Dear Colleagues, We are organizing the Frontiers Research Topic below, aiming to create a collection of articles across the whole field of neuroscience studies of freely moving animals. Please *consider submitting* your related work and *sharing the call* with potentially interested colleagues. Apologies for the cross-post. *The Brain in Action: Neural Dynamics and Behavior in Freely Moving Animals* *Link*: https://www.frontiersin.org/research-topics/20697/the-brain-in-action-neural... *Details: *Understanding the neural basis of complex behaviors is a primary aim of neuroscience. However, until recently, the field lacked an appropriate set of techniques for simultaneously measuring neural activity and behavior in freely moving animals, forcing investigators to use immobilized animals performing simplistic behavioral tasks. Synergistic technological breakthroughs in fluorescent brain imaging and behavioral tracking approaches have paved the way to a new type of neuroscience that enables tracking behavior in setups compatible with brain imaging and manipulation, even at the single-cell level, using optical electrophysiology techniques. A diversity of such neurobehavioral imaging systems have been recently invented, spanning the range of conventional model organisms including C. Elegans, Flies, Zebrafish, and Rodents. Each species and approach showcases unique technical challenges, achievements, and opportunities. Our aim with this Research Topic is to provide an overview of this new field. We will present not only the technological advances but also discuss the novel type of experiments and insights that they promise. To achieve that, we welcome articles that span the following categories: i) Algorithms and imaging systems for tracking and quantifying complex behaviors of freely moving animals; ii) Molecular tools and microscopes, enabling capturing or manipulating neuronal dynamics. Such systems could include tracking or large field of view microscopes in small animals, head-mounted mini scopes and fiber-based systems for mammalian models, -or non-optical methods; iii) Neuroscience studies, using such tools to generate neurobehavioral datasets (ideally shareable with the community) and new biological findings; iv) Perspective articles on the future possibilities of such systems are also welcome -including ones that discuss alternatives approaches; v) Analysis pipelines and computational neuroscience frameworks exploiting the produced datasets, along with ways to integrate them with existing ( or future) knowledge and techniques. *Keywords*: Brain Imaging, Behavioral Tracking, Quantitative Behavior, Neuronal Dynamics, Freely Moving *Participating Journals:*Frontiers in Neuroscience Frontiers in Neuroimaging *Guest Editors Team:* Prof. Gershow, Prof. Venkatachalam, Dr. Marshall, and Dr. Symvoulidis *Deadline:*30 October 20202 Best, Panos