How are images and movements, in fact, memories in general, processed, recorded and stored in the brain? This is a question which has been asked repeatedly by neuroscientists for centuries. Recent experiments from the last year are bringing us closer to the answer.
When we ‘see’ something, our eyes transfer signals via the optic nerve to the visual center of the brain, which, like every part of the brain, is made up of nerve cells called neurons. This brain region processes and visualizes these signals, thus enabling us to recognize and classify objects. This processing occurs by the neurons ‘firing’, i.e, they transfer electrical signals between each other in a pattern that depends on the image being processed. Scientists have developed a procedure called Functional magnetic resonance imaging (fMRI) to map this neuronal activity.
fMRI, a variant of the MRI scans record brain activity by detecting the changing blood flow in the brain using magnetic fields. The magnetic fields produced by blood rich in oxygen differ from those produced by blood poor in oxygen. The balance between oxygen-rich and oxygen-poor blood indicates the level of brain activity. fMRI can zero down to within a few millimetres of the active regions in the brain.
In 2011, researchers at the Gallant lab at the University of California (Berkeley) have observed dynamic neuronal activity patterns in the brain while patients are shown short movies. Described in the journal Current Biology, they first recorded the temporal neuronal patterns for
a number of movies, to try create ‘dictionaries’ (in terms of the observed neuronal pattern) for each scene along with the shapes, colours and edges in it. In other words, they tried to correlate electrical patterns both with the ‘big-picture’ depiction of the scene and with elements in it like
shapes and contours. Then, they tried to find out if they could predict the reverse direction- conjuring movies from brain patterns. The data from the fMRI scans for each movie was fed into a computer to create these ‘dictionaries’. Subjects were then asked to imagine a sequence from a movie that had been shown to them earlier. When patterns from their brain scans were recorded and transmitted to the ‘decoder’ computer, it could reconstruct the scenes they had been imagining with a fair amount of accuracy. With some science, imagining something could bring it to life.
Such studies can be extended beyond visual sensing to any form of brain activity, which could lead to direct communication to and from the brain via a computer. These could have great potential for improved and reliable lie detection tests, speech-impaired patients and perhaps even communication for paralysed patients. Decoding the language in which the brain converses is an important step forward in understanding the mechanisms of the brain.
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