Motor unit recruitment in a distributed model of extraocular muscle

As a step toward investigating how system-level linearity might be achieved despite nonlinear components, a distributed model of motor units in the abducens nucleus and lateral rectus muscle was constructed

P. Dean

2017

Scholarcy highlights

  • As a step toward investigating how system-level linearity might be achieved despite nonlinear components, a distributed model of motor units in the abducens nucleus and lateral rectus muscle was constructed
  • Units in the distributed model were assigned equal strengths and for a given fixation command, the force developed by each unit was calculated, and the sum of unit forces compared with the active force in the entire muscle as measured experimentally
  • The goal of the training procedure was to obtain a good match between the output of the model and the experimental data on muscle force as a function of eye position
  • Plots of trained motor-unit strength against ocular motoneuron threshold revealed a U-shaped pattern with the strongest units being recruited at both extremes of the oculomotor range and the weakest units recruited in the middle
  • The left-hand limb may reflect the two specializations of eye muscle: the functional need for very precise control of eye position in the middle of the oculomotor range and the use of multiply innervated muscle fibers to provide ripple-free control of eye position at low firing frequencies

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