When we perceive a face, we see multiple aspects, such as its location in space, its overall 3-D shape, and the color of the lips and eyes. We know that these different attributes are represented in distinct parts of the brain. But how are they bound together to form a coherent whole? That is, how do we create a visual object out of a barrage of sensory stimuli? This so-called “binding” problem is one of the central challenges to understanding how large groups of neurons work together to encode information. Studying object perception is also a way to study another central challenge of neuroscience: how internal states of the brain give rise to perceptions. For example, when one sees a face and then a vase in the famous face-vase illusion, nothing is changed in the sensory stimulus; yet, what we perceive changes. This change must be the result of changes in the state of the brain that are independent of sensory input. Working in monkeys, we will train them to recognize a specific object in an otherwise cluttered visual scene. By using state-of-the-art techniques for recording and manipulating the activity of neurons, we can study visual object formation at the level of neural circuits. With this experimental setup, our data will provide insight not only into object formation, but also into the fundamental problem of binding. Given the similarity between monkey and human brains, we expect these insights to apply to humans as well.
Doris Tsao, California Institute of Technology