Researchers from Stanford School of Medicine say they have discovered that a brain region activated when people are asked to work out mathematical calculations is also triggered when people use numbers or quantitative terms in everyday conversation.
The research team says their findings could lead to "mind-reading" devices that could allow a person to communicate through passive thinking, or even lead to implants that could read or control a person's thoughts.
To reach their findings, published in the journal Nature Communications, the researchers used a brain monitoring method called "intracranial recording" on three volunteers who were being evaluated for potential surgical treatment for recurring, drug-resistant epileptic seizures.
The procedure involved temporarily removing a part of the patient's skull before positioning packets of electrodes directly against the brain's surface.
Patients monitored in 'real-life' situations
The patients were monitored for up to 1 week in the hospital while attached to the electrodes, which picked up on any electrical activity within the brain. This allowed the researchers to monitor the patients' seizures and determine exactly from where in the brain they were originating.
The researchers emphasize that during this time, although mainly confined to a hospital bed, the patients were free to eat, drink, think, talk to friends and family in person or by phone, watch videos and were comfortable and pain free.
This allowed them to monitor the patients' brain activity when immersed in real-life activity, compared with conventional methods of brain monitoring such as fMRI, which takes place in a controlled environment.
The volunteers were also monitored by video cameras, allowing the researchers to link their real-life activities to nerve cell behavior within the monitored brain region.
During this period, the participants were asked to complete tests. These required "true or false" answers to calculation questions such as, "is it true that 2 + 4 = 5?," as well as episodic memory questions, including "true or false: I had coffee at breakfast this morning."
The volunteers were, at times, asked to stare at blank computer screens in order to monitor the brain's "resting-state."
Quantitative reference sparks intraparietal sulcus activity
Results of the analysis of the patients' daily electrode activity revealed spikes in the intraparietal sulcus area of the brain - a region that plays an important role in attention and hand and eye movement - outside of the testing periods.
The researchers note that previous studies have also shown that this brain area is involved in numerosity, which they define as the mathematical equivalent of literacy.
The team then viewed the video footage to find out what spiked the brain activity.
They discovered that every time a patient said a number or a quantitative reference, such as "some more" or "many," this triggered the same electrical activity in nerve cells of the intraparietal sulcus as when patients were doing mathematical calculations.
Josef Parvizi, associate professor of neurology and neurological sciences at Stanford School of Medicine, explains:
"We found that this region is activated not only when reading numbers or thinking about them, but also when patients were referring more obliquely to quantities.
These nerve cells are not firing chaotically. They're very specialized, active only when the subject starts thinking about numbers. When the subject is reminiscing, laughing or talking, they're not activated."
Potential for 'mind control'
The researchers say their findings open up the possibility of developing mind-control or mind-reading devices. For example, they note, a patient left mute following a stroke may one day be able to communicate through passive thinking.
Henry Greely, the Deane F. and Kate Edelman Johnson professor of law and steering committee chair of the Stanford Center for Biomedical Ethics, had no part in the study but says the findings are "exciting and a little scary."
"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," he adds.
However, Prof. Parvizi says it will be a long time before these mind-control devices are implemented:
"We're still in early days with this. If this is a baseball game, we're not even in the first inning. We just got a ticket to enter the stadium."
Earlier this year, Medical News Today reported on a study demonstrating how a model helicopter could be operated by pure mind control.