Optical magnetic detection of single-neuron action potentials using quantum defects in diamond

Area of Science:

• Neuroscience
• Quantum Sensing
• Biophysics

Background:

• Magnetic fields from neuronal action potentials (APs) offer a noninvasive window into neural dynamics.
• Existing magnetic sensing techniques lack the necessary spatial or temporal resolution for single-neuron studies or are not scalable to intact organisms.

Purpose of the Study:

• To develop a high-resolution, noninvasive magnetic sensing method for detecting neuronal APs.
• To demonstrate the applicability of this method for both excised neurons and intact organisms.

Main Methods:

• Utilized optically probed nitrogen-vacancy (NV) quantum defects in diamond as magnetic field sensors.
• Operated the NV diamond sensor under ambient conditions in close proximity (∼10 µm) to biological samples.
• Applied the technique to excised single neurons and intact marine worms.

Main Results:

• Achieved single-neuron sensitivity in detecting AP magnetic fields.
• Demonstrated noninvasive, label-free, and photodamage-free sensing on intact marine worms for extended periods.
• Precisely measured AP waveforms, conduction velocity correlates, and AP propagation direction.

Conclusions:

• Nitrogen-vacancy (NV) diamond magnetometry provides a scalable and noninvasive platform for studying neuronal activity at the single-neuron level.
• This technique overcomes the limitations of existing magnetic sensing methods, enabling new possibilities for neuroscience research in intact organisms.