Your Brain Is Built To Forget

By Neha Menon

Published 4:38 PM EST, Sun March 28, 2021

Introduction

The theory of memory, its stages, and mechanisms have been an ever-changing topic of discussion and research throughout the years. However, it has always been known that there exist certain loopholes and gray-areas which causes a related phenomena: forgetting. Through the years of study in cognitive psychology & neurology, the process of forgetting was always treated as an afterthought. In contrast to this, more recent studies contradict decades-old assumptions. Specifically they prove that the brain was, in fact, built to forget. That, in order to remember, forgetting is a crucial step.

Memory

Much is still to be learned about memories; how they are created, accessed and, sometimes, lost. But the little that we do know is important to note before studying the significant phenomenon of forgetting. 

• When we talk about the process of memory, it is imperative to understand that what we hear, see or learn does not simply go into the brain unedited as a recording. It is, in fact, constructed and reconstructed several times by what we hear or learn after that. 
• Although we may think that the memory of some people is near-perfect, our active cognitive processing of information ensures that memory is never an exact replica of what we first picked up, learned, or experienced.
• The physical basis of memory is that these higher intellectual processes are based in the cerebral cortex. “If certain parts of the cerebral cortex are stimulated electrically, there will be recall of experiences.”_[1]  It is commonly known that the process of memory entails encoding, retaining, and retrieving information. Other parts that are actively involved in these activities are the amygdala, the hippocampus, the cerebellum, and the prefrontal cortex.
• Autobiographical memories (personally experienced events) develop in the hippocampus, while the actual encoding of memory takes place through synaptic plasticity wherein “neurons constantly produce new proteins to remodel parts of the synapse, which enables the neurons to selectively strengthen their connections with one another”_[2]
• The crux of the topic is this: “Memory is the means by which we draw on our past experiences in order to use this information in the present.” (Sternberg, 1999).

Forgetting: A function of memory, not a failure of it.

The mechanisms of forgetting have been researched and studied in flies and rodents. One major takeaway from what was learned is the effect of AMPA receptors. AMPA receptors are particular types of receptors found at the synapse of a neuron, and the amount of this receptor in a synapse determines connection strength between neurons. Essentially, the strength between neurons is directly proportional to the effectiveness of the encoding process of some memory.

If the synapse of two neurons has the necessary amount of AMPA receptors, it is a given that the strength between these two neurons is good, and in effect, the memory has been encoded properly. The problem is that none of these AMPA receptors are stable. “They are moved in and out of the synapse constantly and turn over in hours or days.”_[2]

Hardt, a researcher, proposed that AMPA receptors can also be removed, which would mean that forgetting is an active process. And if that were true, then preventing the removal of AMPA receptors should prevent forgetting. When this was tried on rats, it seemed as though for the rat to forget, it had to continually destroy certain connections at the synapse. With this, Hardt says, “Forgetting is not a failure of memory, but a function of it”._[2]

Another proposed cause of forgetting was seen by Paul Frankland, a neuroscientist. He discovered that increasing the neurogenesis in mice caused them to forget more. This is, in fact, very ironic and contradictory to what we know about neurogenesis: it is the process by which new neurons are formed. New neurons should ideally mean more capacity to store memory. But the effect of neurogenesis on its proportional loss of memory was explained: “When neurons integrate into the adult hippocampus, they integrate into an existing, established circuitry. If you have information stored in that circuit and start rewiring it, then it’s going to make that information harder to access,” Frankland said.

Conclusion

There are certain other known theories regarding the process of forgetting: dopamine receptors and M.C.H neurons are a few amongst some others. 

Researchers like Ronald Davis believe that the brain employs forgetting and therefore clear out unnecessary pieces of information in order to make retaining other ones easier. This would imply that the brain keeps memories accurate by forgetting other less-important ones. Others also see forgetting as an advantage for the mental flexibility inherent in creative thinking and imagination._[3]

Neha Menon, Youth Medical Journal 2021

References

Chawla, D. S., & Quanta Magazine moderates comments to facilitate an informed, S. (n.d.). To Remember, the Brain Must Actively Forget. Retrieved from https://www.quantamagazine.org/to-remember-the-brain-must-actively-forget-20180724/

Contributors, H. (2009, October 05). Memory. Retrieved from https://health.howstuffworks.com/human-body/systems/nervous-system/memory-info.htm _[1]

Gravitz, L. (2019, July 24). The forgotten part of memory. Retrieved from https://www.nature.com/articles/d41586-019-02211-5 _[2]
Sheikh, K. (2019, September 19). Scientists Identify Neurons That Help the Brain Forget. Retrieved from https://www.nytimes.com/2019/09/19/science/brain-memory-forgetting-mind.html_[3]