| 摘要 |
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. The same parameters that provide independent control of brightness also produce spatial patterns that the subjects' report as being similar to the sum of individual electrode phosphenes. Simultaneous stimulation of multiple electrodes can sometimes produce physical sensation or discomfort in the eye. Time-shifting the pulses cab also be used to reduce the physical sensations felt by the patient.
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