Jan 23, 2003

Neural basis of a simple behavior: abdominal positioning in crayfish

Microscopy Research and Technique
J L Larimer, Darrell Moore


Crustaceans have been used extensively as models for studying the nervous system. Members of the Order Decapoda, particularly the larger species such as lobsters and crayfish, have large segmented abdomens that are positioned by tonic flexor and extensor muscles. Importantly, the innervation of these tonic muscles is known in some detail. Each abdominal segment in crayfish is innervated bilaterally by three sets of nerves. The anterior pair of nerves in each ganglion controls the swimmeret appendages and sensory supply. The middle pair of nerves innervates the tonic extensor muscles and the regional sensory supply. The superficial branch of the most posterior pair of nerves in each ganglion is exclusively motor and supplies the tonic flexor muscles of that segment. The extension and flexion motor nerves contain six motor neurons, each of which is different in axonal diameter and thus produces impulses of different amplitude. Motor programs controlling each muscle can be characterized by the identifiable motor neurons that are activated. Early work in this field discovered that specific central interneurons control the abdominal positioning motor neurons. These interneurons were first referred to as "command neurons" and later a...Continue Reading

  • References21
  • Citations6


  • References21
  • Citations6


Mentioned in this Paper

Extensor Muscle
Behavior, Animal
Class crustacea
Muscle Innervation, Function
Entire Nervous System
Flexor (Anatomical Coordinate)
Synovial Cyst
Motor Neurons

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