It is unlikely that anyone interested in brain research would not have heard of the “American Crowbar Case" concerning Phineas P. Gage, an American railroad construction foreman who miraculously survived an accident in which a large iron rod penetrated his skull, destroying much of his left frontal lobe. While the injury did alter Gage’s personality and behaviour, it also underscored the brain’s ability and flexibility, or plasticity, to survive accidents and function.
Since then, there have been numerous documented instances and studies to demonstrate how the brain rewires itself after an injury, reinforcing the theory of its flexibility. That the brain can also switch between habits and choices was pointed out by Medical University of South Carolina researchers in the 16 March edition of The American Council On Science And Health journal.
Some researchers have suggested that it may be this very flexibility that helps humans outlearn chimpanzees. According to a December 2015 study published in the Proceedings Of The National Academy Of Sciences Of The United States Of America journal, “This anatomical property of increased plasticity (of the brain), which is likely related to the human pattern of development, may underlie our species’ capacity for cultural evolution."
It was hardly surprising, then, that an August 2017 study by the Harvard Medical School noted that the “brain may be far more flexible than thought" when it comes to forgetting, or retaining, memories. The study was conducted not on humans, but on mice navigating a maze. This is perhaps why many researchers consistently caution that no one really knows how the brain reorganizes as you learn new tasks.
On a contrarian note, Carnegie Mellon University (CMU) and University of Pittsburgh researchers believe that the brain is less flexible than previously thought. The research, published in Nature Neuroscience, examined the changes that take place in the brain when learning a new task, according to a 21 March press release.
The researchers made their subjects use a brain-computer interface (BCI) to move a cursor on a screen with only their thoughts—an exercise at which subjects improved with practice. The idea was to investigate how the activity in the brain changed during learning, enabling an improvement in performance.
“In this experimental paradigm, we’re able to track all of the neurons that can lead to behavioural improvements and look at how they all change simultaneously," says Steve Chase, an associate professor of biomedical engineering at CMU. “When we do that, what we see is a really constrained set of changes that happen, and it leads to this suboptimal improvement of performance." This implies, he adds, that “there are limits that constrain how flexible your brain is—at least on these short time scales".
According to the researchers, our neurons are wired in such a way that they do not allow us to become instantaneously proficient when learning a new task. “Just as it takes time to train a person to swing a squash racket like an expert, it takes time to train one’s neurons to produce the ideal activity patterns," says Byron Yu, associate professor of biomedical engineering and electrical and computer engineering at CMU. “When faced with a new task, we’re finding that the brain is constrained to take the neural activity patterns that it’s capable of generating right now and use them as effectively as possible in this new task," he adds.
According to Aaron Batista, an associate professor in the department of bioengineering at the University of Pittsburgh, “Learning over the course of a few hours is suboptimal," because acquiring a skill is difficult, and takes time and practice.
The researchers suggest that by repurposing neuron patterns, which it’s already capable of generating, the brain applies a “quick and dirty fix" to the new problem it’s facing.
Cutting Edge is a monthly column that explores the melding of science and technology.