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A silicon retina that emulates the sustained and the transient responses in the vertebrate retina was fabricated. The circuit of the chip consists of two layers of resistive network that have different length constants. The output emulating the sustained response possesses a Laplacian-Gaussian-like receptive field and, therefore, carries out a smoothing and(More)
We designed a VLSI binocular vision system that emulates the disparity computation in the primary visual cortex (V1). The system consists of two silicon retinas, orientation chips, and field programmable gate array (FPGA), mimicking a hierarchical architecture of visual information processing in the disparity energy model. The silicon retinas emulate a(More)
PURPOSE To determine whether wire microelectrodes implanted in the optic disc can be used to elicit cortical potentials. METHODS Two or four platinum wire electrodes of two types, viz., the cut-end type and the exposed-tip type, were inserted through the vitreous and fixed in the optic disc of 16 rabbit eyes. Electrically evoked potentials (EEPs) were(More)
The horizontal cell is a second-order retinal neuron that is depolarized in the dark and responds to light with graded potential changes. In such a nonspiking neuron, not only the voltage-gated ionic conductances but also Ca(2+) regulation mechanisms, e.g., the Na(+)/Ca(2+) exchange and the Ca(2+) pump, are considered to play important roles in generating(More)
The striatum plays an important role in linking cortical activity to basal ganglia output. We conducted the calcium (Ca2+) imaging to investigate the spontaneous activities of the striatum using acute slice preparations. Corticostriatal slices of rat brain were stained with Fura-PE3-AM. Long-lasting spontaneous intracellular Ca2+ ([Ca2+]i) transients, which(More)
PURPOSE To investigate whether electrical stimulation of the optic nerve can elicit an electrical evoked potential (EEP) in rabbits and to determine whether such stimulation is a useful approach for the placement of a visual prosthesis. METHODS Two needle-type electrodes were inserted into the optic nerve using a transvitreal approach. For electrical(More)
PURPOSE To determine the safety and efficacy of transsclerally placed intrapapillary wire microelectrodes implanted chronically into the optic nerve head of rabbit eyes. METHODS Four platinum wire microelectrodes were passed through the sclera and implanted into the optic nerve head of five rabbit eyes for 4-6 months. Color fundus photography, fluorescein(More)
BACKGROUND Bacteria develop resistance to aminoglycosides by producing aminoglycoside-modifying enzymes such as acetyltransferase, phosphorylase, and adenyltransferase. These enzymes, however, cannot confer consistent resistance to various aminoglycosides because of their substrate specificity. Notwithstanding, a Pseudomonas aeruginosa strain AR-2 showing(More)
PURPOSE Several approaches for placing an electrode device for visual prosthesis have been previously proposed. In this study, we investigated if transretinal stimulation from the suprachoroidal space can elicit an electrical evoked potential (EEP) in albino rabbits. METHODS A flat electrode array (polyimide plate, platinum electrode) was developed and(More)
We propose an equivalent circuit model of a discrete formulation to describe the interaction between the red cone syncytium and the H1 horizontal cell syncytium in lower vertebrate retinas. Analytical solutions of the model provide intuitive understandings of spatio-temporal properties of light-induced responses in reference to membrane impedance, strength(More)