The more detail we can get on the inner workings of the brain, the better our chances of understanding and treating it, and scientists have just unveiled a new high-definition recording probe that's thinner than a human hair.
Its developers say the extra accuracy could revolutionise our insight into the brain's wiring, mapping neural networks in ways that haven't been possible before, and showing us how different brain activities relate to different behaviours.
The new silicon probes are called Neuropixels, and according to the international team behind them, they could prove invaluable in figuring out how diseases like Alzheimer's and conditions such as depression take hold of the brain and interfere with its normal function.
"To understand the brain, we need to understand how a lot of neurons spread all over the brain work together," says one of the researchers, Matteo Carandini from University College London in the UK.
"Until recently, it was possible to measure the activity of individual neurons within a specific spot in the brain or to reveal larger, regional patterns of activity – but not to do both at the same time."
A Neuropixel with attached processing unit. (imec)
These wafer-thin probes measure 10 millimetres (0.39 inches) in length and are just 20 micrometres thick (that's 0.00078 inches).
Despite their small size, they pack in 100 tiny, super-sensitive recording spots per millimetre, enabling them to map the brain in incredible detail as well as automatically getting data ready for computer analysis in real-time, as neural activity happens.
Compare that with the wire electrodes in use today, which only have a few dozen sensors fitted to each one.
"To give a basic analogy, these probes move us from the era of small black and white TV sets, to large, high-resolution flat screen displays," says one of the researchers, Andrew Welchman from the Wellcome Trust in the UK.
"Neuropixel probes will change what we know and even how we think about the brain."
And there's still plenty left to discover about how this most important of organs, fitted with more than 70 billion neurons, actually works – we're learning all the time about the roles of different areas of the brain, how the brain deals with waste and disease, and how it can heal itself.
From next year, Neuropixels will be made available to scientists at cost price, and 400 prototypes are already in use at research centres across the globe. For now they're being used solely on mice and rats, animals with brains known to be good models for the human brain.
The Neuropixels will allow experiments over long time periods, without restricting the animals: researchers have already shown how animals fitted with the sensors can move around freely, and one experiment lasted 150 days.
Another planned study will look at mice foraging for food, and will be able to map data from multiple labs to simultaneously record the activity of 1,000 neurons in mice, covering the animals' entire brains as they all carry out the same task.
Eventually, this high-resolution mapping technique should give us a better idea of how emotions are regulated and how decisions are made, as well as all kinds of other insights.
"These probes are a game changer," says Carandini. "If you place them appropriately, you can really study how different parts of the brain work together at the neuronal level."
The research has been published in Nature.