A recent study has shown a little bit more of the mind’s inner-workings, and taken steps down the path to mind-reading devices.

“We're now able to eavesdrop on the brain in real life,” says Dr Josef Parvizi, a professor of neurology and neurological sciences.

He was referring to a recent study which showed that the pattern of brain activity when performing a mathematical exercise in an fMRI machine is just like that observed when a person engages in quantitative thought in the course of daily life.

It turns out the same part of the brain lights up with anything from algebra or long division to simple statements like “less than” or “quite a lot”.

To make the comparisons, researchers needed a way to measure brain activity in a specific region while the subject went about their everyday life. It is important to find out the possible difference in results between experimental conditions and the random spontaneity in reality.

To make the measurements, patients had a small piece of skull removed and a packet of electrodes placed against the exposed brain. The patients were being evaluated in hospital for possible surgical treatment of their recurring, drug-resistant epileptic seizures.

The electrodes were like a wire-tap for the mind, when combined with video footage of the patients’ activity in their hospital rooms it enabled researchers to gather data on which part of the brain and where particular thoughts were coming from - correlated with the activites at the time.

The study also revealed just how specified small clusters of brain cells actually are.

“These nerve cells are not firing chaotically,” Parvizi said.

“They're very specialised... active only when the subject starts thinking about numbers. When the subject is reminiscing, laughing or talking, they're not activated.”

“This is exciting, and a little scary,” said Henry Greely, JD, the Deane F. and Kate Edelman Johnson Professor of Law and steering committee chair of the Stanford Center for Biomedical Ethics, after he read the findings.

“It demonstrates, first, that we can see when someone's dealing with numbers and, second, that we may conceivably someday be able to manipulate the brain to affect how someone deals with numbers.”

Greely says people should not worry just yet whether someone is secretly reading their mind: “Practically speaking, it's not the simplest thing in the world to go around implanting electrodes in people's brains. It will not be done tomorrow, or easily, or surreptitiously,” the professor claimed.

But then again, that is exactly what a mind-controlling supervillain would say.