Replacing IR wavelength instead of visible wavelength on the BG network model to improve the effects of optogenetic stimulation in Parkinson’s disease

Abstract

Purpose: In optogenetic, visible light is usually used which limits penetration depth into tissue, and placing optical fibers to deliver light to deep areas of brain is necessary.In this paper, to overcome limitations, use of Near-Infrared light (NRI) along with temperature-sensitive opsins has been proposed as a powerful non-invasive or minimally invasive tool due to greater penetration depth, with least damage and most effectiveness in brain tissue.

Materials and Methods:  Effects of optogenetic stimulation with visible light and NIR on model of Parkinson's Basal Ganglia-Thalamic (BG-TH) network to reduce or eliminate pathological effects of Parkinson's disease has been studied. Three and four state optogenetic NpHR and ChR2 opsins at visible wavelengths and four-state optogenetic with TRPV1 and TRPA1 opsins at NIR wavelengths for different frequencies and number of stimulation pulses and light intensity on Error Index (EI) and beta band activity in BG-TH to introduce optimal values for basic parameters of f, ns and A_light have been considered. Finally, we have obtained A_light effects on beta band activity for different optogenetic stimulations and opsins (NpHR, ChR2, TRPV1 and TRPA1).

Results: Four-state optogenetic stimulation TRPA1 at 808 nm is optimal with best results, lowest EI and beta band activity. By increasing A_light, beta band activity for all used opsins has decreased, this decrease is sharp for NpHR, and TRPA1 with 808 nm, with low intensity, has caused less beta band activity.

Conclusion: So, NIR with best results and lowest beta activity (Beta activity=0.2) is more effective.