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Bruno Dubuc, Patrick Robert, Denis Paquet, and Al Daigen

Monday, 25 April 2022
Our brain: neither hardware nor software, but “liveware”!

This week I’d like to tell you about a book by David Eagleman, entitled Livewired: The Inside Story of the Ever-Changing Brain. This book discusses several subjects related to brain plasticity, which is one of Eagleman’s research areas. In this book, one of Eagleman’s main ideas, which he attempts to conceptualize with the term “livewired”, is that the human brain is a machine that spends its time reconfiguring itself. In contrast, computers are “hardwired” with predefined electronic circuits that run software—computer programs that use this computer hardware to perform mathematical calculations and logic operations. The human mind or human thought has often been erroneously compared to a software program that needs the “hardware” of the human brain to manifest itself. This is a very poor metaphor for many reasons, of which the one cited by Eagleman is not the least.

As he explains, the fine structure of your brain, which is manifested through billions of connections between its neurons, is not fixed. Instead, it varies as you acquire new experiences and learn new things. Every thought you have causes changes in your brain’s overall dynamic activity, which will alter, for example, the efficiency of the synapses (neural connections) involved in this thought. As a result, the “hardware” in your brain is never really the same from one moment to the next! Those changes will be minimal when you simply have a passing thought or memory, but they will be more significant if you experience a traumatic event in childhood, or a moment of great joy with a loved one, or acquire a technical skill through hours and hours of practice. And this is what Eagleman is trying to get at with his coined term “livewired”.

That said, not all parts of the brain have the same degree of plasticity. The primary visual cortex, for example, is highly plastic in the early years of life, as it learns how to make sense of visual patterns. But once it has done so, it will have less need to alter its neural connections in future.

Another important point that Eagleman makes is that the plasticity of the brain’s synapses is not the only source of its ability to change and to make its circuits more efficient. Your synapses change in size, shape and number as you learn things over periods measured in minutes, hours or days. But many other phenomena also come into play, on shorter and longer time scales. In just a few seconds, simple changes can take place in the receptor molecules to which neurotransmitters released into the synapses bind. Over longer periods, of weeks or months, changes can occur in the expression of the genes that code for these receptors or for other proteins involved in synaptic transmission.

To sum all these ideas up, Eagleman compares the human brain to a city. Some changes are happening very rapidly all the time—people walking by, cars driving along. Others take place more slowly: trees are planted, curb extensions are built to make intersections safer, two-way streets are made into one-way streets to calm traffic. Other changes are slower still: old buildings or bridges are demolished to make way for new ones, new subway stations are built. And over a few decades or centuries, the routes of the streets and even the paths of the streams that flow through the city will be altered.

From the Simple to the Complex | Comments Closed

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