A neuromechanical simulation of insect walking and transition to turning of the cockroach Blaberus discoidalis

Abstract

A neuromechanical simulation of the cockroach Blaberus discoidalis was developed to explore changes in locomotion when the animal transitions from walking straight to turning. The simulation was based upon the biological data taken from three sources. Neural circuitry was adapted from the extensive literature primarily obtained from the studies of neural connections within thoracic ganglia of stick insect and adapted to cockroach. The 3D joint kinematic data on straight, forward walking for cockroach were taken from a paper that describes these movements in all joints simultaneously as the cockroach walked on an oiled-plate tether (Bender et al. in PloS one 5(10):1-15, 2010b). Joint kinematics for turning were only available for some leg joints (Mu and Ritzmann in J Comp Physiol A Neuroethol Sens Neural Behav Physiol 191(11):1037-54, 2005) and thus had to be obtained using the methods that were applied for straight walking by Bender et al. (PloS one 5(10):1-15, 2010b). Once walking, inside turning, and outside turning were characterized, phase and amplitude changes for each joint of each leg were quantified. Apparent reflex reversals and joint activity changes were used to modify sensory coupling pathways between the CPG at each joint of the simulation. Oiled-plate experiments in simulation produced tarsus trajectories in stance similar to those seen in the animal. Simulations including forces that would be experienced if the insect was walking freely (i.e., weight support and friction) again produced similar results. These data were not considered during the design of the simulation, suggesting that the simulation captures some key underlying the principles of walking, turning, and transitioning in the cockroach. In addition, since the nervous system was modeled with realistic neuron models, biologically plausible reflex reversals are simulated, motivating future neurobiological research.

Encoding wide-field motion and direction in the central complex of the cockroach, Blaberous discoidalis

“…The optomotor response is an orientation behavior in response to rotating wide-field motion (Borst et al, 2010) and is found in the cockroach (Szczecinski et al, 2014). Although the necessary directional motion is characterized in visual lobes (Borst and Haag, 2002;Borst et al, 2010), it is possible that the complete behavior could involve Encoding wide-field motion and direction in the central complex of the cockroach Blaberus discoidalis Nicholas D. Kathman*, Malavika Kesavan and Roy E. Ritzmann associative regions such as the CX.…”

A Synthetic Nervous System Controls a Simulated Cockroach

“…We set h des = 1.2 cm, a value used for oiled plate walking experiments with cockroaches [14]. The resulting posture, shown in Figure 7, is remarkably cockroach-like.…”

“…Thus, the animat's body has 54 degrees of freedom ((5 + 3) DOF × 6 legs + 6 DOF × 1 body)), 30 of which are actuated, and 6 of which are constrained for each leg when it is in contact with the ground. See Figure 4 in [14] for a description of the different body segments and joint angles in a cockroach. …”

“…The cockroach data used for comparison was taken from [14]. For each joint in each leg during simulated walking, the joint angle at the AEP and PEP were measured for a number of steps.…”

“…SimRoach2 ( Figure 2) was adapted from our previous model [14]. Each leg has five actuated hinge joints (Table 1).…”