Attention involves selecting the most relevant information from the abundance of information available in the sensory environment. When we attend to an object, neurons in the brain become more selective to processing information about the attended object at the expense of processing information about other, irrelevant objects. While the phenomenology of attention is well characterized, little is known about the mechanisms by which attention modulates neural responses to influence perception. In this thesis, I explore neural mechanisms of attention with a combination of approaches at several levels: 1) whole-brain functional imaging to characterize the spatiotemporal dynamics of forebrain networks that are engaged during attention, 2) extracellular electrophysiology in the midbrain of tranquilized barn owls to measure and characterize gamma oscillations, a prominent neural signature of attention, and 3) pharmacological techniques in a chick midbrain slice preparation to understand the cellular and circuit mechanisms involved in generating and regulating the structure of these oscillations. I conclude by describing ongoing work on developing neuromorphic (hardware) models of putative mechanisms of attention, as well as the development of a novel behavioral paradigm for rapidly and reliably measuring attention in birds. This work highlights the power of integrative and multi-level approaches for exploring the neural basis of cognitive functions, such as attention.