Prolonged post-stimulation response induced by 980-nm infrared neural stimulation in the rat primary motor cortex

Histological and electrophysiological evidence on the safe operation of a sharp-tip multimodal optrode during infrared neuromodulation of the rat cortex

“…Our prior work on the local stimulation in the deep cortical regions (1,300 µm) and in the hippocampus of rats revealed first that in vivo response to continuous wave infrared irradiation (ƛ = 1,550 nm) exhibit cell-specific patterns 8 , and is tunable with energy density as also proved by Xia et al in cultured rat cortical neurons 5 , and Wang et al in vivo 34 , in case of continuous and pulsed wave illumination, respectively. Regarding the rate of suppression, our findings, in agreement with the work of other studies 5 , 14 , confirms that the relative change of the tissue temperature governs the inhibitory activity, but full block of the neural activity cannot be achieved in vivo if staying within our illumination parameter space.…”

“…3 D). A more recent work of Wang et al stimulating (ƛ = 980 nm, repetition rate = 300 Hz, pulse train duration = 500 ms, pulse width = 100–400 μs, radiant, exposures: 0.268 to 1.071 J/cm 2 ) the surface of the cortex (tip of a 105 µm core-diameter optical fiber placed above the cortex at 7,00–1,000 microns) and measuring the evoked potentials with a Tungsten electrode already in layer V of the motor cortex, and found similar patterns in the change of spike rate, even though the applied wavelength resulted in lower absorption and therefore a different stimulation profile 34 .…”

Two-photon imaging of excitatory and inhibitory neural response to infrared neural stimulation

“…Recently, pulsed infrared neural stimulation (INS) technique has been introduced as a method capable of modulating neural activity safely and reversibly 1 . In contrast to effects induced by alternative wavelengths of infrared stimulation (e.g., 808 nm 2 , 980 nm 3 , 5.6 μm 4,5 ), the pulsed delivery of ∼1.875 μm infrared wavelengths leads to a focal delivery of heat and rapid absorption by water 6 . When delivered via 200 μm fiber optic in short pulse trains (0.25 ms, 200 Hz, 0.5 s), this highly focal (submillimeter) optical approach has provided a unique way of functional column-specific stimulation in primate cortex 7 .…”

“…Understanding complex neural circuits and their relationship to specific behaviors involves precise temporal and spatial modulation of neuronal subtypes. Non-genetic near-infrared optical stimulation was one of the promising non-invasive neural interface technologies for the brain [1][2][3][4][5] . Recently, pulsed infrared neural stimulation (INS) technique has been introduced as a method capable of modulating neural activity safely and reversibly 1 .…”

Spatially specific, closed-loop infrared thalamocortical deep brain stimulation

“…One caveat to our study is that only excitatory responses were considered. It has been observed that continuous pulse-width or high frequency (≥ 200 𝐻𝐻𝐻𝐻) INS stimulation can drive selective inhibitory responses in nerve through introduction of a thermal block(76)(77)(78), though this type of stimulation can produce longer lasting mixed excitatory and inhibitory responses, with a higher proportion of excitatory responses for lower stimulus energies(79). An understanding of joint excitatory and inhibitory effects of circuital INS would potentially allow for bidirectional control of local microcircuits and is planned for further study.INS of thalamocortical neurons produced a variety of short-latency peristimulus responses in auditory cortex neurons, comparable to sound driven auditory cortex responses across species(67,(80)(81)(82)(83).…”