The problem with a memory drug
I'd like a drug that enhances my memory. I'd also like one that improves my ability to focus. I'll take another to prevent anxieties from flooding my mind just as I'm trying to fall asleep at night. And just one more to make me a little more outgoing in social situations - so long as it doesn't make me alcohol-stupid.
I saw a film last year (Limitless) about a drug that allowed the main character to become his super self. First, he cleaned and organized his apartment for the first time in years (that would have sold me right there). The drug also allowed him to read voraciously and remember with perfect clarity everything he read. He could understand topics in economics and math that would have been far beyond him otherwise. It also gave him the confidence and courage to act on his insights to become successful as a fiction writer, and later as a stock trader, employing his newly-invented mathematical models of the stock market. It may not have been a great film, but I was absorbed from the first minute to the last.
Here, let's imagine a drug designed simply to enhance your memory. Would it allow you to better encode (store) memories, or to retrieve memories? Since encoding and retrieval of memories operate by distinct brain mechanisms, a drug that facilitates one is likely to be different than one that facilitates the other. If it improved memory encoding, would it improve your ability to store the memories that you choose
to encode? Or would it simply amp up memory encoding processes, so that things you perceived were more likely to be stored? Once in a while, we say to oursevles "I need to remember this". But typically we automatically store memories of the things we perceive. If the drug directly boosted memory encoding, it would probably increase memory storage across the board. The obvious trouble with a drug that enhances memory encoding is the danger that you’ll fill your brain with unimportant events, faces, names, smells... And that this crowd of memory items will interfere with one another, making it more difficult to retrieve the memory you’re searching for.
Enhanced memory retrieval may be problematic as well. Every time I smell pine cones, do I really want to recall all the childhood memories associated with the smell. Do you want to have memories pop into your mind every time someone mentions a word that relates to one of your memories? Don't you sometimes zone out into memory lane in the middle of a conversation just because the other person mentioned something that evoked a memory (and distracted you momentarily from the rest of the conversation)? Do you want to boost that?
Human memory research shows particular brain areas that are activated when we store or recall particular kinds of information. The hippocampus plays an important role in storing memories of episodes like eating dinner at your friend Joe's house. Say you ate ravioli that night. One set of neurons is apparently activated when you think of sitting at Joe's dinner table, and another is activated when you think of eating ravioli. Memory encoding is believed to involve strengthening connections between of the two sets of neurons - a process that involves the hippocampus. Source memory, on the other hand, involves activity of the prefrontal cortex. By analyzing data recorded with an fMRI scanner, you can visualize the activation of particular brain regions as particular types of memories are stored or retrieved.
Our knowledge of the molecular events that underlie memory-related strengthening of synaptic connections between neurons is also accumulating rapidly. This type of detailed information about memory storage comes mostly from studies in rats. Here the types of memories examined are very simple, for instance, associating a tone and shock, or a tone and a light that often occur together. But the molecular processes that occur when a rat associates two stimuli together appear to be nearly identical to those that occur during memory storage in other mammals, and even in invertebrates. The types of information that can be encoded obviously differ across species (a rat can't encode a physics formula because it can't represent it in the first place). But the biochemical mechanisms underlying neuronal plasticity and memory storage for the information that can be represented are remarkably preserved across species.
I don’t think we’d want a drug that potentiates the molecular activity that underlies memory storage. That would presumably lead to an increased likelihood of storing any experience in memory. Perhaps if you could take a drug that lasts, say 2 hours, and that drug would enhance memory encoding only for experiences during that time period – a student would be able to amp up memory encoding as she crams for an exam. The fact that she also stored memories of the scratch-marks on the desk, or the type of pencil she was writing with may be a minor annoyance that she can live with. Perhaps as I go to some party where I know I’ll meet a lot of people who’s names I really ought to remember- a short-acting cognitive Viagra would come in handy. Maybe I can live with the fact that I also remember the sound of each person's voice and the topic of the nonsense small-talk I engaged in with each person. If such a drug ever becomes available, I think I’d use it infrequently although I suppose I would use it now and then.