The brain and the body must communicate with each other in order to facilitate behaviors that are adaptive to spatiotemporally fluctuating internal physiology and external environments. Here, we identify and share three frameworks that provide distinct perspectives and approaches for exploring how the brain and body work together to communicate internal state. Each approach reveals key components, interactions, and networks that define internal state across different spatial and temporal scales. Whereas a top-down perspective provides a framework with a focus on how internal state is represented in brain structure and function, and how this information is used to modify signals from the brain to regulate and instruct the body, a bottom-up perspective focuses on how internal state is represented in the body, and how this information is used to send signals and coordinate responses from the brain and across different organs. Finally, a bidirectional perspective focuses on how internal state is simultaneously represented in and communicated between the brain and body in order to instruct and influence behavior and whole body function. We will primarily focus on the third framework by exploring studies that reveal the importance of bidirectional brain-body communication on tuning sensory perception to drive adaptive behavior across invertebrate and vertebrate organisms.