By Robert Desimone, Massachusetts Institute of Technology

The responses of neurons in nearly every brain structure with visual functions are modulated when people or animals attend selectively to an object in the visual field. Yet, despite the ubiquitous nature of attention-modulated neural signals, the timing of neuronal responses and synchronous interactions between different areas can be used to distinguish signals for the control of attention from those of visual neurons that are influenced by attention. Causal models are also beginning to emerge from studies that manipulate neural activity with pharmacological or optogenetic methods.