(From left) Choi Jun-ho, Senior Researcher at the Korea Brain Research Institute (first author, corresponding author); Bae Seong-won, Research Fellow (first author); Ra Jong-chul, Principal Researcher (corresponding author). /Courtesy of Korea Brain Research Institute

The Korea Brain Research Institute said on the 16th that a research team led by Ra Jong-cheol, a doctor in the sensory-motor system research group, has uncovered why people often forget short-term memories. Short-term memory lets us briefly hold and use information we just saw, but we often forget it. The study identified how such memory errors arise in the brain.

Ra's team said it is because the neural circuits that store and maintain memories are not perfectly stable, so even if short-term memory is initially encoded properly in the brain, over time the neural signals in the brain gradually become disorganized or drift in another direction. The findings were published on 3rd (local time) in the international journal PLOS Biology.

The team had mice perform a "delayed matching-to-sample task," which requires remembering briefly seen information and then moving in the correct direction, while observing in real time how neurons in the brain were active during that period.

To do this, they used a technique called "two-photon calcium imaging (2-Photon Imaging)," which allows direct visualization of the signals by which neurons process information in the living brain. The brain region studied was the posterior parietal cortex (PPC), which plays an important role in integrating multiple sensory inputs to maintain memory.

Analysis showed that while the mice were maintaining memory, brain signals gradually drifted in other directions. Because of this signal drift, the mice made incorrect choices. As the brain signals diverged from the original memory, they produced different actions. The team confirmed that this change in signals was directly linked to actual behavioral errors.

Ra Jong-cheol said that even if a memory is initially encoded properly, brain signals can become disorganized over time, offering scientific grounds for the everyday question of "why do we keep forgetting?"

The study is expected to provide key clues for understanding and developing early diagnostic technologies for neuropsychiatric disorders in which short-term memory impairment is a major symptom, such as schizophrenia or attention-deficit/hyperactivity disorder (ADHD).

A visual summary illustrating how short-term memory errors occur through the alteration of neural activity. /Courtesy of Korea Brain Research Institute

References

PLOS Biology (2025), DOI: https://doi.org/10.1371/journal.pbio.3003359

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