Figure 1: Ratbot and maze.
(a) The components of V1 ratbots. The rat was implanted with stimulating electrodes at the Medial Forebrain Bundle. The backpack stimulator mounted on the back of the rat received MFB stimulation parameters from the computer, and delivered stimulation pulses into the rats’ brains. A bird’s-eye camera monitored the rats’ movement and position. The detailed structure of the maze and the bird camera is depicted in Section “Method” and shown in Fig. 3. (b) The components of V2 ratbots. The hardware of V2 ratbots was the same as that of V1 ratbots, except that the former carried a head-mounted mini-camera instead of a bird’s-eye camera. The mini-camera transmitted video frames wirelessly to the computer which then tried to recognize the landmarks. (c) Maze. The maze was composed of 10 × 10 units (each of 15 cm × 15 cm × 15 cm). All of the surrounding walls of the units were removable, making the maze reconfigurable with an arbitrary formation. In our experiment, the maze was designed to consist of six decision points. The correct directions of the six decision points could be randomly assigned as left or right, resulting in up to 64 different maze configurations.
