36 results about "Retinal Neuron" patented technology

Existing epiretinal implants for the blind are designed to electrically stimulate large groups of surviving retinal neurons using a small number of electrodes with diameters of several hundred μm. To increase the spatial resolution of artificial sight, electrodes much smaller than those currently in use are desirable. In this study we stimulated and recorded ganglion cells in isolated pieces of rat, guinea pig, and monkey retina. We utilized micro-fabricated hexagonal arrays of 61 platinum disk electrodes with diameters between 6 and 25 μm, spaced 60 μm apart. Charge-balanced current pulses evoked one or two spikes at latencies as short as 0.2 ms, and typically only one or a few recorded ganglion cells were stimulated. Application of several synaptic blockers did not abolish the evoked responses, implying direct activation of ganglion cells. Threshold charge densities were typically below 0.1 mC / cm2 for a pulse duration of 100 μs, corresponding to charge thresholds of less than 100 pC. Stimulation remained effective after several hours and at high frequencies. To demonstrate that closely spaced electrodes can elicit independent ganglion cell responses, we utilized the multi-electrode array to stimulate several nearby ganglion cells simultaneously. From these data we conclude that electrical stimulation of mammalian retina with small-diameter electrode arrays is achievable and can provide high temporal and spatial precision at low charge densities. We review previous epiretinal stimulation studies and discuss our results in the context of 32 other publications, comparing threshold parameters and safety limits.

Methods and compositions useful for neuronal protection in retinal cells in vitro and the protection of mammalian cells from reactive oxygen species in vivo are provided. Ultrafine nano-size cerium oxide particles, less than 10 nanometers in diameter, have been provided to decrease reactive oxygen species (ROS) in retina tissue that generates large amounts of ROS. These reactive oxygen species (ROS) are involved in light-induced retina degeneration and age-related macular degeneration (AMD). Cerium oxide nanoparticles have been used to promote the lifespan of retinal neurons and protect the neurons from apoptosis induced by hydrogen peroxide in vitro and in vivo. The neuronal protection in retinal cells is achieved by decreasing generation of intracellular reactive oxygen species (ROS). Thus, cerium oxide particles are used to promote the longevity of retinal neurons in vitro and mammalian cells in vivo.

This invention relates to an agent for the protection of retinal neurons which comprises, as an effective ingredient, sulfamate derivative having the following formula:and to a method for the protection of retinal neurons by using said sulfamate derivative.

The invention discloses a visual pathway multi-receptive-field directional association-based profile detection method. According to the method, classic receptive field characteristics of retinal neurons and non classic receptive field characteristics of LGN (Lateral Geniculate Nucleus) cells in a visual pathway are simulated from spatial scale characteristics of receptive fields of all levels and mutual associativity of receptive fields of the same level in the visual pathway, and rectangular receptive fields of the LGN cells are associated directionally for simulating direction selection characteristics of simple cells of V1 (primary visual cortex). According to the visual pathway multi-receptive-field directional association-based profile detection method proposed by the invention, an important role of visual characteristics in profile detection is brought into full play.