Temporal processing in Drosophila melanogaster

Introduction

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. However, the rules that shape signals at timescales in between milliseconds and minutes are poorly understood.

Research Aims

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 several factors:

1. The large number of circuit elements.
2. The lack of knowledge about their connectivity.
3. The impracticability of recording from all circuit elements under naturalistic conditions.

Model Organism

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.

Focus Areas

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.
3. Temporal integration of distance during locomotion.

Methodology

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 experiments.
• Genetic experiments.
• Imaging experiments.

This combination will help us test the roles of individual neurons, their biophysical properties, and their synaptic connections in processing signals at intermediate timescales.

Expected Outcomes

The proposed experiments will further our understanding of:

• Motion vision.
• Perceptual decision-making.
• Path integration.