In Memoriam - Ainsley Iggo

Ainsley Iggo, DSc, FRS
Founding Member, IASP President 1981-1984
Edinburgh, UK

Ainsley Iggo, founding member of IASP and President of the Association between 1981 and 1984, died at his home in Edinburgh on March 25, 2012, at the age of 87. He leaves behind an immense legacy to neuroscience – in particular to the science of pain – through his studies on identification of nociceptors and other sensory receptors in the skin, sensory innervation of internal organs, correlation between the morphology and physiology of identified sensory receptors in the skin, and organization of nociceptive neurons in the spinal cord. He was also responsible for the development of techniques that allowed recording the electrical activity of single afferent C fibers; techniques that are still in use today more than 50 years after he described and used them.

Ainsley Iggo was born in Napier, New Zealand, on August 2, 1924. In 1948 he graduated with a Master in Agricultural Sciences from the University of New Zealand and was awarded a McMillan Brown Agricultural Research Scholarship to continue his studies in the United Kingdom. Before then, though, he decided to get training in electrophysiology and Neuroscience and arranged for a 2-year period at the University of Otago where he graduated Bachelor in Science in 1950. These two years marked Ainsley's life as, at that time, the Chair of Physiology at Otago was John C. Eccles, who would be awarded the Nobel Prize for his studies of synaptic transmission. Ainsley and Eccles remained close friends and Ainsley often recounted that his decision to spend two years with "Synaptic Eccles" as he was then known in New Zealand, was the turning point of his scientific career.

In 1950 Ainsley moved to the United Kingdom for what became a one-way trip. He joined the Rowett Research Institute of the University of Aberdeen, in Scotland, an agricultural research facility where he started his pioneering studies on the sensory innervation of the stomach. This work not only led to his PhD from the University of Aberdeen in 1954 but also to the beginning of his interest in recording the electrical activity of the thinnest afferent fibers in the vagus nerve, the unmyelinated afferent fibers. After obtaining his PhD he moved to Edinburgh where he was to remain for the rest of his life, first as a Lecturer in Physiology at the Medical School of Edinburgh University and from 1962 as the Chair and Professor of Veterinary Physiology at the Royal (Dick) School of Veterinary Studies of Edinburgh University.

Ainsley Iggo is best known for his seminal studies of cutaneous nociceptors, which he carried out throughout the late 50's and 60's in parallel with those of Ed Perl in the United States. These studies provided strong support for a specificity interpretation of pain mechanisms in the periphery, which brought both Iggo and Perl into a clash with the pattern theory interpretation of pain led by Pat Wall. The two groups were irreconcilable throughout their lives even though evidence accumulated that both theories, specificity and pattern, had their positive and negative aspects. Iggo's studies of cutaneous nociceptors remain classic papers in the history of pain mechanisms.

In addition, Ainsley studied the sensory innervation of the stomach and other internal organs and found the first evidence for tension and mucosal sensory receptors in the stomach and the bladder. He also identified other types of sensory receptor in the skin, including sensitive thermoreceptors and low-threshold mechanoreceptors. A particularly significant piece of research was the correlation between the morphology and physiology of cutaneous mechanoreceptors in which he was able to demonstrate that the various histological types of sensory corpuscle are associated with distinct types of mechanoreceptor. Later in his career he turned his attention to the central nervous system and produced pioneering studies of the organization of nociceptive systems in the superficial dorsal horn, including the earliest electrophysiological recordings from small neurons in Laminae I and II of the dorsal horn.

His scientific contributions did not end with his retirement in 1990. He revived his interest in peripheral sensory receptors, which, coupled with a return to his origins, produced interesting collaborative studies with Australian colleagues on the sensory organs of animals such as the echidna and the platypus. But he never renounced to his Scottish adopted life and continued to live in Edinburgh throughout his final years.

Ainsley Iggo received numerous honors, including Fellowships of the Royal Society of Edinburgh and of the Royal Society (London), as well as membership of the Academia Europaea and the Bicentenary Medal of the Royal Society of Edinburgh. His friendship with John Bonica led him to become a founding member of IASP, President of the Association and organizer of the 3rd World Congress on Pain in Edinburgh in 1981. He was also a member of the core group that started the journal PAIN and remained a member of its Editorial Board for many years.

Like a good single malt whisky, Ainsley was a bit of an acquired taste. He had a sharp wit and a very dry sense of humor. He did not suffer fools gladly – actually he did not suffer fools at all – and did not take himself, and therefore others, very seriously. This produced a façade that people who did not him well – or who fell in the category of the people that Ainsley did not suffer at all – interpreted as rough and unwelcome, yet those who knew him better did appreciate very much his direct style and enjoyed his sharp sense of humor. He had many close and dear friends among the pioneers of pain research and the founders of IASP, and he created a school of pain researchers who continue his work to this day by upholding the high technical and scientific standards that were the hallmark of Ainsley Iggo's work.

Fernando Cervero, McGill University
An extended obituary appears in PAIN