How Much Do We Really Understand the Brain and Nervous System?
A recent CT scan showed no new changes in my brain. Structurally, everything appears stable. In medical terms that should be reassuring. Yet my body seems to be telling a slightly different story.
The facial numbness I have been experiencing continues to shift and in some areas it has become more noticeable. When tests suggest everything looks stable but your own experience suggests otherwise, it raises a difficult but honest question.
How much do we actually understand about the brain and the nervous system?
Out of curiosity, and perhaps a little frustration, I spent some time reading and reflecting on this question. The more I explored the subject, the clearer it became that the answer is both fascinating and humbling. What follows is a short attempt to summarise what we currently know, and perhaps more importantly, what we still do not understand.
The Most Complex System in the Body
The human brain is often described as the most complex structure known in the universe. It sits inside the skull, weighs roughly 1.3 kilograms, and yet it produces thought, memory, emotion, personality, and consciousness.
However, the brain does not function in isolation.
It operates as the central hub of the nervous system, a vast communication network that includes the brain, spinal cord, and an enormous number of nerves extending throughout the body. These nerves transmit signals that allow us to move, feel, see, hear, and interpret the world around us.
Despite centuries of research and decades of advanced technology, the uncomfortable truth is that our understanding of this system remains surprisingly limited.
The Numbers Behind the Complexity
To appreciate the scale of the challenge, it helps to look at the numbers.
The human brain contains roughly 86 billion neurons. Each neuron can form thousands of connections with other neurons. These connections are known as synapses and they are estimated to number around 100 trillion.
Signals travel across this network through electrical impulses and chemical messengers. Every thought, memory, movement, and sensation depends on this constant flow of information.
The number of possible signalling patterns within this system is astronomically large. It is far beyond what current scientific models can fully describe or simulate. Even the most advanced neuroscience captures only small fragments of this vast and constantly changing network.
Where Nerves Fit Into the Picture
Many symptoms people experience are not purely related to the brain itself but to the nerves that carry signals between the brain and the rest of the body.
Facial sensation, for example, is largely controlled by the Trigeminal nerve. This is one of the major cranial nerves that emerges from the brainstem and spreads across the face. It carries sensory information such as touch, temperature, and pain from the face back to the brain.
Although the trigeminal nerve is not part of the brain tissue itself, it plays a critical role in how the brain receives information from the face.
When this nerve is irritated, compressed, or affected by surgery or neurological conditions, people may experience symptoms such as numbness, tingling, altered sensation, or facial discomfort.
This highlights an important point. The nervous system is not simply the brain. It is a complex network where problems can occur at many points along the pathway.
What Scans Can and Cannot Show
Modern imaging tools such as CT scans and MRI scans are extremely useful. They can detect major structural problems such as tumours, bleeding, strokes, or large injuries.
However, these technologies mainly show structure rather than function.
Many neurological symptoms arise because of subtle changes in how signals travel through nerves or between different areas of the brain. These changes may involve tiny nerve fibres, microscopic signalling disturbances, or altered communication between brain regions.
Problems at this level are often too small or too complex for current imaging technology to detect clearly.
This is why people can experience symptoms such as numbness, fatigue, tinnitus, brain fog, or sensory changes even when scans appear normal.
The Mystery of Consciousness
Even when focusing only on the brain itself, there remain enormous gaps in our understanding.
Scientists can measure electrical activity in the brain and identify which areas become active during certain tasks. Yet they still cannot fully explain how these electrical and chemical signals produce thoughts, memories, emotions, or conscious awareness.
Consciousness remains one of the greatest unsolved problems in science.
In simple terms, we can often observe what the brain is doing, but we do not fully understand how it produces experience.
The Brain Studying Itself
There is also a deeper philosophical challenge involved in studying the brain.
The brain is not only the object being studied. It is also the tool doing the studying.
Every scientific theory, experiment, and model of the brain is created by the very organ we are trying to understand. In other words, the brain is attempting to understand itself.
This creates a kind of intellectual loop. Our ability to investigate the brain is limited by the brain’s own capacities. The instrument and the subject are the same.
It is somewhat similar to a telescope attempting to observe its own lenses while still being limited by the optics through which it sees.
Living With the Unknown
For people living with neurological conditions such as acoustic neuroma, these limits in knowledge are not just theoretical. They show up in everyday life.
Scans can appear stable while symptoms shift. Nerves can behave unpredictably. Sensations can change without an obvious explanation.
The facial numbness many people experience after surgery often involves the Trigeminal nerve, which carries sensory information from the face to the brain. Even when imaging shows no new structural changes, the way this nerve communicates with the brain can still influence how sensation is perceived.
None of this necessarily means something new or dangerous is happening. Often it simply reflects how intricate and sensitive the nervous system really is.
A Lesson in Humility
When viewed from a broader perspective, the difficulty of understanding the brain and nervous system becomes less surprising.
We are dealing with one of the most complex systems known in nature.
Neuroscience has already made remarkable progress and has transformed many areas of medicine. However, it is still a relatively young field compared with disciplines such as physics or chemistry. Much of what we know consists of partial theories and evolving models.
Perhaps the most honest conclusion is this.
The brain allows us to explore distant galaxies, decode DNA, and build complex societies. Yet when it turns inward to examine itself and the nervous system it controls, it encounters one of the deepest mysteries in science.
The very system that allows us to understand the universe is still trying to understand itself.