Australasian Science: Australia's authority on science since 1938

Brain Stimulation Solves Puzzle

By Stephen Luntz

Transcranial brain stimulation has enabled people to solve a puzzle they could not previously crack, offering the promise of a smarter future.

Prof Allan Snyder and Mr Richard Chi of the University of Sydney’s Centre for the Mind used an old puzzle known as the nine dots problem, in which participants are presented with three rows of three dots and, in Snyder’s words, are “asked to join all the dots with four straight lines without taking the pen off the page”.

“Under lab conditions nobody gets it,” Snyder says, although when students at Princeton University were presented with the problem in a more relaxed environment about 5% succeeded.

In work published in Neuroscience Letters Snyder and Chi gave 11 people the problem for 3 minutes before they underwent 10 minutes of transcranial brain stimulation in which the left anterior temporal lobe was inhibited while the right anterior lobe was excited using direct current stimulation. Participants were given the final 3 minutes of stimulation and a further 3 minutes after it ceased to confront the problem.

None got the solution before the stimulation started, but once it began answers started to appear. Four solved it during the stimulation and one almost immediately afterwards, but not all of them could remember how it was done some time later. Meanwhile, no members of a control group given a sham stimulation were successful.

Snyder says that the combination of right stimulation and left inhibition was based on observations. “Savant-like powers are sometimes seen in people with left hemisphere deficiency and right compensation,” he explains.

The reverse process was also tried, with no one solving the problem. “Our hypothesis was that this combination would work best for problems that are computationally simple but for which humans have inherent difficulties,” Snyder says.

While he agrees that students taking transcranial simulators into exam rooms may represent “the future”, he does not think that all fields of mental challenge will benefit from the same sort of stimulation. “Humans are very good at things like face recognition and bad at logic,” he says, indicating that it is the areas where evolution has left us weak that may benefit the most.

Other studies have demonstrated changes in mood from preferential stimulation of one side of the brain, but Snyder says “those are on different areas” and no such effects were observed. Some participants reported a tingling feeling or itching at the contact area, but no pain.