Psychology In The News | Mapping Insect Brains

Scientists have achieved a groundbreaking milestone in neuroscience by mapping the entire brain of a fruit fly, identifying the position, shape, and connections of 130,000 neurons and 50 million synapses. This accomplishment represents the most detailed analysis of an adult animal brain to date.

The research, published in the journal ‘Nature’, involved an intricate process of cutting a fly brain into 7,000 incredibly thin slices, imaging each slice, and then using artificial intelligence to reconstruct the neurons and their connections. This comprehensive map, known as a 'connectome', provides unprecedented insights into how brain networks process information and interact, which is crucial for understanding cognition and behaviour.

Researchers have mapped nearly 140,000 neurons in the fruit-fly brain. This version shows the 50 largest. Credit: Tyler Sloan and Amy Sterling for FlyWire, Princeton University (Reference 1)

Although the human brain has a million times more neurons than a fly's (there are 80 billion neurons and 100 trillion connections in humans), the insights from this study could help explain how we process information and pave the way for mapping larger brains, like those of mice or eventually humans.

The connectome highlights specialised circuits for various functions, including movement and vision, and reveals how these circuits are interlinked. One particularly interesting finding explains why flies are so difficult for humans to swat. The research shows that a fly's vision circuits rapidly detect the direction of incoming threats, such as a swatting hand or newspaper. These circuits then send immediate signals to the fly's legs, with a stronger jumping signal sent to the legs facing away from the approaching object. This allows the fly to jump away without needing to ‘think’ about it, reacting faster than the speed of thought. This pre-programmed escape mechanism gives flies a significant advantage over the relatively slow movements of humans trying to swat them.

This discovery not only explains a common frustration for humans but also demonstrates the practical applications of such detailed brain mapping. It shows how specific behaviours and abilities can be linked to neural circuitry, even in a brain as small as a fly's.

Scientists now aim to use this data to better understand brain function and dysfunction in more complex organisms, including humans. While a human connectome may take decades to complete, this fly study marks a key milestone in unlocking the mysteries of the brain.

The research team, known as the FlyWire Consortium, has made the fly connectome available to scientists worldwide. This open access is expected to accelerate neuroscientific discoveries and improve our understanding of both healthy and diseased brains. Researchers anticipate an ‘avalanche of discoveries’ in the coming years, thanks to this new map.

This ground breaking effort represents a significant leap forward in neuroscience, offering new insights into the complexity of neural networks and paving the way for future advancements in our understanding of brain function across species.

ANSWER THE FOLLOWING QUESTIONS!

1. The research on fly brains revealed specific circuits for functions like movement and vision. How does this relate to the concept of localisation of function in the human brain?
2. The article mentions the use of AI and imaging techniques to map the fly's brain. How do these methods compare to the ways of studying the human brain that you may have studied, such as EEGs and fMRIs?
3. The fly's rapid escape response is described as happening ‘faster than the speed of thought’ How might this relate to the fight or flight response in humans? Consider the role of the autonomic nervous system and adrenaline in this context.
4. The full reference for this study is included in the section below (in number 1). What is missing from the reference?

References:

1. Dorkenwald, S., Matsliah, A., Sterling, A.R. et al (2024) Neuronal wiring diagram of an adult brain. 634, 124–138 https://doi.org/10.1038/s41586...
2. Fly brain breakthrough 'huge leap' to unlock human mind https://www.bbc.co.uk/news/art...;(accessed 17.10.24)