“‘Teleportation’ of Rats Sheds Light On How the Memory Is Organized”
September 28, 2011 Leave a comment
(Edit: It was published the day after, but I think this Wired article explains the experiment better than Science Daily)
Science Daily brings us an article about research conducted at the Norwegian Institute of Science and Technology and published in Nature this week, on the discreteness of memory in regards to classic disorientation.
From the article:
You’re rudely awakened by the phone. Your room is pitch black. It’s unsettling, because you’re a little uncertain about where you are — and then you remember. You’re in a hotel room.
… In an article published in this week’s edition of the journal Nature, researchers at the Norwegian University of Science and Technology’s Kavli Institute for Systems Neuroscience describe exactly how the brain reacts in situations like these, during the transition between one memory and the next. The study employed a method that allowed them to make measurements right down to the millisecond level…
Their findings show that memory is divided into discrete individual packets, analogous to the way that light is divvied up into individual bits called quanta. Each memory is just 125 milliseconds long — which means the brain can swap between different memories as often as eight times in one second…
They accomplished this by very carefully measuring the electrical activity in the brains of rats. They basically trained rats to identify certain rooms by features which were actually just a product of the lighting environment, then suddenly switched the lighting on them. The rats were confused by this “teleportation”, and their brain activity revealed how our brains react to this sort of situation.
In regards to the separate mental maps the rats constructed for each room,
“But the mind doesn’t actually mix up the maps,” she says. “It switches back and forth between the two maps that represent rooms A and B, but it is never in an intermediate position. The brain can ‘flip’ back and forth between the two different maps, but it is always either or, site A or site B.”
The punchline I gather is that when we get confused about our location, we don’t actually “mix up” our location memories, we just flip between them within an 1/8 of a second.
I find the unqualified claim that “memory is divided into discrete individual packets… Each memory is just 125 milliseconds long” to be very, very strong; I hope the Nature article does a better job of justifying that conclusion, unless this ScienceDaily article is just over-asserting their findings. If it is true I imagine it’d be a pretty huge boon for cognitive neuroscientists of every stripe; how long a memory lasts is probably relevant to understanding any kind of human perception.