The Science of Learning

Everyone has at some point attempted to learn something new – whether it be out of interest, necessity/desperation, or simply a requirement for school. However, very few of us actually know how said learning happens. An understanding of basic neuroscience and how it relates to memory formation can prove to be an essential tool in maximizing the effectiveness of learning.

We are probably all familiar at the very least with the concept of memory and learning being thanks to our brain – an organ of the central nervous system that serves as an integration and control center. The brain is made up of specialized nerve cells known as neurons, which can transmit signals to each other, as well as to other parts of the body. These serve a variety of purposes in the body, from causing your heart to pump to being the reason your leg kicks when the doctor smacks your knee with a little hammer. It is these specialized cells that are responsible for memory, as well.

Click here to learn more about how neurons work.

Neurons are nerve cells, and are a major component of the nervous system. They can vary in both structure and function, so we will simply go over the basics here. The general structure of a neuron is a soma (the cell body) with two types of processes that extend from it. Dendrites are the receptive processes that receive signals from other neurons and send the information toward the cell body. Most neurons have a large number of dendrites, allowing for greater surface area and a higher chance of receiving a signal. The other process is known as the axon, with each neuron having only one. The job of the axon is to generate a nerve impulse and send the signal away from the soma to the axon terminals, where neurotransmitters are secreted to inhibit or excite other neurons.

The main way that these nerve impulses are generated and sent along the axon is through a process known as action potentials. This is an “all or nothing” process in which there is either a full action potential or not one at all – there are not degrees of action potential. It relies on a difference in electric potential between the inside and outside of the cell. The general process of an action potential is as follows:

Resting state: The resting membrane potential of -70mV is maintained as all voltage-gated Na+ and K+ channels are closed, preventing the movement of these ions.

Depolarization: Na+ channels open, causing the membrane potential to increase by bringing positively charged ions into the cell. Once it reaches the threshold of roughly -55 mV, we reach the “all” stage, where an action potential will occur.

Repolarization: Na+ channels begin to close, and K+ channels begin to open, which move positively charged ions out of the cell. This begins to restore the negative membrane potential, as it begins to drop again.

Hyperpolarization: K+ ions continue to leave the cell, resulting in the membrane potential reaching a lower point than it started with at the resting state.

Channels will then reset, bringing the neuron back to its resting state.

Action potentials will travel down an axon and are what eventually stimulate the release of neurotransmitters. 

Memory Basics

Memory formation relies on two major physiological processes: neurogenesis (the creation of new neurons) and synaptic plasticity (the ability for connections between neurons to change). At its essence, memory is the reactivation of groups of neurons. It is this reactivation that learning depends on – the goal is to be able to recall and remember the new information that is being learned. Each memory is essentially coded for by a different neuron ensemble – different groups of neurons that will be activated in a specific sequence. As you experience new things (whether it be new examples, hearing a new definition, etc.), new neurons can be made. Thanks to synaptic plasticity, connections can be made between the old neurons and the new ones (or can be made between already existing, but unconnected neurons).

Along with different connections, another component of synaptic plasticity is the strength of the connection. As neurons continually activate each other, a synapse can become stronger – this is why practicing something makes you better at it. The strengthening and weakening of synapses are essential to memory formation as well. Imagine that you are relearning something – maybe you are learning a new way to chop an onion. At first, it’s going to be hard to switch to the new way to do it, but as the new ensemble is activated and strengthened, and the old ensemble fails to activate and therefore becomes weaker, one ensemble can essentially replace the other as the go-to. It is for that same reason that when I think of the word “dog” I think of my current dog, rather than the dog I had in 3rd grade (or why when I hear “Macarena” I think of my student who has that as a nickname rather than the dance I haven’t done in like 15 years; even though the dance is a far more common usage of the word, it’s not one whose ensemble I have been activating lately).

Types of Memory

There is not just one uniform thing known as “memory” – there are different types of memory, each with its own function, capacity, and duration. The most commonly discussed types of memory are long-term and short-term memory. This is not to say that these are the only types, as things like sensory memory exist, but they are the two that we will be looking at in the context of improving learning.

Short-term memory holds new information for brief periods of time. Its major characteristics are that it has “temporal decay”, meaning that it only lasts for roughly 15-30 seconds, and that it has limited capacity, with only a certain number of “chunks” of information being able to be stored (with this number varying depending on the type of information and the person, but being a relatively small number either way, with historical estimates being 5-9 chunks). Working memory, a component of short-term memory, allows one to manipulate the information that is being held within one’s short-term memory and is held to the same capacity and duration limits.

Short-term memory can become long-term memory. This is the type of memory that stores new information for long periods of time, potentially indefinitely or for many years. This type of memory does not have a capacity limit, nor does there appear to be temporal decay (age-related memory loss is due to a separate phenomenon and not an aspect of long-term memory itself). However, this type of memory can decay without use. It is the creation of this type of memory that is most helpful when it comes to learning. Short-term memory converts to long-term memory when the neuron ensembles of the hippocampus that store short-term memory are continually reactivated, resulting in the consolidation of long-term memory in the cortex. 

Long-term memory can be broken up into two types: declarative (the factual components) and procedural (the skills, habits, and activities that you can do without thinking). Semantic networks are concepts within declarative memory that are connected, almost like a web. By activating the memory of one such concept, it can activate nearby memories in the network - this is why making connections between things is so important.

Types of Thinking

In cognitive psychology, there are two major models for how the brain works when it comes to thinking. The general premise is that there are two systems at work, with each taking on different roles. These systems are named, rather simply, System 1 and System 2.

System 1 is the intuitive system of thought. It is fast to work and it is automatic, getting to work without you consciously choosing to or even being aware of it. System 1 is driven by our experiences and essentially automatically runs information through our subconscious and the information stored in our long-term memory. If you have ever driven a familiar path absentmindedly, tied your shoes without thinking about it, or started reading a notification that popped up on your phone before even seemingly making the decision to read it, those are all System 1 at work.

System 2 is the more analytical system of thought. It is slower and takes far more effort to use due to being more deliberate. Using System 2 is a more conscious effort. If you were asked to, without using a calculator, determine what 2 x 2 was, you could probably do that simply and without any effort. However, if you were asked to calculate 34 x 46, you would need to expend a little more conscious thinking to do so. These are System 1 and System 2 at work, respectively. System 2 involves a lot more work on the part of your working memory, and as such can only handle a certain amount of information at a time.