DO EDGE RECORDING SITES ON HIGH-DENSITY SILICON PROBES PROVIDE BETTER RECORDING QUALITY THAN CENTER SITES
Multisite, silicon-based probes are widely used tools to record the electrical activity of neuronal populations. Several physical attributes of these devices (e.g. shaft thickness, tip geometry) are designed to improve the quality of the recorded brain signals by decreasing the damage done to the brain tissue. Here, our goal was to investigate whether the location of recording sites on the silicon shaft might affect the recording performance during acute experiments.Five different types of high-density, single-shank silicon probes with different shaft widths were acutely implanted into the neocortex of anesthetized rats, then wideband spontaneous activity was recorded. After that, various quantitative properties of the recorded cortical activity (e.g single unit yield) were extracted and compared between sites located on the edge or the center of the probes. Our results show that in most of the cases the number of separable single units, the peak-to-peak amplitude of spikes as well as the noise level was similar between the two site locations. However, based on the distribution of amplitudes, edge sites usually recorded more high amplitude spikes than center sites, especially in the amplitude range corresponding to spikes fired by neurons located close the probe (< -200 μV), although the difference was not significant. We conclude that recording sites located close to the edge of the silicon shaft provide a similar recording quality than sites in the center. The slight difference found in the spike amplitude distribution might be the result of less tissue damage caused near the edge of the probe.