Spatial-Jitter Model for Magnetoencephalography Sensor Arrays

Area of Science:

• Biophysics
• Biomedical Engineering
• Neuroscience

Background:

• Sampling jitter in signal acquisition introduces frequency-dependent noise, reducing signal-to-noise ratio (SNR).
• Magnetoencephalography (MEG) uses sensor arrays to measure brain activity's magnetic fields, which are susceptible to spatial sampling errors.

Purpose of the Study:

• To generalize the concept of sampling jitter to spatial jitter in MEG sensor arrays.
• To analyze the impact of spatial, orientation, and aperture jitter on MEG measurements.
• To compare the jitter resistance of on-scalp versus off-scalp MEG sensor configurations.

Main Methods:

• Analysis of spatial jitter effects in the vector spherical harmonics domain.
• Investigation of orientation jitter and aperture error impacts.
• Simulation of spatial jitter using realistic optically pumped magnetometer (OPM) and superconducting quantum interference device (SQUID) sensor arrays.

Main Results:

• Spatial jitter in MEG sensor arrays causes spatial-frequency-dependent noise, reducing SNR and spatial resolution.
• On-scalp MEG sensors are more resilient to high-frequency spatial and orientation jitter compared to off-scalp sensors.
• On-scalp sensors are more susceptible to aperture errors, while off-scalp sensors are less affected.

Conclusions:

• Spatial jitter is a critical factor affecting MEG data quality, necessitating careful sensor placement and array design.
• The choice between on-scalp and off-scalp MEG configurations involves a trade-off between resistance to different types of sensor noise.
• Understanding and mitigating jitter effects are essential for improving spatial resolution and SNR in MEG neuroimaging.