Observing the activity of a brain with autism spectrum disorder
My field of specialization is neuroscience, and I am mainly studying the functions of brains of people with autism spectrum disorders (ASD). I started this research as a result of some impressions I received when I was a university student, interacting with ASD people in my volunteer activities. I saw ASD people happily staring at shiny objects, or demonstrating incredibly good memory, and I wanted to know how those people perceive things and the world.
ASD is a type of neurodevelopmental disorder, characterized by social -communicative difficulties that make it difficult to interact or communicate with others. According to recent studies, the number of people with ASD may be above 3% the population. ASD has a natural brain dysfunction, but its cause is still unknown. ASD includes a number of sensory disorders such as hyper- and hyposensitivity, and motor difficulties such as inability to move the limbs well. In recent years, researchers have focused on the relationship between sensory and motor function and social-communicative function.
I came up with the idea that the region of the brain that controls cognition and behavior and governs the specificity of sensory and motor functions may be the biological basis of lack of social function. I decided to study that region using a technique called functional MRI (fMRI). An fMRI enables us to see which areas of the brain are activated when a person performs tasks such as looking at things, moving the body, and tackling problems. By comparing the state of blood flow in the brain when a person is doing something and when the person is idle, it is possible to identify areas of the brain that are actively working (Fig. 1).
I am studying the regions of the brain whose active functioning is not the same in people with ASD as those with typical development (hereinafter TD) who do not have ASD, in order to eventually discover the reason for the difference between TD and ASD cognition and behavior.
Occipital cortex: the biological basis in the brain that brings on the characteristics of ASD
I conducted an experiment to determine whether ASD and TD people have a biological basis in common by examining fMRI images of the brains of ASD and TD people during three phases of activity, ranging from cognitive function with strong social function to cognitive function with strong sensory and motor function. (Fig. 2).
I began by looking at brain activity related to imitation recognition (realizing that one person is imitating the behavior of another), which is a cognitive function with strong sociality. Adult ASD individuals have lower activity than TD individuals in a region of the brain called the occipital cortex. The occipital cortex is also called the visual cortex, and the next step of my study was to explore vision and perspective recognition (e.g. first-person perspective, such as looking at one’s own hand, and third-person perspective, such as looking at another person’s hand in a photo) in adult TD individuals and ASD individuals. I found that the amount of activity in the occipital cortex when looking at a hand from the first-person perspective was almost the same for both TD and ASD individuals. However, for looking at a hand from the third person perspective, the activity of the occipital cortex was clearly more active in TD individuals than when they were looking at their own hand, while in ASD individuals the two were about the same. From those findings, I determined that adult ASD persons cannot recognize the difference in perspective between other people’s hands and their own hands, i.e. they cannot process perspective.
Next, I conducted an experiment on The subjects were asked to identify a picture of a body among pictures of bodies, faces, landscapes and cars. I found that during visual body recognition, the activity of the occipital cortex is almost the same in TD and ASD adults, but the volume of the active area is smaller in ASD children than in TD children.
In short, in all three tasks (imitation recognition, perspective recognition, and visual body recognition), occipital cortex activity in ASD individuals was lower than in TD individuals; it is clear that there is a common biological basis in the occipital cortex region of the brain for social and sensory/motor functions.
ASD is not a disorder with a single characteristic; there are various individual differences in ASD characteristics such as delayed language development, inability to form friendships, inability to adapt to environmental changes, and narrow range of interest. There are also differences in how such characteristics appear to each person. The data collected by fMRI is in small cubic units of 3 mm3 called voxels, and it is possible to examine the strength of brain activity in each voxel. I am currently engaged in analysis of the spatial activity patterns of multiple voxels using machine learning techniques such as multivoxel pattern analysis (MVPA). I would like to investigate questions such as whether the reactions related to cognitive/behavioral characteristics are different in the occipital cortex, and clarify the brain function that is the source of individual differences in ASD. My future goal is to improve the independence and quality of life of people with ASD and their families through the results of my experiments (Fig. 3).
Interview and composition:
In cooperation with:
Waseda University Graduate School of Political Science J-School