Directional sensitivity of an identified wind-sensitive interneuron duringthe postembryonic development of the locust

Simultaneous extracellular recordings from both locust abdominal connective s show a differential activation of both bilateral homologues of an identif ied long projection interneuron (A4I1) in response to wind stimuli from dif ferent directions. Despite the previously shown extensive structural dynami cs of sensory afferents and synaptic rearrangement of the direct afferent-t o-interneuron connections during postembryonic development, a directional s ensitivity is already present in first instar nymphs. Only quantitative cha nges in the strength of the directional response can be detected. Intracell ular stainings of the A4I1 interneuron in first instar nymphs and adults sh ow that general morphological features do not change during postembryonic d evelopment, in contrast to the presynaptic sensory afferents. This also hol ds for general morphological features of pleuroaxillary flight motoneurons. The output connections of A4I1 to these motoneurons and an unidentified in tersegmental interneuron are already present in flightless nymphs. (C) 2000 Elsevier Science Ltd. All rights reserved.