Are You Sure You Remember Your First Kiss?

You remember your first kiss, don't you? It's etched into your memory, right next to opening your college acceptance letter and passing your driver's test. Well, it turns out sinking back into those memories when you're feeling nostalgic isn't as much like putting on a favorite movie as you might have thought. New research published in the Journal of Neuroscience Wednesday suggests that every time you pull up a memory your mind reinterprets it to include present experiences. The researchers at Northwestern University's Feinberg School of Medicine can help explain why we can believe in things that might not have happened, and why eye-witness testimony can be an incredibly shaky form of evidence.

The team scanned the brains of 17 healthy volunteers while they were taught new information and asked to recall material they had previously memorized. Co-author Joel Voss explained the memory-building process to USA Today:

When you build a new memory, you gather little bits of information — what the room looks like, who's talking, what they're wearing — and store them together. When you bring up an old memory, the bits of information get melded with new bits relevant to your present life, Voss said.

"A memory isn't a static thing that you bring in and it slowly gets moved out and stuck somewhere in the brain," he said. "Every time you retrieve it, you have the ability to modify it."

The researchers were able to pinpoint the hippocampus as the part of the brain where memory modification takes place. Interestingly this is also the part of the brain affected by dementia. The research suggests that memory problems, such as those seen with Alzheimer's, could be a result of memories "freezing" so that the brain can no longer adjust them to current surroundings.

Constantly shifting memories are not something we should be afraid of —this doesn't mean that there's no truth in the memories we have of our childhoods. Instead, the study's authors suggest that these modifications can actually help our brains to adjust to their current surroundings. Our memories are constantly updating to incorporate new information or new experiences, which helps to make them more relevant to our current situations.

So although memories are not a perfect recall of what actually happened, they do offer something much more useful: a record of our current interpretation of the past.