Fig. 4.

Transmission of common synaptic input by a set of motor neurons. Motor neurons were simulated as perfect integrate-and-fire neurons that received a common input signal, whose spectral representation is shown at left. Each motor neuron also received an independent input (indicated by the top and bottom traces at left) with a larger bandwidth (0–50 Hz). The signal-to-noise ratio (SNR) between the common input and the independent input was 0.08, so that the power of the common input was only 8% of the power of the independent input for each motor neuron (note the different scales for the common and independent inputs). The cumulative output of the motor neurons, neural drive to the muscle, has a spectral representation (right; solid line) that converges to that for the common input (dashed line) as the number of motor neurons (MN) receiving the common input increases from 1 to 100.