Hippocampus ( hippocampus ) A major region in the vertebrate brain that plays a key role in the encoding of navigation, memory, and learning. While much neuroscience has investigated the function and organization of this brain region, much remains to be discovered.
Past research has consistently identified populations of cells in the hippocampus, generally called time cells, that form temporal sequences that are critical for navigation in different environments and for episodic memory—recalling the past The ability to event is very important. The ability of these cells to generate temporal sequences is now extensively documented, but whether they represent experiences in tandem, or time itself, remains to be explored.
Researchers from the Hebrew university in Jerusalem recently discovered that different populations of hippocampal cells encode time differently for themselves and others in their environment. The results of their study were published in theNature Neuroscience“Magazine.
Experiments with resilient Egyptian fruit bats reveal two different types of time cells
The research team said: Since any social behavior requires at least two different individuals to coordinate in space and time, and it has been known from previous studies that there are time cells in the hippocampus (that is, relative to self-events, they will adjust to specific cells of time) in the hippocampus to look for signs of time in other people seems reasonable. So the team conducted experiments on Egyptian fruit bats, highly social animals that thrive in different environments and are found in Africa, the Middle East, the Mediterranean and India.
To study the role of cells at different times, the researchers devised a new observational learning task. In this task, two were observation bats and demonstration bats, and the observer watched the flight of the demonstrator and remembered its flight target. After the demonstration bat returned to the starting point, the observation bat was taught to imitate his companion and fly to the same target for a reward.
The research team used tiny wireless devices to record and observe neural activity in the hippocampus of bats. To record the time cells, they looked at neurons in the hippocampus associated with observing the moment a bat lands, called classical time-cells, with another bat’s moment of landing, known as social time-cells Activity. Time cells in bat hippocampus CA1 formed two distinct populations, and a population of time cells produced different time series when the bat was suspended in different positions. The team dubbed the two hippocampal time cell types “contextual” and “pure” time cells. Both can represent your own time, or the time of other people in a social setting. The researchers also discovered that “social time cells” encode temporal sequences that align with each other’s landing sites, and that these cells serve as the spatial and temporal coordination of self and others in social behavior.
The findings suggest that two different types of time cells exist, each using a different time code. “Contextual” time units can represent space and time in the same environment and support episodic memory; whereas “simple” time units encode only elapsed time. Finally, the researchers looked at “social” time cells, groups of cells in the mammalian brain that create temporal representations for peers and other people around the animal.
Research helps clarify how the brain responds to specific events, perceives time, and coordinates with others
Collectively, the findings shed new light on the complex organization of the hippocampus, such as how the human brain encodes specific events from the past, perceives intervals and supports coordination between self and others. The findings contribute to the growing recent evidence that the hippocampal system can encode dimensions other than space, evidence that is not well reflected in current computational models of the hippocampal circuit, which may be addressed in future studies be resolved in. The research team is now planning to study how the hippocampus integrates spatial coding with other codings, such as social coding, among others.
References:
1. https://www.nature.com/articles/s41593-022-01226-y
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