Visual information constantly floods our visual system, yet only a small percentage is relevant to us at each moment. Our brains are capable of filtering out irrelevant information and preferentially processing relevant information, a process known as attention. Of the visual information we attend, a percentage of it remains behaviorally relevant after it is no longer available to the senses. Our brains are capable of retaining this information for subsequent use in cognition and behavior, a process known as working memory. My research uses high-end electrophysiological and optogenetic techniques in non-human primates to examine the brain’s mechanisms underlying visual attention, working memory, and their interaction, at the level of individual neurons, neuronal ensembles, and across multiple brain areas.