[ad_1]
Slow switch: In autistic people (red traces), the brain takes longer to alternate between the images presented to each eye.
Brain signals measured during a single visual task could serve as a biomarker for autism, according to a new study released on Thursday1.
The task tests a person's ability to perceive a phenomenon called binocular rivalry. This occurs when a person views two images simultaneously – one with the left eye and one with the right eye. The viewer's brain manages competing stimuli by inhibiting one entry and then the other. As a result, she sees the pictures one by one.
The study shows that the brains of autistic people switches from one image to the other more slowly than that of neurotypical individuals.
"This is concrete evidence that there are fundamental differences in the visual treatment of autism," says Caroline Robertson, Senior Researcher, Assistant Professor in Psychological and Brain Sciences at Hanover's Dartmouth University. , in New Hampshire.
The findings also support a long-standing theory that autistic people have too little inhibitory activity in the brain.
People with autism often have an increased response to sight, sound and touch, and the intensity of these responses reflects the degree of difficulty the person has with social and emotional treatment. However, the biological reason for this relationship is unknown.
The new study suggests that the link could be related to insufficient inhibition of brain activity, says Mark Wallace, Dean of Vanderbilt University in Nashville, Tennessee, who did not participate to work.
However, these results are inconclusive because binocular rivalry is not a direct measure of the balance between excitatory and inhibitory activity in the brain, warns Ilan Dinstein, associate professor of cognitive science and cerebral palsy at Ben Gurion University in Beer Sheva, Israel.
Neural signature:
In a study conducted in 2013, Robertson's team had shown that people with autism perceive images tilt more slowly into a binocular rivalry task than neurotypical individuals.2. The new work shows "a neuronal signature of this effect," says Robertson.
In the new study, 18 autistic adults and 19 neurotypical adults were sitting in front of a computer screen that showed a picture of a red circle at the left eye and a green image at the left. Right eye. The researchers asked the participants to indicate what color they had seen, while measuring their brain activity using electroencephalography (EEG).
Participants, both autistic and typical, reported the change in color as EEG signals showed their brain to switch between the two. But the GET showed that autistic brains change more slowly than ordinary people.
Autistic people who achieve the best results in the Autism Diagnostic Observation Program, a baseline test for autism, tend to move more slowly
When the researchers alternated a single image that they presented to both eyes, they found no difference in EEG activity between autistic individuals and neurotypical individuals. This suggests that the results are specific to binocular rivalry and do not simply reflect a slow response to new images, say the researchers.
"With a single electrode at the back of the head, we're seeing a fundamental difference in the rate of rivalry," Robertson said.
Diagnostic potential:
The researchers discovered that an automatic learning algorithm analyzing these EEG readings predicts an autism diagnosis with 86.5% accuracy.
This accuracy is similar to that of existing autism screens in young children – for example, those who evaluate how much time a child spends looking at faces, Robertson says. "It makes me think: if we put together this and some of the social markers, could we really [diagnosis]? "
Robertson's team investigated binocular rivalry in verbal adults requiring little help. Therefore, it is unclear whether the results would be likely in children or non-verbal adults with severe autism traits.
If this is the case, the test could be a powerful diagnostic tool because it is simple to perform and does not require the speech of the participants. It could also be used in animal studies and clinical trials.
The association between brain activity and the results of diagnostic tests "gives me a certain degree of optimism that this could be used as a very simple but very powerful tool in the field of diagnosis, "says Wallace.
However, this association is "relatively weak," he says. The next important step will be to determine which traits of autism are most closely related to binocular rivalry.
[ad_2]
Source link