Where are memories stored?
David writes in to ask: what exactly is memory state and how does the brain store this under a biological process?
Jonathan Reisman answered this question...
Jonathan - Well, good to always start out by pointing out that our knowledge is very incomplete on the science of memory, as with most things in the brain. I think it's safe to say that the brain has no equivalent of a gallbladder that stores bile or a bladder that stores urine. There's no sack of memories up there that can be located upon dissecting the brain. But I think some things we do know about memory and how it's stored, is that the brain, like many other aspects of its function, including consciousness and subjective experience is not all in one location, but rather spread out in a number of parts of the brain. It's quite a geographic and distributed process. But, we certainly know that different aspects of memory are operated upon in certain parts of the brain.
For instance, on the inside of both of your ears and the temporal lobe, is an important part of how short-term memories are made into long-term memories (in structures such as the hippocampus that are in there). But we also know that if you have a particular memory, the emotion associated with that memory is stored in another part, called the amygdala (another part of deep in the brain). So that's different than the actual facts of the memory: the place, the person, even let's say someone's face you remember. The long-term memory of that image is that it seems stored in the visual cortex (in the back part of the brain and the occipital lobe). Where other facts about that memory or emotion tied to that face, will be stored in other parts of the brain. So it's all very broken down and certainly complex. And how a neuron actually stores memory? I don't believe is really well-known at this point.