Figure 1.

LFP estimation method. A, The extracellular field potential (EFP) is typically separated into two frequency bands: the LFPs and the MUA. The MUA signal can in turn be separated into multiple SUA clusters through spike sorting. Except for supplemental Figure S9 (available at www.jneurosci.org as supplemental material), all the figures in this manuscript use MUA. An estimate, L_est(t), of the LFP, L(t), was obtained from the spike train, x(t), by convolving the spike train with a Wiener–Kolmogorov filter (for details, see Materials and Methods). The filter h was computed using half of the recorded LFP and spike train (labeled “trial-specific filter” in Fig. 3A). The estimation accuracy was quantified by computing the correlation coefficient (r) between the LFP and the estimate in the remaining half of the recordings. B, Construction of a general filter for the estimation of all LFPs collected with a given electrode in V1 (labeled “electrode-specific filter” in Fig. 3B). Several 4 min time series of spontaneous activity (trials) were simultaneously collected with 8–16 electrodes placed in V1 of seven monkeys. For each electrode, half of the trials (odd-numbered trials) were selected for the construction of a general filter h_mean. The LFPs of the remaining half of the trials collected with the same electrode were then estimated by convolving the general filter with the corresponding spike trains (for details, see Materials and Methods). C, In a similar manner to B, we considered the LFP estimation using a single general filter for all electrodes recorded from a given monkey. For this purpose, half of the electrodes were randomly selected to construct a general filter (labeled “monkey-specific filter” in Fig. 3C). The LFPs recorded from all the remaining electrodes were then estimated by convolving the general filter with each spike train.