How Do We Recall Memory? How Does It Work?
Our minds are full of mysteries that scientists have been trying to solve since they were known as philosophers. One of those mysteries is our memory. Because memories underlie so much of our rich life as humans our ability to learn, to tell stories, even to recognize each other it's unsettling to think that it all hinges on the mass of flesh and goo between our ears.
So, the question of the day is: How does memory work?
Memory is not my field of research and this response of course is very far from complete. But here are some thoughts which I hope you may find interesting.
1) There are different forms of memories and they are also encoded in the brain in very different manners.
2) For instance, working memory (like when you hold a few numbers or an address in your mind) is very different from long-term memory. One way in which working memory is stored is by keeping neural circuits that encode the remembered items active. This may be seen as the physiological analogue of repeating mentally the items we want to remember. Working memory is very narrow and limited and vulnerable to interference.
3) Instead, long-term memories involve more structural changes in the brain. These changes can come in many different forms. The more typical (and widely studied) is when the strength of the connections between two neurons - called synapses - change. This physiological implementation of memories provides an intuition of how they work. For example, imagine that a neuron that encodes a place, and another that encodes an emotion, are activated when a wrong experience is felt at this particular place. As a result of this experience, these two neurons fire together and then wire together (this is known as Hebb's rule). Then, whenever the neurons of this particular place are activated, the emotion is also retrieved.
4) In this view, a memory is a network of connected elements. Whenever one is activated, all this network of associated neurons becomes active. Often this network of neurons encodes an episode, an event in time in which different things were linked. A classic and very relevant example of this is strongly emotional memories. For instance, the majority of people remember an incredible amount of detail of the moment they learned about the attacks of September 11th. The stored memory not only includes all the aspects which are relevant, but also details (like where one was, what lights were turned on and off, with whom we were, where were we coming from, etc.) All of these elements are bundled in an episode, in a memory, in a neural network that encodes all of these elements. This also explains why, in some cases, some irrelevant elements may trigger an entire memory, often with very strong emotional components.
5) Last, a very interesting idea that has come out from the last decades of neuroscience research is that in the moment in which a memory is evoked, it is vulnerable, it can be changed. Just as a metaphor, imagine when you open a word document that was stored in your hard drive. At that time, if someone makes changes on the document, it can be changed. In fact, we do that ourselves when we write many versions of the same document. This is how memories work. It is not that they fade out passively. Instead, each time they are evoked, they are slightly changed, trimmed, incorporated to new items that were floating at the moment it was evoked... and the new memory is stored again with all these changes but without a register that these changes have been made. This is (in part) why we all have false memories, why we feel completely certain that some events have happened when in fact they never occurred.
Again, those are just some random thoughts (which I happen to like and find particularly relevant) about a remarkably complex process which would not fit in just a few hundred words.
See you all tomorrow.
Buh-bye.
So, the question of the day is: How does memory work?
Memory is not my field of research and this response of course is very far from complete. But here are some thoughts which I hope you may find interesting.
1) There are different forms of memories and they are also encoded in the brain in very different manners.
2) For instance, working memory (like when you hold a few numbers or an address in your mind) is very different from long-term memory. One way in which working memory is stored is by keeping neural circuits that encode the remembered items active. This may be seen as the physiological analogue of repeating mentally the items we want to remember. Working memory is very narrow and limited and vulnerable to interference.
3) Instead, long-term memories involve more structural changes in the brain. These changes can come in many different forms. The more typical (and widely studied) is when the strength of the connections between two neurons - called synapses - change. This physiological implementation of memories provides an intuition of how they work. For example, imagine that a neuron that encodes a place, and another that encodes an emotion, are activated when a wrong experience is felt at this particular place. As a result of this experience, these two neurons fire together and then wire together (this is known as Hebb's rule). Then, whenever the neurons of this particular place are activated, the emotion is also retrieved.
4) In this view, a memory is a network of connected elements. Whenever one is activated, all this network of associated neurons becomes active. Often this network of neurons encodes an episode, an event in time in which different things were linked. A classic and very relevant example of this is strongly emotional memories. For instance, the majority of people remember an incredible amount of detail of the moment they learned about the attacks of September 11th. The stored memory not only includes all the aspects which are relevant, but also details (like where one was, what lights were turned on and off, with whom we were, where were we coming from, etc.) All of these elements are bundled in an episode, in a memory, in a neural network that encodes all of these elements. This also explains why, in some cases, some irrelevant elements may trigger an entire memory, often with very strong emotional components.
5) Last, a very interesting idea that has come out from the last decades of neuroscience research is that in the moment in which a memory is evoked, it is vulnerable, it can be changed. Just as a metaphor, imagine when you open a word document that was stored in your hard drive. At that time, if someone makes changes on the document, it can be changed. In fact, we do that ourselves when we write many versions of the same document. This is how memories work. It is not that they fade out passively. Instead, each time they are evoked, they are slightly changed, trimmed, incorporated to new items that were floating at the moment it was evoked... and the new memory is stored again with all these changes but without a register that these changes have been made. This is (in part) why we all have false memories, why we feel completely certain that some events have happened when in fact they never occurred.
Again, those are just some random thoughts (which I happen to like and find particularly relevant) about a remarkably complex process which would not fit in just a few hundred words.
See you all tomorrow.
Buh-bye.
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