Understanding time is crucial for everyday tasks like talking and driving, which rely on our ability to perceive durations unconsciously. Researchers at the University of Utah Health discovered in mice that “time cells,” acting like a clock’s second hand, are vital for learning behaviors requiring precise timing.
These cells fire sequentially to track short periods. As animals learn to differentiate between events of varying durations, time cells’ activity pattern adjusts to represent each timing pattern uniquely. This finding may help detect neurodegenerative diseases like Alzheimer’s early, which can affect time perception.
Researchers at the University of Utah used advanced brain imaging to study how mice learn time-based tasks. Mice were trained to distinguish between different timings of odor stimuli to earn rewards, akin to learning a basic form of Morse code. Using cutting-edge microscopy, researchers observed that before learning, time cells in the mice fired similarly for all stimuli.
However, as the mice learned the different timings, the patterns of time cell activity became distinct for each stimulus pattern. Mistakes in the task correlated with disordered firing of time cells, according to Dr. Hyunwoo Lee, a co-author of the study. This indicates the crucial role of precise time cell sequences in performing time-based tasks.
Erin Bigus, a graduate research assistant in neurobiology and co-author of the study, revealed that time cells have a more complex role than simply tracking time. Blocking the medial entorhinal cortex (MEC), where these cells reside, showed that mice could still sense timing but struggled to learn complex time-related tasks from scratch.
This suggests that the MEC is crucial for learning intricate temporal relationships rather than acting like a basic stopwatch. Previous research has shown the MEC’s involvement in spatial learning and mental mapping.
The study found similarities in brain activity patterns between learning time-based tasks and spatial learning, even when not actively learning. According to Dr. James Heys, the study’s senior author and assistant professor of neurobiology, these findings hint at a dual role for the entorhinal cortex: as both a distance tracker (odometer) and a timekeeper (clock).
The study concludes that “time cells” in the brain are crucial in complex timing learning tasks. These cells are not just simple timekeepers but contribute significantly to learning intricate temporal relationships. Understanding how these cells function could pave the way for better insights into brain processes related to learning and memory.
Journal reference:
- Bigus, E.R., Lee, HW., Bowler, J.C. et al. The medial entorhinal cortex mediates learning of context-dependent interval timing behavior. Nature Neuroscience. DOI: 10.1038/s41593-024-01683-7.