Suzana Herculano-Houzel

First Principles: Neuronal circuits are directional

Electric fields spread wherever a current can be physically carried, for instance along paths that are called circuits. In theory, because electric fields spread omnidirectionally, electrical circuits are non-directional, and changes in charges are propagated along all available wires – unless a gating mechanism is in place. In the nervous system, in contrast, the circuits formed by neurons are directional by way…...

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First Principles: Glial cells isolate, support, and regulate neurons

If nervous systems are distribution networks that transport signals, then their functional units are the neurons: the smallest entity that produces signals, carries them rapidly over long distances, and passes them along to other units. Nervous systems are however not made entirely of neurons: they include vascular and glial cells, and couldn’t possibly function without these non-neuronal cells…....

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Evolution is a story told in retrospect – like the stock exchange

Live long enough to leave descendants before you expire, and there will be a next generation of your kind. If the next generation keeps at it, and the next next generation does too, and the following generations keep that up as the Earth changes around you, then you make it. And like the stock exchange,…...

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First Principles: Nervous systems are networks made of excitable, asymmetrical, SELF-ADJUSTING cells: neurons

Nervous systems are, at their core, heterogeneous networks formed by neurons, connected end-to-end. Three fundamental properties of neurons make nervous systems unique amongst other bodily systems. First, neurons are recharging, excitable batteries, capable of undergoing changes in their membrane voltage that can be communicated to other neurons. That change is referred to as neuronal activity, and the fact that it can be communicated makes…...

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The reality of psychosomatic stress

How annoying it is to hear from others that a problem you feel on your skin is “just in your head”. It’s good that science has freed us from other people’s beliefs, including this one: health problems that are “just psychosomatic”. Well, they’re so real that even rats suffer the effects of stress. What kind […]

You are not a certain way IN ORDER TO do anything; You can do whatever you do BECAUSE you are a certain way

Darwin was really great, but man, have we abused his legacy. Adaptation (as in “the elephant trunk is adapted to drink water without moving a very heavy head”, or “cats’ eyes are adapted to see at night”) is a pretty handy concept to explain what organisms DO, but the concept implies that organisms BECAME a…...

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First Principles: Nervous systems are distribution networks that transport signals

As a rule of thumb, if a living creature is visible to the naked eye, it is because it is endowed with distribution networks – or it would not be viable if its life depended on diffusion, the random movement of molecules powered by their intrinsic energy. Like a circulatory, respiratory or excretory system, the nervous system is yet another transport system…...

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Observations from an autistic neuroscientist on twitter

When a disability is a superpower Bombastic news to start the new year: it’s been four years since I found out I’m autistic. Please spare me the “nice” or “flattering” comments like “gee, you don’t look it”, or “but you look so normal”. Functioning in the world of normals, or “neurotypicals”, takes a lot of […]

Why did it take me so long to realize I was autistic? Because I am autistic, duh

…and it’s all the more telling that it took me FOUR YEARS after my diagnosis to realize that the reason why I didn’t realize sooner that I was autistic was exactly because I was autistic. Let me explain. Autism is characterized by sensory hyper- OR hyposensitivities. Most commonly, the hypersensitivities are visual/auditory/haptic (fancy for “touch-related”) […]

First Principles: Behavior requires no brain

First things first: this section explores what brains are ultimately about, and how they came to be. What is the relationship between brain and behavior? Is there behavior without a brain? If so, what does having a brain change in the life of an animal? Plenty of life – most of it, actually – does…...

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