Cell first observed phase precession in the human brain: the basic code for negotiating between humans and the environment

Written by Chunxiao | We know where we are, where we are going, and where we have been, thanks to the spatial memory and navigation functions of the brain
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The phase precession of the neurons in the hippocampus of rodents is a key mechanism for episodic memory and spatial navigation.
The hippocampus will produce specific pyramidal neurons in a specific spatial environment called location cells, and the firing time of location cells In coordination with the rhythmic theta wave (around 8 Hz) oscillation of the hippocampus, this process is called phase precession [1]
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The phase precession packs the spatial trajectory into the theta cycle time event, and expresses the position sequence through the gradual activation of the early local network theta oscillation, which is conducive to synaptic plasticity, and is the basis of the sequence memory of the rodent brain
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However, phase precession has never been observed in the human brain.
On May 11, 2021, Salman E.
Qasim and Joshua Jacobs, Department of Biomedical Engineering, Columbia University, and Itzhak Fried, University of California, Los Angeles Neurosurgery, jointly published in Cell.
A research paper entitled Phase precession in the human hippocampus and entorhinal cortex.
In this research paper, the author first proved the existence and important role of phase precession in the human brain.
It is not only related to the position sequence memory observed in animals Related, but also related to the abstract process towards a specific goal
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The opportunity for this clinical experiment to be carried out is very rare.
There are 13 bedridden drug-resistant epilepsy patients in neurosurgery who have been implanted with recording electrodes in their brains for clinical treatment
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Researchers let patients use laptop computers and handheld controllers to move in a 2D virtual environment and complete a virtual space navigation task containing six target stores [2,3] (Figure 1)
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At the same time, by analyzing the data recorded by electrodes in the patient's brain, by identifying low-frequency oscillations of 2-10 Hz, the researchers found that the relationship between the relative time of neuronal action potentials and the continuous spatial position is similar to the previous observations in rodents
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Compared with rodents, the human hippocampus has a larger theta wave frequency range and smaller power spectrum peaks (Figure 1)
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Figure 1: Top view of virtual space and local field potential (LFP).
By recording the activity of a single neuron of the patient during spatial navigation, the author identified non-spatially tuned neurons in the human hippocampus and entorhinal cortex The phase precession
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When the patient approaches the center of the area, the spikes of neuronal action potentials appear at the late stage of the local field potential; as they continue to pass through the center of the area, the spikes are advanced
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The early and late spike phase changes are negatively correlated
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After discovering that a person’s phase precession represents a spatial position, the author wants to continue to look for more complex situations such as evidence of phase precession related to a specific target state.
Some neurons only appear when the patient reaches a specific target.
Move
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Of course, the use of epilepsy patients + virtual navigation may affect the results
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But in general, this study extended the theta phase precession to the human hippocampus and entorhinal cortex, and found that this phase precession not only characterizes the spatial position, but also characterizes the neuronal mechanism of human coordinated behavior toward a specific goal.
(Picture below)
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The phase precession of a person is related to the spatial position and specific target navigation
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Itzhak Fried described this phase precession as "the basic code of the brain for negotiating between humans and the environment
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"
Phase precession represents a specific brain state in which humans seek goals.
Decoding the phase precession of different brain regions hopefully opens up new ways to study brain activity, which may be essential for understanding human cognitive behavior
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In addition, the author speculates that phase precession may also have a great impact on memory, because sorting the locations of events in our memory is one of the important activities of the human brain
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In addition, there is phase precession of damaged brain circuits in Alzheimer's disease mouse models with learning and memory impairment
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It is suggested that phase precession may be used as a biomarker of neuronal memory function.
Of course, this aspect needs further exploration
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Based on the above findings and speculations, if phase precession can become the neural code for representing learning and memory and spatial navigation in the human brain, then it will play its great potential in brain stimulation therapy and brain-computer interface in the future
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Original link: https://doi.
org/10.
1016/j.
cell.
2021.
04.
017 Platemaker: Eleven References 1.
O'Keefe, J.
(1979).
A review of the hippocampal place cells.
Prog.
Neurobiol .
13, 419–439.
2.
Jacobs, J.
, Kahana, MJ, Ekstrom, AD, Mollison, MV, and Fried, I.
(2010).
A sense of direction in human entorhinal cortex.
Proc.
Natl.
Acad.
Sci.
USA 107, 6487–6492.
3.
Miller, JF, Fried, I.
, Suthana, N.
, and Jacobs, J.
(2015).
Repeating spatial activations in human entorhinal cortex.
Curr.
Biol.
25, 1080–1085.
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