A new research shows that a cursor on a computer screen can be controlled using thoughts about a range of vowel sounds, research has found. This is done by placing sensors directly on the surface of the Brain the technique is known as Electrocorticography. The authors of the Journal of Neuroengineering paper say the technique will lead to better “brain-computer interfaces” for the disabled.
Brain signals have been translated into motion or even pictures before, but the current research showcases a nascent technique called electrocorticography.
The approach uses sensors placed directly on the surface of the brain.
A great many studies and demonstrations have in recent years made use of the electroencephalograph, or EEG, typically worn as a “cap” studded with electrodes that pick up the electric fields produced by firing neurons.
However, EEGs lose a great deal of the precious information that is available closer to the brain itself, what lead author of the study Eric Leuthardt, of Washington University in St Louis, in the US, calls the “gold standard” brain signal. “You cannot get the spatial or the signal resolution,” he told BBC News.
“One of the key features in signal resolution is seeing the higher frequencies of brain activity – those higher frequencies have a substantial capability of giving us better insights into cognitive intentions, and part of the reason EEG suffers for this’s it acts as a filter of all of these high frequency signals.” The EEG picks up signals outside the skull, which acts to absorb and muddle the signals.
Electrocorticography, by contrast, is so named because it taps directly into the brain’s cortex – the outermost layer of the brain.
But Dr Leuthardt said that the units of speech known as phonemes allow signals of a particular “discrete” nature, rather than signals that range in intensity, as with thoughts of motion. “We would want to facilitate somebody’s abilty to communicate by having different phonemes – or essentially key presses – that could allow them to have discrete type of control.”
Four patients who were already undergoing the electrocorticograph implantation – to establish the source of incurable epileptic seizures – participated in the latest study.
When four patients who were undergoing the eletrocorticography were asked to think of four different vowel sounds, “oo”, “ah”, “ee” and “eh”, the high-frequency signals were displayed to accurately move a cursor on a computer screen.
“For a brain-computer interface, especially for someone who is severely impaired, they need something that is absolutely, completely reliable. If you think of EEG (systems), they move, they’re susceptible to noise, and the likelihood for reliability is much lower.” computer screen.