Figure 4.
A, Schematic of connectivity in two simulations run to open the feedback loop between Renshaw cells and motoneurons. B, Coherence phase between spikes from the population of Renshaw cells and motoneurons. Black and blue lines correspond to models shown in A. Red line, Sum of phases shown by black and blue lines, estimating the total loop phase. Horizontal dashed lines mark in-phase (0 radians) and anti-phase (π radians); vertical dashed lines mark 10 Hz and 30 Hz frequencies. C, Different EPSP shapes tested in simulations described in the lines of corresponding color in the remainder of the figure. Red EPSP is the same as used in simulations in previous figures. D, Coherence phase between motoneuron and Renshaw cell spikes, for the network shown in black in A. This corresponds to the black line in B, but for the different EPSP widths shown in C. E, Total loop phase, corresponding to the red line in B, for the different EPSP widths shown in C. F, Corticomuscular coherence. G, Force power spectrum. Black line in F and G shows the results for a simulation without Renshaw cells for comparison. H, Power spectrum of Renshaw cell population spiking. Simulations were 4017 s long throughout.