Looking for a challenge? Try getting a monkey to sit perfectly still and perform a thought task inside a claustrophobic banging magnet that scans brains. Now the success of two teams--reported in next week's NeuroReport and the June Neuron--could ultimately help scientists get more out of functional magnetic resonance imaging (fMRI) of human brains.
By monitoring the magnetic signals of oxygen in the bloodstream, fMRI records changes in blood flow resulting from neural activity. But what individual neurons are doing in the areas that light up on an fMR image is an open question, because researchers can't stick electrodes into the brains of healthy people. "Monkey fMRI will allow us to test our interpretations," says neuroscientist Robert Desimone, who directs intramural programs at the National Institute of Mental Health.
The first monkey fMR images, which show the visual cortex lighting up as the animal watched a children's cartoon, don't offer any new scientific insights--just a proof of principle. To make them, a team led by Tom Albright of the Salk Institute and the University of California, San Diego, and one headed by Richard Andersen at the California Institute of Technology in Pasadena, separately designed chairlike apparatuses made of nonmagnetic materials that hold the monkey still inside the magnet. "We worried that it would be difficult to get the monkey to cooperate," says Albright, but they found that by rewarding the monkey with juice, they were able to train it to relax in the magnet.
The technique should eventually benefit traditional electrode studies of monkey brain activity by helping to identify the brain regions worth probing, Albright says. But for now, he says, "the important thing was to show we could do it."