title: Dominance of local sensory signals over inter-segmental effects  in a motor system: experiments.
abstract: Legged locomotion requires that information local to one leg, and inter-segmental signals coming from the other legs are processed appropriately to establish a coordinated walking pattern.However, very little is known about the relative importance of local and inter-segmental signals when they converge upon the central pattern generators (CPGs) of different leg joints.We investigated this question on the CPG of the middle leg coxa–trochanter (CTr)-joint of the stick insect which is responsible for lifting and lowering the leg.We used a semi-intact preparation with an intact front leg stepping on a treadmill, and simultaneously stimulated load sensors of the middle leg.We found that middle leg load signals induce bursts in the middle leg depressor motoneurons(MNs). The same local load signals could also elicit rhythmic activity in the CPG of the middle leg CTr-joint when the stimulation of middle leg load sensors coincided with front leg stepping. However, the influence of front leg stepping was generally weak such that front leg stepping alone was only rarely accompanied by switching between middle leg levator and depressor MN activity. We therefore conclude that the impact of the local sensory signals on the levator–depressor motor system is stronger than the inter-segmental influence through front leg stepping.
authors.affiliation: Department of Animal Physiology, Institute of Zoology, University of Cologne, Zülpicher Str. 47b, 50674 Köln, Germany. anke.borgmann@uni-koeln.de
authors.forename: Anke
authors.initials: A
authors.lastname: Borgmann
authors.forename: Tibor I
authors.initials: TI
authors.lastname: Toth
authors.forename: Matthias
authors.initials: M
authors.lastname: Gruhn
authors.forename: Silvia
authors.initials: S
authors.lastname: Daun-Gruhn
authors.forename: Ansgar
authors.initials: A
authors.lastname: Büschges
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D063226:Central Pattern Generators / Q000502:physiology*; D005080:Exercise Test; D005121:Extremities / Q000294:innervation / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D007313:Insecta; D008124:Locomotion / Q000502:physiology*; D010507:Periodicity; D010812:Physical Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D013909:Thorax / Q000166:cytology / Q000502:physiology