The Mushroom Body Circuits For Two Different Olfactory Behaviors In Drosophila

Animals can show definite innate behaviors to certain external stimuli based on their instincts.But in the face of the ever-changing environment,they are more need to be based on the surrounding environment and past experience to adjust their behavior,so as to ensure that they better adapt to the changing environment,we call it adaptive behavior.Adaptive behavior has a decisive effect on the survival and reproduction of all animals,including Drosophila.Therefore,the molecular and neural mechanisms of animal adaptive behavior are of great importance for the survival of animals.It represents one of the hotspots in modern neuroscience research.However,the current mechanism of animal adaptive behavior is not clear.This thesis used Drosophila melanogaster as a model organism,behavioral and molecular genetic techniques as the main methods,using a series of high specific Gal4 drivers driven temperature-sensitive neuronal silence tool ShibireTS1,combined with the Drosophila classic conditioned olfactory learning memory experimental paradigm T-maze,to study the role of mushroom body circuits for two different adaptive olfactory behaviors in Drosophila respectively.Our studies include the following two aspects:1.Drosophila neural circuit Study in identifying the target odor(foreground odor)in the background of saturated odor.The function of the Drosophila mushroom body is necessary for odor identification.This study further explored the mushroom body neural circuit that supports this behavior.The neural circuit was identified by observing the effect of neurotransmitter release from different mushroom subtype neurons,mushroom body output neurons and dopaminergic neurons on odor discrimination.The behavioral results indicated that the α’/β’ lobes and y lobes of the mushroom body participated in the process of identifying the target odor(foreground odor)in the background of saturated odor.While selecting a series of MB split-Gal4 suggested that the MB-MVP2 and MB-V4 in the mushroom body output neurons are also associated with odor identification,which was projected into the γlpedc and α’2 regions of the mushroom body,respectively.Interestingly,although dopaminergic neurons have turned out to be necessary for multiple adaptive behaviors,odor identification does not depend on the normal dopaminergic neuronal output.2.Neural circuit research on blocking odor-avoidance after electric-shockOur laboratory had previously found that nociceptive stimulation could inhibit the odor avoidance behavior in Drosophila.This study found that this inhibition was sustained for at least 30 min after the shock was stopped.And the mushroom body,especially the y lobes,is necessary for this phenomenon.Consistent with the hypothesis that dopaminergic neurons mediate electric-shock signals,the neurotransmitter output of dopaminergic neurons is also important to this inhibition.The results of the above two experiments show that mushroom body plays an important role in odor discrimination and suppression odor avoidance after electric-shock these two different types of odor-related adaptive behaviors.Interestingly,the need for distinct subtypes of the mushroom body is overlap,but not the same.