Studying rats’ brain activity noninvasively

Studying the activity of neurons is important for understanding how the brain functions. Modern noninvasive methods rely on magnetoencephalography (MEG), the use of magnetic sensors to measure the magnetic fields generated outside the brain. However, MEG is difficult to use on small animals, where short length scales lead to large sensor interference, and invasive electrode insertion techniques — which can damage the brain tissue and affect measurement results — are often used instead.

Using optically pumped magnetometers (OPMs) for magnetic measurements, Komuro et al. demonstrated a method for MEG that works on small animals, overcoming some of the scale limitations.

“Measuring MEG in small animals enables non-invasive assessment of brain function, which is highly significant from both scientific and ethical perspectives,” said author Kanta Komuro. “In many animal studies, invasive electrophysiology is still required, whereas MEG offers the possibility of repeated and longitudinal measurements without physical damage to the brain.”

The researchers compared the results of OPM-MEG and traditional electrophysiology on rats with an added gene that causes distinct neural activity when their whiskers are exposed to a specific wavelength of blue light. Using their technique, they found they could map the rats’ neural currents without damaging their skulls.

They hope to continue to explore the limits of OPM-MEG in small animals by stimulating different whiskers or simultaneously stimulating multiple whiskers, helping to better understand somatosensory processing in the brain.

“OPM-based MEG in small animals provides a promising pathway toward more detailed and spatially resolved measurements of neural activity, which can substantially contribute to basic neuroscience research and disease models,” said Komuro.

Source: “Magnetoencephalography measurement of somatosensory responses in optogenetic rats using optically pumped magnetometer,” by Kanta Komuro, Motofumi Fushimi, Yuta Kainuma, Tingyu Zhu, Seiko Funatani, Shinichi Chikaki, Hiroshi Tomita, Hiromu Yawo, and Masaki Sekino, AIP Advances (2026). The article can be accessed at https://doi.org/10.1063/9.0001068 .

This paper is part of the 70th Annual Conference on Magnetism and Magnetic Materials Collection, learn more here .