High-density microfibers as a potential optical interface to reach deep brain regions

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optical Engineering

Background:

• Optical techniques for neural recording are limited to superficial brain areas due to light scattering.
• A need exists for methods to access deep brain regions for optical manipulation and recording.

Purpose of the Study:

• To develop a novel method for optical interfacing with deep brain structures.
• To enable bidirectional optical recording and stimulation in large 3D volumes of the brain.

Main Methods:

• Implantation of microfiber bundles (8 μm diameter) that move independently.
• Utilizing near total internal reflection for optical interfacing with neural tissue.
• Histology, photon fluence modeling, and fluorescent bead diffusion experiments.

Main Results:

• Fibers splay to over 1 mm diameter at 3 mm depth, maintaining proximity to neurons.
• Demonstrated potential for precise neural stimulation by selective fiber illumination.
• Confirmed recording capabilities using fluorescent beads.

Conclusions:

• Optical microfibers offer a minimally invasive, stable interface for deep brain optical recording and stimulation.
• This technique represents a hyper-localized form of fiber photometry for neuroscience.
• Potential applications include recording or stimulating genetically encoded probes in deep brain regions.