How does the brain know which connections to keep?

 The brain is a complex network of nerves that is constantly being set off as a result of neurons communicating with each other. Given that our brain has as many neurons as it does, and an even larger number of synaptic connections, one can’t help but wonder- how does the brain decide which neuronal connections to keep and which should be discarded? 

Well, this article helps in answering just that. In the end, the article will answer some frequently asked questions about the brain.

How does the brain know which connections to keep?

A core phenomenon that decides what information the brain should keep, and which it should throw away is that of ‘plasticity’. Plasticity is the brain’s ability to decide which synapses should be strengthened and weakened on the basis of the extent to which they are active. 

In much simpler words, the more a neural pathway or connection is used, the more regularly it fires up, thereby increasing its chance of being retained by the brain.

Knowing what we know now, thus, we can conclude to some extent that the more we do a certain task, the more likely we are to retain connections in those synapses. 

This is what neuroscientists refer to as ‘rehearsal’. In fact, this is even true for memories. The more we recall a certain memory or think about it, the more its neural network strengthens and the more easily we can recall those memories in the future. This is essentially a memory loop. This theory is referred to as the trace theory of memory.

H.A. Burson explains in his 1978 book titled ‘Dismantling the Memory Machine’ that if we are to correctly learn something and recall it, as opposed to learning and relearning, making a guess, etc., there must a trace within the brain that can be physiologically identified and tracked. 

This is the trace which carries forward the information right from its conception, that is, right from the time we begin to learn something. This also gives us neuroscientific and conclusive proof of the proverb “Practice makes perfect”. 

This is why parents and teachers often advise us to practice skills that we have trouble with. Rehearsal of these skills ensures that the memory trace within our brain is strengthened and that the neural connection is maintained for a much longer time, than when it would not have been rehearsed.

Juxtaposed but complementary to the trace theory of memory is the decay theory of memory. The decay theory of memory posits that when we don’t use a certain neural network or pathway, the disuse can lead to forgetting. 

This is because the memory trace fades as and when it is not used. This is the reason why when we don’t meet someone for a long time and haven’t been in touch with them, we may forget their name and over the years, even their face. 

This is because the lack of rehearsal may weaken the neural pathways and connections within the brain that would otherwise strengthen if they remained active.

Apart from that, there are external factors that also help in strengthening certain neuronal connections, practice and rehearsal being one of them. 

Other than that, consuming nutritious food, consulting a physician about some brain-boosting supplements, and getting proper sleep and exercise can also help strengthen certain connections within the brain’s network. 

This is especially true given the number of harmful toxins and pollutants we are exposed to and are consuming every single day, no thanks to climate change-induced pollution. This explains why keeping the brain healthy is important, as it decides which connections are important and which must be discarded!

What is the brain made up of?

This bundle of tightly woven 86 billion neurons are packed inside the brain and the skull, which together form the central nervous system (CNS). The beauty of this central nervous system, specifically the brain, is that it is always at work. 

There is not a dull moment with neurons firing away constantly, releasing neurotransmitters and chemicals over the synaptic barriers- the part of the neurons where communication is initiated and carried forward. 

Not only do these neurons communicate with each other inside the brain, they also communicated with the organs outside of the central nervous system. These organs also communicate with each other, thanks to the neurons in the brain.

As mentioned above, the brain is always at work and has no moment of rest, even when we are sleeping; especially when we are sleeping. While during the day, the brain is active because we are awake and going about our day-to-day activities, hence the neurons are working full time. 

During the night the brain undergoes the process of incubating creative ideas, consolidating memory traces as well as all that we have learnt during the day. It also carries out the extremely important function- recuperation and repair when we’re ill or injured.

What are some memory models of the brain?

We all know how some theories compare the human brain to a computer system. This is especially true in the case of studying memory systems like working memory. Atkinson & Shiffrin’s ‘multi-store’ memory model (1968) divides the process of memory formation into compartments like “short term memory”, “long term memory” and “working memory”. 

Alan Baddeley and Graham Hitch then went on to build up more on this foundation in 1974 and expanded on Atkinson and Shiffrin’s ‘multi-store model’. They added components to the memory model like the phonological loop, visuospatial sketchpad, episodic buffer and the executive function.

However, the human brain is much, much more complicated than your average computer system. For once, it is wired more tightly and is jam-packed within the skull, it runs on electrochemical signals triggered by the chain of potassium and sodium ions that cross the synaptic barrier to enable the neurons to communicate; whereas the computer runs primarily on the electronic signal. 

While you can switch off the computer, the brain does not have the same luxury whatsoever, as has already been established by neuroscientists.

While you can save your files on your computer system, it is truly fascinating to wonder how the neurons in the brain decide what files they will save and which ones they will move to the recycle bin. 

The part of the brain responsible for this is the synaptic connection. Synapses are minute molecular machines that are incredibly complex and constitute proteins that are responsible for directing, keeping, and making connections stronger.

 Conclusion

This article answered the question “How does the brain know which connections to keep?” The article also discussed what the brain is made up of, how neurons communicate, and memory models of the brain. In the end, the article will answer some frequently asked questions about the brain.

Frequently Asked Questions: How Does the Brain Know Which Connections to Keep?

Where does the brain store memory?

Explicit memories are stored in the hippocampus, the neo-cortex, and the amygdala. Implicit memories are stored in the basal ganglia and the cerebellum. Working memory is operated upon by the Prefrontal Cortex.

What memory functions is the prefrontal cortex involved in?

The prefrontal cortex is involved in the storage of short-term memory. It functions from both the left and the right sides to collectively work on short-term working memory. The prefrontal cortex is also involved in working memory.

What are the main models of memory?

The main models of memory include the Information Processing Model (Atkinson & Shiffrin, 1968), Level of Processing Model (Craik & Tulving, 2002) and Parallel Distributed Processing (Rumelhart & McCleland, 1988).

What is the function of the amygdala?

The amygdala is majorly responsible for the formation of emotional memories. Since the amygdala is closer to the hippocampus and is known to have shared connections, the two work together for the formation of more memorable memories.

References

Atkinson, R. C., & Shiffrin, R. M. (1968). Chapter: Human memory: A proposed system and its control processes. In Spence, K. W., & Spence, J. T. The psychology of learning and motivation (Volume 2). New York: Academic Press. pp. 89–195.

Baddeley A (October 2003). “Working memory: looking back and looking forward”. Nature Reviews Neuroscience. 4 (10): 829–39. doi:10.1038/nrn1201. PMID 14523382. S2CID 3337171

Craik, F. I. (2002). Levels of processing: Past, present… and future?. Memory, 10(5-6), 305-318.

Rumelhart, D. E., McClelland, J. L., & PDP Research Group. (1988). Parallel distributed processing (Vol. 1, pp. 354-362). New York: IEEE.