PNAS: How the brain remembers accurate information about time and space

December 9, 2020 // -- A recent study led by researchers at the Southwest Research Center provides new ideas for how the brain encodes time and positional memory.
the findings, recently published in the journal PNAS, not only increase the scope of basic research on memory, but could ultimately provide the basis for new treatments to combat memory loss due to conditions such as traumatic brain injury or Alzheimer's disease.
about a decade ago, a group of neurons called "time cells" were found in rats.
cells appear to play a unique role in the recording of events, allowing the brain to correctly mark the sequence of events that occur in event memory.
, associate professor of neurosurgery at UTSW and senior author of the PNAS study, explained that the cells are located in the brain's hemass and show characteristic patterns of activity when animals encode and remember events.
, they allow the brain to organize when an event occurs by firing in a repeatable sequence, said Lega.
their emission time is controlled by 5 Hz brain waves, called theta oscillations.
(Photo Source: www.pixabay.com) Lega studied whether humans have similar time units by using memory tasks that strongly demand time-related information.
Lega and his colleagues recruited volunteers from the Epilepsy Monitoring Unit at the Peter O'Donnell Jr. Brain Institute at Southwest University in Utah, where epilepsy patients stay for several days before surgery to remove damaged areas of the brain that cause seizures.
the electrodes implanted in these patients' brains can help their surgeons accurately identify the lesions of seizures and provide valuable information about how the brain works, Lega said.
While recording the electrical activity of the sea mass in the brains of 27 volunteers, the researchers asked them to perform "free recall" tasks, which included reading a list of 12 words in 30 seconds, doing a short math question to distract them from the rehearsal list, and then calling as many words as possible from the list over the next 30 seconds.
this task requires that each word be associated with a period of time (the list in which the word is located), which allows Lega and his team to find time units.
team found exciting results: not only did they identify a large number of time units, but triggering them also predicted an individual's ability to link words together in a timely manner (a phenomenon known as time clustering).
, as predicted, these cells seem to exhibit different properties in the human body.
years, scientists have suggested that time cells, like glue, remember events in our lives.
this finding in particular supports this idea.
() Source: How the brain remembers right place, right time Source: Gray Umbach et al. Time cells in the human hippocampus and entorhinal cortex support episodic memory, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.2013250117。