Bats, Grids, and Oscillations Nearly all animals move around in a three-dimensional (3D) world; however, very little is known about the neural circuitry underlying the representation of 3D space (see the Perspective by Barry and Doeller ). Using whole-cell patch recordings in slices of entorhinal cortex, Heys et al. (p. 363 ) found that bat entorhinal stellate cells must generate grid patterns without theta-frequency oscillatory mechanisms. In another study, Yartsev and Ulanovsky (p. 367 ) used telemetry to record activity from the hippocampus of bats while they were flying around. They found that active pyramidal cells—or place cells—in hippocampal area CA1 fired in positions, depending on where the animals were in the room.