| Abstract: | The patterns of myographic activity in the flexor and extensor tibiae muscles of the locust which accompany learned tibial extension were examined. Three distinct motor strategies were identified: (1) repeated flexion-extension movements, each of which resulted in a momentary excursion beyond the required, pre-set joint angle (demand angle) and in sum met the criterion for learning; (2) changes in basic muscle tonus, which resulted in maintained shifts in tibial position without discernible myographic activity; (3) tonic activity in the single slow excitatory motoneuron of the extensor tibiae ( SETi ) which produced maintained tibial extension. These strategies were selectively employed depending on the particular range of joint angle required. These strategies were compared and their effectiveness evaluated using a variety of behavioral criteria. Neuronal mechanisms which might underlie each of these strategies are discussed. |
