Thursday, July 13, 2006

The Hippocampal Memory Paradox

There's something I find paradoxical about hippocampal memory theory. This theory states that new memories are stored somewhere temporarily, and then permanently stored in long-term memory (LTM)later.

On the one hand, there's good evidence for it. Hippocampal damage inhibits new LTM storage, even though previously encoded items in LTM are intact. The famous patient HM had his hippocampus (among other things) removed and was unable to store new episodic memories (memories of what happens). HM can still store procedural and perhaps semantic memories as well. So this makes sense. Not all memories need to be in LTM, so they are temporarily put somewhere and the important ones stored in LTM later.

On the other hand, it makes no sense to me, because the symbols in the mind only make sense given the other symbols they are connected to. So if you see me wearing a black pencil behind my ear, how are you going to store a temporary representation of that without using the symbols for black, pencil, and JimDavies that are a part of the semantic network used by LTM?

One way out of this mess is to suggest that it works like writing: There is a code that the temporary memories are stored as. For example, if you read the words "JimDavies wore a black pencil" you use those words as cues into your semantic network to know what it means. So perhaps the temporary store is not a meaningful memory at all-- it's only meaningful after being interpreted by the existing LTM. That is to say, before it's stored in LTM it's a bunch of pointers to symbols in LTM.

I call this the "language of memory theory."

1 comment:

Jennie said...

Isn't is like read versus write memory? Your visual input (pencil and color black) are recognized because you can "read" from LTM and find your memory of pencil and black. But then you cannot "write" back to LTM, storing the memory for later retrieval.