In fragile X syndrome (FXS), the most common cause of autism, sensory signals from the outside world are integrated differently, causing them to be underrepresented by cortical pyramidal neurons in the brain.
That’s the conclusion of a new study by a team from the Université de Montréal and the UofM-affiliated CHU Sainte-Justine Research Center. The phenomenon the team observed could provide important clues to the underlying cause of FXS symptoms, and not only provides insight into the mechanism at the cellular level, but also opens the door to new targets for therapeutic strategies.
Autism is characterized by a wide range of symptoms that may stem from differences in brain development. With advanced imaging tools and genetic manipulation of neurons, the CHU Sainte-Justine team of researchers was able to observe the functioning of individual neurons, specifically, the pyramidal neurons of cortical layer 5, one of the main output neurons of cortex information. the thin layer of tissue found on the surface of the brain.
The researchers found a difference in how sensory signals are processed in these neurons. The image of a tree helps to illustrate the morphology and function of pyramidal neurons in fragile X syndrome. These neurons are one of the main integrators of information in the cerebral cortex, with long “branches” and “roots” representing dendrites.
A protein called FMRP that is absent in the brains of people with FXS modulates the activity of a type of potassium channel in the brain. According to the research group’s work, it is the absence of this protein that alters the way in which sensory inputs are combined, causing them to be underrepresented by the signals coming out of the brain’s cortical pyramidal neurons.
This finding opens the door to new strategies to support people with FXS and possibly other autism spectrum disorders to correctly perceive sensory signals from the outside world at the level of pyramidal neurons in the cortex.
This study was published in the Proceedings of the National Academy of Sciences.