Nobel laureate David Hubel studied visual perception Canadian-born and trained David Hubel was half of an enduring scientific team that won a Nobel Prize for explaining how the brain assembles information from the eye's retina to produce detailed images of the world. Dr. Hubel and his collaborator, Torsten Wiesel, shared the 1981 Nobel in Physiology or Medicine with Roger Sperry for discovering ways that the brain processes information. Dr. Hubel and Dr. Wiesel concentrated on visual perception, initially experimenting on cats; Dr. Sperry described the functions of the brain's left and right hemispheres. The work of Dr. Hubel and Dr. Wiesel further showed that sensory deprivation early in life can permanently alter the brain's ability to process images. Their findings led to a better understanding of how to treat certain visual birth defects. The researchers collaborated for more than two decades, becoming, as they made their discoveries, one of the best-known partnerships in science. "Their names became such a brand name that H&W rolled off the tongue as easily in the lab as A&W root beer did at lunch," Robert Wurtz, a neuroscientist, wrote in a review article about their work. Dr. Hubel died Sunday in Lincoln, Mass., at the age of 87. The cause was kidney failure, said his son Carl. Before Dr. Hubel and Dr. Wiesel started their research in the 1950s, scientists had long believed that the brain functioned like a movie screen - projecting images exactly as they were received from the eye. Dr. Hubel and Dr. Wiesel showed that the brain behaves more like a microprocessor, deconstructing and then reassembling details of an image to create a visual scene. By measuring the electrical impulses of cells in the visual cortex, the scientists discovered that cells respond to straight lines, movement and contrast - features that delineate objects in the environment. They further found that some cells fire rapidly in response to horizontal lines, while other cells prefer vertical lines or angles. Cells with similar functions are organized into columns, they said, tiny computational machines that relay information to a higher region of the brain, where an image is formed. They also found that vision does not develop normally if the brain fails to make connections with the eye during a critical window early in life. In a 1962 experiment, the scientists showed that kittens that had one eye sewn shut after birth became blind in that eye because their brains were deprived of visual stimulation. In a related experiment, the scientists showed that exposure to light did not by itself provide enough stimulation; it was necessary for newborn animals to see the patterns and contours of the world around them. Doctors now operate on infants born with cataracts early in life to prevent vision loss; before the research of Dr. Hubel and Dr. Wiesel, doctors removed cataracts from infants between ages 6 months and 24 months, with poor results. The research also led to earlier treatment for strabismus, a condition in which the eyes are not properly aligned. Scientists have since found evidence of similar "critical periods" in hearing and language acquisition. "David and Torsten did more than open up the study of the primary visual cortex; they laid the basis of all that was to follow in the sensory systems," Eric Kandel, a Nobel laureate, wrote in a recent commentary about their research. Together this body of work stands as one of the great biological achievements of the 20th century. David Hunter Hubel was born in Windsor, Ont., on Feb. 27, 1926, to American parents. His father was a chemical engineer. After the family moved David grew up in Montreal, where his boyhood hobbies included chemistry. He once rocked his neighbourhood by firing a small cannon in the middle of his street; in another experiment, he launched a hydrogen balloon that was found by a farmer's daughter 100 miles away. He went to McGill University, where he studied math and physics because he preferred solving problems to memorizing facts. But after earning his bachelor's degree in 1947, he decided against a career in mathematics. "To make it in that field required a virtuosity - like becoming a concert pianist - that I probably lacked," he told an interviewer. Thinking he might like to do medical research, he went on to medical school at McGill and soon found himself straining to remember every muscle in the body. But he got to spend summers at the Montreal Neurological Institute, where he became fascinated with the nervous system. After receiving his medical degree in 1951, he studied neurology at McGill for three years before heading to Johns Hopkins University in Baltimore for a neurology fellowship. The Korean War interrupted his plans. He was drafted into the U.S. Army and assigned to the neuropsychiatry division at Walter Reed Army Institute of Research, where his efforts soon turned to the visual system. He developed an implantable tungsten electrode and a method for using it to measure the firing of brain cells in cats as they watched a moving spot on a screen. He found that cells were very selective - they fired when the spot moved in one direction but not another. Some cells did not fire at all. Dr. Hubel's Army service ended in 1958, but he could not immediately resume his Johns Hopkins fellowship because the laboratory that had recruited him was being remodelled. Another Johns Hopkins neurologist, Stephen Kuffler, impressed with Dr. Hubel's work at Walter Reed, invited him to spend a year in his lab. Dr. Kuffler paired Dr. Hubel with another young scientist interested in vision, Dr. Wiesel. In 1959, the scientists were recruited with their mentor to Harvard Medical School, where Dr. Hubel spent the rest of his career. He maintained his lab well past his official retirement, and until January taught a freshman seminar in which students learned to use soldering irons to build biomedical instruments and received training in surgical techniques. Dr. Hubel's wife, Ruth, died in February. In addition to his son Carl, he leaves two other sons, Eric and Paul, and four grandchildren. Dr. Hubel and Dr. Wiesel liked to recall that their initial discovery about how vision works resulted from luck. Working in a tiny basement laboratory at Johns Hopkins, the pair struggled for days to coax brain cells in cats to respond to images of dark and light spots. Becoming increasingly frustrated, they waved their arms, jumped around and, in a moment of levity, displayed images of glamorous women from magazines. Then, as they shifted a slide in the ophthalmoscope, a cell in the cat's visual cortex suddenly started to fire. The edge of the slide had cast a straight, dark line on the animal's retina. "It was what the cell wanted, and it wanted it, moreover, in just one narrow range of orientations," Dr. Hubel said in his Nobel lecture. They studied the cell for nine hours and then, Dr. Wiesel recalled, ran down the hall screaming with joy.