These analyses revealed less brain-wide availability of a specific kind of glutamate receptor, known as metabotropic glutamate receptor 5 (mGlu5) in autistic participants. The findings support the idea that an imbalance of excitatory and inhibitory signals in the brain could be contributing to traits associated with autism, the researchers say.

Fifteen of the autistic participants also underwent an electroencephalogram (EEG), a measure of electrical activity of the brain. Based on the EEG, the researchers identified that these electrical measurements were associated with lower mGlu5 receptors.

This finding could have significant clinical implications, the researchers say. While PET scans are a powerful tool for studying the brain, they are also costly and involve exposure to radiation. EEG could be a cheaper and more accessible way to further investigate excitatory function in the brain.

“EEG isn’t going to completely replace PET scans, but it might help us understand how these glutamate receptors might be contributing to the ongoing brain activity in a person,” says Adam Naples, PhD, assistant professor in the Child Study Center at YSM and the study’s first author.