(A) LFP power spectral density for primary motor cortex (M1) (left), dorsal premotor cortex (PMd) (middle), and area 2 (right). Coloured traces, individual sessions colour-coded by monkey (legend); line and shaded areas, mean ± s.e.m. across all monkeys and sessions (n=16, 12, 8 for M1, PMd, and area 2, respectively). (B) Comparison between the band-specific power spectral density across all pairs of regions (X and Y axes). Data pooled across all sessions. Line and shaded areas, mean ± s.e.m. (n=16, 12, 8 for M1, PMd, and area 2, respectively). Note the strong similarity in LFP spectral content across regions. (C) LFP power variance in each frequency band for M1 (left), PMd (middle), and area 2 (right). Note that the LFP variance is quite similar across regions, and that the bands with highest correlations with the latent dynamics (LMP, 100–200 Hz, 200–400 Hz) are among those with lowest variance. Violin, probability density for one frequency band; horizontal line, median. (D) LFP power spectral density for M1 (left) and PMd (right) during movement preparation and execution (legend). Coloured traces, single sessions from all M1 (left) and PMd (right) sessions from Monkey M and Monkey CL; black traces, mean. (E) Comparison between the band-specific power spectral density across behavioural epochs. Markers, single comparisons colour-coded by frequency band as in Panel B; different markers indicate different monkeys (legend); grey dashed line indicates identity. Note that the LFP spectral properties are very well preserved between movement preparation and execution except for an outlier M1 session from Monkey CL.