La conferenza del Prof. Mauro Zordan al Convegno del Dipartimento di Biologia
Pubblicato il: 14.05.2020 09:00
Lunedì 3 e martedì 4 Febbraio 2020 si è tenuto il quarto Convegno del Dipartimento di Biologia.
Il convegno è stato aperto da un intervento del Prof. Cesare Montecucco, patologo e neurobiologo di fama internazionale e anche Professore Emerito dell’Università di Padova. Un totale di 16 presentazioni scientifiche, tenute da ricercatori del Dipartimento, è stato diviso in 4 sessioni. Il convegno si è chiuso con una conferenza aperta alla città di Padova, tenuta dal. Prof. Telmo Pievani.
A questo link potrete visionare una selezione delle presentazioni scientifiche del nostro convegno:
A questo link mettiamo invece in evidenza la conferenza del Prof. Mauro Zordan dal titolo "Searching for relief: Drosophila melanogaster navigation in a virtual bitter maze"
Searching for relief: Drosophila melanogaster navigation in a virtual bitter maze
Here we exploited a powerful molecular genetic tool, which allowed the optogenetic activation of a blue-light sensitive channelrhodopsin, the expression of which was specifically targeted to bitter-sensing neurons in Drosophila. Pulses of blue light were used to stimulate such neurons in single flies which were free to walk (but not fly) within a circular arena surrounded by a cylindrical wall of LED panels programmed to display two identical and diametrically opposed dark stripes on a homogeneously lit green background. Cessation of the artificially stimulated bitter taste depended upon the successful identification, by the fly, of a "safe" region localised in the proximity of one of the dark stripes. So far, most of research on this subject has relied on visual-guided place-learning paradigms with heat, water or electrical shock acting as pain- and/or distress-inducing stimuli, and relief being provided by a safe location matched to a specific, unambiguous visual marker.
We show that optogenetic activation of bitter-sensing neurons is distressing, and that flies tend to seek relief from this stimulation alternatively between one of two identical landmarks. Interestingly, bitter taste is innately wired to the threat of intoxication and is sufficient to guide escape responses and relief-based place learning, much in the same way as more "classical" pain- and/or distress-inducing stimuli.
In our experiments, each of the two identical stripes are linked alternatively to relief or to the lack of relief. Thus, after the second trial of training, either stripe has been linked to bitter-taste relief or the lack thereof. In the latter case, if the negative bitter experience were to trigger an operant conditioning generalisation, the flies' following bouts of relief searching would be directed away from the stripes. In our experiments, even though the association between relief and proximity to one of the stripes is ambiguous, the most recent memory of relief appears to override any generalisation. We also show that path integration does not play a role in this localisation process, and that visual cues are necessary to locate the safe area. Our results further suggest that the study of learning in freely-behaving animals may be facilitated by analysing, among other variables, variations in locomotor kinetics: while sudden accelerations and increases in locomotor velocity may be considered as markers of startle reflexes, decelerations/decreased velocities may be linked to relief. On this basis, it should thus be possible to identify learning processes, perhaps even in the wild, without the need for conducting dedicated testing.