A weak electrical signal can boost people's powers of mental arithmetic over a period of months, suggests a small scale study at the University of Oxford.
The technique involves placing electrodes on the scalp of the head and applying random electrical noise to stimulate parts of the brain and encourage nerve cells to fire. In this case the electrodes were placed on the head to target regions of the brain known to be involved in doing maths.
Dr Roi Cohen Kadosh of the Department of Experimental Psychology at the University of Oxford, who led the research, says the brain stimulation technique called transcranial random noise stimulation (TRNS) is painless, non-invasive and relatively cheap.
The group asked 51 Oxford students to perform two arithmetic tasks over a five-day period that tested their ability to perform calculations in their head and learn arithmetic facts by heart. 25 participants took part in the main experiment and 26 in a control experiment.
The study was designed to test whether TRNS applied while performing the mental arithmetic tests each day had an effect.
'We found that with just 5 days of TRNS-accompanied cognitive training, we were able to bring about long-lasting improvements in cognitive and brain functions,' says Dr Cohen Kadosh.
Performance on both the calculation and rote learning tasks improved over the 5 days. The improvements in performing mental calculations lasted for 6 months after the training.
Dr Cohen Kadosh adds: 'Our neuroimaging results suggested that TRNS increases the efficiency with which stimulated brain areas use their supplies of oxygen and nutrients.'
The research was funded by the Wellcome Trust and the findings are reported in the journal Current Biology.
This was a small-scale lab study, and more work needs to be done to know how the technique might be used in future. It's certainly not something that should be attempted at home, for instance, because of the potential for harm.
But Dr Cohen Kadosh is positive about the possibilities. 'The progression of [these] techniques to the clinic and classrooms is a realistic aim, yet several socio-ethical, financial and scientific barriers need to be overcome before it can be achieved,' he says.
Dr Cohen Kadosh says the current results open up a line of study to see if the findings are repeated in larger and more diverse groups of people, and in more natural settings such as a classroom.
'If experimental results continue in this positive direction, we hope that these painless, safe and cheap non-invasive stimulation techniques will one-day be used in the clinic, classrooms and even home to help those who struggle with certain cognitive tasks. This could include anyone from a child falling behind in his/her maths class to an elderly patient suffering from neurodegenerative disease,' he says.
TRNS has only emerged in the last few years, and how it influences the firing of individual neurons in the brain is still unclear. It is thought that TRNS may increase the synchronization in firing of neurons in the areas of the brain receiving the stimulation.
Work so far has shown TRNS to be physically harmless, and it is part of a group of techniques called transcranial electrical stimulation (TES) that have been shown to positively influence a vast range of cognitive faculties. The safety of other, similar forms of TES has received much greater attention, and Dr Cohen Kadosh says the outlook is very positive.
The Oxford group has previously shown that another form of brain stimulation called TDCS could make people better at learning and processing new numerical symbols. But they also have demonstrated as well as boosting these abilities, TDCS could have downsides in affecting other cognitive functions.
In the current work, the researchers see no downsides from TRNS in other non-mathematical cognitive tasks. TRNS did not influence performance in these tasks, either positively or negatively. But they note it is not possible in a single study to evaluate all mental faculties that might have been influenced by stimulation.
'It is very important that future work in this field makes an effort to identify any downsides of TES, and ensure that the boosting of one cognitive ability does not come at the expense of another,' concludes Dr Cohen Kadosh.