The neuroscience of Autism Spectrum Disorder: Cerebellum

On a cold Christmas day 1989, in a cramped room in Romania, the verdict of the Court-Martial was handed down. General Secretary Nicolae Ceausescu, the man who had ruled Romania with a tyrant’s fist for the last 20 years, was sentenced to death for committing genocide. Like so many other Soviet nations, the brutal Romanian communist dictatorship that had murdered tens of thousands of people and left many millions more in terrible poverty was suddenly over. Photos, videos and stories from journalists began pouring out to the rest of the world for the first time since the end of World War II, and the contents of those images were far more terrible and shocking than anyone could have known. Poverty and starvation were everywhere since Ceausescu had ordered the food, medicine, and other basic supplies be sold to pay off government debt. Worst of all came the pictures of the children. News story after news story broke showing orphanages packed full of starving, dirty, sick children. Ceausescu had made it illegal to stop having children in an effort to boost the nation’s population.

The rest of the world opened their arms, and the stream of refugee children came pouring out of Romania. To the United States, Canada, United Kingdom and many other wealthy nations they were sent, into the arms of empathetic parents that couldn’t see children in such need without opening their hearts and lives to them. But the battle to save these children was only just beginning.

The children were severely underweight, and they suffered from gastrointestinal, respiratory and skin disorders. Food and medicine were heavily prescribed to stave off their malnourishment and their illnesses. But even after their physical bodies had been brought back to life, there were major mental disorders as well. In particular, the children suffered many social deficits that were strikingly similar to those deficits seen in Autism Spectrum Disorders.

This brutal case study in childhood deprivation seemed to be showing that severe neglect of very young children caused Autism symptoms to appear. But what could these poorly treated children have in common with most children diagnosed with Autism Spectrum Disorder that are raised in warm, loving families?

Dr. Sam Wang of Princeton University has developed a surprising theory about this, which he described in detail in his paper published last year. After decades of studying Autism Spectrum Disorders Dr. Wang began growing very suspicious of a brain region that is routinely overlooked and undervalued: the cerebellum. Could the cerebellum be the brain region responsible for causing Autism Spectrum Disorders?

Normally when I start talking about a brain region, I pace back and forth thinking about how I can describe what the region looks like and where it is in a way that will mean something to people since most of the brain is a gray and white blob with very few defining features. You could pull out a brain that was cut in half and point directly at the hypothalamus and all you would see is a gray blob surrounded on all sides by more gray. But with the cerebellum, I do not have that problem at all. It actually looks like it’s a separate structure. It is the region sticking out of the bottom of your brain with parallel grooves all over it (shown in red below).

Cerebellum_animation_smallThe reason this region is almost always overlooked when it comes to mental disorders of all kinds is because its job in the brain is almost entirely movement related. When a police officer asks you to hold your finger out in front of you and quickly pull it back and touch your nose, he is checking to see if your cerebellum is functioning properly or if perhaps it is compromised by too many alcohol molecules floating around.

In studies looking at the cerebellum of children with an Autism Spectrum Disorder, lots of abnormalities have been found. For starters the entire brain area is smaller in autistic patients compared to normal children, and one part of the cerebellum in particular, an area called the vermis, was consistently found to be smaller in autistic brains. The list goes on and on. Autistic brains have fewer of the special neurons that make up the cerebellum, the Purkinje cells; the main brain region that sends information into the cerebellum is smaller; and the part of the cerebellum that sends information out to the rest of the brain shows differences too. Basically everything about the cerebellum in autistic patients seems to be just a little different.

So what does this have to do with Autism if the cerebellum’s job is almost entirely related to movement? The key is that “almost entirely” part. Even though most of the tasks the cerebellum is working on are involved with your muscles, scientists have known for a long time that it also connects to the brain regions involved in complex thinking. In particular, the cerebellum seems to help the rest of the brain when it is learning. And not just any learning, the cerebellum seems to play a key role in tying things together that are being detected using several different senses. For example, it helps you learn that that feeling of skin on your cheek, that sound of a voice in your ear, and the sight of a woman reaching towards you are all the same thing; your mom singing you a lullaby and caressing you. Now that you’re older tying all these different signal together is easy, but to an infant surrounded by thousands of things it can see, hear, feel, taste and smell all at the same time, it can be quite a challenge to figure out which things go together. Your cerebellum helps your brain figure it out.

So, what happens to an infant’s brain if the cerebellum isn’t doing its job properly? The rest of the brain would struggle to learn which of the sights, sounds, tastes, and touches go together. This would mean that the infant brain would struggle to learn about complex things in the real world. When you think about it, social interactions are incredibly complex. Putting together the sounds into words is just the beginning. To fully understand the social interaction you also need to process the pitch and intonation of the words, the expression on the person’s face, the body language of the person, and the way others are reacting to the words. Without a working cerebellum the infant’s brain would struggle to learn about this confusing onslaught of complex social information. And if it couldn’t put the signals together, it would never get that experience of learning that those soft touches, those soft sounds, those smiling eyes, and the nourishment of being fed, those are all Mom. What do children with Autism Spectrum Disorders and children raised in a Romanian orphanage have in common? Neither one gets the critical experience of nurturing parents; the orphan because there is no parent or care-taker, the autistic child because even though the parent is there desperately trying to give that nurturing love, the brain can’t make sense of all the overwhelming signals.

This cerebellum theory could also explain why people with an Autism Spectrum Disorder tend not to like over-stimulating things. Perhaps the brain struggles to put the different signals together leaving everything a confusing, chaotic mess to them.

Basically, a broken cerebellum makes sorting the thousands and thousands of signals babies encounter everyday impossible. And an unsorted world is a frightening place.

And I can’t let this story end without telling you what happened to the Romanian children. The same study that showed the children had lots of Autism symptoms also showed that once they were placed in loving homes those symptoms began going away over the course of a few years. Diane Taylor at the Guardian wrote a nice article in 2012 looking at the fate of many of these children now that they are grown.

Politicus Cerebri

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