Feature-based attention induces surround suppression during the perception of visual motion

Attention to a stimulus feature prioritizes its processing while strongly suppressing the processing of similar features, a non-linear phenomenon called surround suppression. Here we investigated this phenomenon using neurophysiology and psychophysics. We recorded responses of motion direction-selective neurons in area MT/MST of monkeys in different conditions. When attention was allocated to a stimulus moving in the neurons' preferred direction responses to a distractor were strongly suppressed for directions nearby the preferred direction. These effects were modeled as the interaction between two Gaussian fields representing narrowly-tuned excitatory and widely-tuned inhibitory inputs into a neuron, with attention more strongly modulating the gain of the inhibitory inputs. We additionally demonstrated a corresponding behavioral effect in humans: Feature-based attention strongly reduced motion repulsion in the vicinity of the attended motion direction. Our results demonstrate that feature-based attention can induce non-linear changes in neuronal tuning curves via unbalanced gain changes to excitatory and inhibitory inputs into neurons ultimately translating into similar effects during behavior.