Humberto Maturana

Maturana was born in Santiago, Chile. After completing secondary school at the Liceo Manuel de Salas in 1947, he enrolled at the University of Chile, studying first medicine in Santiago, then biology in London and Cambridge, Mass. Anatomy and physiology In 1954, he obtained a scholarship from the Rockefeller Foundation to study anatomy and neurophysiology with J. Z. Young (the “discoverer” of the squid giant axon and who later wrote the foreword to The Tree of Knowledge) at University College London. Maturana wrote that he was as an ”invisible” student never officially accepted in University College, London. Nonetheless, he did research and produced a paper(1) investigating the possibility of the presence of efferent fibers running from the brain to the retina. In this study, he unilaterally severed optic nerves of toads who were maintained weeks to months post-surgery. Maturana then examined the ocular and brain stumps of the cut nerves using the conventional Weigert’s and Holmes’s nerve fiber staining methods and although 'thin', concluded that efferent fibers existed. Amphibians, unlike avian and reptile species, lacked a distinct isthmo-optic nucleus located in the caudal part of the midbrain with direct connections to the retina. Maturana then went to Harvard for his PhD work with George B Chapman as his advisor. Chapman’s speciality was cell biology and ultrastructure. Maturana produced a PhD thesis in 1958 and a research paper(2) on the amphibian optic nerve. Why he did this particular work is not clear. Chapman was a cytologist using ultrastructural methods. He never worked on frogs or optic nerves even during his later distinguished career at Georgetown University. However, at MIT, down the street from Harvard, Jerome Lettvin was electrophysiologically recording from the frog optic nerve. Maturana made contact with Lettvin through J.Z. Young (who knew Lettvin and colleagues from work they carried out at the Zoological Station in Naples, Italy). Maturana's thesis revealed the frog optic nerve contains thirty times more fibers than previously estimated (3). Most of the fibers are unmyelinated and collectively the number of optic nerve fibers is around 500,000. He found that the number of fibers in the optic nerve approximately matches the number of ganglion cells in the retina. Maturana formally joined Lettvin’s laboratory at MIT’s Research Laboratory of Electronics (RLE) as a post-doctoral fellow. The details from his thesis about the frog optic nerve were useful for subsequent physiological studies. Maturana and Lettvin recorded electrical activity in the frog optic nerve and in the midbrain optic tectum, the principal target of the retina. They found that the unmyelinated optic nerve fibers terminate in the most superficial layers of the tectum and the myelinated optic nerve fibers terminate in layers below. Several sets of optic nerve fibers form visuotopic maps of visual space in the tectum. They published the paper "What the Frog's Eye Tells the Frog's Brain" (4) with Warren McCulloch and Walter Pitts, also at MIT, that became extensively cited and may have been one of the earliest papers in the realm of neuroethology. Their work was distinguished from other similar studies at the time by using “natural” visual stimuli rather than spots of light of various sizes and durations. They discovered five physiological types of retinal ganglion cells. Four of these five types are restricted to an individual layer of the tectum. One of these types is insensitive to spots of light but are exquisitely sensitive to small, dark, convexly-shaped moving objects that they dubbed "bug detectors". Lettvin and Maturana carried out the physiological and anatomical experiments and McCulloch and Pitts, famed for earlier theoretical work modeling neurons and neural networks and for epistemological approaches to the recognition of universals, provided theoretical rigor. Maturana as first author, co-wrote a longer paper elaborating on the results of the Frog’s Eye paper(5). The MIT group also produced a brief but notable physiological paper on regeneration of cut frog optic nerve fibers and showed they grow back to their original tectal locations(6). They also produced a paper describing two classes of visually evoked tectal cells. One class responded primarily to novel visual stimuli (“newness” cells); the other class responded best to stimuli repeatedly presented (“sameness” cells)(7). Maturana followed his anuran studies with studies in pigeon vision(8, 9) and with Lettvin and Wall, one of the first electrophysiological studies in octopus(10). After a 2 year post-doctoral period at MIT, he returned to Chile in 1960. Academic career Maturana was appointed Assistant Prof in Dept of Biology of Medical School of University of Chile Santiago, at the age of 32. He worked in neuroscience at the University of Chile, in the Biología del Conocer (Biology of Knowing) research center. Maturana's work has been developed and integrated into the work on ontological coaching developed by Fernando Flores and Julio Olalla. In 1994, he received Chile's National Prize for Natural Sciences. Maturana established his own reflection and research center, the Instituto de Formación Matriztica. In 2020, he was awarded an honorary fellowship by the Cybernetics Society. Maturana died in Santiago on May 6, 2021, at age 92, due to pneumonia. ==Work==