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Yao Chen, Pengcheng Sun, Zhuofan Lu, Xinyu Chai; The comparison of cortical responses evoked by transcorneal electrical and visual stimulation by intrinsic optical imaging. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4205.
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© ARVO (1962-2015); The Authors (2016-present)
Transcorneal electrical stimulation (TcES) is a promising therapeutic tool in ophthalmic neurodegeneration diseases. It has also been applied in screening candidates for retinal prostheses implantation. Our previous work found (TcES) through an ERG-jet corneal electrode could consistently elicit response areas in cats’ visual cortex, using intrinsic optical imaging of signals (OIS) (IOVS, 2014). These OIS activation regions were mainly located in cortical areas representing peripheral visual field. However whether cortical areas corresponding to central visual field could be activated is still unclear. Furthermore, comparing the cortical responses evoked by electrical and visual stimulation could enhance the comprehension of neurophysiological mechanisms underlying prosthetic vision. The purpose of this study was to investigate the difference of spatial-temporal patterns of cortical response evoked by TcES through ERG-jet and visual stimulation.
Optical imaging of intrinsic signals were recorded from area 17 and 18 in 11 adult cats with normal vision to study the cortical responses evoked by TcES and visual stimulation. An ERG-jet contact lens electrode placed on one eye was used to deliver different electrical pulses. For visual stimulation, peripheral gratings with inner diameter varied from 30° to 2.5° and full screen gratings were used.
The retinotopic map of the cortical area by OIS imaging was measured with the visual stimulation. The cortical responses to TcES primarily located in area 18 representing peripheral visual field. With the increment of current intensity, the electrical activated cortical area extended to 17/18 border. The size of activated area significantly increased (Wilcoxon test, P<0.05, n=11) when the current intensity was above 4 mA, which means the cortical area of 17 corresponded to central visual field with about 5° eccentricity were activated. Furthermore, compared with visual stimulation, negative response always show up in adjacent area when cortical area representing peripheral visual field were activated by TcES.
The result of this study demonstrated that TcES through ERG-jet corneal electrode preferentially activated peripheral area of the retina and central retina could be activated using higher current intensity.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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