People with autism have difficulties in social interaction and behavior. A new study looked at abnormalities in brain cells among several types of autism and chemical releases associated with platonic love and sociability.
The study was recently published by researchers from Johns Hopkins Medicine in the journal Neuron. In the laboratory experiments, the scientists used genetically engineered mice to observe social information processing between neurons.
There are several forms of autism spectrum disorders which are also known as Fragile X syndrome. Nearly one out of every 4,000 males and one out of 6,000 females are diagnosed with autism, generally characterized by learning disabilities and inability to form close social connections.
Oxytocin Neurons
The genetic abnormality has been traced back to parvocellular and magnocellular oxytocin neurons within the hypothalamus. Oxytocin is a hormone known as the "cuddle" or "love" hormone that is released when people hug or socially bond. It also reduced stress and is a factor in bonding within mammalian species.
Dr. Gül Dölen explained that "autism is defined by impaired social behaviors," but there is a wide range of social behaviors. Those with autism typically struggle with developing close bonds, even with family members, more than they do with forming friendships.
The two types of affection of platonic love and sociability are encoded by different oxytocin neurons, explained Dölen. When these specific neurons are impaired, it results in the social disabilities that autistic people have.
Magnocellular oxytocin neurons release large quantities of oxytocin throughout the entire body. These neurons release at least 500 times more oxytocin than parvocellular oxytocin neurons, which give limited feelings of love or affection.
One function of magnocellular oxytocin neurons is filial love or "mad love" as Dölen calls it. Filial love is the bond between mother and infant as well as between sexual partners.
On the other hand, parvocellular oxytocin neurons encode social behaviors associated with reproduction, such as parental bonding, and platonic love between friends and colleagues. Dölen calls this "love in moderation."
The mice models were engineered to have all oxytocin neurons glow with fluorescent light. Dyes were used to indicating the chemical projections of the rarer parvocellular neurons. At the same time, the magnocellular neurons were observed to have chemical projections outside the blood and brain barrier.
Genetic Indicators of Autism
Using a technique called single-cell sequencing, the team analyzed the genetic profiles of individual RNA cells. Professor Loyal Goff explained that the results showed how different the two types of neurons are in terms of "anatomical, morphological, electrophysiological, transcriptional, genetic, and behavioral features."
Next, the team recreated the autism from the mice models using the human FMR1 gene, which is associated with Fragile X, an identifier of autism. Those with autism have their FMR1 gene silenced. The researchers also discovered that parvocellular neurons have higher expression levels that increased the risk of autism genetically.
In conclusion, Dölen said that the two types of oxytocin neurons play a major role in impaired social behaviors, "but not diseases where this behavior is not a defining symptom." All brain cells may be carrying mutations associated with autism, but perhaps "some neurons are more vulnerable to the symptoms related to social bonding."
Check out more news and information on Autism on Science Times.
