Patterns of activity in the antennular motoneurones of the hermit crab Pagurus alaskensis (Benedict).
1. Using electromyogram recordings from the antennular muscles of intact animals and recordings from the antennular nerves of partially dissected preparations, the patterns of activity in specific antennular motoneurones have been described during antennular flicking and antennular withdrawal. 2. The slow extensor motoneurone A30S is active during flicking in addition to the phasic component of the antennular motor system (A30F, A31F and A32F). 3. The flexion phase of a flick is the result of a burst of variable duration and number of spikes within flexor motoneurones A31F and A32F. 4. The extension phase of a flick is the result of a burst of variable duration and number of spikes in extensor motoneurones A30F and A30S. 5. Extension-withdrawal and slow flexion-withdrawal reflexes, tonic flexion withdrawal and maintained flexion at the MS-DS joint usually result from activity in part of the tonic component of the antennular motor system:moto-neurones A30S, A31S and A32S. 6. Fast flexion-withdrawal reflexes result from a burst of spikes in motoneurone A31F-S which constitutes the phaso-tonic component of the antennular motor system. 7. During high-frequency activity (15-60/sec), reciprocity exists between the slow flexor motoneurones A31S and A32S and slow extensor motoneurone A30S.
D000200:Action Potentials; D000818:Animals; D033381:Anomura / Q000033:anatomy & histology / Q000502:physiology*; D002628:Chemoreceptor Cells / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*; D009132:Muscles / Q000294:innervation / Q000502:physiology; D012018:Reflex