Although it may seem strange, the implications of studies conducted with mice can translate over to human studies, including those concerning autism. In a recent study conducted by neuroscientists and molecular biologists at USC, the data suggests that missing brain protein may lead to “severe over-worry,” where the person (or in this case, mouse) is overly afraid of something with unjust cause. This study involves the enzymes monoamine oxidase A and B (MAO A/B), located next to each other in both humans and mice. The researchers based their study off previous studies, which suggest that a lack or deficiency of MAO A/B in humans, particularly those diagnosed with autism, can result in an inability to “change or modulate actions along with social context,” known as “clinical perseverance.” [i]
In the study, the mice without MAO A/B were placed in a new environment with wild mice, and given a mild electric shock. Although both groups showed learned fear, the effected mice showed much greater levels of fear than the wild mice. In addition, this group was reluctant to explore new areas of the environment for fear of shock, while the wild mice were still willing to wander, and “did not display any differences in learning for spatial skills and object recognition.” In a different part of the study, the mice without MAO A/B learned eye-blink conditioning at an exceptionally fast pace, similar to what has been noted with children with autism.
More on the relation of these findings to autism, Jean C. Shih, USC University Professor and Boyd & Elsie Welin Professor of Pharmacology and Pharmaceutical Sciences at the USC School of Pharmacy and the Keck School of Medicine of USC notes,
“The severity of the changes in the MAO A/B knockout mice compared to MAO A knockout mice supports the idea that the severity of autistic-like features may be correlated to the amounts of monoamine levels, particularly at early developmental stages.”
Her co-researcher, Chanpreet Singh added,
“When both enzymes are missing, it significantly increases the levels of neurotransmitters, which causes developmental changes, which leads to differential expression of receptors that are very important for synaptic plasticity – a measure of learning – and to behavior that is quite similar to what we see along the autism spectrum.”
Some fear is okay; it helps in the process of learning from our mistakes. But this study can shed light on why people with autism tend to behave in certain manners.
[i] “Medical News Today” Missing brain enzyme leads to abnormal levels of fear in mice: Findings have implications for autism. 18 Jul 2013. Web. <http://www.medicalnewstoday.com/releases/263458.php>