Multi-Joint Coordination During Walking and Foothold Searching in the<i>Blaberus</i>Cockroach. I. Kinematics and Electromyograms

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In the arthropod brain, the central complex (CX) receives various forms of sensory signals and is associated with motor functions, but its precise role in behavior is controversial. The optomotor response is a highly conserved turning behavior directed by visual motion. In tethered cockroaches, 20% procaine injected into the CX reversibly blocked this behavior. We then used multichannel extracellular recording to sample unit activity in the CX in response to wide-field visual motion stimuli, moving either horizontally or vertically at various temporal frequencies. For the 401 units we sampled, we identified five stereotyped response patterns: tonically inhibited or excited responses during motion, phasically inhibited or excited responses at the initiation of motion, and phasically excited responses at the termination of motion. Sixty-seven percent of the units responded to horizontal motion, while only 19% responded to vertical motion. Thirty-eight percent of responding units were directionally selective to horizontal motion. Response type and directional selectivity were sometimes conditional with other stimulus parameters, such as temporal frequency. For instance, 16% of the units that responded tonically to low temporal frequencies responded phasically to high temporal frequencies. In addition, we found that 26% of wide-field motion responding units showed a periodic response that was entrained to the temporal frequency of the stimulus. Our results show a diverse population of neurons within the CX that are variably tuned to wide-field motion parameters. Our behavioral data further suggest that such CX activity is required for effective optomotor responses.

Section: Animal Preparation and Electrophysiologymentioning

confidence: 99%

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

Kathman

Kesavan

Ritzmann

2014

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“…Ritzman et al (Ritzman et al, 2004) contend strong convergent evolution for locomotion in insects and quadrupeds, particularly with respect to front leg orientation and its associated degrees of freedom. Cockroaches (Tryba and Ritzmann, 2000) and other many-legged arthropods typically use their front legs in a sensory role to reach forward (Durr, 2001). Hind legs might show similar force patterns in hexapods and quadrupeds because in both they appear oriented to generate thrusting forces (Ritzmann et al, 2004).…”

Section: Effect Of Leg Numbermentioning

confidence: 99%

Dynamics of rapid vertical climbing in cockroaches reveals a template

Goldman

Chen

Dudek

et al. 2006

189

242

. Single-leg force patterns differed significantly from level running. During vertical climbing, all legs generated forces to pull the animal up the plate. Front and middle legs pulled laterally toward the midline. Front legs pulled the head toward the wall, while hind legs pushed the abdomen away. These singleleg force patterns summed to generate dynamics of the whole animal in the frontal plane such that the center of mass cyclically accelerated up the wall in synchrony with cyclical side-to-side motion that resulted from alternating net lateral pulling forces. The general force patterns used by cockroaches and geckos have provided biological inspiration for the design of a climbing robot named RiSE (Robots in Scansorial Environments).

“…To test this hypothesis, we required a multi-legged runner that exhibits SLIP-like running mechanics, that has documented virtual leg properties, and for which the neural control architecture has been studied. We therefore selected cockroaches, Blaberus discoidalis, because they exhibit SLIP-like running mechanics (Full and Tu, 1990), the stiffness of their virtual leg spring on rigid surfaces has been measured (15Nm -1 ) (Full and Tu, 1990), and their neural control has been studied during slow (Mu and Ritzmann, 2005;Ridgel and Ritzmann, 2005;Ridgel et al, 2007;Ritzmann and Buschges, 2007;Tryba and Ritzmann, 2000a;Tryba and Ritzmann, 2000b;Watson and Ritzmann, 1998a) and fast (Sponberg and Full, 2008;Watson and Ritzmann, 1998b) locomotion.…”

Section: Introductionmentioning

confidence: 99%

Insects running on elastic surfaces

Spence

Revzen

Seipel

et al. 2010

SUMMARY In nature, cockroaches run rapidly over complex terrain such as leaf litter. These substrates are rarely rigid, and are frequently very compliant. Whether and how compliant surfaces change the dynamics of rapid insect locomotion has not been investigated to date largely due to experimental limitations. We tested the hypothesis that a running insect can maintain average forward speed over an extremely soft elastic surface (10 N m−1) equal to 2/3 of its virtual leg stiffness (15 N m−1). Cockroaches Blaberus discoidalis were able to maintain forward speed (mean ± s.e.m., 37.2±0.6 cm s−1 rigid surface versus 38.0±0.7 cm s−1 elastic surface; repeated-measures ANOVA, P=0.45). Step frequency was unchanged (24.5±0.6 steps s−1 rigid surface versus 24.7±0.4 steps s−1 elastic surface; P=0.54). To uncover the mechanism, we measured the animal's centre of mass (COM) dynamics using a novel accelerometer backpack, attached very near the COM. Vertical acceleration of the COM on the elastic surface had a smaller peak-to-peak amplitude (11.50±0.33 m s−2, rigid versus 7.7±0.14 m s−2, elastic; P=0.04). The observed change in COM acceleration over an elastic surface required no change in effective stiffness when duty factor and ground stiffness were taken into account. Lowering of the COM towards the elastic surface caused the swing legs to land earlier, increasing the period of double support. A feedforward control model was consistent with the experimental results and provided one plausible, simple explanation of the mechanism.