Passive movement of the basal (thoracic-coxal) leg joint in the shore crab Carcinus maenas normally elicits a resistance reflex in the promotor and remotor motoneurones. Remotion of the joint excites promotor moto-neurones and promotion excites remotor motoneurones. This reflex behaviour may reverse and become an assistance reflex, where movement of the joint excites the motoneurones innervating the muscle which would assist the passive movement. This reversal of reflex activity appears to be dependent upon the central state of activity of the animal.

This content is only available via PDF.