Summer Blog Serie together with the 3RCC , Part 3: Unravelling the Brain’s Dance with Time: Insights from Fruit Flies

In every living being, from humans to tiny bacteria, a rhythmic pattern of activity and rest is primarily guided by light signals. For instance, humans wake up and become active during the day when sunlight is present, while nocturnal animals, such as bats, exhibit increased activity at night. This orchestration of daily rhythms is managed by a tiny brain structure known as the suprachiasmatic nucleus. We will call this the ‘brain clock’ for simplicity. Until recently, scientists believed that the cells within this brain region operated independently. However, groundbreaking research from Peking University, published in Science Advances, has challenged this assumption.

A study by Min Tang and colleagues found that certain areas of the brain, outside the ‘brain clock’, can influence its rhythm. They demonstrated this using fruit flies, which have long been ideal for such research due to their simple brain structure, comprising just 150 neurons. To measure how neurons synchronized their activity, the researchers employed a technique called multiple-electrode patch-clamp recordings. This method allowed them to record the activity of multiple individual neurons simultaneously. The question was: would neurons without access to the ‘brain clock’ demonstrate a daily rhythm? Remarkably, synchronised neural activity persisted even in the absence of the ‘brain clock’ in genetically modified flies. This significant finding sheds light on fundamental body functions and highlights the fruit fly as a valuable model for studying brain functions.

The discovery that some neurons outside the ‘brain clock’ contribute to synchronizing rhythms challenges previous beliefs about its mechanism. This discovery not only enhances our understanding of how daily (“circadian”) rhythms are regulated in the brain but also underscores the importance of further research, particularly in mammals. Notably, early studies on circadian rhythms, including the identification of clock genes, were pioneered in fruit flies, laying the groundwork for subsequent research in mammals. This deeper understanding holds promise for developing treatments for circadian disorders, which disproportionately affect older adults.

Authors : Christopher Cederroth, Jessica Lampe & Robbie I’Anson Price, Swiss 3R Competence Centre

Reference: Tang M et al. (2022) An extra-clock ultradian brain oscillator sustains circadian timekeeping. Science Advances. 8:eabo5506. https://doi.org/10.1126/sciadv.abo5506.