Multiple head direction signals within entorhinal cortex: origin and function.

Sensory systems show hierarchical computation, starting from primary sensory receptors, with information transformed into multimodal representations as they move through subcortical and cortical brain regions. Here, we discuss recent evidence illustrating that the signaling of direction within the mammalian brain is likewise transformed and multiplexed as it progresses from subcortical regions that contain tightly direction-coupled neurons through thalamus to regions that support navigation, such as the subiculum, entorhinal cortex and hippocampus. Such transformations in the directional signal as it ascends from thalamus to higher-order regions may allow the directional system to support a repertoire of behaviors that go beyond an animal orienting in space.