Around 80 percent of children with autism spectrum disorder (ASD) have motor coordination issues, which means that learning the cause of these issues is a priority for autism researchers. A University of Chicago research team investigated the underlying cause of ASD’s motor deficits using a mouse model. The researchers discovered that abnormal synaptic connections in the cerebellum are at the likely cause of autism’s motor deficits.
The researchers focused the study on the cerebellum, a part of the brain coordinates motor skills. Because mice have cerebellums that resemble those of humans, they used ASD model mice that had a chromosomal mutation associated with ASD. The ASD model mice were similar to mice without the genetic mutation, but had motor deficits like an unstable gait and impaired motor learning.
To test the mice’s motor skills, the researchers had the mice learn to respond to a short light signal with blinking. To train the mice, the researchers shot a puff of air at the mice’s eyes when they saw the light. Eventually, the researchers removed the puff of air. The ASD model mice took longer to learn to blink in response to the light and made mistakes more often.
Next, the researchers examined the mice’s Purkinje cells. Purkinje cells are a type of cell that receives signals about environmental disturbances through neuronal projections known as climbing fibers. In a typically functioning cerebellum, the cerebellum receives one signal from the climbing fibers to motivate the body to move. However, in the ASD model mice, the cerebellum received multiple signals from the climbing fibers. This may be because the Purkinje cells do not properly prune excess neurons in the ASD model mice.
Senior author of the study Chris Hansel, PhD, professor of neurobiology at University of Chicago explains that this study’s findings link it to other work in autism. “Inefficient synaptic pruning seems to be a common motif in autism. There are not many types of synapses in the brain where pruning can be measured easily, but climbing fibers provide an excellent model and allow us to make predictions about synaptic pruning deficits elsewhere in the brain as well.
The researchers hope that their study may lead to clinical trials for something that can treat the underlying synaptic dysfunction in autism spectrum disorder.
This research is published in the journal Nature Communications.
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