Despite important progress in recent years, social robots are still far away from showing advanced behavior for interaction and adaptation in human environments. Thus, we are interested in studying social cognition in human-robot interaction (HRI), notably in improving communication skills relying on joint attention (JA) and knowledge sharing. Since JA involves low-level cognitive processes in humans, we take into account the implications of Moravec's Paradox and focus on the aspect of knowledge representation. Inspired by 4E cognition principles, we study egocentric localization through the concept of sensory ego-sphere. We propose a neural network architecture named AEGO to model attention for each agent in interaction and show how to fuse information in a common representation space. From the perspective of dynamic fields theory, AEGO takes into account the dynamics of bottom-up and top-down modulation processes and the effects of neural excitatory and inhibitory synaptic interaction. In this work we evaluate the model in simulation and experiments with the robot Pepper in JA tasks based on proprioception, vision, rudimentary natural language and Hebbian plasticity. Results show that AEGO is convenient for HRI, allowing the human and the robot to share attention and knowledge about objects in scenarios close to everyday situations. AEGO constitutes a novel brain-inspired architecture to model attention that is suitable for multi-agent applications relying on social cognition skills, having the potential to generalize to several robotics platforms and HRI scenarios.