A model of head direction and landmark coding in complex environments

Yijia Yan, Neil Burgess, Andrej Bicanski

Abstract: Author summary Animals need a ‘compass’ to maintain a sense of orientation relative to their environment in order to support spatial navigation and memory. This ‘compass’ has been identified with head direction cells, found in various species. These cells fire at a high rate when an animals’ head is facing in a specific allocentric direction regardless of the current location. Their firing needs to be stabilized by sensory inputs to prevent drift. Since the discovery of head direction cells most experiments and computational models have employed visual input in the form of a single polarizing cue. It is unknown how the global sense of direction can be maintained in more complex environments with multiple cues of differing stability, salience, and directional specificity. Our model suggests that (contrary to models with simple cues) a new type of neuron (abstract landmark bearing cells) endows the head direction system with powerful abilities, including unimodal landmark encoding at a sensory level despite partially conflicting cues, robustness against unreliable and ephemeral cues, and a high encoding capacity across environments. The model is consistent with numerous empirical findings, and provides a novel perspective on the neural mechanisms of spatial navigation in more realistic, cue-rich settings across multiple environments.