Second-harmonic generation imaging of membrane potential with photon counting.

Area of Science:

• Neuroscience
• Biophysics
• Optical Imaging

Background:

• Second-harmonic generation (SHG) is a valuable technique for imaging neuronal membrane potential.
• Accurate measurement of small voltage transients is often limited by poor signal-to-noise ratios (S/N).

Purpose of the Study:

• To improve the signal-to-noise ratio (S/N) for detecting weak SHG signals.
• To enable more accurate measurements of fast neuronal voltage dynamics.

Main Methods:

• Utilized photon counting techniques to detect weak SHG signals.
• Compared photon counting with traditional analog voltage detection methods.

Main Results:

• Photon counting achieved a shot-noise limited and integrable signal.
• Demonstrated a twofold increase in S/N compared to analog detection in single trials.
• Reduced trial-to-trial variability by 50%.

Conclusions:

• Photon counting effectively enhances S/N for SHG-based membrane potential imaging.
• This technique allows for more accurate recording of fast neuronal events, like action potentials.