Effects of neck and circumoesophageal connective lesions on posture and locomotion in the cockroach.
Few studies in arthropods have documented to what extent local control centers in the thorax can support locomotion in absence of inputs from head ganglia. Posture, walking, and leg motor activity was examined in cockroaches with lesions of neck or circumoesophageal connectives. Early in recovery, cockroaches with neck lesions had hyper-extended postures and did not walk. After recovery, posture was less hyper-extended and animals initiated slow leg movements for multiple cycles. Neck lesioned individuals showed an increase in walking after injection of either octopamine or pilocarpine. The phase of leg movement between segments was reduced in neck lesioned cockroaches from that seen in intact animals, while phases in the same segment remained constant. Neither octopamine nor pilocarpine initiated changes in coordination between segments in neck lesioned individuals. Animals with lesions of the circumoesophageal connectives had postures similar to intact individuals but walked in a tripod gait for extended periods of time. Changes in activity of slow tibial extensor and coxal depressor motor neurons and concomitant changes in leg joint angles were present after the lesions. This suggests that thoracic circuits are sufficient to produce leg movements but coordinated walking with normal motor patterns requires descending input from head ganglia.
Ridgel
Angela L
AL
Department of Biology, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106-7080, USA. angela.ridgel@case.edu
Ritzmann
Roy E
RE
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001696:Biomechanical Phenomena; D003058:Cockroaches; D004305:Dose-Response Relationship, Drug; D004947:Esophagus / Q000293:injuries / Q000502:physiology*; D008124:Locomotion / Q000187:drug effects / Q000502:physiology*; D008954:Models, Biological; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology; D018721:Muscarinic Agonists / Q000008:administration & dosage; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D009333:Neck / Q000294:innervation / Q000502:physiology*; D009655:Octopamine / Q000008:administration & dosage; D010862:Pilocarpine / Q000008:administration & dosage; D011187:Posture / Q000502:physiology*; D013997:Time Factors
D000316:Adrenergic alpha-Agonists; D018721:Muscarinic Agonists; D010862:Pilocarpine; D009655:Octopamine