This is a short but interesting video from NIMH on the development of children's brains - the timing of this could not be better consider the research that came out last week on the apparent lack of neuronal pruning in autistic children.
This is a huge finding and I'll post the whole article (and abstract) below the video. Typically, infants are born with more neurons than we will ever have again in our brains (we will actually have more brain cells later, but the increase is in glial cells), and then during the first two years, as brain wiring occurs, damaged or unused neurons are pruned from the brain.
The implication of this study, although not mentioned, is that there may be a defective pruning process in autistic children.
For more than twenty years, National Institute of Mental Health neuroscientist Dr. Jay Giedd has studied the development of the adolescent brain. Decades of imaging work have led to remarkable insight and a more than a few surprises.
Here is the article on autism, from the Live Science blog offered in conjunction with My Health News Daily. Keep in mind what you just read (or listened to as you read this article, and the abstract below).
Announcer: Parents and caregivers have always been fascinated with the development of children- their physical and intellectual growth. Studying the development of the adolescent brain has been the life work of National Institute of Mental Health researcher Dr. Jay Giedd.
Dr. Giedd: At different ages of life certain parts of the brain have much more dynamic growth than at other times. And so for very early in life we have our five senses where our visual system and audio system is getting established and optimized for the world around us. In adolescents, the key changes are in the frontal part of the brain involved in controlling our impulses, long range planning, judgment, decision making.
Announcer: Imaging has shown by the time children reach the first grade the physical size of the brain is nearly complete. But what goes on within the brain is nothing short of remarkable.
Dr. Giedd: The brain can grow extra connections sort of like branches, twigs and roots to use a gardening metaphor and then after it has these connections there’s also another gardening metaphor called pruning or cutting back or eliminating the excess or unused connections. And it’s this process of overproducing and then having fierce competition amongst all these connections to see which ones are most useful and which are most helpful for us to adapt to the environment.
Announcer: Our brains have been challenged by the effects of multi-tasking in many ways brought on by the age of social media and use of computer gadgets.
Dr. Giedd: The way that we get information, entertain ourselves and interact with each other has changed more in the last ten years than in the previous five hundred- since Gutenberg’s introduction of the printing press. And so these changes are a real challenge for researchers because they happen so rapidly. So, that adolescents today average about eleven and a half hours of media time. And this is up from six and a half hours just five years ago so that the activities of children and teens has been changing so much. We’ve been challenged- how do we keep up with the changing world and how do we assess the impact for good or for bad on the developing brain.
Announcer: So how well are our children handing multi-tasking in a digital age that changes, seemingly, by the hour? Early evidence suggests -pretty well. In fact, the human brain has a track record of successfully adapting to challenges it wasn’t initially designed to take on- such as reading.
Dr. Giedd: It’s sobering to realize most humans that have lived and died have never read. And so, we’ve been able to change what our brain does based on having the written word and having this environment. And so now the questions is will we be able to change to keep up with the new flood of information coming from all kinds of sources. And up until now the human brain has done a great job of changing- adapting to these environments but there are limitations to this capacity. And so it will be very interesting to see that these so-called digital natives… the children that have grow up never not knowing the multimedia devices… whether their brains will be able to adapt differently than older people.
Announcer: So, what was the human brain originally developed to do? Well, Dr. Giedd says our brains are fundamentally designed to learn through example.
Dr. Giedd: This learning by example is very powerful and that parents are teaching even when they don’t realize they are teaching just by how they handle everyday aspects of their life. How they treat each other as spouses. How they talk about work. When they get stuck in traffic. How they manage their time and their emotions. And this is how most of the teaching is done. It’s not when you set down at these special moments and have a conversation- it’s the everyday moments that really have a huge impact on how the brain forms and adapts.
Announcer: Through the work of Dr. Giedd and his colleagues, we’ve learned so much about the development of the adolescent brain. But researchers like Dr. Giedd may be entering a new golden age of research… as these so-called “digital natives” lead us to new findings in the ever-evolving childhood brain.
The full article is available to media and subscribers from JAMA's Archives of General Psychiatry. Here is the full abstract.MyHealthNewsDaily StaffDate: 02 May 2011
The brains of children who have autism spectrum disorder are larger than those of other children, a difference that seems to arise before they are 2 years old, according to a new study.
In 2005, researchers from the University of North Carolina at Chapel Hill found that 2-year-old children with autism had brains up to 10 percent larger than other children of the same age. This new study reveals that the children with enlarged brains at age 2 continued to have enlarged brains at ages 4 and 5, but by no more than the amount at age 2.
"Brain enlargement resulting from increased folding on the surface of the brain is most likely genetic in origin and a result of an increase in the proliferation of neurons in the developing brain," study researcher Heather Cody Hazlett, an assistant professor in UNC’s Department of Psychiatry, said in a statement.
Hazlett and her colleagues conducted behavioral assessments and magnetic resonance imaging (MRI) scans on 97 children at age 2, of whom 59 had received an autism diagnosis.
About two years later, she and her colleagues repeated the tests on those same children who were still available to them: 57 in all, of whom 36 had an autism spectrum disorder diagnosis.
The researchers found that children with an autism spectrum disorder had larger brain volume (including more white and gray matter) at all ages than children without autism. However, the rate of brain growth had been similar to the rate seen in children who did not have autism.
Research has shown that the brain overgrowth occurs during the latter part of the first year of life, and the new finding reveals that there is a relationship between onset of autistic behavior and brain overgrowth, the study said.
"It is possible that brain overgrowth directly results in the development of autistic behavior, perhaps through a physical disruption of neural circuitry," the researchers wrote.
Their study appears in the May 2011 issue of Archives of General Psychiatry.
Pass it on: The brains of children with autism are bigger than kids without the condition.
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Early Brain Overgrowth in Autism Associated With an Increase in Cortical Surface Area Before Age 2 Years
Arch Gen Psychiatry. 2011;68(5):467-476. doi:10.1001/archgenpsychiatry.2011.39
Context Brain enlargement has been observed in 2-year-old children with autism, but the underlying mechanisms are unknown.
Objective To investigate early growth trajectories in brain volume and cortical thickness.
Design Longitudinal magnetic resonance imaging study.
Setting Academic medical centers.
Participants Fifty-nine children with autism spectrum disorder (ASD) and 38 control children.
Intervention Children were examined at approximately 2 years of age. Magnetic resonance imaging was repeated approximately 24 months later (when aged 4-5 years; 38 children with ASD; 21 controls).
Main Outcome Measures Cerebral gray and white matter volumes and cortical thickness.
Results We observed generalized cerebral cortical enlargement in individuals with ASD at both 2 and 4 to 5 years of age. Rate of cerebral cortical growth across multiple brain regions and tissue compartments in children with ASD was parallel to that seen in the controls, indicating that there was no increase in rate of cerebral cortical growth during this interval. No cerebellar differences were observed in children with ASD. After controlling for total brain volume, a disproportionate enlargement in temporal lobe white matter was observed in the ASD group. We found no significant differences in cortical thickness but observed an increase in an estimate of surface area in the ASD group compared with controls for all cortical regions measured (temporal, frontal, and parieto-occipital lobes).
Conclusions Our longitudinal magnetic resonance imaging study found generalized cerebral cortical enlargement in children with ASD, with a disproportionate enlargement in temporal lobe white matter. There was no significant difference from controls in the rate of brain growth for this age interval, indicating that brain enlargement in ASD results from an increased rate of brain growth before age 2 years. The presence of increased cortical volume, but not cortical thickness, suggests that early brain enlargement may be associated with increased cortical surface area. Cortical surface area overgrowth in ASD may underlie brain enlargement and implicates a distinct set of pathogenic mechanisms.