Oligodendrocytes, the cells that are known to produce the myelin sheaths which enable saltatory
conduction of action potentials along the myelinated axons, are modulators of signal transmission along neuronal connections (axons) and also promote neuronal survival by providing metabolic support.
Intermediate factors are those that are affected by either extrinsic or intrinsic factors and which impact on the resulting EMG signal, such as the electric
potential difference in neighbouring muscles that produces crosstalk, or the
conduction velocity
of the
action potentials in the motor neurons (De Luca, 1997).