Figure 1.
A schematic of neuromechanical equilibrium points during biting, swallowing and rejection in Aplysia. Each of these “snapshots” represents the mechanical configurations toward which the system will tend given different steady patterns of neural input. Meshes are based on in vivo magnetic resonance imaging recordings and a kinematic model (Neustadter et al., 2002a,b, 2007; Novakovic et al., 2006). The grasper is shown using a green mesh; the radular stalk, whose position indicates the opened or closed state of the grasper surface, is shown using a red mesh; and the jaw musculature (I3) is shown using a blue mesh. Initial states (leaving the rest position) are distinct: the radula is more open in biting than in swallowing (arrow 1 vs arrow 2), and closed in rejection (arrow 3). Protraction is distinct: there is a stronger peak protraction in biting than in swallowing or rejection (arrow 4 vs arrows 5 and 6). Peak retraction is distinct: the peak retraction of swallowing is strongest (arrow 8 vs arrows 7 and 9), and the radula is open during the retraction of rejection.