Biological Neural Network Explained (vs Artificial Neural Networks)

Updated 20 October 2026

Quick answer: A biological neural network is a group of interconnected nerve cells (neurons) that work together to process information in the brain and nervous system. Neurons communicate through electrical impulses and chemical messengers called neurotransmitters, passed across tiny gaps called synapses. The human brain contains roughly 86 billion neurons linked by trillions of synapses. These networks let us sense, move, think, learn and remember, and they change with experience, a property called neuroplasticity. Artificial neural networks in AI are loosely inspired by them, but work very differently.

Every thought you have, every memory you form and every movement you make depends on vast networks of cells communicating with each other at lightning speed. The human brain is often described as the most complex structure known in the universe, and understanding how its neural networks work is one of science's greatest challenges.

This guide explains what biological neural networks are, how neurons communicate, how networks learn and adapt, how they compare with artificial neural networks used in AI, and what current research is revealing.

What Is a Neuron?

A neuron is a specialised cell that transmits information. The human brain contains an estimated 86 billion neurons, according to research by neuroscientist Suzana Herculano-Houzel and colleagues, along with a similar number of supporting cells called glia.

A typical neuron has four main parts:

Dendrites: branching extensions that receive signals from other neurons.
Cell body (soma): contains the nucleus and integrates incoming signals.
Axon: a long fibre that carries electrical signals away from the cell body, sometimes over long distances. Some axons in the human body are about a metre long, running from the spinal cord to the feet.
Axon terminals: endings that pass signals to other neurons, muscles or glands.

Many axons are wrapped in a fatty layer called myelin, produced by glial cells. Myelin acts like insulation on a wire, allowing signals to travel much faster. Diseases that damage myelin, such as multiple sclerosis, disrupt communication in the nervous system.

Types of Neurons

Sensory neurons carry information from sense organs, such as the eyes, ears and skin, to the brain and spinal cord.
Motor neurons carry signals from the brain and spinal cord to muscles and glands, producing movement and responses.
Interneurons connect neurons within the brain and spinal cord, processing and integrating information. They make up the vast majority of neurons.

Glial Cells: The Brain's Support Team

Neurons get most of the attention, but they couldn't function without glial cells. Once thought of as mere "glue", glia are now known to play active roles:

Astrocytes supply nutrients to neurons, regulate chemicals around synapses, and help control blood flow in the brain.
Oligodendrocytes (in the brain and spinal cord) and Schwann cells (in peripheral nerves) produce myelin.
Microglia are the brain's immune cells, clearing debris and helping prune unnecessary synapses during development.

Research increasingly shows that glia influence learning, memory and disease, making them an important focus of modern neuroscience.

How Neurons Communicate

The Electrical Signal: Action Potentials

Neurons maintain a small electrical charge across their membranes, called the resting potential, typically around -70 millivolts. When a neuron receives enough stimulation, channels in its membrane open, allowing charged particles (ions such as sodium and potassium) to flow in and out. This creates a brief electrical spike called an action potential, which travels along the axon.

Action potentials are "all or nothing": a neuron either fires fully or not at all. The strength of a signal is encoded by how often a neuron fires and how many neurons fire together. Signals can travel at speeds ranging from about one metre per second in thin, unmyelinated fibres to over 100 metres per second in thick, myelinated ones.

British scientists Alan Hodgkin and Andrew Huxley explained the mechanism of the action potential using experiments on squid giant axons, work for which they shared the 1963 Nobel Prize in Physiology or Medicine with John Eccles.

The Chemical Signal: Synapses and Neurotransmitters

Neurons don't usually touch each other directly. They communicate across tiny gaps called synapses. When an action potential reaches the axon terminal, it triggers the release of chemical messengers called neurotransmitters. These cross the synaptic gap and bind to receptors on the next neuron, making it more or less likely to fire.

Important neurotransmitters include:

Neurotransmitter	Main roles
Glutamate	The main excitatory neurotransmitter; important for learning and memory
GABA	The main inhibitory neurotransmitter; calms neural activity
Dopamine	Motivation, reward, movement
Serotonin	Mood, sleep, appetite
Acetylcholine	Muscle movement, attention, memory
Noradrenaline (norepinephrine)	Alertness, stress response
Endorphins	Pain relief, sense of wellbeing

Many medications, from antidepressants to anaesthetics, work by influencing neurotransmitters or their receptors.

Excitation and Inhibition

Each neuron may receive inputs from thousands of others. Some inputs excite it, pushing it toward firing; others inhibit it. The neuron effectively "adds up" these signals. A healthy brain depends on a careful balance between excitation and inhibition. Too much excitation can lead to seizures; too much inhibition can suppress activity.

From Neurons to Networks

A single neuron can connect to thousands of others, creating networks of staggering complexity. Estimates suggest the human brain has on the order of 100 trillion synapses or more.

Neural networks are organised at multiple levels:

Local circuits: small groups of neurons performing specific computations, such as detecting edges in visual information.
Brain regions: areas specialised for functions like vision (occipital lobe), language (areas in the left hemisphere for most people), movement (motor cortex) and memory (hippocampus).
Large-scale networks: connected regions that work together, such as the default mode network, active during daydreaming and self-reflection, and attention networks that help us focus.

The complete map of neural connections in a nervous system is called a connectome. Scientists mapped the full connectome of the tiny roundworm C. elegans, which has just 302 neurons, in the 1980s. In 2024, an international consortium published a complete wiring map of the adult fruit fly brain, containing around 140,000 neurons and tens of millions of synaptic connections. Mapping the human connectome at that level of detail remains far beyond current technology.

How Biological Neural Networks Learn

Synaptic Plasticity

Learning happens largely by changing the strength of connections between neurons. In 1949, psychologist Donald Hebb proposed that when one neuron repeatedly helps fire another, the connection between them strengthens. This idea is often summarised as "neurons that fire together, wire together".

Experiments later confirmed this. In 1973, Timothy Bliss and Terje Lømo described long-term potentiation (LTP): a lasting increase in synaptic strength following repeated stimulation, observed in the hippocampus. The opposite process, long-term depression (LTD), weakens connections. Together, they allow networks to store information.

Neuroplasticity

The brain's ability to reorganise itself is called neuroplasticity. It's strongest in childhood but continues throughout life. Examples include:

Learning a new skill, like playing an instrument, strengthens related networks.
A well-known study by Eleanor Maguire and colleagues found that London taxi drivers, who memorise the city's complex streets, had larger posterior hippocampi on average than control participants.
After a stroke, rehabilitation can help other brain areas take over some lost functions.
People who lose their sight may use visual brain areas for processing touch or sound.

Memory

Memory formation involves several brain regions. The hippocampus is crucial for forming new memories of facts and events. The famous patient Henry Molaison, known in research as H.M., had parts of both hippocampi removed in 1953 to treat severe epilepsy and afterwards could not form new long-term memories of facts and events, revealing the hippocampus's central role. Sleep plays an important role in consolidating memories, as the brain replays and strengthens neural patterns from the day.

How Neural Networks Develop From Birth

A newborn's brain already contains most of the neurons it will ever have, but the connections between them change dramatically in the first years. Synapses form at an astonishing rate in early childhood, creating far more connections than will eventually be kept. Then, through a process called synaptic pruning, unused connections are gradually removed while frequently used ones are strengthened. This "use it or lose it" process continues through adolescence, refining networks based on experience.

Myelination also continues into the twenties, particularly in the prefrontal cortex, which supports planning, judgement and impulse control. This helps explain why teenagers may take more risks and why rich experiences in childhood and adolescence matter so much for development.

Brain Waves: Networks in Rhythm

When large groups of neurons fire together, they create rhythmic electrical patterns called neural oscillations, or brain waves, which can be measured with EEG:

Wave	Frequency (approx.)	Associated with
Delta	0.5–4 Hz	Deep sleep
Theta	4–8 Hz	Drowsiness, some memory processes
Alpha	8–12 Hz	Relaxed wakefulness, eyes closed
Beta	13–30 Hz	Active thinking, focus
Gamma	30+ Hz	Processing and integrating information

These rhythms help coordinate communication between brain regions. Disruptions in them are linked to conditions such as epilepsy and some sleep disorders.

The Brain's Remarkable Energy Efficiency

The human brain makes up only about 2% of body weight but uses roughly 20% of the body's energy at rest, mainly to maintain the electrical gradients neurons need to fire. Even so, its total power consumption of about 20 watts is tiny compared with the computers used to train large AI models. This efficiency, achieved through sparse firing, local processing and massive parallelism, is one reason engineers study the brain when designing new kinds of computer chips.

Emotions and Neural Networks

Emotions arise from networks spanning several brain regions. The amygdala is involved in detecting threats and processing fear; the prefrontal cortex helps regulate emotional responses; the insula is linked to awareness of bodily feelings; and reward circuits involving dopamine shape motivation and pleasure. Practices such as mindfulness meditation and cognitive behavioural therapy appear to strengthen the prefrontal regulation of emotional responses over time, an example of neuroplasticity in everyday life.

Biological vs Artificial Neural Networks

Artificial neural networks (ANNs), which power modern AI systems including image recognition and large language models, were inspired by biological neurons. In 1943, Warren McCulloch and Walter Pitts proposed a simple mathematical model of a neuron, and Frank Rosenblatt built the "perceptron" in the late 1950s. But today's ANNs differ greatly from the brain.

Feature	Biological neural networks	Artificial neural networks
Basic unit	Living neurons with complex chemistry	Mathematical functions ("nodes")
Scale	About 86 billion neurons, ~100 trillion synapses	Large models may have billions to trillions of parameters
Signals	Electrical spikes and chemical neurotransmitters	Numbers passed between layers
Learning	Synaptic plasticity, continuous, often from few examples	Usually trained with backpropagation on huge datasets
Energy use	About 20 watts	Training large models can require enormous amounts of electricity
Adaptability	Learns continually throughout life	Often trained once, then fixed or periodically retrained
Structure	Highly recurrent, three-dimensional, varied cell types	Usually organised in layers

Researchers are also developing spiking neural networks and neuromorphic chips, such as Intel's Loihi and IBM's TrueNorth, which mimic the brain's spiking activity more closely to achieve greater energy efficiency.

How the Senses Use Neural Networks

Each sense relies on specialised networks that convert physical signals into neural activity:

Vision: light-sensitive cells in the retina convert light into electrical signals, which pass through several layers of retinal neurons and then to the visual cortex. Pioneering work by David Hubel and Torsten Wiesel, recognised with the 1981 Nobel Prize, showed that neurons in the visual cortex respond to specific features such as lines at particular angles.
Hearing: hair cells in the inner ear convert sound vibrations into signals sent to the auditory cortex.
Touch: receptors in the skin detect pressure, temperature and pain, sending signals through the spinal cord to the brain.
Smell and taste: chemical receptors send signals to brain areas closely linked with memory and emotion, which is why smells can trigger vivid memories.

The brain then combines information from all senses into a single, coherent experience of the world.

When Neural Networks Go Wrong

Many neurological and psychiatric conditions involve disrupted neural networks:

Alzheimer's disease: loss of synapses and neurons, especially in memory-related regions.
Parkinson's disease: loss of dopamine-producing neurons affecting movement.
Epilepsy: abnormal, excessive synchronised activity in neural networks.
Depression: changes in networks involved in mood, reward and stress regulation.
Multiple sclerosis: damage to myelin that slows or blocks signals.
Stroke: interruption of blood supply that kills neurons in affected areas.

Understanding these networks is key to developing better treatments.

Tools Scientists Use to Study Neural Networks

EEG (electroencephalography): records electrical activity from the scalp.
fMRI (functional magnetic resonance imaging): measures changes in blood flow linked to brain activity.
Electrophysiology: records signals from individual neurons using tiny electrodes.
Optogenetics: uses light to switch genetically modified neurons on or off in animals, revealing their roles.
Electron microscopy: maps synaptic connections in fine detail for connectome projects.
Brain-computer interfaces: devices that record neural activity to control computers or prosthetics, helping some people with paralysis communicate or move robotic limbs.

Reflexes: The Simplest Neural Networks

Not every response involves the brain. When you touch a hot surface, a reflex arc pulls your hand away before you consciously feel pain. Sensory neurons send a signal to the spinal cord, where interneurons pass it directly to motor neurons that contract your arm muscles. Only afterwards does the signal reach the brain, creating the sensation of pain. The knee-jerk reflex your doctor tests with a small hammer works similarly. Reflexes show how even small neural circuits can produce fast, protective behaviour.

Major Brain Initiatives

Governments and research institutions have invested heavily in understanding neural networks:

The US BRAIN Initiative, launched in 2013, funds technologies to map and understand brain circuits.
The Human Brain Project in Europe ran from 2013 to 2023, building digital research infrastructure for neuroscience, now continued through the EBRAINS platform.
The Allen Institute for Brain Science produces detailed open-access atlases of brain cells and connections.
India has also invested in brain research through institutions such as the National Brain Research Centre in Manesar and IISc's Centre for Brain Research in Bengaluru, which studies brain ageing in the Indian population.

Common Myths About the Brain

"Left-brained people are logical; right-brained people are creative." While some functions are more lateralised, such as language in the left hemisphere for most people, everyday thinking uses both hemispheres working together. Studies have not found that people are dominantly "left-brained" or "right-brained".
"Brain damage is always permanent." Neuroplasticity allows some recovery, especially with rehabilitation.
"Adults can't learn as well as children." Children have some advantages, especially for language accents, but adults can learn new skills throughout life.
"Listening to Mozart makes you smarter." The so-called Mozart effect has not been supported by robust evidence for lasting intelligence gains.

How to Keep Your Brain's Networks Healthy

Exercise regularly: physical activity increases blood flow to the brain and supports the growth of new connections.
Sleep well: sleep consolidates memories and clears waste products from the brain.
Keep learning: new skills and challenges strengthen neural networks.
Stay socially connected: social engagement is linked to better cognitive health in later life.
Eat a balanced diet: patterns rich in vegetables, fruits, whole grains, fish and healthy fats support brain health.
Manage stress: chronic stress can harm the hippocampus and other brain regions.
Protect your head: wear helmets when cycling or riding two-wheelers.
Control blood pressure and blood sugar, which protect the brain's blood vessels.

Frequently Asked Questions

How many neurons are in the human brain?

About 86 billion, according to widely cited research, plus a similar number of glial cells.

Can the brain grow new neurons?

New neurons are formed in some brain regions in many animals, a process called neurogenesis. Whether and how much this happens in the adult human hippocampus is still debated among scientists. However, the brain constantly forms and modifies connections throughout life.

Do we only use 10% of our brain?

No. This is a myth. Brain imaging shows that virtually all areas of the brain are active, though not all at the same time.

Are artificial neural networks the same as the brain?

No. They were inspired by biological neurons, but they work very differently in structure, learning, energy use and flexibility.

How fast do neural signals travel?

From about one metre per second in thin, unmyelinated fibres to more than 100 metres per second in large, myelinated fibres.

What is the difference between the brain and the nervous system?

The brain is part of the central nervous system, along with the spinal cord. The peripheral nervous system includes the nerves that connect the central nervous system to the rest of the body.

How do memories get stored?

Memories are thought to be stored as patterns of strengthened connections across networks of neurons, rather than in single cells. Different types of memory involve different brain regions, such as the hippocampus for facts and events and the cerebellum for some motor skills.

Can brain-computer interfaces read thoughts?

Current devices can decode specific signals, such as intended movements or attempted speech, after training with an individual user. They cannot read general thoughts, and research continues to raise important ethical questions about privacy and consent.

Why is sleep so important for the brain?

During sleep, the brain consolidates memories, reorganises connections and clears waste products. Research suggests the brain's waste-clearance system is especially active during sleep. Poor sleep impairs attention, learning and mood.

Does the brain stop developing at 25?

Major structural development continues into the mid-twenties, but the brain keeps changing throughout life as we learn and adapt.

Final Thoughts

Biological neural networks are nature's most remarkable information-processing systems. Through electrical and chemical signals passing among tens of billions of neurons, they allow us to perceive the world, move, feel, learn and remember. They constantly reshape themselves in response to experience, which means the habits you choose, from learning and exercise to sleep and social connection, literally shape your brain. As neuroscience and AI continue to learn from each other, our understanding of these living networks will only deepen.

If you found this article fascinating, share it with someone curious about the brain.

Cite this page: Blog Digest, “Biological Neural Network Explained (vs Artificial Neural Networks)”, updated 2026-10-29, https://randomthoughtsever.blogspot.com/2023/02/a-study-about-biological-neural-network.html