Brain Basics: The Life and Death of a Neuron (2023)


Brain Basics: The Life and Death of a Neuron (1)

Until recently, most neuroscientists thought that we are born with all the neurons we will ever have. As children, we can grow some new neurons to help build the pathways - called neural circuits - that act as information highways between different areas of the brain. However, scientists believed that once a neural circuit was in place, adding new neurons would disrupt the flow of information and disable the brain's communication system.

In 1962, scientist Joseph Altman challenged this belief when he saw evidence of neurogenesis (the birth of neurons) in a region of the brain of adult rats called the hippocampus. He later reported that newborn neurons migrated from their birthplace in the hippocampus to other parts of the brain. In 1979, another scientist, Michael Kaplan, confirmed Altman's findings in the rat brain, and in 1983 he found neural progenitor cells in the forebrain of an adult monkey.

These findings about neurogenesis in the adult brain surprised other researchers who didn't think they could be applied to humans. But in the early 1980s, a scientist trying to understand how birds learn to sing suggested that neuroscientists reexamine neurogenesis in the adult brain and begin to see how this might make sense. In a series of experiments, Fernando Nottebohm and his research team showed that the number of neurons in the forebrain of male canaries increased dramatically during the mating season. This was the same time that birds had to learn new songs to attract females.

Why did these bird brains add neurons at such a critical time for learning? Nottebohm believed this was because new neurons helped store new music patterns in neural circuits in the forebrain, the area of ​​the brain that controls complex behavior. These new neurons made learning possible. If birds were creating new neurons that help them remember and learn, Nottebohm thought that mammalian brains might be doing the same.

Other scientists thought these results might not apply to mammals, but Elizabeth Gould later found evidence of newborn neurons in a specific area of ​​monkey brains, and Fred Gage and Peter Eriksson showed that the adult human brain has new neurons produced. in a similar area. 🇧🇷

(Video) Brain Basics: The Life and Death of a Neuron

For some neuroscientists, neurogenesis in the adult brain is still an unproven theory. But others think the evidence offers intriguing possibilities about the role of adult-produced neurons in learning and memory.

The architecture of the neuron

The central nervous system (which includes the brain and spinal cord) is made up of two basic types of cells: neurons (1) and glial cells (4) and (6). In some parts of the brain, glial cells are superior to neurons, but neurons are the main players in the brain.

Neurons are messengers of information. They use electrical impulses and chemical signals to transmit information between different areas of the brain and between the brain and the rest of the nervous system. Everything we think, feel and do would be impossible without the work of neurons and their supporting cells, glial cells called astrocytes (4) and oligodendrocytes (6).

Neurons are composed of three basic parts: a cell body and two processes called the axon (5) and dendrite (3). Within the cell body is a nucleus (2), which controls the cell's activities and contains the cell's genetic material. The axon looks like a long tail and carries messages out of the cell. Dendrites look like the branches of a tree and receive messages for the cell. Neurons communicate by sending chemicals called neurotransmitters across a small gap called a synapse between the axons and dendrites of neighboring neurons.


Brain Basics: The Life and Death of a Neuron (2)

There are three classes of neurons:

  1. sensory neuronstransmit information from sensory organs (such as eyes and ears) to the brain.
  2. motor neuronsthey control voluntary muscle activity, such as speech, and transmit messages from nerve cells in the brain to muscles.
  3. All other neurons are calledinterneurons.

Scientists believe that neurons are the most diverse cell type in the body. Within these three classes of neurons, there are hundreds of different types, each with specific message-passing abilities.

The way these neurons communicate with each other making connections makes each of us unique in how we think, feel and act.


The extent to which new neurons are formed in the brain is a matter of debate among neuroscientists. Although most neurons are already present in our brains when we are born, there is evidence that neurogenesis (the scientific word for the birth of neurons) is a lifelong process.

Neurons are born in areas of the brain that are rich in concentrations of neural progenitor cells (also called neural stem cells). These cells have the potential to create most, if not all, of the different types of neurons and glial cells in the brain.

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Neuroscientists have observed how neural progenitor cells behave in the laboratory. While these cells might not exactly behave like this when they're in the brain, they do provide us with information about how they might behave when they're in the brain's environment.

Stem cell science is still very new and may change with new discoveries, but researchers have learned enough to be able to describe how neural stem cells make the other cells in the brain. They call this a stem cell lineage and it's basically similar to a family tree.

Neural stem cells reproduce by dividing into two parts and producing either two new stem cells or two initial progenitor cells or one each.

When a stem cell divides to produce another stem cell, it is said to renew itself. This new cell has the potential to produce more stem cells.

When a stem cell divides to produce an initial progenitor cell, this is called differentiation. Differentiation means that the new cell is more specialized in form and function. An early progenitor cell does not have the potential of a stem cell to produce many different types of cells. He can only create cells of his particular lineage.

The first progenitor cells can self-renew or leave in one of two ways. One type will lead to astrocytes. The other type will eventually produce neurons or oligodendrocytes.


After a neuron is born, it needs to travel to the place in the brain where it will do its job.

How does a neuron know where to go? What helps you get there?

Scientists have discovered that neurons use at least two different methods of travel:

  1. Some neurons migrate following long cell fibers called radial glia. These fibers extend from the inner layers to the outer layers of the brain. Neurons glide along the fibers until they reach their destination.
  2. Neurons also travel using chemical signals. Scientists have discovered special molecules on the surface of neurons - adhesion molecules - that bind to similar molecules on neighboring glial cells or nerve axons. These chemical signals guide the neuron to its final location.

Not all neurons succeed in their journey. Scientists assume that only a third will reach their goal. Some cells die during the neuronal development process.

Some neurons survive the journey, but end up where they shouldn't. Mutations in the genes that control migration create areas of misplaced or oddly shaped neurons that can cause conditions like childhood epilepsy. Some researchers suspect that schizophrenia and the learning disorder dyslexia are due in part to misdirected neurons.


Brain Basics: The Life and Death of a Neuron (3)
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Brain Basics: The Life and Death of a Neuron (4)

After a neuron arrives at its destination, it has to get used to work. This last differentiation step is the least understood part of neurogenesis.

Neurons are responsible for transporting and taking up neurotransmitters – chemicals that transmit information between brain cells.

Depending on its location, a neuron can play the role of a sensory neuron, motor neuron, or interneuron, sending and receiving specific neurotransmitters.

In the developing brain, a neuron depends on molecular signals from other cells, such as astrocytes, to determine its shape and position, the type of transmitter it produces, and which other neurons it connects to. These newborn cells build neural circuits — or pathways that connect neuron to neuron — that persist into adulthood.

But in the adult brain, neural circuits are already developed and neurons have to find a way to fit together. When a new neuron implants, it looks like neighboring cells. It develops an axon and dendrites and begins to communicate with its neighbors.


Although neurons are the longest living cells in the body, many of them die during migration and differentiation.

The lives of some neurons can take unusual turns. Some brain disorders are the result of the unnatural death of neurons.

(Video) My Neurons, My Self

  • I amParkinson diseaseNeurons that produce the neurotransmitter dopamine die in the basal ganglia, the area of ​​the brain that controls body movements. This leads to difficulties in starting the movement.
  • I amHuntington's diseasea genetic mutation causes overproduction of a neurotransmitter called glutamate, which kills neurons in the basal ganglia. As a result, people twist and squirm uncontrollably.
  • I amAlzheimer's diseaseUnusual proteins form in and around neurons in the neocortex and hippocampus, parts of the brain that control memory. When these neurons die, people lose the ability to remember and perform everyday tasks. Physical damage to the brain and other parts of the central nervous system can also kill or disable neurons.
  • blows to the brain, or the damage caused by a stroke, can kill neurons entirely or slowly deprive them of the oxygen and nutrients they need to survive.
  • spinal cord injurycan disrupt brain-muscle communication when neurons lose their connection with axons located downstream from the site of injury. These neurons can still live, but they lose the ability to communicate.


Brain Basics: The Life and Death of a Neuron (5)


Brain Basics: The Life and Death of a Neuron (6)
(Video) Brain anatomy and function, an overview | Neuroscience basics

hope through research

Scientists hope that by understanding more about the life and death of neurons, they will be able to develop new treatments and possibly even cures for brain diseases and disorders that affect the lives of millions of Americans.

The latest research suggests that neural stem cells can create many, if not all, of the different types of neurons found in the brain and nervous system. Learning to manipulate these stem cells into certain types of neurons in the lab can produce a fresh supply of brain cells to replace dead or damaged ones.

Therapies can also be developed to use growth factors and other signaling mechanisms in the brain that direct progenitor cells to form new neurons. This would allow the brain to be repaired, redesigned and renewed from within.


What is the death of neurons? ›

During nervous system development, about one-and-a-half times the adult number of neurons are created. These "extra" neurons are then destroyed or commit suicide. This process of programmed cell death occurs through a series of events termed apoptosis and is an appropriate and essential event during brain development.

What is the life cycle of a neuron? ›

The Neuronal cell cycle represents the life cycle of the biological cell, its creation, reproduction and eventual death. The process by which cells divide into two daughter cells is called mitosis. Once these cells are formed they enter G1, the phase in which many of the proteins needed to replicate DNA are made.

What are the 5 stages of neuronal development? ›

Several stages of neuron development have been identified- neuron production (or proliferation), migration, differentiation, synaptogenesis (increased connectivity), myelination, and synaptic pruning.

What are brain basics? ›

The brain can be divided into three basic units: the forebrain, the midbrain, and the hindbrain. The hindbrain includes the upper part of the spinal cord, the brain stem, and a wrinkled ball of tissue called the cerebellum. The hindbrain controls the body's vital functions such as respiration and heart rate.

What is the process of brain death? ›

Brain death can occur when the blood and/or oxygen supply to the brain is stopped. This can be caused by: cardiac arrest – when the heart stops beating and the brain is starved of oxygen. heart attack – a serious medical emergency that occurs when the blood supply to the heart is suddenly blocked.

Why is neuron death important? ›

Neuronal cell death occurs extensively during development and pathology, where it is especially important because of the limited capacity of adult neurons to proliferate or be replaced.

Where is life of a neuron? ›

Life of a Neuron, which first premiered at ARTECHOUSE DC in fall of 2021, is presented on an 18-channel, CAVE floor-to-wall surround projection array, combined with a 31.5-channel spatialized audio system showcasing ARTECHOUSE's ​​state-of-the-art capabilities.

What are the three stages of neuron activity? ›

It consists of three phases: depolarization, overshoot, and repolarization. An action potential propagates along the cell membrane of an axon until it reaches the terminal button. Once the terminal button is depolarized, it releases a neurotransmitter into the synaptic cleft.

Do neurons regenerate? ›

While lower organisms possess extensive capacity for neural regeneration, evolutionarily higher organisms including humans are limited in their ability to regenerate nerve cells, posing significant issues for the treatment of injury and disease of the nervous system.

What are the four basic principles of brain development? ›

The four principles are: (1) the brain is uniquely organized; (2) the brain is continually growing; (3) a ''brain-compat- ible'' classroom enables connection of learning to positive emotions; and (4) children's brains need to be immersed in real-life, hands-on, and meaningful learning experiences.

What are the 5 principles of neuroscience? ›

Principles of Neuroscience for Cognitive Development
  • Principle 1: Neuroplasticity. ...
  • Principle 2: Automaticity. ...
  • Principle 3: Integration (cross-training). ...
  • Principle 4: Progressive challenge. ...
  • Principle 5: Frequency and intensity. ...
  • Principle 6: Feedback. ...
  • Principle 7: Engagement.

What are the 7 stages of brain development? ›

There are 7 stages of brain development:
  • Cell Birth.
  • Cell Migration.
  • Cell Differentiation.
  • Cell Maturation.
  • Synaptogenesis.
  • Cell death and synaptic pruning.
  • Myelogenesis.

What is the three brains theory? ›

The triune brain theory is an evolutionary theory of brain development that emphasizes three key brain regions consisting of the brainstem, the limbic system, and the cortex that function relatively independently in coping with stress via fight or flight, emotion, and cognition, respectively.

What are the 7 functions of the brain? ›

What is the brain's function?
  • Thoughts and decisions.
  • Memories and emotions.
  • Movements (motor function), balance and coordination.
  • Perception of various sensations including pain.
  • Automatic behavior such as breathing, heart rate, sleep and temperature control.
  • Regulation of organ function.
  • Speech and language functions.
Mar 30, 2022

What are the three principles of the brain? ›

This essay will review three key concepts of this dynamic process: neural plasticity, progressive differentiation and commitment, and sources of developmental constraint. Each of these topics draws upon examples that illustrate brain development as progressive, dynamic, and adaptive, rather than innately specified.

What happens to the brain during brain death? ›

When someone is brain dead, it means that the brain is no longer working in any capacity and never will again. Other organs, such as the heart, kidneys or liver, can still work for a short time if the breathing machine is left in place, but when brain death is declared, it means the person has died.

What are the 4 criteria of brain death? ›

Brain death is typically diagnosed in an intensive care unit by a doctor trained in brain death evaluation. Brain death diagnosis requires presence of 3 conditions: persistent coma, absence of brainstem reflexes, and lack of ability to breathe independently.

Does the brain stop at death? ›

However, a new study published to Frontiers in Aging Neuroscience suggests that your brain may remain active and coordinated during and even after the transition to death, and be programmed to orchestrate the whole ordeal.

What do neurons need to stay alive? ›

Neurons are thought to primarily rely on glucose to fuel mitochondrial metabolism.

What do neurons need to survive? ›

In order to survive, developing neurons must reach and innervate their appropriate target cells, which supply critical survival promoting trophic factors, but in limiting amounts.

Can dead neurons be replaced? ›

Nerve Cells Do Not Renew Themselves

They do not divide at all. There are very few exceptions to this rule – only two special places in the brain can give birth to new neurons. For the most part though, the brain cannot replenish dead neurons.

Where do dead neurons go? ›

The cells that die are consumed by scavenger cells called phagocytes. Researchers have not completely understood how this process works, which phagocytes are unique to the brain and how the removal of dead neurons influences the creation of new neurons, until now.

Do neurons grow throughout life? ›

New hippocampal neurons continue to form in older adults, including those with MCI, Alzheimer's. Neurogenesis—the process of forming new brain cells—appears to continue in people well into old age, according to a recently published study funded in part by the NIA.

What happens when neurons are damaged? ›

Neurons are fragile and can be damaged by pressure, stretching, or cutting. An injury to a neuron can stop the signals transmitted to and from the brain, causing muscles to not work properly or a loss of feeling in an injured area. Nerve injuries can impact the brain, the spinal cord, and peripheral nerves.

How many neurons are in the brain? ›

Human Brain as a Scaled-Up Primate Brain

Remarkably, at an average of 86 billion neurons and 85 billion nonneuronal cells (25), the human brain has just as many neurons as would be expected of a generic primate brain of its size and the same overall 1:1 nonneuronal/neuronal ratio as other primates (26).

How does a neuron work? ›

Neurons are information messengers. They use electrical impulses and chemical signals to transmit information between different areas of the brain, and between the brain and the rest of the nervous system.

What are the 3 main neurons and what are their functions? ›

Although there are billions of neurons and vast variations, neurons can be classified into three basic groups depending on their function: sensory neurons (long dendrites and short axons), motor neurons (short dendrites and long axons) and relay neurons (short dendrites and short or long axons).

What foods build brain cells? ›

Foods linked to better brainpower
  • Green, leafy vegetables. Leafy greens such as kale, spinach, collards, and broccoli are rich in brain-healthy nutrients like vitamin K, lutein, folate, and beta carotene. ...
  • Fatty fish. ...
  • Berries. ...
  • Tea and coffee. ...
  • Walnuts.

What promotes nerve healing? ›

Magnesium promotes the regeneration of the peripheral nerve.

Which is the best food for nerves? ›

Six Great Plant-Based Foods to Fight Nerve Pain
  • Green and leafy vegetables. Broccoli, spinach and asparagus all contain vitamin B, a nutrient important for nerve regeneration and nerve function. ...
  • Fruits. Eat at least one fruit daily to help heal damaged nerves. ...
  • Zucchini. ...
  • Sweet potato. ...
  • Quinoa. ...
  • Avocado.
Mar 30, 2021

What are the 6 pillars of brain health? ›

Through this research, six lifestyle pillars that support brain health were identified:
  • Engage Your Brain.
  • Stay Socially Engaged.
  • Manage Stress.
  • Exercise.
  • Get Restorative Sleep.
  • Eat Right.
Nov 23, 2021

What is the most important factor in brain development? ›

Nurturing and responsive care for the child's body and mind is the key to supporting healthy brain development. Positive or negative experiences can add up to shape a child's development and can have lifelong effects. To nurture their child's body and mind, parents and caregivers need support and the right resources.

What is the biggest question in neuroscience? ›

In a nutshell, then, the biggest unsolved problem is how the brain generates the mind, conceived of in a way that does not simultaneously require answering the problem of consciousness (Box 1).

What are the 5 principles to live by? ›

Five Great Principles for Life, The: Focus, Strength, Success, Wisdom, Responsibility.

How many five principles of life are there? ›

The Five Great Principles for Life: Focus, Strength, Success, Wisdom, Responsibility.

What age does the brain stop developing? ›

Though the brain may be done growing in size, it does not finish developing and maturing until the mid- to late 20s. The front part of the brain, called the prefrontal cortex, is one of the last brain regions to mature.

What are the 9 stages of life? ›

The average human life span falls into nine stages:
  • prenatal development.
  • infancy and toddlerhood.
  • early childhood.
  • middle childhood.
  • adolescence.
  • early adulthood.
  • middle adulthood.
  • late adulthood.

What part of the brain develops last? ›

The frontal lobes, home to key components of the neural circuitry underlying “executive functions” such as planning, working memory, and impulse control, are among the last areas of the brain to mature; they may not be fully developed until halfway through the third decade of life [2].

What 3 things does the brain need to survive? ›

Your brain is like a car. A car needs gasoline, oil, brake fluid and other materials to run properly. Your brain also needs special materials to run properly: glucose, vitamins, minerals and other essential chemicals.

What is the brain theory philosophy? ›

Mind-brain identity theory is a philosophy that purports the mind and brain are the same. In other words, the state of mind is the same as brain processes; that mental state is the same as the physical state of the brain.

Do human beings have 3 brains? ›

Neuroscience now tells us that we each have three brains. The one we most often think about and pay attention to is the “head” or cephalic brain. We also have a heart (cardiac) and a gut (enteric) brain. Each has sensory neurons, motor neurons, ganglia, and neurotransmitters.

Why is the brain the most important organ? ›

The brain is arguably the most important organ in the human body. It controls and coordinates actions and reactions, allows us to think and feel, and enables us to have memories and feelings—all the things that make us human.

Is the brain a Muscle or an organ? ›

As it turns out, your brain isn't actually a muscle. It's an organ — one that actually plays a huge role in controlling muscles throughout your body. Muscle is made up of muscle tissue, which is muscle cells grouped into elastic bundles that contract together to produce motion and/or force.

What is the most amazing thing about the brain? ›

Your brain's storage capacity is considered virtually unlimited. Research suggests the human brain consists of about 86 billion neurons. Each neuron forms connections to other neurons, which could add up to 1 quadrillion (1,000 trillion) connections. Over time, these neurons can combine, increasing storage capacity.

What are the 3 interactive elements for applying the brain based principles? ›

Making Connections: Teaching and the Human Brain includes many wonderful real-life examples of how the three elements of relaxed alertness, orchestrated immersion, and active processing occur in successful teaching situations at all levels, from elementary school to college and beyond, and with a variety of methods.

What is loss of neurons in the brain? ›

Cerebral atrophy—the loss of nerve cells (neurons) and the connections that help them communicate in the brain's tissues—occurs in many disorders that affect the brain, such as stroke, Alzheimer's, disease, traumatic brain injury, multiple sclerosis, or infections.

What causes motor neuron death? ›

The researchers confirmed that the cause of the motor neurons' death was a toxin released into the environment by immersing healthy motor neurons in the astrocytes' culture media. The presence of the media, even without astrocytes, killed the motor neurons.

Do dead neurons grow back? ›

Nerve Cells Do Not Renew Themselves

Yet, nerve cells in your brain, also called neurons, do not renew themselves. They do not divide at all. There are very few exceptions to this rule – only two special places in the brain can give birth to new neurons. For the most part though, the brain cannot replenish dead neurons.

Can damaged brain neurons regenerate? ›

As with most tissues in the body, the brain has mechanisms to regenerate itself, such as, previously mentioned, endogenous neurogenesis and neuroplasticity (Sharma et al., 2013). However, these processes are limited after injury (Modo, 2019).

What age do we lose neurons? ›

While basic cognitive faculties decline slowly, they nevertheless decline starting after the age of 20. One of the primary reasons for this decline is that our brain shrinks. Neurons die off faster than they are replaced, leaving us with a smaller brain.

Why do we lose neurons as we age? ›

Unfinished DNA repair contributes to the damage and age-related loss of neurons. However, it might be possible to protect the nerve cells, which may have implications for the prevention of Parkinson's disease.


1. Aging Brain Part 1: Brain Basics - Professional Caregiver Webinar
(Caregiver Stress)
2. Meet Your Master - Getting to Know Your Brain: Crash Course Psychology #4
3. Dr. Octavio Choi presents Brain Basics: An Introduction to Cognitive Neuroscience
4. Understanding the Brain: Why neurons are not enough | Hannah Loo | TEDxSUNYGeneseo
(TEDx Talks)
5. Basics 1: The Brain & Dementia
(Pat Snyder)
6. The Aging but Resilient Brain: Keeping Neurons Happy
(University of California Television (UCTV))


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