One of the techniques we use to investigate the neural basis of vision and attention in humans is functional magnetic resonance imaging (fMRI) . We use fMRI to track blood flow, and thus the underlying neural activity, in the brains of subjects performing various tasks in the scanner. We not only produce "activation maps" from the resultant data, but we can also extract the signal from a specified area and look more closely at the patterns of activity associated with particular conditions. This allows us to not only get a handle on "where" in the brain a process may occur but also "what" that area might be doing.

One of the techniques we employ in our lab is transcranial magnetic stimulation (TMS). TMS is delivered by a coil on the surface of the head, which generates a brief put powerful magnetic pulse that induce a temporary current in a small area on the surface of the brain. This current can interfere with processing of the brain with high temporal and fair spatial precision. Our facility includes a stereotactic guidance system for the TMS coil that enables us to visualize the precise site of stimulation in the brain.

Work in our laboratory involves applying TMS to the visual cortex to induce visual losses of function known as scotomas. These scotomas are used to measure the timing and contributions to visual perception of the various visual areas. Furthermore, effects of attention upon these visual deficits are investigated.