Jercog, Pablo E., Yashar Ahmadian, Caitlin Woodruff, Rajeev Deb-Sen, Laurence F. Abbott, and Eric R. Kandel. “Heading direction with respect to a reference point modulates place-cell activity.” Nature Communications 10, Article number: 2333 (2019).

Abstract
The tuning of neurons in area CA1 of the hippocampus emerges through a combination of non-spatial input from different sensory modalities and spatial information about the animal’s position and heading direction relative to the spatial enclosure being navigated. The positional modulation of CA1 neuronal responses has been widely studied (e.g. place tuning), but less is known about the modulation of these neurons by heading direction. Here, utilizing electrophysiological recordings from CA1 pyramidal cells in freely moving mice, we report that a majority of neural responses are modulated by the heading-direction of the animal relative to a point within or outside their enclosure that we call a reference point. The finding of heading-direction modulation relative to reference points identifies a novel representation encoded in the neuronal responses of the dorsal hippocampus.

Successful navigation requires knowledge of both location and direction, quantities that must be computed from self-motion and from environmental cues. Place cells in the dorsal hippocampus1 and grid cells in entorhinal cortex2,3 are the best known example of neurons modulated by location. In addition, neurons modulated by head direction have been reported in various brain areas4,5,6,7,8,9, including the hippocampus7,8,10,11,12. In some cases, firing rates are modulated by the animal’s spatial relationship to visual cues8, to objects13,14, or to task goals15. Here we provide evidence for a novel form of direction tuning of place-selective neurons in area CA1 of the mouse hippocampus: modulation of neurons by heading direction (HD) relative to various reference points located inside or outside the enclosure. These results extend the scope of spatial representations in the hippocampus beyond the well-known place-cell maps.

For further info, please read the paper Jercog et al. 2019

Jercog, Pablo E., Yashar Ahmadian, Caitlin Woodruff, Rajeev Deb-Sen, Laurence F. Abbott, and Eric R. Kandel. “Heading direction with respect to a reference point modulates place-cell activity.” Nature Communications 10, Article number: 2333 (2019).