In rats, spatial navigation involves hippocampal place cells, which encode the animal's location in an environment, and head-direction cells, which are located outside the hippocampus and encode the orientation of the animal's head. This study showed that in bats exploring an open-field arena, many hippocampal neurons encode both location and head direction. Moreover, in some neurons, the head-direction tuning was preserved even when the animal was outside the neuron's place field. Further analysis may reveal the existence of similar place–head-direction cells in rats. Alternatively, there may be species differences in neural encoding of head direction.
Rubin, A., Yartsev, M. M. & Ulanovsky, N. Encoding of head direction by hippocampal place cells in bats. J. Neurosci. 34, 1067–1080 (2014)