Characteristics of Brain Activities in Visual Reasonings in Autistic Children: a MEG Study
Neuronal activities of the brain of 18 typically-developing children and 18 children with autism spectrum (AS) were investigated by using the custom child-sized MEG. The study has revealed for the first time that with AS children, the higher the functional connectivity of the visual occipital area with other areas of the brain through the gamma band, the higher the ability to perform visual reasoning tasks (visual space tasks and visual analogy tasks).
Among patients with autism spectrum (AS), certain patients exhibit high ability to perform visual reasoning tasks; a three-dimensional view of an object can be rotated in an imaginary manner, for example. By the research of adult AS patients, high functional connectivity of the occipital area and other areas of the brain has been considered to be important in performing such tasks.
Magnetoencephalograph, MEG, is able to detect neurons’ activities as magnetic signals from outside of head with superconducting quantum interference device (SQUID). It has a high time resolution (on millisecond order) as well as high space resolution. Thus, it is a powerful tool to evaluate neuronal activities and networks in the brain. In addition, it does not use any radiation and it is completely non-invasive.
So far, research of child brain has not sufficiently been carried out since such research has been difficult for lack of suitable equipment for children. In 2008, a custom child-sized MEG was made with superconducting sensors, which can cover whole head, being adjustable depending on the size of child head. This enables researchers to investigate neurons’ activities in the head of a child with high sensitivity but without any harm to subjects. Currently, only one copy is available in Kanazawa across Japan.
In this investigation using the custom child-sized MEG, the researchers of Kanazawa University in collaboration with the researchers of other institutions, both domestic and international, have studied 18 AS children as well as 18 typically-developing children, between 4 and 10 in age, for the relationship between functional connectivity of the occipital area with other areas of the brain and the ability to perform visual reasoning tasks. It is revealed that those AS children show high ability to perform visual reasoning tasks in the cases where functional connectivity of the visual occipital area with other areas of the brain by the gamma band is high; the gamma band is a type of neural oscillation in humans with a frequency around 40 Hz (between 30 and 58 Hz). Upon considering that the gamma band oscillations reflect bottom-up influence, the ability to perform visual reasoning tasks is increased in the cases where bottom-up influence is enforced in such AS children.
Because there was limited availability of experimental means, brain functions of AS children were not investigated to a sufficient extent. The results of the present research reveal, for the first time, characteristics of brain activities of AS children, especially concerning visual reasoning tasks. This research will lead to better understanding of child brain and its development.
The picture shows a child (a typically-developing child) under measurement with the custom child-sized MEG
An AS child with increased functional connectivity indicated by red lines was shown
to have high ability to perform visual reasoning tasks.
Title: The contribution of increased gamma band connectivity to visual non-verbal reasoning in autistic children: a MEG study
Journal: PLOS ONE
Authors: Natsumi TAKESAKI1, Mitsuru KIKUCHI1, Yuko YOSHIMURA1, Hirotoshi HIRAISHI1, Chiaki HASEGAWA1, Reizo KANEDA1, Hideo NAKATANI1, Tetsuya TAKAHASHI2, Laurent MOTTRON3, Yoshio MINABE1
1Kanazawa University, 2University of Fukui, 3University of Montreal, Canada
COISTREAM of MEXT and JST