Activity of Retinal Neurons Can Be Modulated by Tunable Near-Infrared Nanoparticle Sensors

Area of Science:

• Biomedical Engineering
• Neuroscience
• Ophthalmology

Background:

• Photoreceptor degeneration causes blindness, with surviving retinal ganglion cells (RGCs) offering a target for vision restoration.
• Conventional electrical stimulation for RGCs has limitations in producing naturalistic visual percepts.
• Nanoparticle-based optical sensors, particularly nanoparticle-enhanced infrared neural modulation (NINM), are emerging as promising alternatives.

Purpose of the Study:

• To investigate the efficacy of NINM for stimulating and inhibiting RGCs in explanted rat retinae.
• To explore the potential of NINM as a method for vision restoration in retinal prosthesis applications.
• To assess the impact of different laser pulse durations on RGC responses.

Main Methods:

• Application of NINM laser pulses (100 μs, 500 μs, 200 ms) to RGCs in explanted rat retinae.
• Recording single-cell responses using patch-clamp techniques.
• Utilizing gold nanorods for tunable absorption in the near-infrared window.

Main Results:

• Short NINM laser pulses (100 μs, 500 μs) effectively stimulated RGCs via capacitive current generation.
• Long NINM laser pulses (200 ms) inhibited spontaneous action potentials through thermal block.
• An observed bias towards OFF-type RGC inhibition was noted.

Conclusions:

• NINM is a viable technique for both stimulating and inhibiting RGCs, demonstrating its potential for differential neural modulation.
• The findings suggest NINM's suitability for retinal prosthesis development, particularly for high-acuity vision restoration.
• The observed OFF-type inhibition bias has significant implications for designing future retinal prostheses.