FIG. 1.

Noise across days. Bars denote SE of the dataset on a given block of days. Number of sites on a given block of days, n, is listed on the x-axis. Over the course of the study, sites referenced to a common average reference exhibited 30% less noise than standard methods of referencing (P < 10⁻¹⁵). Sites referenced to a ground screw placed over parietal cortex exhibited increased noise floor variability in comparison to referencing with common average referencing (CAR) or the single-best microelectrode site. Noise floor amplitude calculated using CAR or single-best microelectrode site references decreased immediately following surgery and increased afterward, consistent with the trend in noise level found in prior studies (Ludwig et al. 2006; Schwartz 2004; Vetter et al. 2004.; Williams et al. 1999).