SPPIN, Université Paris Cité
Why neuroscientists love the Head Direction system
This talk focuses on the sense of orientation in space, and the integration of relevant multisensory inputs in the cortical microcircuit. Like an internal compass signal, the neural networks of orientation encode the direction of the head. This “head direction” (HD) signal is generated based on vestibular information. Angular velocity signals are transformed into a directional signal in the hypothalamus, and sent to cortical areas, via the thalamus.
I will present the neural components and connections underlying the thalamocortical HD network in mice. In the presubicular HD cortex, pyramidal neurons and GABAergic interneurons form a highly interconnected excitatory-inhibitory network. The HD cortex relies on activity dependent inhibitory feedback that matches the computational needs of the orientation system and supports head directional firing in the microcircuit. From dual wavelength optogenetics work in slices we show how presubicular pyramidal cells integrate head direction and landmark inputs and project integrated signals to specific downstream targets.
To investigate the population processes involved in the anchoring and flexible updating of HD signals we use high density recordings in awake mice. I will show that HD signals are coherently tuned in subicular neurons during passive rotation, and controlled by visual cues. We seek to better understand how information from internal and external sources combine to produce our sense of orientation.