The Tell-Tale Brain

Each of us has one. It is what lets us read this text and make sense of it. But how does the brain work?

This simple, straightforward, question about how a lump of fatty tissue can do complex computation is the subject of this book written by V.S. Ramachadran. The one word answer is “weirdly”.

So before going any further, a content warning: this book has been written some time ago, and uses, at times, language that is no longer acceptable nowadays. It has some off-color jokes which feel too offensive for their humor value.

That said, it does feel like Ramachadran is not doing this out of bigotry. Though his discussion of LGBT and mental health issues does not use modern sensitivie language, throughout reading it, I perceived him as compassionate and caring. Language changes, and the language in this book did not age well.

I do not know how the ideas in this book changed. I am not a (literal) brain scientist. But at the very least, it is a great inside into the state of knowledge about the brain as of ten years ago.

It would not surprise anyone who has tried to program a computer that the brain has some really weird bugs. Evolution is worse than the least responsible, least principled, software development organization. If a bug does not happen often enough “in production”, if the cost of fixing it is too high, or if there is an ugly, but quick, workaround, evolution is quicker to allow the bug into production than the most aggressive of product managers.

From the inside, though, the brain feels like it makes sense. It feels like it is living in a world, getting sensory input, and making decisions.

In reality, there are five different paths for sensory inputs to affect behavior, none of them necessarily consistent with each other. Some parts of the brain will actively lie to other parts.

A neuroscientist’s job is to figure out how we got here. Ramachadran has been on a quest to find the internal structure of thought, its features and bugs, and how evolution produced it.

When a programmer tries to figure out how a program works, they have a lot of tools at their disposal. They can modify specific parts, even break them intentionally, and observe the behavior. They can attach debuggers and add log statements. They can check the history of the code.

A neuroscientist, especially one specializing in the human brain, is much more constrained. Society has specific laws against modifying parts of the brain and especially against breaking them intentionally. Attaching sensors to the inside of the brain requires complex, dangerous, surgey that is also quite frowned upon. Worse of all, the fatty tissue in the brain fossilizes poorly.

A neuroscientist must cobble together what evidence falls their way, and find compatible theories. The richest source of such evidence, sadly, are damaged brains. Brains can be damaged by both external trauma and internal problems.

A damaged brain reveals a lot about what is required for parts to work. A patient with blindsight can catch balls that they cannot consciously “see”. Different kinds of aphasia, depending on the part of the brain that is damaged, can cause a patient to construct meaningless grammatical sentences or meaningful sentences with grammatical and vocabulary mistakes.

There are other sorts of evidence. Since evolution left us some code-forks that have less ethical and legal issues, experiments on other animals can teach us a lot. We can attach electrodes to the surface of the skull. During some brain surgeries, electrodes are implanted deeper in the brain. The ear canal is close enough to the brain that disturbing it can have an effect. Finally, neurodiversity is a source of brains that work slightly differently, allowing comparing and contrasting.

Ramachadran pieces together all these pieces of evidence into an entertaining narrative that shows how the most complicated structure in our world operates. The chapter connecting the aesthestics of art to the structure of the brain, taking detours through the colonial occupation of India and the brain structure of baby birds, is one of the best examples.

Ramachadran builds a theory of nine universal rules of aesthetics, and explains how each is connected to the brain and its evolution. His position as an Indian immigrant who lived in the UK and the US gives him insight into how different art looks in different traditions, and contextualizes his ability to find universal rules.