W. Kutsch et W. Hemmer, ONTOGENIC STUDIES OF FLIGHT INITIATION IN LOCUSTA - WIND RESPONSE OF AN IDENTIFIED INTERNEURON (TCG), Journal of insect physiology, 40(2), 1994, pp. 97-106
The tritocerebral commissure giant (TCG) wind-sensitive interneurone i
s involved in initiation and maintenance of flight in adult locusts. I
n this paper we study this interneurone in the imago and non-flying la
rval instars. Cobalt fills show that the TCG established its adult mor
phology by the first larval instars. Cobalt fills show that the TCG es
tablishes its adult morphology by the first larval instar. An accompan
ying axon, apparently representing the peculiar tritocerabral commissu
re ''dwarf'' (TCD) is present, too, at least for the last preimaginal
instars. Physiological tests show similar responses of the TCG to wind
stimuli in the 4th, 5th instar and adult stages. Spike activity, howe
ver, is usually higher in adult compared to larval instars. It is poss
ible that all interneurones, involved in adult-specific motor patterns
(such as flight), are present in preimaginal stages and can be activa
ted independently of the function of the final motor system.