Are New Neural Connections Formed When We Learn? Neuroplasticity & Neurogenesis

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Short answer: YES.
Long answer: Probably YES on most occasions as far as we know from laboratory experiments. (I am saying ‘Probably Yes’ because not enough experiments are done to look for exceptions)

I’ll begin by introducing the idea of neurogenesis and then write about forming new neural connections. This post highlights how learning creates changes in the brain.

Before we begin looking at the evidence, we should understand one very important term.

Plasticity: This is the ability of our biological brain to change over time as a result of predisposition (genes), environment, and learning or perception. Plasticity or neuroplasticity or brain plasticity represents a change in the brain’s structure via new neural connections in old as well as newly formed neurons. When brain changes involve only the synapses, it is called synaptic plasticity. When the changes involve more things, it is called neuroplasticity. Synaptic plasticity involves 2 important mechanisms: long-term potentiation (systematic strengthening of a connection) and long-term depression (systematic weakening/loss of a connection). These 2 work together to create a “neural circuit.”

Synapses are the junctions which connect 2 neurons. They are small gaps which transmit an electro-chemical signal.

The questions we are really addressing are – Is the brain plastic? If yes, is it always plastic? How plastic is the brain and to what degree are new neural connections formed?

Words in this article can get confusing so here is a quick reference for prefixes and suffixes:

Prefix: Neuro – umbrella term for a lot of things about neurons

Prefix: Synapto – refers to synapses

Suffix: Genesis – creation of new things

Suffix: Plasticity – changes in new things and old things

The combination of these prefixes and suffixes creates 4 new words with unique 4 meanings.

Are new neural connections formed every time we learn something? 

Memory storage (or learning) involves many factors. At the smallest level, it involves molecular changes in neurons. At the highest level of new learning, it recruits neurons to change their activity. Not every single newly learned fact may change the brain structure; minute molecular changes within existing neural circuits may be sufficient for those. Not surprisingly, reading fiction and searching on google might induce these changes too!

Learning involves a gain in new synapses or a loss in existing synapses and it may take up to 15 hours for a change to stabilize. It’s one of the reasons why the effects of learning manifest after a short break.

Neurogenesis

This is the ability that lets the human body create new cells in the brain that later become neurons. In most of the currently published studies, neurogenesis occurs in the hippocampus regularly. Throughout adult life as well. Which is, surprise surprise, largely implicated in Memory and Learning.


There is evidence that we can promote neurogenesis by doing some exercise.

Below is an excerpt from You Can Grow New Brain Cells.

In one of the first studies to highlight the links between aerobics and neurogenesis, Rusty Gage of the Salk Institute examined new brain cell growth in mice. The ‘control’ mice had no running wheel in their cages, while the ‘runners’ were able to run in their cages regularly. In the snapshots below, from Gage’s experiment, the black dots are new neurons-to-be.

Neurogenesis: Are new neurons formed while learning?

Another study has demonstrated evidence for neurogenesis. Here is an excerpt.

Our study demonstrates that cell genesis occurs in human brains and that the human brain retains the potential for self-renewal throughout life. Although earlier studies in adult primates have been unsuccessful in showing neurogenesis in the dentate gyrus, a recent report has demonstrated neurogenesis in three-year-old marmoset monkeys.

As of 2020, the accepted science is – the brain does facilitate the growth of new cells and connections. We are predisposed with the ability to grow new brain cells and we can deliberately learn to induce lasting changes – sometimes subtle changes in neural activity and sometimes with large structural changes.

But, for what purpose? To use them as back-up cells? Learning new things? 

Let us look at the evidence from a few more studies that suggest learning something new directly translates into biological changes in the form of neural connections.

Musical training induces structural changes in the brain which emerge from synaptic plasticity and even counteract cognitive decline in old-age. Changes in neural connections and density of connections may be more profound during “critical periods” of learning where the brain is more sensitive to change. Researchers observed increased white-matter (myelinated axons) in the corpus callosum (link between 2 halves of the brain) with early musical training. Not all structural changes are in the brain are related to synaptic plasticity and neurogenesis. Many times, learning something like music changes connectivity by making neural signals more efficient through increased myelination (fatty deposits on axons to promote electrical signalling).

Learning a new language also creates large-scale changes in the brain. A study shows that learning a foreign language creates additional growth in language-related brain regions. They found an increase in the volume of the hippocampus and cortical thickness of the left middle frontal gyrus, inferior frontal gyrus, and superior temporal gyrus after language training. These areas are involved in first-language learning. So second or third language training enhances activity in those regions along with a change in their structures. Higher proficiency is related to additional growth in the right hippocampus and left superior temporal gyrus. A different study highlights an increase in gray density and white matter integrity after learning a new language. These changes are dependent on the duration of learning, level of proficiency, age of learning, characteristics of the language, and differences in each individual.

A few more studies suggests a number of things.

The researchers studied mice as they learned new behaviors, such as reaching through a slot to get a seed. They observed changes in the motor cortex, the brain layer that controls muscle movements, during the learning process. Specifically, they followed the growth of new “dendritic spines,” structures that form the connections (synapses) between nerve cells.

This suggests that new connections are formed to accommodate the learning. This formation is sometimes called Synaptogenesis (generation of new connections in existing neurons). New synapses are formed all throughout adulthood and their organization depends on the entirety of our experience.

One of the more famous aspects of synaptic plasticity is the saying “What fires together, wires together.” This is known as Hebb’s law. If 2 neural circuits or individual neurons repeatedly fire together in response to some other signal, they are likely to form a connection between each other. Simultaneous firing of neurons or in firing in close succession also strengthens the connection between the two neuron pathways. This is where a correlation can become a cause.

Research led by Yi Zuo (associate professor of molecular & developmental biology at the University of California, Santa Cruz) suggests that many new neurons emerge in clusters. They observed new synapses being formed in the pyramidal neurons of the motor cortex and their growth strengthened as the mice learned their task. These neurons also persisted after the learning was discontinued. About 1/3rd of the new ones appeared next to each other. Clusters of new neurons were formed as a direct consequence of learning the task at hand.

In their research, they found out that repeating the task was positively correlated to the number of neurons in a cluster. Learning new tasks daily without continued practice led to the growth of new connections as well, but, in a spaced out form.

“We found very quick and robust synapse formation almost immediately, within one hour of the start of training,” said Yi Zuo, assistant professor of molecular, cell and developmental biology at UCSC.


Another study done on cab drivers from London who were extensively trained to learn 25,000 city streets had a very interesting finding. Researchers found out that their hippocampus was larger than untrained people.

These drivers went through with memorizing roads few at a time systematically for a number years and as a result, their hippocampus grew larger than untrained people!

A fascinating study used Carbon-dating to birth-date neurons and found extremely robust evidence for adult neurogenesis in the human brain: About 1/3rd of the neurons are in a state of renewal – population of cells which can get replaced – and 1.75% of them “turnover” per year and actually get replaced. The turnover rate shows that about 700 new neurons are created in the hippocampus every single day. Non-neuronal cells (astrocytes, microglia) turnover at the rate of 3.5% per year. These cells are like the supporting cast for the main actors – neurons.

These research studies show that the brain is plastic and it underpins learning & memory.

The kicker: New research has now confirmed that neurogenesis occurs in the hippocampus of old humans, even in those brains which have Alzheimer’s. This has massive implications for what people can do to defend against cognitive impairment, old-age, and Alzheimer’s. Turns out you can teach an old dog new tricks and the brain is ready for that.


In conclusion, we can say 3 things:
1. New brain cells are constantly formed
2. Learning leads to newer connections in the brain
3. The brain is highly plastic


As for considering all types of different learning tasks, it may be premature to say that there will certainly be new neural connections. It’ll be great to have more experiments conducted on things like learning music when deaf, learning how to compute faster, or even simple things like learning how to say the alphabet in reverse and learning the names of 10 new friends.

I am certainly inclined to subscribe to this conjecture: Learning new things requires brain re-wiring along with the formation and utilization of new neurons in a variety of ways.

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