The Distributed Nociceptive System: A Framework for Understanding Pain

Chronic pain remains challenging to both diagnose and treat. These challenges, in part, arise from limited systems-level understanding of the basic mechanisms that process nociceptive information and ultimately instantiate a subjectively available experience of pain. Here, I provide a framework, the distributed nociceptive system, for understanding nociceptive mechanisms at a systems level by integrating the concepts of neural population coding with distributed processing. Within this framework, wide-spread engagement of populations of neurons produces representations of nociceptive information that are highly resilient to disruption. The distributed nociceptive system provides a foundation for understanding complex spatial aspects of chronic pain and provides an impetus for nonpharmacological cognitive and physical therapies that can effectively target the highly distributed system that gives rise to an experience of pain. Multiple converging lines of anatomic, neurophysiological, and behavioral evidence from studies of humans, primates, as well as rodents support the conceptual framework of the distributed nociceptive system.Nociceptive stimulus intensity is encoded by a population-based mechanism involving both the numbers of neurons recruited and the frequencies at which they discharge.Nociceptive processing is highly distributed at multiple levels of the neuraxis.The highly distributed processing, in combination with the degenerate nature of mechanisms encoding nociceptive stimulus intensity, produces a system that is highly resilient to disruption.Given the distributed nature of nociceptive processing, the development of improved therapies that simultaneously target multiple regions of the distributed nociceptive system is critically needed for the treatment of both clinical and chronic pain.