3210 Tolman Hall
University of California
Berkeley, CA 94720
I'm interested in neural mechanisms of visual and auditory perceptual processing, space representation, echolocation, and crossmodal plasticity in humans.
About half the human neocortex is thought to be devoted to visual processing. If it were as simple as that, you'd expect a huge expanse of neural real estate to fall silent in blind people, who are deprived of the visual input that drives those brain regions. In fact, those areas remain active, often in response to auditory and tactile stimuli. What kinds of computations take place under these circumstances, and are these connections present in sighted people as well? I approach this question in part by studying the phenomenon of echolocation. Similarly to many bats and marine mammals, some blind echolocating humans (using reflections from tongue clicks) have demonstrated remarkable precision in navigation and object perception. What information does echolocation afford its practitioners? What are the factors contributing to learning it?
Actions as simple as localizing an object or sound in space remain puzzling despite all we've learned in decades of studying sensory systems. For example, we know humans can localize sounds to a maximum precision of about 1 degree, but we have yet to identify all the brain networks that carry such fine spatial information, nor do we know just how the cortex contributes to generating an internal representation of auditory space. I study auditory spatial localization using fMRI and TMS to identify the neural regions that perform position discrimination at the finest scales.
Research and education on perception tends to divide the senses into their components: vision, hearing, touch, taste and smell tend to be treated separately. This is artificial, of course: many real-world events and objects, for example, are both seen and heard; what is seen can affect what is heard, and vice versa. In this vein, I use psychophysics to investigate the effects of visual motion on auditory spatial perception.