Several weeks after damage of the sciatic nerve in adult rats, a stable electrical (ephaptic) interaction forms between pairs of injured sensory and motor axons. Fiber-fiber interaction occurs when the nerve ends in a neuroma, after end-to-end nerve suture and after nerve crush injury. Unlike the transient "artificial synapse" created acutely on section of a nerve, this form of crosstalk is long-lasting. Its existence lends support to the hypothesis that ephaptic interaction is an important factor in neurologic pathophysiology.