Development of a whole-head child MEG system
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1
Kanazawa Institute of Technology, Japan
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2
Kanazawa Institute of Technology, Applied Electronics Laboratory, Japan
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3
Yokogawa Electric Corporation, Japan
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4
Macquarie University, Macquarie Centre for Cognitive Science, Australia
A whole-head magnetoencephalography (MEG) system was developed to study cognitive processing in young children. The child MEG system contrasts with conventional systems that have a helmet-shaped sensor array designed to fit the head sizes of adults. In current adult MEG systems, the distance between the sensors and the magnetic sources are far enough apart to accommodate the head sizes of adults. This makes it difficult for these systems to achieve a sufficient S/N ratio when applied to young children, because children’s head sizes are much smaller than those of adults. This prompted us to develop a customized child MEG system equipped with a helmet-shaped sensor array that is designed for a young child's head. The sensor array is composed of 64 LTS-SQUID axial-type gradiometric magnetometers, arranged about 100 mm from the center of the child’s head. The sensor array is installed in the helmet of a horizontal dewar with a head circumference of about 530 mm. The liquid helium capacity of the dewar is roughly 100 liters, and the helium consumption rate is less than 6 liters/day. The sensors have been positioned in the dewar using a ship-in-a-bottle technique[1]. All sensor positions, as well as their direction and sensitivity in the cryostat, were calibrated after cooling, using the Higuchi method[2]. To verify the performance of the child MEG system, an auditory evoked field measurement was taken of a healthy 4-year-old child subject. Large simultaneous magnetic field components corresponding to the N100 were successfully observed in the child over both the right and the left hemispheres. The latency of the effect was observed at around 150 ms, and two equivalent current dipoles were found in the temporal lobes in both hemispheres of the child subject.
Conference:
Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010.
Presentation Type:
Poster Presentation
Topic:
Instrumentation and Multi-modal Integrations: MEG, Low-field MRI,EEG, fMRI,TMS,NIRS
Citation:
Adachi
Y,
Miyamoto
M,
Kawai
J,
Kawabata
M,
Higuchi
M,
Uehara
G,
Ogata
H,
Kado
H,
Haruta
Y,
Tesan
G and
Crain
S
(2010). Development of a whole-head child MEG system.
Front. Neurosci.
Conference Abstract:
Biomag 2010 - 17th International Conference on Biomagnetism .
doi: 10.3389/conf.fnins.2010.06.00411
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Received:
09 Apr 2010;
Published Online:
09 Apr 2010.
*
Correspondence:
Yoshiaki Adachi, Kanazawa Institute of Technology, Kanazawa, Japan, adachi@ael.kanazawa-it.ac.jp