Kinematics and motor activity during tethered walking and turning in the cockroach, Blaberus discoidalis

Abstract

When insects turn from walking straight, their legs have to follow different motor patterns. In order to examine such pattern change precisely, we stimulated single antenna of an insect, thereby initiating its turning behavior, tethered over a lightly oiled glass plate. The resulting behavior included asymmetrical movements of prothoracic and mesothoracic legs. The mesothoracic leg on the inside of the turn (in the apparent direction of turning) extended the coxa-trochanter and femur-tibia joints during swing rather than during stance as in walking, while the outside mesothoracic leg kept a slow walking pattern. Electromyograms in mesothoracic legs revealed consistent changes in the motor neuron activity controlling extension of the coxa-trochanter and femur-tibia joints. In tethered walking, depressor trochanter activity consistently preceded slow extensor tibia activity. This pattern was reversed in the inside mesothoracic leg during turning. Also for turning, extensor and depressor motor neurons of the inside legs were activated in swing phase instead of stance. Turning was also examined in free ranging animals. Although more variable, some trials resembled the pattern generated by tethered animals. The distinct inter-joint and inter-leg coordination between tethered turning and walking, therefore, provides a good model to further study the neural control of changing locomotion patterns.

Segment Specificity of Load Signal Processing Depends on Walking Direction in the Stick Insect Leg Muscle Control System

“…It is quite conceivable that the mechanism of context-dependent reflex reversal presented here can also be expanded to contribute to the turning behavior in insects. It has been shown previously in stick insects (Dürr and Ebeling, 2005) and cockroaches (Mu and Ritzmann, 2005) that joint kinematics change from extension during stance to extension during swing in the inside leg during turning, whereas the outside leg remains the same as in forward walking. Given a unilateral organization of the leg muscle control systems in the stick insect, it is conceivable that the mechanisms for the reflex reversal, demonstrated here, could also contribute unilaterally in case of the turning.…”

Locomotion control of hybrid cockroach robots

“…The goal of those studies has been to remotely control insects with the purpose of taking advantage of their natural movements [2,8,9,12]. However, establishing efficient control of the natural leg movements of living insects has proven to be a difficult task [10,13,14]. One of the effective approaches was used by Holzer & Shimoyama [6], who observed the reaction of living insects to electrical stimulation.…”

Kinematics of phonotactic steering in the walking cricketGryllus bimaculatus(de Geer)

“…As the rotations of the trackball were generated by the steering front and middle legs, they could have imposed a tilt on the hind leg trajectories in the opposite direction. However, similar tilts in hind leg trajectories were found when cockroaches turned on a slippery surface, which mechanically decoupled their legs (Mu and Ritzmann, 2005). Femur-thorax angle (deg)…”

“…High-speed video has previously provided an important insight into how faster walking insects, such as the cockroach, adjust the trajectories of their front and middle legs to execute a sensoryinduced turn (Mu and Ritzmann, 2005). In our study of cricket phonotaxis there is the additional advantage of understanding the kinematic adjustments made to steer towards an experimentally controlled sensory input.…”

“…Different forms of asymmetric walking have been observed: stick insects increase their stepping frequency or step length on one side of the thorax relative to the other (Graham, 1972). Video recordings of walking stick insects performing visually induced turning (Dürr and Ebeling, 2005;Rosano and Webb, 2007) and of cockroaches with tactile-induced turning (Mu and Ritzmann, 2005) have all demonstrated the dominant role of the front legs in shaping walking direction.…”