Optical Stimulation of Neurons

Abstract

Our capacity to interface with the nervous system remains overwhelmingly reliant on electrical stimulation devices, such as electrode arrays and cuff electrodes that can stimulate both central and peripheral nervous systems. However, electrical stimulation has to deal with multiple challenges, including selectivity, spatial resolution, mechanical stability, implant-induced injury and the subsequent inflammatory response. Optical stimulation techniques may avoid some of these challenges by providing more selective stimulation, higher spatial resolution and reduced invasiveness of the device, while also avoiding the electrical artefacts that complicate recordings of electrically stimulated neuronal activity. This review explores the current status of optical stimulation techniques, including optogenetic methods, photoactive molecule approaches and infrared neural stimulation, together with emerging techniques such as hybrid optical-electrical stimulation, nanoparticle enhanced stimulation and optoelectric methods. Infrared neural stimulation is particularly emphasised, due to the potential for direct activation of neural tissue by infrared light, as opposed to techniques that rely on the introduction of exogenous light responsive materials. However, infrared neural stimulation remains imperfectly understood, and techniques for accurately delivering light are still under development. While the various techniques reviewed here confirm the overall feasibility of optical stimulation, a number of challenges remain to be overcome before they can deliver their full potential.

Optically Stimulated Artificial Synapse Based on Layered Black Phosphorus

“…Stimulation of neuronal activities by different optical methods is well known in neuroscience . Excitatory and inhibitory photoresponse of few‐layer BP synaptic devices under different excitation wavelengths is analogous to the neuronal activities triggered by light in different biological neurons.…”

Biological effects and medical applications of infrared radiation

“…A low frequency pulsed IR laser significantly stimulated bone nodule formation in rat calvarial cells in vitro with a low-energy Ga-Al-As laser (2-Hz, 830 nm, 500 mW, 0.48 3.84 J/cm 2 ) [44]. With respect to the INS, it is considered that the threshold for safety involves avoiding the heating of tissue depending on the neural targets, wavelength, pulse rates, power etc [45, 46]. INS for a cochlear implant is comparable to electrical stimulation, while other neural targets may have lower safety thresholds for INS.…”

Ryanodine and IP3 receptor-mediated calcium signaling play a pivotal role in neurological infrared laser modulation

“…[1][2][3][4][5][6][7][8] Likewise, ∼1.8 μm IR pulse exposure has also been demonstrated to block action potential (AP) generation and propagation. [9][10][11][12][13] While a rapid increase in temperature, due to absorption of the laser radiation, is required to evoke the neural depolarization, and IR stimulation pulses have been shown to produce an acoustic pressure wave, 14-17 the mechanism(s) to stimulate or inhibit an AP is not fully understood.…”