Comparative Validation of Scintillator Materials for X-Ray-Mediated Neuronal Control in the Deep Brain

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Optogenetics enables precise control of neuronal activity using light.
• X-ray-mediated optogenetics offers deeper tissue penetration and wireless control compared to traditional methods.
• Scintillators convert X-rays into visible light, crucial for X-ray-mediated optogenetics.

Purpose of the Study:

• To assess the safety and efficacy of scintillator materials for X-ray-mediated optogenetics.
• To identify suitable scintillator candidates for neuronal control applications.
• To evaluate the potential of X-ray-mediated optogenetics for therapeutic interventions.

Main Methods:

• In vitro and in vivo safety assessments of lead-free halide scintillators and cerium-doped gadolinium aluminum gallium garnet (Ce:GAGG) nanoparticles.
• Electrophysiological recordings in awake mice to measure neuronal activation by X-ray-induced radioluminescence.
• Application of the technique to selectively stimulate midbrain dopamine neurons and modulate behavior in freely moving mice.

Main Results:

• Lead-free halide scintillators showed cytotoxicity and neuroinflammation in mouse brains.
• Ce:GAGG nanoparticles demonstrated no detectable cytotoxicity or neuroinflammation over four weeks.
• Ce:GAGG nanoparticles reliably activated 45% of surrounding neurons, significantly more than Eu:GAGG microparticles (10%).
• Selective stimulation of midbrain dopamine neurons and modulation of place preference behavior were achieved wirelessly.

Conclusions:

• Ce:GAGG nanoparticles are a safe and effective material for X-ray-mediated optogenetics.
• This technology enables deep-tissue, wireless, and cell-type-specific neuronal control.
• Ce:GAGG nanoparticles hold significant promise for neuroscience research and therapeutic applications.