My broad interest is to understand the neural circuit mechanisms of cognitive behaviors. I am presently focusing on attention, an essential element of cognitive functions, fundamental to our conscious experience. At the neural circuit level, attention selectively modulates neural activities within sensory areas, and synchronizes activities across brain regions. To understand how these neural activity patterns arise and influence attentional behavior, we use a variety of temporal precise techniques, including optogenetics, in vivo automated patch clamp recording, in vivo high-density extracellular recording, mouse genetics and automated behavioral psychophysics. These methods will be combined to perform a time resolved analysis of the causal role of specific cells or anatomical connections in attention with the millisecond time resolution.Specially, we aim to understand the causal role of dynamic interactions between cortical and subcortical regions in mediating top-down control of attention. For example, we will investigate when and how prefrontal cortex exerts its attentional modulation over sensory areas and behavior. We will test whether prefrontal top-down control is through direct cortical connections or through diffusely projecting thalamic or basal forebrain connections.