Imagine a cheetah ambling through its natural habitat of shrubs and tall grasses. The individual spots on its legs and torso may appear to bounce around in different directions, but it’s clear that the animal is moving in only one direction. This phenomenon illustrates our ability to perceive not only the local movements of individual parts of a moving object, but also the global motion of the entire object.
Based on psychophysical evidence for this effect in humans, Joseph Anthony Movshon, director of the Center for Neural Science at New York University, predicted and discovered the existence of neurons in the brain that enable global motion perception. “I was looking for what I considered to be the Holy Grail,” Movshon said. “No one else had ever used perceptual evidence as the basis for a search for neurons involved in a higher-order stage of visual analysis.”
For his foundational contributions to the field of visual neuroscience, Movshon has been named the recipient of the 2013 Golden Brain Award from the Berkeley, California-based Minerva Foundation. The award, now in its 29th year, recognizes outstanding contributions in vision and brain research. Movshon was honored in a private ceremony on Saturday, November 9th, at the Society for Neuroscience's 43rd annual meeting which took place in San Diego, California. “I am honored to be recognized by the Minerva Foundation,” Movshon said. “It means a great deal to me to join the company of great visual neuroscientists who have received the Golden Brain Award.”
When Movshon embarked on his groundbreaking research several decades ago, it was known that a given neuron in primary visual cortex (V1), the cortical area in the brain where visual information is first processed, responds to motion within a small part of the visual field. As a result, V1 neurons are well suited to process the local motion of individual components of an object, but nothing was known about where global motion was processed in the brain.
In the 1980s, Movshon and his collaborators discovered the existence of neurons involved in global motion perception in a higher-order motion area called MT, or V5. This visual cortical area receives V1 signals, which convey local motion information, and combines them to process global motion across larger regions in space.
“It was quite controversial for a while whether this was really important and told us something fundamentally new and interesting about how we see motion,” Movshon said. “Ultimately, over the test of time, it has won the day, and it’s now part of people’s default way of thinking about motion processing in the cortex. It is also a standard model for how higher cortical areas take information from V1 and reorganize it to reveal complex features of images.”
Movshon and his collaborators also conducted pioneering experiments in which they recorded from individual neurons in MT and compared their responses with behavioral performance on psychophysical tasks involving motion discrimination. As reported in the Journal of Neuroscience in 1992, they discovered a close match between the two; the activity of single neurons was sufficient to predict behavioral performance.
In addition to his critical contributions regarding the neural basis of motion perception, Movshon published a trio of groundbreaking papers in the Journal of Physiology in 1978. In those classic studies, he and his collaborators used quantitative models to describe the responses of two types of V1 neurons known as simple cells and complex cells. “Tony was the first person to really take the methods of linear systems analysis and do quantitative measurements on simple and complex cells in V1,” said Bill Newsome, professor of neurobiology at Stanford University and former Golden Brain Award recipient. “This is really foundational work for thinking about models of cellular processing of visual information, and it has influenced many subsequent generations of visual and sensory physiologists as a model of how to characterize early sensory systems in a quantitative fashion.”
More recently, Movshon has made important discoveries about the neural underpinnings of smooth pursuit eye movements, which allow us to follow moving objects with our eyes. In order to accomplish this seemingly simple task, neurons must process information about an object’s motion to precisely calculate how to move the eyes to ensure that the image of the object stays on the same position on the retina. Movshon and his collaborators elucidated the role of MT and a nearby visual area called the medial superior temporal (MST) area in this process. “In higher mammals, it’s now one of the best understood sensory-motor loops where we can really understand the different stages of signal processing, from motion input to movement output of the eye,” Movshon said.
Movshon continues to pursue an active and wide-ranging research program. Earlier this year, he and his collaborators published a study in Nature Neuroscience in which they identified a new functional role for V2, a major area in visual cortex that had remained mysterious despite years of research. They found that V2 neurons respond to naturally occurring texture patterns in a way that V1 neurons did not, suggesting how these cells may contribute to our ability to parse and ultimately perceive visual scenes.
Throughout his career, Movshon has been a preeminent expert in neurophysiological techniques as well as psychophysics and computational methods. “For a couple of decades, Tony was the leading figure in vision research for understanding the mammalian visual system and how the brain helps us see, and he was the one person in the world who best combined competence in all three of those approaches,” Newsome said.
Movshon’s far-reaching impact in the field of visual neuroscience stems in part from his commendable personal traits, according to Newsome. “Tony is uncompromising in his sense of quality and his rigorous approach to designing experiments,” he said. “Many scientists try to use very high standards of evidence, but Tony holds himself and others to even higher standards. I’ve always admired that about him.”