Our brains handle memories in different ways, and long-term memories stick around much longer than short-term ones because of special biological processes that lock them in place.
Short-term memories last just minutes or hours, like remembering a phone number long enough to dial it. They rely on temporary brain activity without much change to the cells. Long-term memories, though, go through a process called consolidation. This turns fragile new memories into stable ones that can last days, years, or a lifetime.[1][2]
One key player is protein synthesis. Right after you learn something, your brain makes new proteins in areas like the hippocampus, a seahorse-shaped part deep in the brain. These proteins strengthen connections between neurons, called synapses. This is like building stronger bridges between brain cells so the memory does not fade. Studies show that blocking protein synthesis right after learning weakens memories, proving its role.[2]
Another helper is BDNF, a protein that acts like a fertilizer for brain cells. Research found that BDNF is crucial for making long-term memories persist. In experiments with animals, adding BDNF to the hippocampus turned short-lived memories into lasting ones. It triggers a chain reaction involving ERK, a molecule that helps maintain the memory over time. Without BDNF, even strong memories decay.[1]
Sleep plays a big part too. During deep sleep, the brain produces sharp-wave ripples, quick bursts of activity that replay the day’s events. These ripples move memories from the hippocampus to the neocortex, the outer brain layer for permanent storage. Boosting these ripples in mice helped them remember things they would normally forget, even if they had brain impairments.[4]
Emotional events last even longer because of stress hormones like cortisol and epinephrine. These chemicals amp up activity in the amygdala, the brain’s fear and emotion center. The amygdala talks to the hippocampus, tagging exciting or scary memories as important. That is why you vividly recall your first roller coaster ride but forget what you ate for lunch last Tuesday.[2][3]
Stress can also link arousal networks and memory networks in the brain. Under cortisol, these networks overlap more, making emotional memories stronger while neutral ones stay weak.[3]
In short, long-term memory lasts longer thanks to proteins, BDNF, sleep ripples, and emotional boosts that rewire the brain for stability.
Sources
https://www.pnas.org/doi/10.1073/pnas.0711863105
https://en.wikipedia.org/wiki/Memory_consolidation
https://pmc.ncbi.nlm.nih.gov/articles/PMC12693973/
https://neurosciencenews.com/sleep-ripples-memory-30041/
