Chicken Noodle Soup, Phone Lines, and Autism
In fourth grade, I had a friend named John who meandered through the hallways of our school with an aid always following him. He was lanky, a little awkward, and had a mushroom cut to tame his dirty blonde hair. I first met John because he joined my class one day a week and sat next to me. Over time, I talked to him and noticed that he would ask me the same question multiple times in a conversation: “Do you like soup? What’s your favorite kind of soup? I like chicken noodle.” Even when we were talking about something completely different, he would sometimes interrupt our conversations to ask about my feelings toward soup. Sometimes he wouldn’t look at me when either one of us talked—he would look down instead. At first, I was confused about John’s fixation on soup. I was later told that John had autism, which peaked my interest in this disorder.
In recent years, autism has escalated to one of the top areas of research in neuroscience. More and more children are diagnosed with autism as awareness of the disorder increases, and scientists are racing to figure out what, if anything, causes autism. So what do we know so far?
Autism is a spectrum disorder, which means that it can range in severity. Asperger’s syndrome is the mildest form of autism, usually characterized by offset social behaviors but intact speech. On the other end of the spectrum, autism is characterized by abnormal social abilities (like playing by themselves rather than with other children), abnormal communication abilities (repeating what someone else says or not making eye contact), and repetitive behaviors (like asking the same questions over again).
Dr. Matthew Belmonte and fellow researchers at the Autism Research Centre in Cambridge have also elucidated differences in neuronal connectivity in autistic and non-autistic brains. These researchers suggest that connectivity can be defined in four ways: local connectivity, long-range connectivity, physical connectivity, and computational (information-transfer) connectivity. An easier way to keep these all straight is probably with a simile: local connectivity is like calling your neighbor on the phone. Long-range connectivity is like calling your family in India, physical connectivity is like the long telephone wires that connect to one another, and computational connectivity is like the actual gossip you get from a phone call to your middle-aged aunt.
Belmonte and scientists suggest that in the autistic brain, there is high local connectivity but low long-range connectivity, potentially indicating that specific regions in the brain are highly activated but these regions of the brain do not communicate with each other. Furthermore, Belmonte et. al. suggests that high physical connectivity and low computational connectivity reinforce each other, so these neurons are physically close to one another but there is not much information transfer between them. These differences begin to put together the puzzle pieces of why an autistic child can tell you all the details about kangaroos without you asking but may not be able to look you in the eye and hold out a mutual conversation.
Researchers at the Center for Research on Autism in California also argue that brain volume in 2-4-year-old autistic children are larger than normal. This rapid enlargement in brain matter is subsequently followed by a dramatic slow-down, or as Belmonte argues, a cessation of growth. The frontal lobes, which are responsible for all higher-order thinking, show the most overgrowth. The overgrowth followed by growth cessation suggests that synaptogenesis (creation of connections between neurons) and myelination (insulation of neurons to increase the firing speed of signals) either doesn’t happen or doesn’t happen to the extent it needs to happen. This is bad. Why? Because not enough neurons mean not enough brain communication which means abnormal functioning.
I did want to include something interesting that was noted in both articles I read. The cerebellum is a structure that sits below the brain and is generally responsible for balance and coordination of movement. What I found incredibly puzzling is that in autistic brains, there is underdevelopment of the cerebellum due to fewer cells and neurons. The sizes of each cerebellar hemispheres are also reduced. Researchers argue that the cerebellum has been associated with cognitive and social deficits in autistic children as well. Who knew?!
Autism has become a huge puzzle with individual pieces focusing on genes, neurons, parts of the brain, and environmental factors. Unfortunately, researchers struggle to connect these pieces to create an overall better picture of autism.