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Updated: Aug 17, 2026
Functional Near Infrared Spectroscopy of the Sensory and Motor Brain Regions with Simultaneous Kinematic and EMG Monitoring During Motor Tasks
Published on: December 5, 2014
Volumetric estimation of functional brain regions in small children using spatially filtered magnetoencephalography:
1Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, Canada. jing.Xiang@sickkids.ca
Insights
Magnetoencephalography (MEG) can now map the somatosensory cortex in young children using spatially filtered MEG. This advanced technique successfully identified distinct functional areas for the thumb and middle finger, with the thumb showing a larger estimated region.
Area of Science:
- Neuroscience
- Biophysics
- Developmental Neuroscience
Background:
- Localizing the somatosensory cortex in children under 6 using magnetoencephalography (MEG) is challenging due to poor signal-to-noise ratios.
- Conventional median nerve stimulation methods are insufficient for this age group.
Purpose of the Study:
- To investigate neuromagnetic activities following finger stimulation using spatially filtered MEG in young children.
- To develop and validate a novel approach for mapping the somatosensory cortex in children aged 3-6 years.
Main Methods:
- Utilized a whole-cortex MEG system with spatially filtered MEG.
- Applied electrical stimulation to the thumb and middle fingers using Digital Rings.
- Employed spectrogram and synthetic aperture magnetometry (SAM) for localization.
Main Results:
- A clear neuromagnetic response was identified at 21 ms latency in 3 out of 4 children.
- SAM successfully localized the somatosensory cortex in all 4 children.
- The functional region for the thumb was significantly larger than for the middle finger (p < 0.01).
Conclusions:
- The developed spatially filtered MEG approach enables effective mapping of the somatosensory cortex in children aged 3-6.
- This study provides the first non-invasive quantitative evidence of a larger functional thumb area compared to the middle finger in young children.
Abstract:
It is difficult to localize the somatosensory cortex in children under 6 years using magnetoencephalography (MEG) with conventional median nerve stimulation. One main reason is that MEG data recorded from small children have poor signal-to-noise ratio due to their small heads and short hands. To find a better approach, this study investigated neuromagnetic activities following finger stimulation using spatially filtered MEG. Four healthy children have been studied with a whole cortex MEG system. Electric stimulation was applied to the thumb and the middle fingers with two Digital Rings. Two trials were recorded for each hand. Focal increases of spectral power were localized using spectrogram and synthetic aperture magnetometry (SAM). A clear response at a latency of 21 ms was identified in 3 children (3/4). Dipole modeling localized the somatosensory cortex in 2 children (2/4). SAM successfully localized the somatosensory cortex in 4 children (4/4). Interestingly, the functional region estimated for the thumb was significantly larger than that of the middle finger (p < 0.01). However, it is possible that this effect is due to a larger source amplitude rather than larger source volume. Our results demonstrated that the developed approach could map the somatosensory cortex in children ranging in age from 3 to 6. To our knowledge, this is the first report using non-invasive methods to provide quantitative data indicating that the functional area of the thumb is larger than that of the middle finger in small children.
