The finding holds huge applications for patients who may have lost their speech through brain injury or disabled patients with limited movement.
By directly connecting the patient's brain to a computer, the researchers showed that the computer could be controlled with up to 90 percent accuracy even when no prior training was given.
The study involves a technique called electrocortiography (ECoG) - the placing of electrodes directly onto a patient's brain to record electrical activity - which has previously been used to identify regions of the brain that cause epilepsy and has led to effective treatments.ore recently, the process of ECoG has been applied to brain-computer interfaces (BCI) which aim to assist or repair brain functions and have already been used to restore the sight of one patient and stimulate limb movement in others.
The study used four patients who suffered from epilepsy. Each patient was given a craniotomy - an invasive procedure used to place an electrode onto the brain of the patient - and was monitored whilst undergoing trials.
During the trials, the electrodes placed on the patient's brain would emit signals, which were acquired, processed, and stored on a computer.
The trials involved the patients sitting in front of a screen and trying to move a cursor toward a target using pre-defined words that were associated with specific directions.
For instance, saying or thinking of the word "AH" would move the cursor right.
At some point in the future researchers hope to permanently insert implants into a patient's brain to help restore functionality and, even more impressively, read someone's mind.
"This is one of the earliest examples, to a very, very small extent, of what is called 'reading minds' - detecting what people are saying to themselves in their internal dialogue," said Eric C Leuthardt, the lead author, of Washington University School of Medicine.
This study was the first to demonstrate micro scale ECoG recordings, meaning that future operations that require this technology may use an implant that is very small and minimally invasive.
Also, the study identified that speech intentions can be acquired through a site that is less than a cm wide, which would require only a small insertion into the brain. This would greatly reduce the risk of a surgical procedure.
"It's exciting and a little scary to think of reading minds, but it has incredible potential for people who can't communicate or are suffering from other disabilities," said Leuthardt.
The study is published in IOP Publishing's Journal of Neural Engineering.