1. Is autism on the rise?
2. Nature and
nurture, but not vaccines
3. The system-making mind
up the brain
This boy is part of an experiment that measures how his brain processes
light and motion. The experiment is part of a major new effort to
understand exactly what goes wrong inside the brains of children
AP Photo/Evan Vucci
Researchers at Yale University have shown what happens in the brain as an autistic person considers a series of facial expressions. The brain area, called the fusiform face area, which lights up in an MRI of healthy people doing this task is not as active in autistic people.
Courtesy Robert Schultz, Yale Developmental Neuroimaging Laboratory
Perhaps the biggest mystery in autism research is how, and why, the autistic brain produces autistic behaviors. One way to get at this question is by watching the brain in action with medical imaging tools like magnetic resonance imaging (MRI) and positron emission tomography (PET). Functional MRI pictures can show which brain regions are active when people make decisions, look at pictures, are asked to solve a puzzle, and so on. Researchers at Yale University are using MRI to reveal what structures of the brain are involved in autism as well as what circuits light up when an autistic person performs some task.
The human brain is itself an incredibly complex system -- it must be studied slowly, carefully, and with painful attention to detail. Lucky for those of us who lack the patience for that sort of thing, entire teams of researchers are willing to spend their days doing it for us, piece by tiny piece.
"Neuroimaging is a very promising area," says Robert Schultz, director of the Yale Developmental Neuroimaging Laboratory. "We will have a pretty well worked out model of the neural systems most affected by the disorder in the next five to ten years. Treatment will probably lag behind, but effective biological treatments, such as medications, and perhaps even gene therapies may follow on from the successes we should have."
We thought you might like to know some the early successes:
Schultz and his colleagues at Yale have studied a brain region called
the fusiform face area, which they believe is involved in "storing social knowledge." MRI
studies show that this area, which normally lights up when a person processes
faces, is impaired in autistic individuals.
The amygdala, known as the emotional center of the brain, appears to be less active in autistic people than in others. When an autistic person views images of emotional faces, for instance, the pathways that normally light up remain dark.
In a brain region known as the prefrontal cortex, certain areas are known to play a role in empathizing behaviors. These areas become more active when a person is figuring out what people are thinking or feeling. MRI studies have shown that in autistic people, the prefrontal cortex is less active in these tasks.
The autistic brain is, on average, larger and heavier than a normal brain.
In 1999, Baron-Cohen and his colleagues found that autistic individuals reading facial expressions had less activation in the front part of the brain -- and no activation in the amygdala -- compared to others, who showed a lot of activity in both regions.
Nerve cells in one region of the brain, the superior temporal sulcus (STS), light up when another person (or animal) looks at you. Ordinarily, connections from the STS to the amygdala are activated when a person tries to understand what's going on in the mind of another. In autistic people, this pathway may be missing or incomplete.
The science of autism is a mammoth endeavor. And despite the research that increasingly fills library shelves and fattens science journals, much remains to be learned.
"Autism presents an interesting neuro-developmental puzzle," says Schultz, "because it is not like mental retardation, where you see deficits across the board. Persons with autism can have preserved intellectual functions... .In this way, autism promises to teach us something about the inherent organization of the brain itself. It is one of the reasons that I enjoy this area of study so much."
Tempted to learn more?