Breakthrough scanning technique allows researchers to look deeper into the brains of living organisms
A team of researchers from the University of Zurich, Switzerland, have developed a non-invasive infrared scanning technique that allows them to produce images of the fine structure of the brains of living mice in unprecedented detail.
Dubbed ‘diffuse optical localisation imaging’, or DOLI, the technique is based upon a method of imaging known as fluorescence microscopy. In fluorescence microscopy, beams of high intensity light are directed at a fluorescent substance known as a fluorophore. The light is absorbed by the fluorophore and then emitted at a lower wavelength. This emitted light can then be filtered out from any surrounding radiation and used to construct an image.
The technique has previously been used to image the brains of animals, but it was only able to image small areas at low resolutions due to the light being scattered by the animals’ skin and skulls.
To overcome this, the team at Zurich used cutting-edge infrared cameras that can penetrate deeper into the animals’ brain than previous devices and therefore experience far less scattering.
They tested their technique by injecting microscopic fluorophores into the bloodstreams of living mice. By tracking these particles as they flowed through the animals’ brains using the new infrared cameras, they were able to construct a detailed image of the organs’ fine microvascular structure.
“Our study represents the first time that 3D fluorescence microscopy has been performed fully noninvasively at capillary level resolution in an adult mouse brain, effectively covering a field of view of about one centimetre,” said study team leader Prof Daniel Razansky.
“Enabling high-resolution optical observations in deep living tissues represents a long-standing goal in the biomedical imaging field. DOLI’s superb resolution for deeptissue optical observations can provide functional insights into the brain, making it a promising platform for studying neural activity, microcirculation, neurovascular coupling and neurodegeneration.”