Figure 7.

Decoding accuracy as a function of the number of input channels. A, LFP amplitude. In each recording session (solid lines), decoding accuracies rose rapidly as the number of channels increased, reaching a maximum with 15–20 channels. Decoding accuracies were higher in monkey X than monkey Y, even after correcting for the different number of movement types being decoded (dotted lines). B, LFP power. Decoding was performed separately for each of the seven frequency bands. As illustrated by this session (X0918), movement-related information typically was greatest for LFP power in the 1–4 and 100–170 Hz bands, whereas the 16–24 Hz band contained relatively little movement-specific information (chance level of 33%). C, Spike firing rate. Movement-related information was present with even a single spike and reached maximal values using ∼30 spikes. Decoding accuracies were similar across all recording sessions and achieved levels similar to those obtained with LFP amplitude (A). Each point represents the mean ± SE of 20 LDAs performed with the indicated number of randomly selected LFP or spike recordings.