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Mind-reading a conversation with completely paralyzed people possible, study says


Completely paralyzed people may be able to converse by means of a new brain scanner that enables users to spell words by thought alone, according to new research published online Thursday.

The device uses functional magnetic resonance imaging fMRI to select among 27 choices, representing letters of the alphabet and a space key. Each choice produces a different pattern of blood flow the fMRI device detects and interprets, according to the report in Current Biology , a Cell Press publication.

Short conversation in real time were conducted with study participants using the device, the research paper stated.

"The results substantially extend earlier uses of fMRI, which allowed individuals to answer the equivalent of multiple-choice questions having four or fewer possible answers, by enabling free-letter spelling," said researcher Bettina Sorger , in a press release. "That could make all the difference for people who are completely paralyzed and unable to benefit from other means of alternative communication," said Sorger, of Maastricht University in The Netherlands.

Sorger was inspired by the work of neuroscientist  Adrian Owen , she said in the press release. Owen demonstrated that some people in a "vegetative" state were conscious and, given the right tools, capable of communication.

The research paper said the device used the "hemodynamic" responses of blood flow in the brains of participants to discern which character they were choosing.

Participants were given brief training to perform 27 different mental tasks, each linked to a alphabetical letter or the space key. The fMRI device measured the blood flow in the brain corresponding to these tasks, and determined which character participants had chosen.

"For the last 20 years, research on motor-independent communication has focused on developing ‘‘brain-computer interfaces’’ (BCIs) implementing neuroelectric signals for communication, and BCIs based on electroencephalography (EEG) have already been applied successfully to concerned patients ," the paper stated. "However, not all patients achieve proficiency in EEG-based BCI control. Thus, more recently, hemodynamic brain signals have also been explored for BCI purposes."

The process is extremely easy to learn, the paper said:

"In order to represent each letter of the English alphabet and the blank space by a distinct neural activation pattern, we conceived a letter encoding technique that requires almost zero pretraining," the paper stated. "The technique exploits spatiotemporal characteristics of single-trial blood oxygenation level-dependent (BOLD) signals that are associated with the participant’s performance of different mental tasks and certain temporal aspects of task execution.

"The letter-by-letter 'translation'  of any freely chosen answer into single-trial BOLD signals required only little effort from participants as the encoding process was facilitated by using a convenient visual letter encoding display designed according to the coding scheme. For encoding a certain letter, participants merely had to attend to the desired letter and to perform the designated mental task as long as the letter was highlighted in the display."

The paper is titled, "A Real-Time fMRI-Based Spelling Device Immediately Enabling Robust Motor-Independent Communication."

Sorger is the lead author, and Ranier Goebel, also of Maastricht, is senior author. The other authors are Joel Reithler, also of the university, and Brigitte Dahmen, of Aachen University in Germany.