, 2006). Veraart׳s group are continuing testing of their device (Brelen et al., 2010), and have since been joined by two others developing optic nerve prostheses using electrodes stimulating either the optic nerve or the optic disk (Lu

et al., 2013, Sakaguchi et al., 2009 and Wu et al., 2010). The lateral geniculate nucleus (LGN) is considered a favorable stimulation target due to its compact dimensions, retinotopic organization and the physical separation of pathways specific to color and motion (Mullen et al., 2008 and Wiesel and Hubel, 1966). The Protease Inhibitor Library mouse proximity of the LGN to structures targeted surgically for pain control and movement disorders resulted in reports of visual phenomena experienced during thalamic stimulation procedures over three decades ago. Some of these reports were published by Marg and Driessen (1965), with their patients describing highly complex visual phenomena during deep brain stimulation. In a recent macaque study however, it was shown that simple, discrete visual percepts could be elicited by microstimulation of LGN (Pezaris and Reid, 2007). While in that study Pezaris et al. analyzed visual saccades in response to LGN stimulation, Panetsos et al. (2011) recently analyzed rat and rabbit Volasertib cortical responses to LGN stimulation, concluding that such stimulation could generate visual cortical responses resembling those elicited

by natural vision. While much work remains to be done, both groups report plans for further studies in support of developing a functionally useful visual prosthesis based on LGN stimulation (Panetsos et al., 2011 and Pezaris and Eskandar, 2009). Reports exist of complex visual percepts elicited 4��8C by stimulation of the optic radiations during neurosurgical procedures (Chapanis et al., 1973 and Marg and Driessen, 1965), however to date there are no groups known to us for whom this site is a stimulation target for developing a visual prosthesis. Primary visual cortex, or V1, is an area of the occipital lobe that encompasses the buried

portions of cortex in the calcarine sulcus and its upper and lower banks, extending posterolaterally to the occipital pole. The reported surface area of V1 varies between 1400 and 6300 mm2, depending on the method of estimation (Andrews et al., 1997, Genc et al., 2014 and Stensaas et al., 1974), with approximately 67% of that area buried inside the calcarine fissure (Stensaas et al., 1974). Most efferent fibers from the LGN synapse with layer 4 of V1, from which numerous connections to other layers within V1 and those of higher visual centers are made (Troncoso et al., 2011). Human trials of visual cortex electrical stimulation with both surface and penetrating electrodes have demonstrated the viability of this brain region as a target for a visual prosthesis (Dobelle, 2000 and Schmidt et al., 1996).