Traditional understandings of the human brain tend to portray it as the most breathtakingly complex biological machine on the planet. Like all machines, it consists of a series of bounded components – or brain regions – each of which performs a particular task. However, a new study published in the journal eLife suggests that the barriers between these regions may not be as rigid as previously thought, and that by learning complex tasks it may be possible to reorganize the way the brain works.
Inspiration for the study came from previous research that provided evidence that the neurons of the visual cortex, which are normally responsible for processing visual information, can become “retuned” in blind people, adapting for other tasks such as processing tactile sensory input received when reading Braille. As such, the study authors sought to determine if the same effect could be achieved in sighted people learning to read Braille.
To achieve this, they enrolled a number of volunteers on a nine-month Braille reading course, during which they attained a high level of proficiency. The researchers then used functional magnetic resonance imaging (fMRI) to measure the brain activity of participants while reading Braille.
According to the “mechanical” model of the human brain, extensive training in tactile-based reading techniques should produce an increase in activity in the somatosensory cortex, as connections in this part of the brain would be expected to have become strengthened. However, results showed that reading Braille actually corresponded to an increase in activity in the visual cortex of highly practiced individuals, suggesting that this brain region can be trained to process non-visual stimuli.
Much of this activity was found to be based in the visual word-forming area (VWFA), a part of the visual cortex that is heavily involved in visual reading, thereby indicating that the neurons responsible for this function can learn to process other types of sensory inputs.
To confirm these results, the researchers then used a technique known as transcranial magnetic stimulation to inhibit the activity of neurons in the VWFA and the visual cortex in general, and found that this reduced participants’ ability to read Braille.
To a certain extent, these results redefine our understanding of the division of labor between brain regions, indicating a much higher level of flexibility than the brain had previously been given credit for. Furthermore, the researchers propose that this cognitive retuning – or “cross modal plasticity” – may be largely responsibility for humans’ unrivaled ability to learn new tasks.
For instance, they point to previous research that revealed that the morphology of the cerebral cortex is less genetically defined in humans than in chimpanzees, suggesting that the wiring of our brains may be highly influenced by cognitive training.
