BrainCast · Sussex Neuroscience Society

Circadian Rhythms and the Biological Clock: Understanding Sleep Patterns with Dr. Rzechorzek

·42 min·2 clips

A four-dimensional map showed about 2.5 degrees of difference between the hottest and coolest parts of the human brain.

1. BrainCast speaks with Dr. Jacques Ojec about circadian rhythms, human brain temperature, and sleep-pattern research. 2. Dr. Jacques Ojec is a clinician-scientist who worked at the MRC Laboratory of Molecular Biology in Cambridge and is now at AstraZeneca, which matters because he spans basic science and drug translation. 3. The episode asks what normal human brain temperature is and how that question connects to tau, hibernation, and neurodegeneration. 4. Ojec says schoolwork experience in the late 1990s, during the BSE crisis, first hooked him on brain research and progressive neurodegenerative disorders. 5. He studied physiology at Edinburgh, where he was drawn to molecular neurodegeneration and brain plasticity inside a vibrant neuroscience community. 6. He also did veterinary work at Edinburgh Vet School on equine respiratory disease and equine grass sickness, a disorder involving selective degeneration of the autonomic nervous system. 7. A medical expedition to high altitude in the Bolivian Andes took him to 5,200 meters, where he led a team and collected sleep data with the charity Apex. 8. His career then moved through veterinary practice in Warwickshire, a PhD in the Chandran lab at Edinburgh, and specialty training in veterinary neurology and neurosurgery near Roslyn. 9. The PhD focus was tau protein, which he links to Alzheimer’s disease, frontotemporal dementia, microtubules, and insoluble aggregates in neurons. 10. A paper from Thomas Arendt’s lab in Leipzig on wild-type tau in hibernating ground squirrels shifted his thinking toward reversible tau changes in a normal physiology. 11. He describes brain connections in hibernating animals as physically coming apart and then faithfully rejoining during arousal, which he calls mind blowing. 12. That line of work used human cortical neurons grown from stem cells and exposed them to temperatures resembling moderate hypothermia and suspended animation. 13. He says cooling changed tau protein while also increasing cold-shock RNA-binding proteins and making cells better able to handle oxidative stress and excitotoxic chemicals. 14. By the end of the PhD, he could not find primary evidence for the assumption that normal human brain temperature is 37 degrees. 15. He then worked with Dr Jonathan Rhodes at NHS Lothian, plus Centre TBI collaborators, on directly measured brain temperature from traumatic brain injury patients. 16. He also used MRS thermometry with Dr Michael Thrippleton and Professor Ian Marshall at Edinburgh Imaging to measure temperature across the whole day and across multiple brain regions. 17. The prospective study included equal numbers of males and females, checked menstrual-cycle phase with urine testing, and controlled for chronotype using wrist-worn actigraphy. 18. The first four-dimensional map of human brain temperature showed about 2.5 degrees between the hottest and coolest parts of the brain, daily drops near predicted sleep time, and a rise in mean temperature from ages 20 to 40. 19. Ojec describes circadian rhythms as cell-autonomous oscillators that are responsive to external cues, temperature compensated, and studied in neurons, astrocytes, microglia, and cerebral organoids with Bit Bio and Dr Lancaster’s work. 20. The episode uses an interview style with detailed method explanations, and it will suit listeners interested in sleep, neuroscience, and biological timing while likely skipping those wanting a short celebrity-style chat.

As heard by us

A measured tour of brain temperature, circadian rhythms, and the limits of measuring living biology.

BrainCast centers on human brain temperature and daily rhythms, then keeps circling back to the harder question of what can actually be measured in a living brain.

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If you want brain-temperature science that takes measurement limits seriously, this is your lane.

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