A picture of the past, a memory of a nice afternoon, sitting on the grass doing homework with someone you love. An image or a movie takes up space on a computer's hard drive, so what causes the reactions to store these memories in our mind? Let's take a look at a couple of recently discovered molecules that might be able to impact human memory in the coming decades.
Top image: Pixelclash.eu/Shutterstock.
Our Understanding of Memory is still in its Infancy
Memories form because of interactions between several parts of the brain, with learning arising from the changes in neuron synapses. We are still in the infancy of knowing exactly how a memory is formed and subsequently altered, with most conclusions coming from trial and error observations involving hormones.
For example, injections of cortisol, a steroid hormone released by the adrenal gland in response to stress, and adrenaline into subjects have been shown to increase the retention of short term memory.
Long-term stress situations, however, which would allow for streams of cortisol to be present, have be shown to hamper short term memory (with this showing that there is a delicate chemical balance in place to separate remembering and forgetting). Additional work has looked at cell signaling and neurotransmitters, like dopamine, and what regions of the brain are populated by specific neurotransmitters.
Protecting our Memories
Using the small molecule P7C3, first mentioned in the journal article Discovery of a Pro-neurogenic, Neuroprotective Chemical, is a possibly way in which to aid in restoring memories. P7C3, due to its neuroprotective properties, could be used to ward off the later stages of Alzheimer's by aiding in the branching of neurons and protecting neurons from being degraded.
Exactly how P7C3 works, however, is not known. P7C3 and a more potent analogue, were discovered through a screen of over 1,000 individual molecules through in vivo assays. This is quite the "shotgun" approach, throwing a lot of previously synthesized molecules at a problem and seeing if any work. This is a common method used in drug discovery, and also shows that there is no "one" good way to design a memory enhancing molecule. Yet.
Can we Erase Bad Memories?
When the amount of the large molecule CaMKII (to give an idea of scale of CaMKII, it is about one thousand times larger than cortisol or P7C3) is spiked within in the brain of a mouse, the recall of a short term memory associated with fear decreases. That's according to research reported in the journal article Inducible and Selective Erasure of Memories in the Mouse Brain via Chemical-Genetic Manipulation
However, as with stress induced cortisol release, too much CaMKII can lead to the impaired ability to recall memories, and extending past cortisol, the erasure of new and fear-induced memories specifically without harming other memories.
These experiments were only performed in mice, so implementation in humans might be years away or not possible at all, but it gives hope for research looking to radically change the memories on an individual for positive reasons.
CaMKII is also for sale as a reagent, increasing the accessibility and thus ease of research. It's not cheap, however, and if you do try to use it, it's not likely to be administered properly, so don't run out and buy it to black out your memories of the monsters that did live under your bed.
CaMKII release has recently been shown to be extremely specific and activated in the formation of dendritic spines, lending insight into how the molecule behaves and putting a bit of theory behind the molecule's ability to significantly alter neurochemistry enough to block memories.
If you play with your memories, are you changing who you are?
Would you want to erase a bad memory? In situations of physical abuse or harm, yeah, more than likely. But what about that test you failed or your first break-up? That time you drove home with the lights on in your car after watching a scary movie? These are the moments that help make us who we are, and in sum, condition us to change our decision-making in the future.
So before we go around erasing memories, we probably want to make sure we are erasing the right types. For example, if all memories of a certain type (like those pertaining to fear) were erased, we would probably have to spend time acclimating ourselves to our environment and possibly remembering why we don't put our hand on a hot stove. Further research to help us learn the mechanism for how the molecules work couldn't hurt either.
Bottom image shows a pyramidal neuron from the hippocampus, stained in GFP (green fluorescent protein). Sources linked within the article.