A brain-recording device with a quantum diamond sensor has been used to measure neural activity in mouse brain tissue. The device is less accurate than standard brain-imaging techniques, but if it can be improved, it could be useful for non-invasive brain scanning.
The most common technique to study how neurons interact with each other is to directly measure their electrical signal, typically by inserting tiny wires into a tissue sample. But this method might alter neural activity, confusing the picture about what is going on, so a non-invasive method would be preferable.
One possible method is by using a modified diamond that shines more or less brightly depending on the brain-generated magnetic field passing through it due to a quantum mechanical quirk: certain defects in the diamond have their electron spin affected by external fields, which shows up as luminescence. This has been previously done with giant squid and , but has yet to be demonstrated on mammals.
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The mouse brain tissue is much more delicate, says at the Technical University of Denmark, near Copenhagen. 鈥淚t鈥檚 biologically much more complex than other types of tissue and it鈥檚 also much more intriguing because it鈥檚 kind of close to how our human tissues function and work.鈥�
Huck and his colleagues developed a quantum diamond sensor to measure the activity of mouse nerve cells. They tested it on axons 鈥� connections between nerve cells 鈥� in a slice of brain from a region of the organ called the corpus callosum, which connects the two hemispheres. By placing the scanner over the tissue sample, after 300 trials, the team recorded neural activity that was largely in agreement with data from inserted wires.
While the sensitivity and resolution 鈥� it can only detect the signal from groups of neurons rather than individual ones 鈥� were worse than current methods, Huck says an improved sensor could help us observe what happens in brain samples at the microscopic scale, where you must be very close to the neurons in order to measure them, without adversely affecting them.
at the University of Oxford questions whether this method really would be non-invasive, because it works with brain slices, rather than on whole brains. 鈥淥btaining acute brain slices from an intact mouse brain is orders of magnitude more disruptive than inserting wires or loading dyes into the brain slices for experiments,鈥� he says.
鈥淭here are still substantial hurdles that need to be overcome until, if ever, this becomes a usable technology for recordings from single neurons in the intact brain,鈥� says at University College London.
The lack of resolution also means the method is unlikely to replace any current brain-recording or imaging techniques, says Viney. However, novel approaches to brain imaging have led to breakthroughs in the past, so developing the quantum diamond sensor could one day result in new techniques, he adds.
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