Patrick (Pat) Wall was a neurophysiologist and true pioneer in the science of pain. He discovered that the sensory information arising from receptors in our body, such as those for touch and heat, could be modified, or ‘gated’, in the spinal cord by other sensory inputs and also by information descending from the brain; this meant, as is now well recognized, that the final sensory experience is not necessarily predictable from the original pain-eliciting sensory input. He used this to explain the poor relationship between injury and pain, and to illustrate the fallacy of judging what someone ‘should’ be feeling from the sensory input alone. In 1969, together with his colleague, Ron Melzack, Pat proposed the ‘gate control theory of pain’ and the circuit diagram that summarized how central spinal cord circuits can modulate sensory inputs. Later on, he began to regret that ‘goddamned diagram’, which had come to dominate his life and work, but, like all great models, it paved the way for the future. Now, over 50 years after it was first published, molecular genetic dissection of dorsal horn neuronal circuitry has indisputably confirmed that sensory inputs are indeed ‘gated’ in the spinal cord dorsal horn. Through a career that started with a medical degree in Oxford, followed by almost 20 years at Yale and MIT in the USA, and continued at University College London, Pat Wall was a highly influential, critical, creative and original thinker who revolutionized our understanding of the relationship between injury and pain, and who also became a champion for all who suffered from chronic pain.
The emulation theory of representation: Motor control, imagery, and perception
