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Experiments suggested that very low-level electrical stimulation to the back of the head could improve a person’s mathematical skills.
Dr Christopher Chambers, BBSRC David Phillips Fellow, School of Psychology, Cardiff University, said:
“”This is a really intriguing finding, showing that brain stimulation can boost numerosity skills, enhancing the ability to learn the link between arbitrary symbols and numbers, and then processing the symbols as though they actually are numbers. The findings add to a growing body of research showing that certain types of brain stimulation, in certain contexts, can enhance brain function.
How do the findings represent an advance over previous research?
“Most studies in this field, and in brain stimulation generally, focus on temporarily disrupting or impairing function. This tells us which parts of the brain are important for everyday abilities. But the researchers in this case focused on boosting ability, which has important implications for enhancing these skills in clinical and healthy populations.
How are the approaches unique?
“The method used by the authors, transcranial direct current stimulation, is rising in prominence in neuroscience. For many years it has been known that TDCS can induce neuroplasticity in the brain, but it hasn’t been until recently that the method is being applied to study higher cognitive functions.
What are the broad implications?
“One obvious implication for these findings lies in the development of methods for enhancing numerical skills in the general population, even for those who are not clinically impaired. Brain stimulation methods, like TDCS and transcranial magnetic stimulation, also have a lot of potential applications in promoting recovery following brain injury or developmental disorders.
“The results of this study also have exciting ramifications for the use of brain stimulation techniques in other domains, including attention and other aspects of human cognition. The ability to tweak activity in parts of the brain, turning it slightly ‘up’ or ‘down’ at will, opens the door to treating a range of psychiatric and neurological problems, like compulsive gambling or visual impairments following stroke.
What are the unanswered questions?
“The results are fascinating but, as with all studies that report new and interesting phenomena, they raise a lot of questions. One issue here is how the effect arises in the brain. The researchers in this case boosted number skills after stimulation was given to the left and right sides of the brain at the same time, turning the left parietal lobe down and right parietal lobe up. So which had the greater effect, the upward or downward change in brain activity? We know that the way the two halves of the brain communicate is fundamental for a range of everyday abilities, including attention and the representation of space, and the relationship is complex. So it could be that their brain stimulation protocol altered something critical about the flow of information between the brain hemispheres.
“It will be important in future work to stimulate each hemisphere separately and see if the results can be replicated. It would also be interesting to combine the methodology here with a technique called magnetic resonance spectroscopy, which allows us to measure the concentration of different chemicals in the brain. Other research groups are making great strides in understanding the physiology of brain stimulation using this approach.
What would critics say?
“A critic could argue that while the results show an enhanced association between arbitrary symbols and numbers, they don’t necessarily isolate number skills because the effects of brain stimulation weren’t compared with a non-numerical task. This is still an exciting new piece of research, but if we don’t know how selective the effects of brain stimulation are then we don’t know what other brain systems could also be affected, either positively or negatively.
“To draw the more specific conclusion that brain stimulation selectively enhances number skills following learning, you would need to compare the effects of stimulation on a number versus a non-number task, making sure that each task required the person to learn an association between concepts and arbitrary symbols. Instead the authors controlled for general enhancement of perceptual and cognitive abilities by testing the effect of brain stimulation on processing of everyday digits (1,2,3 etc), but naturally these don’t need to be learned, which may explain why this ability was unaffected by brain stimulation.
“So while the results are exciting, I think it remains to be seen whether the effects are specific for numerical competence, or whether they translate to other abilities that depend on learning.
“Also, one of the most remarkable results was that the group who showed enhanced learning for numbers continued to show effects on numerical ability even after six months. Most likely this isn’t due to a long lasting effect of brain stimulation itself, but rather that brain stimulation given six months before helped the associations form clearly in memory.
“This is good news for those wanting to develop tools for clinical intervention. To others, however, this will raise the question of what changes might have also taken place in the group that showed abnormal number skill after brain stimulation. Were they still abnormal after 6 months? It isn’t clear whether the researchers asked the impaired group back to repeat the experiment, but obviously the persistence of any long-term effects (whether positive or negative) serve to remind us that while we focus on the important task of optimising brain stimulation protocols, making them more effective and long-lasting, we need to keep in mind the safety implications of these methods.”