Sensory processing during sleep

Sensory systems act as an interface between an organism and its environment, communicating relevant information to instruct

appropriate behavioural outputs, such as locating food, a mate or evading danger. Remaining alert to cues present in the

environment is therefore paramount to survival and is a need that prevails even during sleep. To benefit from the restorative

properties of sleep, animals transition into an unconscious state which is characterised by a marked sensory disconnection from the

world. This leaves them not only vulnerable but less able to respond to cues which may have a direct impact on their fitness. How do

animals balance the need to sleep with other competing behavioural drives? One solution is to remain partially awake, which some

animals achieve by sleeping one brain hemisphere at a time. Others, including humans and even fruit flies can rapidly wake up upon receiving salient information, implying that some sensory neurons may act as awake "sentinels".

Using the fruit fly olfactory system as a sensory-arousal model, I will determine which olfactory pathways have a privileged role in

waking and whether the neurons involved exhibit distinctive physiological properties or differentially connect to arousal centres.

Secondly, I intend to investigate the plasticity of wake promoting pathways and ascertain whether learned as opposed to innate

valence can be integrated into this circuit. Lastly, I will address whether the arousal system has evolved in closely related yet

ecologically discrete fruit fly species. Fly chemosensory systems evolve rapidly and whether valence encoding during sleep has been

translated appropriately across species borders, remains to be seen: Do different species wake to cues that are relevant to their

ecology? This work promises to delve into an unexplored realm of sensory neuroscience and offer mechanistic explanations for a phenomenon that enables animals to benefit from sleep yet mitigate the challenges it poses.