Recruitment of octopaminergic neurons in different insect species

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Octopaminergic dorsal or vental unpaired median (DUM or VUM) neurons occur in all insects, and are involved in modulating neuromuscular transmission and in regulationg energy metabolism of their target tissues. They are diffenentially recruited during various motor behaviors although the extract mechanisms of activation are unknown, in particular no presynaptic neurons are known to make direct synaptic contacts with DUM/VUM neurons. By using a compoarative approach between two orthopteran species, the "primitive" New Zealand weta, the African locust, and an American moth, differences in recruitment of octopaminergic neurons and their adaptations to different behavioral constraints will be studied. In particular, the following questions will be adresses: 1i) how are these neurons recruited in wetas and locusts during diffenrent tibial movements each of which has a different behavioral function, (ii) are different neuronal pathways involved in this recruitment, for example local versus intersegmental activation, or sensory activation versus descending command from motor control areas. (iii) In the moth, recruitment of the same class of neurons will be studies in adults and compared to that of larvae. (iv) It is assumed that during metamorphosis the connectivity of these neurons changes, and that the suboesophageal ganglion as a motor control area is involved in this reorganization. Therefore, neurons in the suboesophageal ganglion that may provide inputs to DUM/VUM neurons will be sought and characterized. (v) In addition, DUM/VUM neurons of the suboesophageal ganglion itself that innervate all major brain areas will be characterized.