Project Summary Synchronous low-frequency brain activity, as measured by human EEG, has been implicated in both normal cognition and in disease states such schizophrenia. However, we still do not know whether changes in such rhythms directly alter neuronal information processing, or are merely epiphenomenal. To address this issue, we will measure how single and multi unit activity linked to task performance in non-human primates is altered by endogenous alpha rhythms, and how that activity is changed when alpha rhythms are directly modulated via closed-loop electrical stimulation. The proposal will offer a mechanistic explanation for the relationship between alpha rhythms, attention, and perceptual decision making and validate the potential of direct modulation of alpha rhythms as a therapeutic approach to attentional pathologies.