (MU) in the rat medial gastrocnemius (Celichowski et al. 2014). Force was normalized by maximum force. C Modeled and in vivo data from fast fatigable MU (FF MU) response to 20 Hz stimulation. D Model and data from fast fatigue-resistant motor unit (FR MU) response to 40 Hz stimulation. E Model and data from slow MU (S MU) response to 16.6 Hz stimulation