Neuronal Tuning and Its Role in Attention

Abstract

The activity of sensory neurons can be modulated by both external stimuli and an animal’s internal state. Characterizing the role of these bottom-up and top-down factors as well as the way in which they interact is critical for an understanding of how the activity of sensory neurons contributes to perception. To this end, we recorded from the middle temporal area (MT) in awake-behaving primates in order to measure the joint tuning properties of these neurons for two commonly studied feature dimensions, direction of motion and binocular disparity. Additionally, we set out to determine whether attention directed to these two features can modulate the responses of MT neurons. We showed that MT neurons have fixed tuning preferences for direction of motion and binocular disparity and thus represent these features in a separable manner. Further, we have demonstrated that MT neurons can be modulated by feature attention for both direction of motion and binocular disparity and that the amount of this modulation depends on a neuron’s tuning strength. These results further our understanding of how stimulus features are jointly represented in the brain and how the attentional system interacts with these representations in order to facilitate perception.