In the Brain Space Time Podcast, I will be talking plenty about place, grid, head direction cells and other cells in the hippocampal zoo.
If you have never heard about them, this primer may be helpful.
Note: This primer provides a canonical perspective on these cells, describing how they code for physical space. Other studies have shown that these cells may also code for the non-spatial dimension/ conceptual spaces. We will explore both in the podcast. :)
Place cells
Place cells were first discovered in the hippocampus of rats (O'Keefe and Dostrovsky, 1971).
Place cells fire when an animal enters a specific place in its local environment (see video below). This even happens when the animal is in a dark room (Quirk et al., 1990), suggesting place cells code for the space and are not modality-specific (i.e. they don't code for the visual features of a place).
Head direction cells
Head direction cells were first discovered in the subiculum of rats (Taube et al., 1990).
They fire when an animal’s head is facing a particular direction.
Grid cells
Grid cells were first discovered in the entorhinal cortex of rats (Hafting et al., 2005).
A grid cell fires at regular intervals as an animal navigates an open area, allowing it to understand its position in space by storing and integrating information about location, distance, and direction.
Hippocampal zoo
There are a variety of other cells in the hippocampal formation that code for space.
Object-vector cells (Høydal et al., 2019) are active when an animal is in a particular direction and distance from any object.
Reward cells (Gauthier and Tank, 2018) are active when an animal is in the vicinity of reward.
Boundary vector cells (Lever et al., 2009) are active at a given distance away from a boundary in a particular allocentric orientation.
Goal direction cells (Sarel et al., 2017) are active when the goal (G) of an animal is in a particular direction relative to its current movement direction.
‘‘Social place cells’’ (Danjo et al., 2018; Omer et al., 2018) are active in one animal when it observes that another animal is in a particular location.
Recommended reading
Grieves, R. M., & Jeffery, K. J. (2017). The representation of space in the brain. Behavioural Processes, 135, 113–131. https://doi.org/10.1016/j.beproc.2016.12.012
References
Behrens, T. E. J., Muller, T. H., Whittington, J. C. R., Mark, S., Baram, A. B., Stachenfeld, K. L., & Kurth-Nelson, Z. (2018). What Is a Cognitive Map? Organizing Knowledge for Flexible Behavior. Neuron, 100(2), 490–509. https://doi.org/10.1016/j.neuron.2018.10.002
Dudchenko, P. A., Wood, E. R., & Smith, A. (2019). A new perspective on the head direction cell system and spatial behavior. Neuroscience & Biobehavioral Reviews, 105, 24–33. https://doi.org/10.1016/j.neubiorev.2019.06.036
Gauthier, J. L., & Tank, D. W. (2018). A Dedicated Population for Reward Coding in the Hippocampus. Neuron, 99(1), 179-193.e7. https://doi.org/10.1016/j.neuron.2018.06.008
Grieves, R., Duvelle, E., & Jeffery, K. (2020). Place cell (rat hippocampus CA1) activity recorded over 50 minutes of foraging. 4880416 Bytes. https://doi.org/10.6084/M9.FIGSHARE.8063324.V2
Hafting, T., Fyhn, M., Molden, S., Moser, M.-B., & Moser, E. I. (2005). Microstructure of a spatial map in the entorhinal cortex. Nature, 436(7052), Article 7052. https://doi.org/10.1038/nature03721
Høydal, Ø. A., Skytøen, E. R., Andersson, S. O., Moser, M.-B., & Moser, E. I. (2019). Object-vector coding in the medial entorhinal cortex. Nature, 568(7752), Article 7752. https://doi.org/10.1038/s41586-019-1077-7
Moser, M.-B., Rowland, D. C., & Moser, E. I. (2015). Place Cells, Grid Cells, and Memory. Cold Spring Harbor Perspectives in Biology, 7(2), a021808. https://doi.org/10.1101/cshperspect.a021808
O’Keefe, J., & Dostrovsky, J. (1971). The hippocampus as a spatial map. Preliminary evidence from unit activity in the freely-moving rat. Brain Research, 34(1), 171–175. https://doi.org/10.1016/0006-8993(71)90358-1
Omer, D. B., Maimon, S. R., Las, L., & Ulanovsky, N. (2018). Social place-cells in the bat hippocampus. Science, 359(6372), 218–224. https://doi.org/10.1126/science.aao3474
Quirk, G. J., Muller, R. U., & Kubie, J. L. (1990). The firing of hippocampal place cells in the dark depends on the rat’s recent experience. Journal of Neuroscience, 10(6), 2008–2017. https://doi.org/10.1523/JNEUROSCI.10-06-02008.1990
Sarel, A., Finkelstein, A., Las, L., & Ulanovsky, N. (2017). Vectorial representation of spatial goals in the hippocampus of bats. Science, 355(6321), 176–180. https://doi.org/10.1126/science.aak9589
Taube, J. S., Muller, R. U., & Ranck, J. B. (1990). Head-direction cells recorded from the postsubiculum in freely moving rats. I. Description and quantitative analysis. Journal of Neuroscience, 10(2), 420–435. https://doi.org/10.1523/JNEUROSCI.10-02-00420.1990