SINGLE-UNIT RECORDING CAPABILITIES OF A 100-MICROELECTRODE ARRAY

We have developed a three-dimensional silicon electrode array which pr ovides 100 separate channels for neural recording in cortex. The devic e is manufactured using silicon micromachining techniques, and we have conducted acute recording experiments in cat striate cortex to evalua te the recording capabilities of the array. In a series of five acute experiments, 58.6% of the electrodes in the array were found to be cap able of recording visually evoked responses. In the most recent acute study, the average signal-to-noise ratio for recordings obtained from 56 of the electrodes in the array was calculated to be 5.5:1, Using st andard window discrimination techniques, an average of 3.4 separable s pikes were identified for each of these electrodes. In order to compar e the two-dimensional mapping capabilities of the array with those der ived from other technologies, orientation preference and ocular domina nce maps were generated for each of the evoked responses. Histological evaluation of the implant site indicates some localized tissue insult , but this is likely due to the perfusion procedure since high signal- to-noise ratio neural responses were recorded. The recording capabilit ies of the Utah Intracortical Electrode Array in combination with the large number of electrodes available for recording make the array a to ol well suited for investigations into the parallel processing mechani sms in cortex.