This type of brain imaging, fMRI, is considered the gold standard in research on the brain (and is used in many of the studies on meditation’s effects on the brain). I find it fascinating, and I’m glad to find more and more articles in less-technical jargon talking about it.
Can a brain scanner decode your inner thoughts?
By Daniel Bor
As a favor to friends in my academic department, the MRC Cognition and Brain Sciences Unit in Cambridge, UK, I’ve frequently been a guinea pig in the fMRI scanner. Normally I fight valiantly against slumber as the stimuli flash on the small screen in front of me and the hypnotic, high-pitched beeps of the scanner reverberate around me. This time, though, it was very different. This time, my colleague Martin Monti was going to read my mind. As the bed I lay on robotically slid into the giant donut shape of the scanner, I had a strange sense that I was about to be mentally naked.
The task was simple: for each upcoming scan in the session, Martin would ask me either to imagine that I was playing tennis, or that I was moving around the rooms of my home. These two mental tasks activate very similar regions to actually carrying out the activity – mainly motor regions for tennis and navigation regions for roaming about a building. And because the brain scans of these two different tasks look totally different, Martin was going to guess my thoughts from my neural activity alone. When each scan was finished, and Martin accurately ascertained the contents of my imagination, the experience was thrilling and unnerving in equal measure.
In 2006, Adrian Owen, of the same department, has already used a similar technique to prove that a patient with a diagnosis of persistent vegetative state was in fact conscious. One day soon, it should be possible even to communicate with such patients, where no other means are available, by linking, say, imagining tennis, with a yes answer, and imagining moving around a building with a no answer. Similar methods are being used to train patients with motor neurone disease (also known as amyotrophic lateral sclerosis, or ALS), whose motor functions are slowly failing, to control a communication interface by thought alone.
This feat of scientific telepathy was largely unheard of a decade ago. But now, in various guises, it is taking over the field. What has caused such a revolution in brain-scanning? The simple answer is that over the last five years, the way that many researchers analyze their brain-scanning data has radically shifted.
fMRI datasets can be vast. There might be 100,000 3D pixels, called voxels, in each brain activity image, with a new image being taken every 2 seconds – for up to an hour. Then there will be around 20 subjects in a study, which equates to perhaps 4 billion different voxels to examine in total. The traditional, common way of breaking this problem down is to go back to just one of those 100,000 voxels in each image, in one location across subjects, and see whether it will rise or fall in activity over time, in accord with the mental fluctuations under study.
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