This paper presents a wireless sensor-brain interface (SBI) system featuring a linked bidirectional neural interface IC and an image sensor IC for animal tracking. The system enables a novel experiment in which swimming rats navigate a water maze guided solely by brain stimulation. Closed-loop mapping of extracted rat behaviors to stimulation parameters is implemented with novel hardware acceleration for real-time operation with short latency. The neural interface device integrates stimulators with a new charge-balancing design and neural recording front-ends with stimulation artifacts rejection. A low-power UWB link is designed for wireless communication. The system has been successfully validated in multiple rats.