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Simultaneously Acquired Magnetoencephalography and Diffuse Optical Tomography Data Reveals Correlated Somatosensory
Salla Autti1,2, Pauliina Hirvi3, Mariia Keitaanniemi1
1Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland.
Human Brain Mapping
|July 28, 2025
Summary
This study introduces a novel fiberoptic probe for simultaneous diffuse optical tomography (DOT) and magnetoencephalography (MEG) brain recordings. The new system successfully mapped hemodynamic responses correlated with electrophysiological activity, improving brain signal localization.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Medical Imaging
Background:
- Simultaneous measurement of electrophysiological and hemodynamic brain signals requires specialized instrumentation.
- Existing methods face challenges in accurately capturing both signal types concurrently.
Purpose of the Study:
- To develop and validate a high-density fiberoptic probe for concurrent diffuse optical tomography (DOT) and magnetoencephalography (MEG) recordings.
- To investigate the correlation between hemodynamic and electrophysiological brain activity during somatosensory stimulation.
Main Methods:
- A novel, flexible, non-magnetic fiberoptic probe with a dense optode arrangement was fabricated using carbon black-dyed silicone.
- The probe enabled simultaneous HD-DOT and whole-head MEG recordings of somatosensory responses to median nerve stimulation in 18 human subjects.
- Two correlation-based clustering methods were employed to analyze the relationship between DOT-derived total hemoglobin concentration (HbT) changes and MEG source activity.
Main Results:
- Statistically significant correlations were found between HbT changes around the postcentral gyrus and MEG primary somatosensory cortical activity (P35m response at ~35 ms).
- A significant cluster also indicated correlation between HbT and secondary somatosensory cortical activity in the postcentral gyrus and parietal operculum.
- The developed system demonstrated improved localization accuracy compared to previous DOT studies and confirmed the feasibility of simultaneous HD-DOT-MEG experiments.
Conclusions:
- The developed high-density fiberoptic probe facilitates simultaneous HD-DOT and MEG recordings, enabling better understanding of brain activity.
- The findings demonstrate the feasibility of concurrent hemodynamic and electrophysiological measurements for improved brain signal localization.
- This technology advances the study of neurovascular coupling and opens avenues for future research into neuronal circuits.
