Study Hall presents the results of scientific studies as described by the researchers and their sponsors. This week’s report comes from Britain’s University of Cambridge.
A patient in a seemingly vegetative state, unable to move or speak, showed signs of attentive awareness that had not been detected before, a new study reveals. This patient was able to focus on words signaled by the experimenters as auditory targets as successfully as healthy individuals. If this ability can be developed consistently in certain patients who are vegetative, it could open the door to specialized devices in the future and enable them to interact with the outside world.
The research, by scientists at the Medical Research Council Cognition and Brain Sciences Unit and the University of Cambridge, was published last week in the journal Neuroimage: Clinical.
For the study, the researchers used electroencephalography, which noninvasively measures the electrical activity over the scalp, to test 21 patients diagnosed as vegetative or minimally conscious and eight healthy volunteers. Participants heard a series of different words — one word a second over 90 seconds at a time — while being asked to alternatingly attend to either the word “yes” or the word “no,” each of which appeared 15 percent of the time. (Some examples of the words used include “moss,” “moth,” “worm” and “toad.”) This was repeated several times over a period of 30 minutes to detect whether the patients were able to attend to the correct target word.
The researchers found that one of the vegetative patients was able to filter out unimportant information and home in on relevant words they were being asked to pay attention to. Using fMRI brain imaging, the scientists also discovered that this patient could follow simple commands to imagine playing tennis. They also found that three other minimally conscious patients reacted to novel but irrelevant words but were unable to selectively pay attention to the target word.
These findings suggest that some patients in a vegetative or minimally conscious state might in fact be able to direct attention to the sounds in the world around them.
Srivas Chennu, a research associate at the University of Cambridge’s department of clinical neurosciences, said: “Not only did we find the patient had the ability to pay attention, we also found independent evidence of their ability to follow commands — information which could enable the development of future technology to help patients in a vegetative state communicate with the outside world.”