Hsing-Duan Louh Master’s Thesis Defense

July 22, 2020 | 3:00 pm | Zoom

Title: Parametric Sensitivity in a Model of a Motor Pattern Generator in Aplysia


An animal’s survival depends on its ability to adapt to a constantly shifting environment. Mathematical models of rhythmic motor patterns typically incorporate a central pattern generator (CPG) circuit, driving motor output in the body. In this thesis, we study Shaw and Lyttle’s model for the feeding system of the marine mollusk Aplysia californica, which eats seaweed. The CPG has a heteroclinic channel architecture with three metastable fixed points. Using mean rate of seaweed ingestion as an objective function, we studied the system’s sensitivity to parameters representing (i) the force with which seaweed opposes swallowing, and (ii) threshold and weighting parameters controlling when the feeding apparatus (grasper) opens or closes on the seaweed. We found eight motor “strategies,” corresponding to whether the grasper was open or closed near each of the CPG’s fixed points. In addition, we studied how rhythmic movements break down when challenged by excessively large resisting forces.

Advisor: Dr. Peter Thomas

Dissertation Committee

  • Dr. Hillel Chiel
  • Dr. Wanda Strychalski
  • Dr. Erkki Somersalo

Please contact mams-staff@case.edu for Zoom access.


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