If memories are stored through electrical and chemical signals, what physically changes in the brain when we forget something?
If memories are stored through electrical and chemical signals, what physically changes in the brain when we forget something?
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So, if you are exposed to more saturated media environment would the brain have to compete with the energy or noise of adding all kinds of new weak connections, potentially taking away from the establishment or maintenance if of existing or more important connections?
The issue is complex because we don’t really fully understand how memories are formed, stored and accessed. We have some idea of the process, but a lot of it is speculative. The current belief is that memories are stored in the connections between neurons. During the day memories are formed in the ‘daily short term’ part of the brain, and then in the night while you sleep your brain sorts through stuff accumulated during the day and decides what to keep and what to neglect (memory consolidation). When a memory is stored, the triggers that recall the memory are also set, strengthened and weakened, so it is possible to have a clear memory but have issues retrieving it, and those can actually work in interesting ways.
During the day connections tend to be strengthened but not often weakened, but during the night the brain enters a low-energy mode where it also weakens connections across the brain. Simultaneously it processes and refines memories acquired during the day.
There are tricks to forcing the brain to not wipe memories acquired during the day. One example is ‘active recall’. Basically say you’re in a class and learn about the product rule and quotient rule in calculus. That night, get a blank sheet of paper and write down everything you learned about the product and quotient rule, with zero notes or references. This act of deliberate retrieval (a bit of struggle is good! Fight for it!), followed by a brief review will tend to encode that information/memory as important and not tagged for wiping.
There are memories that aren’t episodic either. Procedural memory for example is consolidated greatly during REM sleep, which is how you for example get better at playing the guitar. If you don’t get any REM sleep, that consolidation process is disrupted and you’re slow to actually acquire those automatic skills. Declarative or episodic memory however is consolidated more during slow-wave sleep.
I find out of all the areas of scientific research, the research on memory and skill formation, retention and access to be among the most interesting.
We do know why, it’s because of Long Term Depression (LTD) of synapses, which means their weakening over time.
As for why that happens, there are obviously many possible mechanisms and reasons in the brain for that. For the eventual forgetting of information and skills that are already learned but not used anymore, buildup of an enzyme called HDAC3 in the infrequently-accessed synapses (the connections that make up memories) is the biggest factor responsible for the forgetting process. The presence of HDAC3 represses certain synaptic-strengthening related genes and weakens the connections to other synapses, and it builds up over time when a synapse is not accessed, and gets “reset” when it is strongly accessed. HDAC3 is why spaced repetition works – effortful recall and activation of the synapses resets the HDAC3 clock, and its ability to build up in the relevant synapses is slower next time.
Memory is pretty complicated and not very well understood. It’s also become clear that it’s very often not a binary process of remembering or not remembering something.
Forgetting as I understand it tends to be a psychological process. There’s a separate process for actually perceiving something, storing it, and then retrieving that memory.
Very often you have not truly lost a long term memory in a conventional sense of it being physically gone, you just have lost the ability to easily retrieve that memory. We have not fully understood this process, but we definitely do understand that recognition works easier and faster in successfully retrieving memories than just blindly trying to recall things.
Likewise, memory is not permanent or perfect. They can be rewritten at recall. Your current perceptions or even the manner in which you are asked about an event can color your own memories.
That physical process is still being studied and cannot really be attributed to singular neurons as of yet. Heck, sometimes different area of the brain are involved in different aspects of memory recall and formation. It’s a much more complicated process than it seems despite all being part of “memory”.
Neuropsychology student here. The more you learn about memory, the harder the answer to this question gets. Do we have a good idea of how memory works and how information is stored? Short answer, not really. We know that the brain has a limited storage capability, and we also know that your neural pathways can be “pruned”, aka cut down via the removal of certain neurons. If your brain deems a certain piece of information unimportant or finds it consumes too much energy, it will get rid of it, often through a process known as long term depression (LTD).
Additionally, you need to consider the aspect of memory retrieval. Forgetting something isn’t necessarily the complete loss of that information in your memory storage: sometimes, the environmental or physical circumstances mess with your ability to recall information. This is why you sometimes forget something, but then are able to remember it at a later moment. This is a fascinating aspect of psychology which ties into topics of cognition, attention, and so on.
When we forget, the physical wiring of the brain changes back — the connections that once held the memory become weaker, fewer, or reorganized. It’s not like deleting a file, it’s more like the trail through the forest grows over because nobody walks it anymore.
Think of it like the internet. But with no IPv4 addresses, no DNS and no search engines. The only way that you can navigate to the page that you want is to find a page that links to it. You’ve got your frequently used pages bookmarked so you can easily jump to them but from there you’ve got to figure out a series of links to the page that you want. Now when you dream your brain looks at what you’ve done for the day and goes and makes new links. So the more frequently you access a particular page the more pathways there will be to get to that page.
The vast majority of your memories are unavailable to you simply because there’s no link.
So far everyone has given good explanations for memory and forgetting. But one thing missing is situational and physical context. When you are encoding a memory you are also encoding the social, situation , and physical context into the memory pathway. So when you go to retrieve the memory it becomes much easier to retrieve when in a similar or same context as the encoding. Study drunk, test drunk. (You will do poorly, but will do better than if you study sober and test drunk) .
So let’s say you were thinking and encoding a grocery list in the living room. If you leave the room, and cross a threshold there is a good chance you might forget the list because you changed contexts and lost the train of thought and now both fail to encode and fail to retrieve. Check out the doorframe effect
Ps wiki is a great source for psych since a project for many psych students is to edit and correct psych articles on Wikipedia