LEARNING ABOUT THE SOCIAL BRAIN FROM ZEBRAFISH
By Sharon Aschaiek
Individuals with autism typically socialize in ways outside the norm. Most scientific literature labels this difference a “deficit”; “difference” is the term used by proponents of the science-based neurodiversity movement, which supports acknowledging and respecting natural human brain variations. Either way, the resulting impact on the autistic person is, regrettably, often negative: social disconnection in our still neurotypically oriented world, making it harder for them to maintain relationships, achieve goals and participate in their communities.
One solution being investigated by brain and behaviour researchers lies in better understanding the hormones involved in our brain chemistry, particularly oxytocin. Produced by the hypothalamus and secreted by the pituitary gland, this neuropeptide helps us form close ties with others. A substantial body of research confirms oxytocin’s efficacy at promoting the prosocial traits of trust, generosity and gregariousness.
Oxytocin and social functioning in relation to autism is the focus of behavioural neuroscientist Soaleha Shams. She studies the brain of the zebrafish, which serves as a useful animal model because it is highly social. As a postdoctoral fellow in the Department of Pharmacology at Sweden’s University of Gothenburg, she mapped the location of oxytocin neurons and studied the function of two oxytocin receptors in the zebrafish’s social behavioural network to determine their involvement in social and non-social tasks. Last June, she shared her findings at the annual conference of the International Society for Autism Research in a presentation called “Responses of Oxytocin-Receptor-Mutant Zebrafish to Social Stimulation in Groups and Individually: Support for Zebrafish Autism Model.”
For the experiment, the CRISPR-Cas9 gene-editing tool was used to remove either of the two oxytocin receptor genes, called oxtr and oxtrl, from adult male and female zebrafish. Shams then placed each fish in a tank with three other modified fish, and each non-modified fish with three others, for 30 minutes. She observed that the non-modified zebrafish spent most of their time shoaling (being together), which is typical. However, the mutant fish stayed twice as far from each other as their non-modified peers, and they made frequent excursions from the group, ultimately spending only half as much time with the others. These findings reflect a marked decrease in the socialization of the fish missing an oxytocin receptor.
Shams is now preparing to submit her study for publication. Shams will build on her research into autism, zebrafish and socialization this fall as an Azrieli International Postdoctoral Fellow in The Levkowitz Lab at the Weizmann Institute of Science in Israel. Her endgame is to provide the scientific foundations for more effective pharmacological agents to support social regulation in individuals with autism and other clinical populations.
“I want to really understand what the social brain is,” Shams says. “There is such variety on the autism spectrum, and for those who struggle with anxiety, depression or just connecting with others, what do their brains need to thrive?”