Temporal processing in Drosophila melanogaster

Description du projet

Traitement de l’information temporelle par le cerveau

Pour traiter les informations, le cerveau s’appuie sur des modèles spatiaux et temporels d’activité électrique. Alors que les schémas spatiaux sont dictés par l’anatomie du cerveau, les mécanismes qui régissent la dynamique de l’activité temporelle sur des périodes allant de quelques millisecondes à plusieurs minutes demeurent mal compris. Le projet TEMPRODROME, financé par le CER, se propose d’étudier ces mécanismes en utilisant Drosophila melanogaster comme organisme modèle. Les chercheurs s’appuieront sur des enregistrements patch-clamp in vivo, l’imagerie fonctionnelle et des expériences comportementales pour étudier la manière dont le cerveau filtre et stocke les informations concernant les stimuli visuels au fil du temps, la manière dont il recueille des informations sur le mouvement visuel et dont il garde la trace de la distance parcourue au fil du temps pendant le mouvement.

Objectif

All information processing in nervous systems relies on spatial and temporal patterns of neural activity. While spatial patterns are dictated by neuroanatomy, the mechanisms that give rise to temporal activity patterns are diverse. They range from fast voltage dynamics of single neurons at one end of the spectrum to slow transcriptional and structural changes at the other, but the rules that shape signals at timescales in between milliseconds and minutes are poorly understood. The proposed research aims to uncover mechanisms of temporal information processing at these intermediate timescales, at which temporal patterns are thought to emerge from recurrently connected circuits. Detailed insight into the function of these circuits has been limited by the large number of circuit elements, by the lack of knowledge about their connectivity, and by the impracticability of recording from all circuit elements under naturalistic conditions. In Drosophila melanogaster, these limitations no longer apply. The comparatively low number of neurons, their well-mapped connectivity, and our ability to record and control their activities make mechanistic concepts testable. We will focus on three processes in the brain of Drosophila that unfold over three timescales ranging from milliseconds to minutes: 1) temporal filtering in the motion vision system, 2) sequential sampling of motion information in the lead-up to a perceptual judgement, and 3) temporal integration of distance during locomotion. Patch clamp experiments in the smallest of invertebrate neurons in vivo will allow us to record activity at the highest temporal resolution. We will combine this technique with behavioural, genetic, and imaging experiments to test the roles of individual neurons, their biophysical properties, and their synaptic connections in processing signals at intermediate timescales. The proposed experiments will further our understanding of motion vision, perceptual decision-making, and path integration.