  Chronic pain affects about 100 million adults in the US. Despite their great
need, neuropharmacology and neurostimulation therapies for chronic pain have
been associated with suboptimal efficacy and limited long-term success, as
their mechanisms of action are unclear. Yet current computational models of
pain transmission suffer from several limitations. In particular, dorsal column
models do not include the fundamental underlying sensory activity traveling in
these nerve fibers. We developed a (simple) simulation test bed of electrical
neurostimulation of myelinated nerve fibers with underlying sensory activity.
This paper reports our findings so far. Interactions between stimulation-evoked
and underlying activities are mainly due to collisions of action potentials and
losses of excitability due to the refractory period following an action
potential. In addition, intuitively, the reliability of sensory activity
decreases as the stimulation frequency increases. This first step opens the
door to a better understanding of pain transmission and its modulation by
neurostimulation therapies.
