Ziying Fu, Jia Tang, Qicai Chen. Neuroscientists are questing to unlock the secrets of three-dimensional navigation in the brains of bats. In Journal of Chinese Science Bulletin, Dec 13, 2019. https://doi.org/10.1360/TB-2019-0404.

Abstract
“Unlocking the secrets of spatial orientation and navigation in the brains of humans and animals is a fascinating challenge question. Over the past 50 years, studying the brains of rats, bats, and other animals have provided insights into the neural basis of two dimensional (2D) navigation. Cells exist in the brain that direct navigation, including place, grid, border and head-direction cells. The fields of these cells provide cognitive maps (i.e. a unified representation of the spatial environment) and compass, which regulate 2D navigation. Place cells are hippocampal neurons that are activated when an animal traverses a specific location in the environment and the distance between different places is thought to be identified by grid cells in the medial entorhinal cortex. Distinct borders in the environment are encoded by border cells which are found in the medial entorhinal cortex and subiculum. The place, grid and border cells function as a navigational map. Head direction cells have been found in multiple brain regions and become active when the animal’s head points to a specific direction. The combination of all these cells is thought to be a neural compass for navigation. However, humans and animals basically live in a three-dimensional (3D) spatial environment, so how does the brain navigate in 3D? Recently, surprising findings were obtained by studying free moving or flying bats. Response properties of cells taking part in 2D navigation could generate obviously changes under 3D conditions. Place cells in a 3D environment were active in confined 3D volumes, and all three axes of the 3D environment were encoded with similar resolutions. Head direction cells in 3D environment were tuned to azimuth, pitch or roll, or to conjunctive combinations of these 3D angles, and the 3D head direction cells were represented in azimuth × pitch toroidal coordinates. A new navigational cell type, called social place cell, has been found in the bat hippocampus, and these cells are responsible for obtaining place information of other bats in the environment. Moreover, other hippocampal cells discern directional goals, which suggest that representations of goal-direction are memory-based. These findings demonstrate that the navigational cells in the brain collectively form the basis of 3D spatial navigation by forming a “neural Global Positioning System” through complex functional integration. This review mainly introduces the recent work of Nachum Ulanovsky and his colleagues in 3D spatial navigation that is accomplished in the brains of bats.”

Ziying Fu, Jia Tang, Qicai Chen. Neuroscientists are questing to unlock the secrets of three-dimensional navigation in the brains of bats. In Journal of Chinese Science Bulletin, Dec 13, 2019. https://doi.org/10.1360/TB-2019-0404.