What’s the News: A non-invasive test that measures brain waves could help doctors better diagnose whether a patient is truly in a vegetative state, according toÂ a preliminaryÂ study published today in Science. What’s more, the results suggest that a particular pathway of communication in the brain is disrupted in vegetative patients but not patients with somewhat less severe brain damage—which could not only improve diagnosis, but help researchers better understand these tragic conditions.
How the Heck:
- The researchers recorded the brain activity of 21 people with severe brain injuries and 22 healthy controls using an EEG, a set of electrodes placed on the scalp that pick up electrical signals generated by the brain’s neurons firing. Of the patients with brain damage, eight had been previously diagnosed as being in a vegetative state, while the other thirteen were in a minimally conscious state, meaning they retained some level of conscious awareness and ability to interact.
- While recording the subjects’ brainwaves, the researchers played each of them a series of sounds with unexpected changes of tone (a one-time warble in the note). When healthy people and patients in a minimally conscious state heard the blip, their brain waves showed a spike that lasted around 170 milliseconds. For patients in a vegetative state, the spike lasted less than 100 milliseconds. That may not sound like much, but 70 milliseconds is a significant chunk of time when you’re looking at brainwaves.
- The researchers made a mathematical model, combining their data with information about how different areas of the brain are connected to see what neurological processes might have led to this pattern of brain waves. Communication from the frontal cortex—a high-level brain region that’s important in decision making and rational thought—to other parts of the brain seemed to be disrupted in vegetative patients, they found.
- In other patients and healthy controls, the surprising sound triggered auditory brain regions to send signals to the frontal cortex, which then responded by sending another set of signals. In vegetative patients, the auditory regions still sent signals to the frontal cortex—but the frontal cortex didn’t send any back.
What’s the Context:
- Current methods of testing whether someone is truly in a vegetative state are time-consuming and often depend on judgment calls by clinicians. Up to 40% of patients in a minimally conscious state may be incorrectly diagnosed as vegetative, earlier work has found. Using objective recordings of brain activity rather than subjective assessments could make diagnosis easier and vastly reduce the number of mistakes.
- Other researchers have also investigated ways to use brain scans to determine whether a patient is in a vegetative state, such as using an MRI scanner to pick up brain activity suggesting responsiveness in patients who can’t communicate.
Not So Fast:
- The study was preliminary, and involved only a small number of patients. To suss out whether this test will make an effective diagnostic tool, the researchers say, more patients must be tested.
Reference: Melanie Boly et al. “Preserved Feedforward But Impaired Top-Down Processes in the Vegetative State.” Science, May 13, 2011. DOI: 10.1126/science.1202043
Julie188 writes “A small PC device company wants to bring thought-controlled apps to the Android market. Mind Technologies (once known by the cute name of Jedi Mind) has promised to make it so. Mind Technologies makes PC devices (a game controller and mouse) that work with the strange-but-true Emotiv headset. Emotive uses brain waves to operate machines. Although it sounds far fetched, electroencephalogram (EEG) controllers do work, but the products on the market so far are not as easy to use, let alone master, as their makers claim.”
cortex writes with an excerpt from the L.A. Times: “In a first step toward helping severely paralyzed people communicate more easily, Utah researchers have shown that it is possible to translate recorded brain waves into words, using a grid of electrodes placed directly on the brain. … The device could benefit people who have been paralyzed by stroke, Lou Gehrig’s disease or trauma and are ‘locked in’ — aware but unable to communicate except, perhaps, by blinking an eyelid or arduously moving a cursor to pick out letters or words from a list. … Some researchers have been attempting to ‘read’ speech centers in the brain using electrodes placed on the scalp. But such electrodes ‘are so far away from the electrical activity that it gets blurred out,’ [University of Utah bioengineer Bradley] Greger said. … He and his colleagues instead use arrays of tiny microelectrodes that are placed in contact with the brain, but not implanted. In the current study, they used two arrays, each with 16 microelectrodes.”
An anonymous reader writes “Why can some people sleep through anything? According to this article in Wired Science, some lucky people have an extra helping of a certain kind of brain static that essentially blocks out noise and other stimuli. These ‘sleep spindles’ can be detected via EEG, and show up as brief bursts of high-frequency brain waves; some people naturally produce more than others. The researchers say these spindles are produced by the thalamus, the brain region that acts as a waystation for sensory information. If the thalamus is busy producing sleep spindles, sensory information can’t make it through the thalamus to the cortex, the perceptive part of the brain.”
An anonymous reader writes “Imagine technology that allows you to get inside the mind of a terrorist to know how, when, and where the next attack will occur. In the Northwestern study, when researchers knew in advance specifics of the planned attacks by the make-believe ‘terrorists,’ they were able to correlate P300 brain waves to guilty knowledge with 100 percent accuracy in the lab, said J. Peter Rosenfeld, professor of psychology in Northwestern’s Weinberg College of Arts and Sciences.”
An anonymous reader writes “How about typing on a computer just by thinking about it? The downside is you have to wear a skull cap with electrodes that capture your brain waves like an EEG machine. According to this EE Times story a team of researchers from Belgium and the Netherlands has presented Mind Speller, a thought-to-text device intended to help people with movement disabilities.
The system does rely on a lot of processing on a remote computer but it is a wireless system. And these thought-to-computer systems have wider applicability than medical support. One of the research groups involved in this development has already looked at wireless electroencephalography (EEG) to enable measures of emotion to be fed back into computer games.”
magacious writes “Gtec has showcased a computer that can read your mind over at the CeBIT trade show in Germany. Designed primarily to help those who can’t write or speak, the system makes use of a skull cap and wireless technology to transform brain waves into letters. It’s the first patient-ready computer-brain interface, according to its Austrian makers. It takes around 30 seconds per letter for the computer to recognise what you’re saying the first time you use it, according to Gtec, but this improves vastly with practice. ‘”One second per letter is very tough,” Gtec’s Engelbert Grunbacher said, adding users can usually easily get to five or 10 letters per minute. “You learn to be relaxed, focused. You improve.”‘ It might look quite wacky (pictures here) and at €9,000 the system is not cheap, but it could help enhance the lives of many people who have a great deal to say but no real way of saying it.”