Justin DuJardin |O_o| |x_X| |-_-| |o_O|

Kandel on Memory Storage

In response to a blog post I wrote recently, a friend kindly pointed out that I seemed to have overlooked the work of Dr. Eric Kandel and others with respect to molecular changes that occur in neurons during learning.  In 2000 Eric Kandel was awarded the Nobel Prize along with Arvid Carlsson and Paul Greengard for their work detailing such molecular changes.  As it turns out because of their work, we actually have a pretty fantastic understanding about how things are committed to short and long-term memory, as well as the general way in which synaptic connections relate to the storage of things in memory.

Nobel Lecture 2000

My friend also provided a link to the lecture that Kandel gave while he was in Stockholm accepting the Nobel Prize.   I must admit that very little of the talk made complete sense to me, partly because the camera man chose not to show the screen while Kandel was using his laser pointer to go through the diagrams, and partly because I’m not a molecular biologist.   A few very cool insights did come out of watching the lecture, that are interesting enough to share…

Remembering Through Repetition

At one point or another in life you’ve probably run into someone that is keen on using repetition to help you remember things.   Be it a grade-school teacher or a parent trying to help you study for a test, this is a bit of common knowledge that has been around for years, and it would seem Kandel confirms that this is a legitimate way to commit things to long term memory.   In fact during his lecture he goes to great lengths to graph and show the effect repetition has on the length of time something is stored in memory for recall.   A single stimulation resulting in storage for just a few hours, while repeated stimulation (5 times) causes new protein synthesis, committal to long term memory, and recall for long periods of time.

Stronger vs New Synaptic Connections

Another interesting point Kandel and his fellows have brought to light is the distinction between what causes synaptic connections to strengthen, and what causes new synaptic connections to be formed.   In all of their testing cases, short-term memory storage involved only the modification of strength in existing synapses.   On the other hand, long-term memory storage has been associated with both modification of the strength of existing connections, as well as the formation of entirely new synaptic connections.  To be clear modification could mean strengthening or weakening of a synaptic connection.

CREB2 the bouncer

By far the most interesting thing to take away from this presentation was the process by which things are committed to long-term memory.   As I mentioned above, repetition seems to be the key factor in committing things to long term memory, but what’s more is that Kandel has figured out the reason for this.   In order for things to be committed to long-term memory, there needs to be new protein synthesis and part of new protein synthesis in a neuron requires activation of what is called the CREB1 transcription factor.   The catch is that CREB1 is repressed by another transcription factor called CREB2.   At this point you may have guessed that when you create the same stimulation in the neuron multiple times, eventually CREB2 let’s down its guard and CREB1 can be activated, which allows the process to continue and the memory to be committed to long-term storage.   Put in other words repeated stimulation acks like a secret handshake in the neuron that convinces CREB2 the bouncer to let in to the long-term memory storage party that’s happening just behind the door.  Kandel speculates that when there is a deficit in CREB2, this may be the reason behind certain individuals having photographic memories.  In fact they have observed this to be true in mice…

Oh but to be a mouse

In ending his lecture Kandel talked about some interesting thoughts about the clinical applicability of this research.   In particular he notes that as people tend to age, there are a number of disorders that affect their ability to convert short-term to long-term memory.   In experiments on mice Kandel and his team have been able to show that this is caused by a single defect that makes it difficult to initiate the transcriptional cascade process that was talked about earlier as being responsible for the storage of things into long-term memory.   By using their magic to overcome this deficit, they have been able to produce flash-bulb memory in mice.   As Kandel himself jests.. “So if you’re a mouse, we can really help you with age-related memory loss”

While we may not be to a point that we can come up with a convenient little pill to help us convert things to long-term memory storage, the idea that it is possible in the future is quite appealing.