Inherent asymmetry and reflex modulation of the locust flight motor pattern.

In this paper I will present new data and ideas on two interrelated questions regarding the nervous control of insect flight. The answers to these two questions may be important for understanding other aspects of insect behaviour as well. The two problems are: (1) How perfect is the motor score which is built into the thoracic ganglia? (2) How is this motor score modified when anatomical damage makes the inherent score inappropriate? In addition to providing partial answers to these questions the results show that the phenomenon of adaptation of locomotory patterns to limb loss, called Plasticitdt by Bethe (1930), does not imply that locomotion is coordinated purely by proprioceptive reflexes. Although Bethe did not hold this view, later authors have often interpreted his work in this sense. They show also that two categories of possible central organization of locomotory behaviour, motor scores or sensory templates (the 'motor tapes' and 'sensory tapes' of Hoyle, 1964), are not mutually exclusive.