What happens when neurological conditions challenge our fundamental sense of self?
What makes you, you? Is it your memories, your personality, your unwavering sense of self? Modern neurology presents a startling revelation: this core identity is fragile, a construct of the intricate neural networks within our brains. When neurological conditions strike, they don't just impair function—they can fundamentally alter who a person is, forcing us to confront profound questions about identity, belonging, and the very essence of the human experience 1 .
The journey to understand these questions is not just a scientific pursuit but a deeply human one, illuminated by the stories of patients and the doctors who learn from them.
This exploration lies at the heart of "Our Brains, Our Selves: What a Neurologist's Patients Taught Him About the Brain" by Masud Husain, which has been awarded the 2025 Royal Society Trivedi Science Book Prize. The book stands as a beautiful exploration of how pathological problems in the brain can cause people to change completely and, as a consequence, be rejected by society. It is a very empathetic book, told in a wonderful way, and from a very personal perspective of a doctor who feels deeply for these people 1 .
The Royal Society Book Prize annually searches for the most informative and readable new books on scientific subjects. The 2025 shortlist, chosen by a panel led by botanist Dr. Sandra Knapp, celebrates works that masterfully mix learning and pleasure, offering readers a compelling and enjoyable experience 1 .
Our Brains, Our Selves emerged as the winner from a shortlist of exceptional titles. These included:
By Daniel Levitin, exploring how music can be used to treat neurological issues 1 .
By Tim Minshall, a revealing book about global supply chains 1 .
By Simon Parkin, a heartrending account of the struggle to save the world's first seed bank during WWII 1 .
By Sadiah Qureshi, a history of extinction in the colonial world 1 .
Neurology sits at the fascinating intersection of biology and identity. To understand its revelations, one must first grasp a few core concepts:
The concept of a stable "self" is a mental entity, a way our brain makes sense of the world and our place in it 2 . This sense of self is not housed in a single spot but is an emergent property of countless neural connections working in concert.
The brain is not a static organ. It constantly rewires itself based on experience—a phenomenon known as neuroplasticity. However, diseases like Alzheimer's, brain tumors, or traumatic injuries can hijack this adaptability.
A central theme in Husain's work is that the consequences of brain changes are not merely biological. When a person's personality alters, they can become "completely different, and therefore be rejected by society" 1 .
As Dr. Knapp notes: The book forces us to ask: if you suffer brain damage and your personality changes, are you still 'yourself'? And if not—who are you? 1
The quest for knowledge in science often involves sifting between competing theories. How do scientists decisively prove one idea over another? Historically, they have relied on what is known as an experimentum crucis (crucial experiment) 3 .
An experimentum crucis is an experiment capable of decisively determining whether a particular hypothesis is superior to all other widely accepted theories. It must produce a result that rules out all competing hypotheses, demonstrating that they are false while leaving the experimenter's theory standing 3 .
Robert Boyle hailed this as an experimentum crucis. It involved carrying a mercury barometer up a mountain and showing that the mercury fell as altitude increased, proving that the height of the mercury was determined by the weight of the air, and not by nature's resistance to a vacuum 3 .
Led by Arthur Eddington to observe stars near the sun during an eclipse, this experiment confirmed Einstein's prediction of gravitational lensing from his general theory of relativity. It provided the first solid evidence favoring Einstein's theory over Newtonian mechanics 3 .
These decisive moments in science share a common thread with the methodology in Our Brains, Our Selves. While Husain's work is based on clinical observation rather than a single laboratory test, his approach is similarly built on pivotal case studies—moments of revelation where a patient's symptoms provide a clear, decisive insight into the brain's relationship with the self.
One of the most elegant examples of an experimentum crucis comes from the 19th-century debate about the nature of light: is it a particle or a wave?
In 1818, French physicist Augustin-Jean Fresnel entered a competition by the French Academy on the subject of diffraction. He submitted a wave theory of light. The eminent mathematician Siméon Denis Poisson, who was a judge and a supporter of the particle theory, studied Fresnel's work. He deduced a startling consequence: if Fresnel's wave theory were correct, then the shadow of a perfectly circular, opaque object should have a small, bright spot at its center—a result that seemed absurd and had never been observed 3 .
The Academy decided to test this prediction. Another scientist, François Arago, performed the experiment. He obtained a small, perfectly round disc and set up a light source to cast the disc's shadow.
Arago's experiment revealed a bright spot precisely in the center of the shadow, just as Fresnel's theory had predicted. This result, now known as the Arago spot or Poisson's bright spot, could not be explained by the particle theory of light. It provided decisive evidence in favor of the wave theory of light, leading to its widespread acceptance 3 .
A small bright spot appears at the center of a circular shadow due to constructive interference of diffracted light waves.
A completely dark shadow with no central spot, as particles travel in straight lines and are blocked by the object.
| Theory | Prediction for Circular Shadow | Explanation of Diffraction |
|---|---|---|
| Particle Theory (Newtonian) | Completely dark shadow | Particles travel in straight lines and are blocked by the object. |
| Wave Theory (Fresnel) | Small bright spot at center | Waves diffract around the edges and constructively interfere at the center. |
| Experimental Parameter | Observation |
|---|---|
| Object Casting Shadow | A small, perfectly circular disc |
| Predicted by Wave Theory | A bright spot in the center of the shadow |
| Actual Result | A bright spot was observed |
| Implication for Particle Theory | Ruled out (in its contemporary form) |
| Experiment / Observation | Scientists Involved | Field | Decisive Outcome |
|---|---|---|---|
| Arago Spot | Fresnel, Poisson, Arago | Optics | Supported wave theory of light over particle theory. |
| Puy-de-Dôme Barometer | Pascal, Périer | Physics | Showed mercury height determined by air pressure, not vacuum resistance. |
| Eddington's Eclipse | Eddington, Einstein | Physics | Confirmed General Relativity's prediction of gravitational lensing. |
| DNA Structure | Watson, Crick | Biology | Double helix structure explained the mechanism of genetic inheritance 3 . |
Whether in a historical physics experiment or a modern neurology clinic, progress depends on a toolkit of essential materials and concepts. Below is a list of key "reagents" used in the field of cognitive neurology and neuroscience research.
| Tool / Material | Function in Research |
|---|---|
| fMRI (functional Magnetic Resonance Imaging) | Measures brain activity by detecting changes in blood flow, allowing scientists to see which areas are active during specific tasks. |
| Patient Case Studies | Detailed clinical observations of individuals with brain injuries or conditions provide invaluable, real-world insights into brain function. |
| Neuropsychological Tests | Standardized tasks (e.g., memory recall, problem-solving) to objectively assess cognitive functions and identify deficits. |
| The Concept of 'Self' | A fundamental, if fuzzy, mental construct used as a lens to investigate and understand the profound effects of neurological change 2 . |
The stories from neurology, like those so empathetically shared in Our Brains, Our Selves, and the decisive experiments from physics, like the Arago spot, all lead us to the same conclusion: science is a profoundly human endeavor. It is not just a cold collection of data, but a pursuit filled with moral decisions, leaps of understanding, and a deep desire to make sense of our world and ourselves 1 .
From the dedication of botanists who starved to save a seed bank to a neurologist listening to what his patients can teach him about the brain, the best science writing reminds us that you cannot separate science from society 1 .
It challenges us not only to understand the universe but also to reflect on our place within it, asking the most fundamental question of all: What does it mean to be human?