Optical Topography and the Color of Blood
OT gives neuroscientists a new and faster view of the brain, and an alternative to fMRI
By Laura Spinney
Anyone who has been subject to a magnetic resonance imaging (MRI) scan knows its limitations: the claustrophobia-inducing tunnel, the machine gun rattle, the instruction not to move - none of which is conducive to relaxation. For confused patients and newborn babies, MRI scans are not possible, and researchers who study movement or hearing are severely restricted in what they can test. Now, an alternative noninvasive brain-imaging technique called optical topography (OT) is illuminating areas of brain function previously considered inaccessible and exploding some myths about brain development at the same time.
"The concept of optical topography is really unique," says Atsushi Maki, a cognitive neuroscientist at the Hitachi Advanced Research Laboratory in Saitama, Japan, where OT has been under development since 1987. "It is small, easy to use, and it can measure brain function under natural conditions, from neonates to older people."
It was with the idea of bringing brain imaging into the clinic and daily life that Hitachi put its faith in OT to begin with, says Maki. Its investment seems to be paying off. OT is already in routine clinical use, and even veteran users of functional MRI (fMRI) are turning to OT as their preferred tool for certain kinds of research. "Eyeballing it, it's fantastic," says Brian Butterworth of the Institute of Cognitive Neuroscience in London. "Unlike with fMRI, you can actually see a reconstruction of the blood flowing as it happens."
Actually, both techniques measure the brain's hemodynamic response. But where fMRI measures the difference between the iron content of oxy- and deoxyhemoglobin in blood, based on the metal's response in a magnetic field, OT relies on the different light absorption characteristics of the two forms. "We are measuring the color of blood," says Maki.
Full Text at TheScientist
Robert Karl Stonjek
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