We use Drosophila as a genetic model system to study mechanisms of perception in the brain. We are interested in three phenomena: selective attention, sleep, and general anaesthesia. How does the brain selectively block perception of competing stimuli? Is this blocking mechanism similar to what happens during sleep? How do general anaesthetics achieve a similar effect? These are questions which drive research in our laboratory, all under a common quest to understand how brains support conscious awareness. Image: multichannel brain activity recorded from a fly.
Attention and Memory
Behavioural choices result from an ongoing interplay between attention and memory. We have developed paradigms to study visual attention and memory in Drosophila, thereby allowing us to investigate this complex problem in a powerful genetic model. Two levels of investigation are involved: behaviour and brain electrophysiology. Behavioural paradigms allow us to determine visual responsiveness levels resulting from gene mutations or drug treatments, and electrophysiology in individual flies identifies brain processes affected by our manipulations. Our goal is to identify mechanisms of visual attention, and to elucidate how these processes interact with memory systems to guide decision making. Image: a fly paying attention to visual stimuli in virtual reality.
Sleep in the Fruit Fly
Although everyone spends about a third of their life sleeping, the function of sleep remains mysterious. Sleep deprivation is an increasing concern in modern societies, and deleterious effects of sleep deprivation on attention and performance can be as tragic as the consequences of excessive alcohol consumption. We have developed sleep models in Drosophila melanogaster, and are investigating how sleep and attention are mechanistically related in the fly brain. We are currently working on models to induce sleep on demand. We have also discovered different sleep stages in Drosophila, and hypothesise that these accomplish distinct functions. Image: flies sleeping deeply, or lightly, in tubes.
Most of us will undergo general anaesthesia at some point in our lives. Despite being used for over 180 years, mechanisms of general anaesthesia are still not fully understood. We propose that general anaesthesia is a two-step process, whereby sleep (thus loss of consciousness) is produced first, followed by impaired neurotransmission across the brain. It is this second step, loss of synaptic coordination, which makes surgery possible, and which produces the recovery inertia typical after surgery. To understand general anaesthesia thus requires linking local effects at synapses and circuits to whole-brain consequences. Image: single particle tracking of syntaxin1A in fly larva synaptic boutons.
Neural circuits for locomotion
As animals walk, run, or hop, motor circuits in the spinal cord convert descending “command” signals from the brain into the coordinated movements of many different leg muscles. How are command signals from the brain deconvolved into the appropriate patterns motor neuron activity? We aim to answer this question for Drosophila by studying the functional organization of leg motor circuits in the ventral nerve cord, the fly’s analogue of the spinal cord. In Drosophila, individual neuronal cell types can be reproducibly identified and manipulated using genetic reagents that have been developed to target specific descending neurons, interneurons, or motor neurons. We use methods including genetics, multiphoton imaging, optogenetics and quantitative behavioural analysis to elucidate the structure and function of the motor circuits controlled by a specific class of descending neuron. (See more: https://qbi.uq.edu.au/dicksongroup. Image: neuron types in the fly nerve cord