Figure 8. Causal filters.

Mean estimation accuracies (“electrode-specific” filters, V1, spontaneous activity) for three different filters: NC (non causal filter, as used in Figures 2–7), C⁺ (only has information for positive time lags; h_C+(α) = 0 for α < 0)) and C⁻ (only has information about negative time lags; h_C−(α) = 0 for α > 0)). The conventions are the same as in Figure 3. Error bars denote one SEM (n=88 electrodes). The squares indicate the mean reconstruction accuracy. The triangles indicate the mean estimation accuracies under the null hypothesis (generating a Poisson spike train with the same number of spikes). All the LFP estimation accuracies shown here are statistically significant compared with the estimations obtained under the null hypothesis (p<0.01, two-sample Kolmogorov-Smirnov test). The estimations obtained with NC and C⁺ are statistically indistinguishable (p>0.1) and there is a significant difference between the estimations obtained with either NC or C⁺, and C⁻ (p<0.01).