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Yulia A. Luneva, Boris K. Baziyan, Marianna E. Ivanova, Andrey N. Serkov; Pilot Study Comparing Non-invasive Laser And Invasive Microelectrode Array (MEA) Stimulation Of Neurons For Cortical Visual Prosthesis (CVP) Development. Invest. Ophthalmol. Vis. Sci. 2012;53(14):316.
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© ARVO (1962-2015); The Authors (2016-present)
Development of highly selective penetrating noncontact and noninvasive multichannel light stimulation of brain neurons is an extremely desired alternative to MEA for CVP. Noncontact light stimulation requires trepanation of occipital bone with subsequent closure of the formed opening by transparent polymer with attached external laser stimulation device. Such noncontact technique would help to avoid challenges associated with MEAs. Based on the work performed by J. Wells (2007) on pulsed laser neuronal stimulation, we designed and conducted series of experiments on laser stimulation of visual cortex in feline model. Purpose of this work was to study responses of feline's visual cortical neurons to laser stimulation and compare its efficacy to standard electrical stimulation.
Two cats trained to produce "phosphene model" reaction (published in our earlier works) were used in the experiment. MEA of 10 varnish-coated nichrome electrodes with 100-µm diameter was implanted into layer 3-4 V1 area of visual cortex in cat 1. To induce phosphenes, electric stimuli of 1.0-3.0 J/cm2 with 0.1-0.5ms impulse duration were used. Visual cortex of cat 2 was stimulated by multispot YAG-laser with custom-made 600-µm optic fiber, using wavelength of 2.12µm, and stimuli of 0.7-5.0 J/cm2. During the stimulation brain surface was continuously moisturized with saline. Visual evoked potentials (VEP) were recorded in both animals during stimulation. Responses received from the optical stimulation were filtered and amplified.
Cat 1 produced clear behavioral responses to induced phosphenes (raising paw) from electrical stimulation. VEP of cat 2 clearly demonstrated neuronal action potentials induced in the layer 3-4 of visual cortex, however, distinct behavioral response to the range of used parameters was not observed.
Pulsed laser stimulation induced distinct selective response in neurons of layer 3-4 of V1 visual cortex area in felines. Our results suggest that laser can be used as possible noncontact stimulation agent in CVP. Further investigation of the efficacy and safe parameters of laser stimulation of visual cortex is required.
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