Spatiotemporal imaging of neuronal and glial signals in the mammalian master circadian clock at multiple timescales

The mammalian master circadian clock in the suprachiasmatic nucleus (SCN) orchestrates circadian rhythms in physiology and behaviour to maintain health and well-being. The SCN generates circadian rhythms across the brain and body by producing 24-hr oscillations in clock gene expression. This drives SCN neurons to become depolarised, firing at high rates with elevated intracellular calcium ([Ca2+]i) during the day and more hyperpolarised, spiking at lower rates with low [Ca2+]i at night.

This daily contrast in SCN neurophysiology is critical for SCN clock function and blunts during ageing and disease.

For the SCN to function as the brain's master clock, SCN neurons must appropriately coordinate the dynamical interactions and daily oscillations in their ionic, [Ca2+]i, clock genes, and protein signalling that occur at multiple timescales (from the ultra-slow to fast rhythms) and across specified spatiotemporal frequency domains. Overtly, this is achieved through ([Ca2+]i,) signalling as well as synaptic, extra-synaptic, and neuropeptidergic communication across the SCN neuronal and glial circuit.

Remarkably, although these cellular timing events are critical for our sense of daily rhythm, when and how they interact to generate and coordinate circadian rhythm in the SCN, and brain, remains poorly understood.

These pivotal questions are the focus of this PhD CASE studentship, and the combined expertise of this supervisory team, and expertise, training and resources from our partner and collaborator Cairn Research Ltd make these following specific key objectives attainable:

1) Determine the spatiotemporal relationship between the daily electrical, [Ca2+]i, and clock gene activity in single SCN neurons, and across SCN circuit.

2) Determine when and how the synaptic, extra-synaptic and peptidergic neurochemicals, that are intrinsic or extrinsic to the SCN, sculpt the spatiotemporal relationship between the daily electrical, [Ca2+]i, and clock gene activity in the SCN.

3) Develop sophisticated mathematical and computational models to understand the spatiotemporal relationship of the biological signals measured in objectives 1 and 2.

The overarching aim is to generate important understanding in when and how rhythms at multiple spatiotemporal frequency domains regulate SCN neurophysiology, clock gene expression, and behaviour, using sophisticated and state-of- real-time imaging, computational modelling, and appropriate animal models.

Working in Belle's and Bano-Otalora's labs, the student will receive training in sophisticated and state-of- real-time long-term clock-gene and [Ca2+]I, imaging in SCN brain circuit, and data analysis. These will be coupled with optogenetics, chemogenetics and pharmacology stimulation (all techniques and animal models are established). We are in the process of establishing membrane voltage reporter imaging in our labs in collaboration with Cairn Research Ltd.

Working in Storchi's lab, the student will receive training in sophisticated machine-learning AI-driven data assimilation and analysis, and mathematical/computational modelling. The student will also be trained in large-scale in vivo recordings where the activity of thousands of neurons can be simultaneously recorded and analysed (mouse lines are already established).

The students will also work alongside mathematical biologists who are Belle's and Bano-Otalora'slabs long-term collaborators to continue modelling work on important aspects of the project (some of the scripts and modelling pipelines are already established). Working with Cairn Research Ltd, we would use the latest imaging and illumination technologies, while being supported by expert engineers, software programmers and scripts coders.

This will also provide opportunities for the student to obtain training in computational neuroscience.