Thursday, January 26, 2006

Now Where Did I Put That Pill?

Memory is a tricky thing. I walk into a room and can't remember why I went there. Alzheimer's? Dementia? Or just distracted?

Recent research is making headway in understanding some of the mechanisms involved.

Here are some basics. In order to store long term memories, they must go through a period of consolidation. This is the period in which the short term memories are encoded for long term storage. In order to retain long term memories over time, we must periodically retrieve them, at which point they go through a period of reconsolidation.

Basically, this means that whenever you remember something, your brain must go through a process of storing it again in order to be able to remember it again. This is reconsolidation. However, whenever you store the memory again, it is possible for it to be associated with other inputs that weren't there the last time the memory was stored.

It is this reconsolidation process which allows memories to change over time. Sometimes, events and sensory inputs that are occuring at the time you remember and reconsolidate the memory get intermixed with the restored memory. Also, the brain tends to fill in missing information - in fact, this is one of the primary mechanisms going on all over the brain, all the time. When you recall an event, you may fill in gaps in the memory with something close to what happened, or what you think happened. These fillers can be heavily influenced by current events and triggers for the memory recall, and therefore the memory itself can change over time, sometimes morphing quite a bit in the process.

There have been advances in neuroscience which allow both the initial consolidation process and the reconsolidation process to be interfered with, either enhancing or disrupting the process. Most of the research has been done around fear based memories (in relation to PSTD), but other studies have indicated that the same mechanisms apply to other sorts of long term memories as well.

Someday in the not too distant future, there will be pills available to support mediation of all four of these states (enhancing or disrupting either the initial memory consolidation or the later reconsolidation upon recall). Applications are multiple.

Studying for your bar exam? Enhance the initial memory consolidation during the semester so that you can recall the material easily. (Although don't overdo it - unless you'd like the memories of your textbooks to overwhelm the memories of your childhood, your first girlfriend, the first time you, well, you know...)

Got a memory you'd like to lose? Take the reconsolidation inhibiters while recalling the memory - eventually, the memory will fade. (This latter will be particularly useful in PTSD patients, where every time the vivid, violent memories of the trauma consume their attention, then can lessen the future impact by interfering with the reconsolidation of the memory).

We're not quite at the level of Eternal Sunshine of the Spotless Mind yet, but we're getting there. What will this say about how we view continuity of self? What is it that makes someone who they are but their memories?

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