| We analyzed rejection behavior in Aplysia californica . Rejection moves inedible material out of the feeding apparatus using a grasping structure. To study the effect of grasper shape, we built two kinetic models, one with a shape-changing grasper. Both models included the odontophore (the grasper), I2 (which pushes the grasper forward), I1/I3 (which pushes the grasper backward), and the hinge (which holds the odontophore). The models predicted that shape change improved rejection behavior. Through analysis of the biomechanics, we predicted that neural control should include retraction using active I1/I3 contraction, a gap between I2 activation and the beginning of I1/I3 activation, shorter periods, and I2 activation during a specific fraction of the period. Neural controllers were evolved using a genetic algorithm. The fittest neural controllers exhibited the predicted features. Allowing odontophore shape change always increased the fitness of a neural controller. Analysis of biomechanics successfully predicted constraints on the neural control. |
