Tapered Fibers Combined With a Multi-Electrode Array for Optogenetics in Mouse Medial Prefrontal Cortex

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optogenetics

Background:

• Optogenetics enables precise cell-type-specific neural circuit investigation.
• Optrodes combine optical control and electrical recording but face challenges with light distribution.
• Uneven light delivery by flat-cleaved fibers (FF) limits studies in vertically organized brain regions like the medial prefrontal cortex (mPFC).

Purpose of the Study:

• To develop and evaluate tapered optical fibers (TFs) for improved optogenetic stimulation in the mPFC.
• To enhance simultaneous optical control and electrical readout of neural activity with better light control.
• To address limitations of light scattering and absorption in vertically oriented neural populations.

Main Methods:

• Integration of tapered optical fibers (TFs) with a 16-electrode neural probe.
• Design of a probe base for seamless TF integration without interfering with electrical connections.
• Utilizing Monte Carlo simulations to optimize TF-probe positioning and light distribution.
• Performing in vivo recordings in newborn mouse mPFC.

Main Results:

• Engineered TF-based optrodes provide more uniform light distribution along the dorso-ventral axis.
• The TFs allow for restricted light delivery to specific recording sites.
• Demonstrated successful simultaneous optical stimulation and electrical readout in the mPFC.

Conclusions:

• Tapered optical fibers significantly improve optrode performance for neuroscience research.
• The TF-based optrode design enhances spatial control of light delivery in the mPFC.
• This technology facilitates more accurate investigation of functional connectivity in layered cortical structures.