The role of gamma-motoneurons in mammalian reflex systems.

A gamma-motoneuron pathway to intrafusal muscle has been added to a previously studied model of the neuromuscular system and its reflex pathways. A general differential-difference equation is derived for the system which can be solved analytically and numerically. The homogeneous part of the solution determines the stability of the feedback pathway which to a first approximation is unchanged from the previous model. However, the additional filtering in the gamma-pathway reduces the tendency for oscillations to central inputs, which is illustrated for the particular solutions to sinusoidal and impulse inputs. Thus, the gamma pathway offers the advantage of stability at the expense of increased sluggishness of response.