Tim Buschman

Massachusetts Institute of Technology

Attention regulates the flood of sensory information into a manageable stream, and so understanding how attention is controlled is
central to understanding cognition. Previous work has shown attention can be focused volitionally by “top-down” signals derived from task
demands and automatically by “bottom-up” signals from salient stimuli. To emphasize these two forms of attention two monkeys were
trained to covertly search an array for a target stimulus under visual search (endogenous) and pop-out (exogenous) conditions. While it is
known that the frontal and parietal cortices are involved, their neural activity has not been directly compared. Therefore, we recorded from
them simultaneously. I will present three key findings from this study. First, we find evidence that volitional control of attention is directed
from the frontal cortex while posterior cortex reflects the external grabbing of attention. Second, I will discuss neural evidence for serial,
covert shifts of attention during search but not pop-out. Finally, I will discuss the role of synchrony in the control of attention, including
evidence that attention shifts were correlated with 18-34 Hz oscillations in the local field potential, suggesting a ‘clocking’ signal.