Real-time imaging of action potentials in nerves using changes in birefringence

Area of Science:

• Neuroscience
• Biophysics
• Optical Imaging

Background:

• Electrical activity in nerves, like action potential propagation, causes dynamic changes in optical birefringence.
• Optical birefringence changes can potentially be used for minimally invasive neuroimaging.
• High spatiotemporal resolution is crucial for studying neuronal activation patterns.

Purpose of the Study:

• To demonstrate the feasibility of imaging action potential propagation in nerve fibers using polarized light.
• To explore the use of optical birefringence as a tool for neuroscience research.
• To establish a method for real-time, high-resolution imaging of neuronal electrical activity.

Main Methods:

• Utilized a fast linear photodiode array to capture optical signals.
• Employed polarized light to detect changes in nerve birefringence.
• Recorded signals from an excised lobster walking leg nerve in a custom chamber.

Main Results:

• Successfully imaged propagating action potentials in lobster nerves over a ≥2 cm span.
• Demonstrated reliable imaging of the crossed-polarized signal (XPS) through signal averaging.
• Achieved real-time imaging of action potentials in single-scan "movies".

Conclusions:

• Optical birefringence changes reliably correlate with nerve electrical activity.
• Polarized light imaging of birefringence is a viable technique for neuroimaging.
• This method shows promise for imaging complex neuronal activity in nerve fibers and organized tissues.