Current steering and current focusing with a high-density intracochlear electrode array

Creating high-resolution or high-density, intra-cochlear electrode arrays may significantly improve quality of hearing for cochlear implant recipients. Through focused activation of neural populations such arrays may better exploit the cochlea's frequency-to-place mapping, thereby improving sound perception. Contemporary electrode arrays approach high-density stimulation by employing multi-polar stimulation techniques such as current steering and current focusing. In our procedure we compared an advanced high-density array with contemporary arrays employing these strategies. We examined focused stimulation of auditory neurons using an activating function and a neural firing probability model that together enable a first-order estimation of an auditory nerve fiber's response to electrical stimulation. The results revealed that simple monopolar stimulation with a high-density array is more localized than current steering with a contemporary array and requires 25–30% less current. Current focusing with high-density electrodes is more localized than current focusing with a contemporary array; however, a greater amount of current is required. This work illustrates that advanced high-density electrode arrays may provide a low-power, high-resolution alternative to current steering with contemporary cochlear arrays.