Infrared neural stimulation of primary visual cortex in non-human primates

• Published in: NeuroImage (Orlando, Fla.) Fla.), 2014-01, Vol.84, p.181-190
• Main Authors: Cayce, Jonathan M., Friedman, Robert M., Chen, Gang, Jansen, E. Duco, Mahadevan-Jansen, Anita, Roe, Anna W.
• Format: Article
• Language: English
• Subjects: Action Potentials - physiology; Action Potentials - radiation effects; Animals; Behavior; Biological and medical sciences; Brain; Brain Mapping - methods; Evoked Potentials, Visual - physiology; Evoked Potentials, Visual - radiation effects; Eye and associated structures. Visual pathways and centers. Vision; Feasibility Studies; Fundamental and applied biological sciences. Psychology; Humans; Infrared Rays; Light; Macaca; Monkeys & apes; Nervous system; Neurons; Neurons - physiology; Neurons - radiation effects; Optics; Photic Stimulation - methods; Primates; Rodents; Vertebrates: nervous system and sense organs; Visual Cortex - physiology; Visual Cortex - radiation effects
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2013.08.040

Infrared neural stimulation (INS) is an alternative neurostimulation modality that uses pulsed infrared light to evoke spatially precise neural activity that does not require direct contact with neural tissue. With these advantages INS has the potential to increase our understanding of specific neural pathways and impact current diagnostic and therapeutic clinical applications. In order to develop this technique, we investigate the feasibility of INS (λ=1.875μm, fiber diameter=100–400μm) to activate and modulate neural activity in primary visual cortex (V1) of Macaque monkeys. Infrared neural stimulation was found to evoke localized neural responses as evidenced by both electrophysiology and intrinsic signal optical imaging (OIS). Single unit recordings acquired during INS indicated statistically significant increases in neuron firing rates that demonstrate INS evoked excitatory neural activity. Consistent with this, INS stimulation led to focal intensity-dependent reflectance changes recorded with OIS. We also asked whether INS is capable of stimulating functionally specific domains in visual cortex and of modulating visually evoked activity in visual cortex. We found that application of INS via 100μm or 200μm fiber optics produced enhancement of visually evoked OIS response confined to the eye column where INS was applied and relative suppression of the other eye column. Stimulating the cortex with a 400μm fiber, exceeding the ocular dominance width, led to relative suppression, consistent with involvement of inhibitory surrounds. This study is the first to demonstrate that INS can be used to either enhance or diminish visual cortical response and that this can be done in a functional domain specific manner. INS thus holds great potential for use as a safe, non-contact, focally specific brain stimulation technology in primate brains. •INS in primate visual cortex evokes excitatory neural responses.•INS modulates visually evoked OIS responses in eye specific manner.•INS is a focally specific neurostimulation technology that is safe in primates.