Abstract: A visual prosthesis apparatus including a video capture device for capturing a video image, a video processing unit associated with the video capture device, the video processing unit configured to convert the video image to stimulation patterns, and a stimulation system configured to stimulate subject's neural tissue based on the stimulation patterns, wherein the stimulation system provides a span of visual angle matched to the subject's neural tissue being stimulated.

Abstract: The present invention is a flexible circuit electrode array for stimulating neurons where the electrode are less than 20 ?m in size and less than 60 ?m apart. The array is preferably arranged in a hexagonal pattern to maximize electrode density, and longer in the horizontal direction to correspond to a normal visual scene. The array includes a polymer base layer, metal traces deposited on the polymer base layer, including electrodes suitable to stimulate neural tissue, and a polymer top layer deposited on the polymer base layer and the metal traces defining openings for the electrodes smaller than the electrodes to overlap the electrodes.

Abstract: A visual prosthesis apparatus including a video capture device for capturing a video image, a video processing unit associated with the video capture device, the video processing unit configured to convert the video image to stimulation patterns, and a stimulation system configured to stimulate subject's neural tissue based on the stimulation patterns, wherein the stimulation system provides a span of visual angle matched to the subject's neural tissue being stimulated.

Abstract: To accurately represent a visual scene a visual prosthesis must convey luminance information across a range of brightness levels. To do this, the brightness of phosphenes produced by an individual electrode should scale appropriately with luminance, and the same luminance should produce equivalently bright phosphenes across the entire electrode array. Given that the function relating current to brightness varies across electrodes, it is necessary to develop a fitting procedure that will permit brightness to be equated across an entire array. The current invention describes a method of performing a brightness fitting that normalizes brightness across electrodes. The method determines a set of parameters that are stored in the subjects Video Configuration File—the look-up table that converts the video camera input to stimulation profiles for each electrode. One electrode would be specified as the standard.

Abstract: In a visual prosthesis or other neural stimulator it is advantageous to provide non-overlapping pulses in order to provide independent control of brightness from different electrodes. Non-overlapping pulses on geographically close electrodes avoid electric-field interaction which leads to brightness summation or changes in the shape and area of percepts. It is advantageous to apply pulses to nearby electrodes in a way that the currents do not overlap in time at all. The new finding is that even a small amount of separation results in a significant improvement as small as (ie. 0.225 msec). ‘Nearby’ is defined as within a few millimeters of each other. Another new finding is that there is some additional benefit of separating the pulses in time even further. In particular, some experiments showed a benefit of separating them more than 1.8 msec. Another experiment showed a benefit of separating them greater than 3 msec. But, there is probably no benefit to separating them more than 5 msec.

Abstract: A method of editing a video configuration file downloadable to or from a video processing unit of a fitting system for a visual prosthesis is shown. The visual prosthesis has a plurality of electrodes and the video configuration file defines mapping of a video signal captured from a camera of the visual prosthesis to an electrical signal for the electrodes. The editing controls a brightness map for an individual electrode or electrode groups, together with a temporal stimulation pattern to which an individual electrode or electrode groups are assigned. A related computer-operated system is also disclosed.

Abstract: A visual prosthesis apparatus including a video capture device for capturing a video image, a video processing unit associated with the video capture device, the video processing unit configured to convert the video image to stimulation patterns, and a stimulation system configured to stimulate subject's neural tissue based on the stimulation patterns, wherein the stimulation system provides a span of visual angle matched to the subject's neural tissue being stimulated.

Abstract: In a visual prosthesis or other neural stimulator it is advantageous to provide non-overlapping pulses in order to provide independent control of brightness from different electrodes. Non-overlapping pulses on geographically close electrodes avoid electric-field interaction which leads to brightness summation or changes in the shape and area of percepts. It is advantageous to apply pulses to nearby electrodes in a way that the currents do not overlap in time at all. The new finding is that even a small amount of separation in time results in a significant improvement with a time separation as small as 0.225 msec. ‘Nearby’ is defined as within a few millimeters of each other.

Abstract: In order to generate the smallest phosphenes possible, it is advantageous to selectively stimulate smaller cells. By hyperpolarizing the somas of the large cells selectively with sub-threshold anodic ‘pre-pulse’ stimuli (making them more difficult to stimulate) and then selectively depolarize the smaller cells one can selectively stimulate smaller cells. Alternatively, one can hyperpolarize the dendrites of the cells with larger dendritic fields by applying sub-threshold anodic currents on surrounding electrodes and then depolarizing the smaller cells in the center. Further, one can manipulate the phases of an individual biphasic wave to affect selective stimulation resulting in more focal responses. It is possible to increase resolution with the ‘pre-pulse’ described above. One can also effect resolution by modifying the pulse order of the cathodic and anodic phases.

Abstract: A visual prosthesis apparatus including a video capture device for capturing a video image, a video processing unit associated with the video capture device, the video processing unit configured to convert the video image to stimulation patterns, and a stimulation system configured to stimulate subject's neural tissue based on the stimulation patterns, wherein the stimulation system provides a span of visual angle matched to the subject's neural tissue being stimulated.

Abstract: A method, device and system for stimulating visual tissue, typically in the retina or visual cortex, to achieve an artificial percept of light or image. The method includes providing stimulating electrodes suitable for placement in proximity to the visual tissue and generating a series of short-duration stimulation signals having a duration of less than about 0.5 milliseconds each. The short-duration stimulation signals are applied through the stimulating electrodes with varying frequencies that are substantially matched to a spiking range of frequencies of at least one ganglion cell for perceiving brightness or image.

Abstract: Polymer materials are useful as electrode array bodies for neural stimulation. They are particularly useful for retinal stimulation to create artificial vision, cochlear stimulation to create artificial hearing, and cortical stimulation, and many related purposes. The pressure applied against the retina, or other neural tissue, by an electrode array is critical. Too little pressure causes increased electrical resistance, along with electric field dispersion. Too much pressure may block blood flow. Common flexible circuit fabrication techniques generally require that a flexible circuit electrode array be made flat. Since neural tissue is almost never flat, a flat array will necessarily apply uneven pressure. Further, the edges of a flexible circuit polymer array may be sharp and cut the delicate neural tissue. By applying the right amount of heat to a completed array, a curve can be induced.

Abstract: The present invention is a method of improving the contrast of electrical neural stimulation and expanding the dynamic range for brightness, and specifically a method of improving the contrast of an image supplied to the retina, or visual cortex, through a visual prosthesis. The background brightness for a blind subject is often not perfectly black, but a dark gray or brown. When stimulating visual neurons in the retina, low current stimulation tends to create a dark percept, the perception of a phosphene darker than the background brightness level perceived in the un-stimulated state. The human retina contains neurons that signal light increments (“on” cells) and neurons that signal light decrements (“off” cells). In a healthy retina, the on cells tend to fire in response to an increase in light above the background level, while the off cells tend to fire in response to a decrease in light below the background level.

Abstract: The present invention is a method of improving the contrast of electrical neural stimulation and expanding the dynamic range for brightness, and specifically a method of improving the contrast of an image supplied to the retina, or visual cortex, through a visual prosthesis. The background brightness for a blind subject is often not perfectly black, but a dark gray or brown. When stimulating visual neurons in the retina, low current stimulation tends to create a dark percept, the perception of a phosphene darker than the background brightness level perceived in the un-stimulated state. The human retina contains neurons that signal light increments (“on” cells) and neurons that signal light decrements (“off” cells). In a healthy retina, the on cells tend to fire in response to an increase in light above the background level, while the off cells tend to fire in response to a decrease in light below the background level.

Abstract: An apparatus and method for retinal stimulation are shown. The method comprises varied parameters, including frequency, pulse width, and pattern of pulse trains to determine a stimulation pattern and neural perception threshold, and creating a model based on the neural perception thresholds to optimize patterns of neural stimulation.

Abstract: This system gives the experimenter great flexibility to present spatio-temporal stimulation patterns to a subject. A video configuration file (VCF) editor allows the experimenter to determine the electrical stimulation parameters for each electrode. A Pattern Stimulation software program allows direct stimulation of chosen patterns of electrodes, scaled by the subject's VCF, through a Graphical User Interface. The subject then responds by drawing the outline of the phosphene he or she perceives on a touchscreen. The Pattern Stimulation program saves all of the trial parameters and the parameters of an ellipse fit to their drawing, as well as a raw data file containing the input to the touchscreen is saved. After the experiment, offline image analysis can be performed to obtain a detailed quantitative description of the subject's percepts. Image descriptors can assigned to the touchscreen data; these image descriptors can be used to make formalized comparisons between various experimental conditions.

Abstract: The present invention is a fitting system with a graphical interface with specific interface screens for specific functions. Methods and devices for fitting a visual prosthesis are described. In one of the methods, threshold levels and maximum levels for the electrodes of the prosthesis are determined and a map of brightness to electrode stimulation levels is later formed. A fitting system for a visual prosthesis is also discussed, together with a computer-operated system having a graphical user interface showing visual prosthesis diagnostic screens and visual prosthesis configuration screens.

Abstract: An apparatus and method for retinal stimulation are shown. The method comprises varied parameters, including frequency, pulse width, and pattern of pulse trains to determine a stimulation pattern and visual perception threshold.

Abstract: A method, device and system for stimulating visual tissue, typically in the retina or visual cortex, to achieve an artificial percept of light or image. The method includes providing stimulating electrodes suitable for placement in proximity to the visual tissue and generating a series of short-duration stimulation signals having a duration of less than about 0.5 milliseconds each. The short-duration stimulation signals are applied through the stimulating electrodes with varying frequencies that are substantially matched to a spiking range of frequencies of at least one ganglion cell for perceiving brightness or image.

Abstract: Methods and devices for fitting a visual prosthesis are described. In one of the methods, threshold levels and maximum levels for the electrodes of the prosthesis are determined and a map of brightness to electrode stimulation levels is later formed. A fitting system for a visual prosthesis is also discussed, together with a computer-operated system having a graphical user interface showing visual prosthesis diagnostic screens and visual prosthesis configuration screens.