A Quebec study could turn our understanding of autism upside down
It seems that certain signals do not take up enough space in the brains of children with the most common form of autism, whereas until now it was assumed that they took up too much.
A discovery made by a researcher at CHU Sainte-Justine could completely shake up experts' understanding of the most common form of autism.
By studying what is known as fragile X syndrome, Roberto Araya's team found that sensory signals that come from the outside world are under-represented in the brain, while we thought until now that they were overrepresented.
In other words, it seems that these signals do not take up enough space in the brain, whereas it was assumed until now that they take up too much.
< p class="e-p">It was quite a surprise for us, because usually, we talk about autism as a situation of sensory hypersensitivity, said Mr. Araya, who is a neuroscientist, biophysicist and researcher at the CHU Sainte-Justine Research Center.
Even more precisely, the researchers managed to distinguish the way the brain interprets the signals that come to it from outside (sound, light, touch and others) from the way it interprets its internal signals. (those, for example, that allow him to recognize an object or a relative).
These internal signals remain overrepresented in patients with fragile X syndrome, a explained Mr. Araya, but it now appears that external cues are underrepresented, which he says is a complete paradigm shift.
This combination of issues is what generates this very difficult behavioral change for people with autism, he said. I think this is one piece of the puzzle that will completely change the understanding of autism.
Previous work concluded that fragile X syndrome was characterized by a hyperexcitable cortex. Experiments on mice rather indicate that it would be the reverse, hence the under-representation of the signals described by the researchers.
This is what which explains why autistic mice seem to perceive signals from the outside world differently, Araya said.
Their internal signals are overrepresented, he explained. But at the same time, their external cues, the ones you really shouldn't distort because it's reality, are underrepresented. Antennae that are turned to the outside world do not represent things correctly.
This is why people with autism may face certain difficulties, the researcher added: they struggle distinguish relevant signals from insignificant signals, and everything ends up seeming important to them.
This under-representation of external signals is thought to be due to the absence of the FMRP protein in the brains of people with fragile X syndrome. A member of the team, Soledad Miranda-Rottmann, then demonstrated that it is possible to correct the problem.
This opens the door to the development of new therapies that could help patients with fragile X syndrome correctly perceive signals from the outside world, Araya said.
We have found the mechanism and we can make the correction of the interpretation of sensory information, assured the researcher. This is a very important first step in solving the disease.
We can then tackle the processing of internal information, he said. concluded, but only if necessary, since it cannot be excluded that the correction of the representation of external signals alone is sufficient.
The conclusions of this study were published earlier this year by the Proceedings of the National Academy of Sciences .
