Hard-won insights of men who opened our eyes

Brain and Visual Perception
September 30, 2005

It is no understatement to say that David Hubel and Torsten Wiesel revolutionised vision research. They did this by refining methods for recording activity from single nerve cells (neurons) and applying them to the almost unexplored visual cortex.

The cortex is the large cauliflower-shaped structure that forms the mass of white and grey matter under our skulls. It surrounds the much-maligned brain stem and is regarded as the seat of higher brain functions in man and our mammalian cousins. The visual cortex is located at the rear of the head and is particularly large in frontal-eyed animals such as cats, monkeys and humans.

To all intents and purposes, Hubel and Wiesel founded the field of research referred to today as cortical visual physiology, which forms the core of all studies of the neural basis of visual perception. The length and success of their 25-year collaboration is truly remarkable, and the work they did led to the award of a Nobel Prize for Medicine and Physiology in 1981.

Hubel and Wiesel discovered that the cat and monkey cortex transformed the relatively simple point-by-point brightness information obtained from the eye into a unique code allowing neurons to respond in highly selective ways. The primary finding was that cortical neurons responded optimally when stimulated by lines, shadows and edges at specific orientations. This property, referred to as orientation selectivity, underpins the perception of most features in the visual world, whether they be geometrical structures or complex biological forms such as faces.

Through a series of experiments that pushed the boundaries of 1960s technology, Hubel and Wiesel went on to show that orientation selectivity is organised in the cortex such that neurons with similar orientation preferences are grouped together into orientation columns. Not content with these fundamental discoveries, the pair also did work on the neural basis of colour processing, depth perception and the development of the visual cortex.

It would be easy to suggest that those who first enter a field of research are likely to leave their mark on everything within. But this is not automatically the case. Only through intelligent development of ideas based on a steady flow of single-cell data from cats and monkeys was it possible for Hubel and Wiesel to leave such an indelible mark. They worked by going on fishing trips in which they used microelectrodes to record from the visual cortex, all the time relying on their ingenuity and a little luck to work out what visual stimulus each neuron preferred. Only after recording from thousands of neurons over many years were they eventually able to see clear trends.

The more relaxed scientific era and lack of direct competitors for the first decade of their work allowed them to progress carefully and obtain the complete answer before rushing to publication. It is a testimony to their abilities that they were able to cover so many topics, all today regarded as separate fields.

Their book does two things. First, it brings together most of the work that led to the Nobel prize. In itself, this is a wonderful achievement because in one relatively cheap book people can access all their key papers without having to trawl endless electronic search engines, battle with uncooperative printers and photocopiers or read ancient dog-eared copies of their work. For this alone, I recommend that everybody interested in the neural basis of perception have the book on their shelf.

Second, and perhaps more important, the book provides a biography of both authors, the story of how they came to do what they did and an introduction and update of every paper. This original approach has produced a truly scientific work, but one that reads more like a travel diary.

The book is structured into five sections, the first two covering the biographies and background to their research. The third and fourth parts provide high-quality reproductions of their original papers, each with a foreword and afterword that summarise and update the work. These additions to the original papers help to put each article in context. The final section provides three reviews of their work, the last two being their respective Nobel lectures.

Throughout the book, the authors discuss the easier academic and funding environment in which they worked and suggest that it made for better science. In chapter 28, they paint a slightly gloomy picture of the future, but I am happy to disagree with them on this point.

Even with the difficulties of often misinformed animal-rights activism, time spent writing grants and the reduced emphasis on neuroanatomy, the field is still vibrant. They state on several occasions that what they achieved might not be possible today because scientists are obliged to write endless funding requests, all of which require a well-developed theory, preliminary results and concrete aims. Moreover, the granting agencies expect answers in just three years. On this point, I certainly agree with Hubel and Wiesel: more time researching and less time grant writing would be welcomed by all.

I recommend this book to everybody interested in vision and neuroscience, and also to members of the art world interested in the scientific basis of image perception. Some of the medical terminology might appear technical, but it can be skipped over without losing the bigger picture. There is also a comprehensive glossary of terms to help the non-expert reader. The papers are written in a rather jaunty fashion compared with modern science, and the figures are self-explanatory. Even today, with all our modern techniques, the images of the brain they produced, particularly those using radioactive substances, are inspiring and beautiful. I remember first reading a selection of their papers as an 18-year-old undergraduate. I was so inspired that I spent my life working on vision. The book is filled with anecdotes and humour, making for some enjoyable science reading and a few genuine laughs.

A review of the book cannot end without mention of scientific genealogy, which Hubel and Wiesel discuss in the fourth chapter. I was trained in cortical physiology in Australia by Geoff Henry and Bogdan Dreher, who were both scientific sons of Peter Bishop. All three are mentioned in chapters ten and eleven as "good enemies" who provided some of the first competition for Hubel and Wiesel. As the scientific grandson of Bishop, I am proud to be training the fourth generation of cortical physiologists, all the time using the basic principles revealed by Hubel and Wiesel. Moreover, we still provide strong competition for our American colleagues.

Michael R. Ibbotson is chair of faculty, Research School of Biological Sciences, Australian National University, Canberra, Australia.

Brain and Visual Perception

Author - David H. Hubel and Torsten N. Wiesel
Publisher - Oxford University Press
Pages - 729
Price - £29.99
ISBN - 0 19 517618 9

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