DROSOPHILA MELANOGASTER AS A VERSATILE MODEL TO STUDY COMPLEX NERVOUS ACTIVITIES AND INTERACTIONS WITH ACTIVE COMPOUNDS

In this thesis, I present two distinct experimental protocols conducted during my internship in a neurophysiology laboratory. Featuring advanced genetic tools, a brief lifecycle, cost-efficiency, and high physiological relevance to human biology, Drosophila melanogaster serves as an established model organism that has profoundly shaped diverse biological fields, most notably neurophysiology. I utilized Drosophila melanogaster in two protocols: the primary investigation is dedicated to the study of sleep, a foundational biological process required for proper immune, metabolic, cardiovascular, and cognitive functioning. Specifically, this is the major portion of the work I carried on and evaluates the physiological and behavioral alterations induced by exposure to Lavandula angustifolia essential oil – frequently employed in human aroma-therapeutics – on the animals' circadian rhythms and sleep. I managed to obtain the preliminary results presented in this thesis, which indeed show how the compound alters sleep dynamics. Complementing this primary procedure, the second protocol entails the investigation of data obtained from tracking the optomotor reflex. Such reflex constitutes a major pillar of the fly's complex flight-control and gaze-stabilization neural network, and it’s a crucial component of the navigational behaviors of this and many other species, including vertebrates. This second technique is more challenging – as it involves the manipulation of wake flies and raw behavioral data – but nonetheless I managed to obtain some good recording that I show in this thesis as examples. By integrating these protocols, this thesis reflects the thorough acquisition on my part of precise laboratory methodologies essential for tackling complex neurobiological and behavioral questions using an animal model in which sophisticated genetic and molecular techniques can be combined with similarly sophisticated techniques in behavior analysis, neurophysiology (both electrophysiology and calcium imaging) and nervous system anatomy. Someone could argue that these studies have no or few interest in the understanding of vertebrate brain and ultimately of human brain function. However, studies in the last 30-40 years clearly demonstrated profound cognitive abilities in arthropods and other invertebrates which, for instance, behave similarly to vertebrates during navigation in the environment or show selective attentional responses to external stimuli or engage voluntary responses based on a decision-making process. Moreover, molecular studies show that arthropod and vertebrate brains are defined by a constrained neurological ground pattern which Cambrian fossil brains of arthropod, insects and crustacean ancestors showed to be already present at that age. In other words, this ground pattern is present since Cambrian age persisted for a vast length of geological time. Therefore, it is reasonable to consider that Drosophila melanogaster brain may offer as much insight into the principles of cerebral evolution and functionality, including cognition, as would the brain of a vertebrate.