A New Theory of How Neural Sequences Encode Space
Publication cover by eLife
October 4, 2023: A recent publication in eLife suggests that 2-D space can be represented through sequential activations of place cells in two ways: one traces along the animal's running trajectory, while the other follows predetermined spatial pathways.
While an animal navigates an environment, hippocampal place cells associated with a rat's past, present, and future locations have been observed to activate sequentially representing the animal's movement trajectory. Researchers at the Bernstein Center Freiburg, however, proposed a theory suggesting that the internal network connectivity concurrently propagates additional place cell sequences, exhibiting a topology and temporal order independent of the animal's trajectory.
"Imagine a rat moving and, simultaneously, leaving a trail on a surface. This trail, however, branches out to other locations along predetermined lines. The primary trail corresponds to the place cell sequence driven by the rat's movement, while the branches represent fixed sequences induced by pre-existing connections between place cells," explains Yuk-Hoi Yiu.
To substantiate their theory, they simulated a network of hippocampal place cells and demonstrated that this two-sequence model can account for previous experimental findings related to hippocampal sequential activity. Specifically, it can explain the effect of movement directions on place cell sequences in 2-D space, a phenomenon previously lacking a mechanistic explanation.
The fixed sequences could function as stable memories reflected by the temporal pattern of spikes. The study sheds light on how 2-D space can be encoded by multiple 1-D sequences and their relation to hippocampal representation memories.
Original publication
Yuk-Hoi Yiu, Christian Leibold (2023) A theory of hippocampal theta correlations accounting for extrinsic and intrinsic sequences eLife 12:RP86837. https://doi.org/10.7554/eLife.86837.4
Contact
Yuk-Hoi Yiu
hoi.yiu@biologie.uni-freiburg.de
Albert-Ludwigs-Universität Freiburg
Fakultät für Biologie & Bernstein Center Freiburg
Prof. Dr. Christian Leibold
christian.leibold@biologie.uni-freiburg.de
Albert-Ludwigs-Universität Freiburg
Fakultät für Biologie & Bernstein Center Freiburg