Inhibition and Excitation: the Yin and Yang of the Brain

Do excitatory and inhibitory neurons make binary logic in the brain?

Not really. But it’s a good question because we learn a lot when we try to answer it.

First, we have to clarify what the words ‘excitatory’ and ‘inhibitory’ mean.

  • Excitation is the process by which a neuron’s membrane potential (or voltage) increases. If excitation is sufficient, a neuron will produce an action potential.
  • Inhibition is the process by y which a neuron’s membrane potential (or voltage) decreases. If a neuron is already firing, then if it receives enough inhibition, it will stop firing.

So the statement “If some neurons are excitatory meaning they will fire and some inhibitory meaning they won’t” is not quite right. All neurons, whether excitatory or inhibitory, can fire, but only if they receive adequate excitation. If an inhibitory neuron fires, it can reduce the voltage of other neurons, whether they are excitatory or inhibitory. Excitation is the accelerator for all neurons. Inhibition is the brake for all neurons.

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Dopamine is not the “feel good” molecule (and the very concept of a feel good molecule is meaningless)

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Dopamine is not the feel good molecule or the basis of pleasure. The idea that any molecule considered in isolation could be the basis of a subjective experience is basically nonsense.

For people who can’t really reason through this idea, there is plenty of experimental evidence showing the complexity of each and every “celebrity” neurochemical — dopamine, serotonin, oxytocin, and so on.

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In what format is information stored in the brain?

I was asked this question on Quora.

We don’t really know. But as one of my professors once said half-jokingly, “the brain is a bag of tricks”. There is no reason to assume that all brain regions use the same coding scheme.

Here are some basic concepts that guide how neuroscientists think about information in the brain:

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What is neuroplasticity?

I was asked this question on Quora:

Can you explain to a layman what neuroplasticity entails?

Neuroplasticity is the umbrella term for all of the brain’s mechanisms for learning and memory.

Since the average layperson already knows about learning and memory, I’m not sure whether there are any interesting implications.

Unless of course you are surprised that the brain is involved in learning and memory. Then the implications are vast. 🙂

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Is a memory a bunch of atoms? And does this mean we can transfer exact memories?

I was asked the following question on Quora.

Are specific memories just arrangements of atoms in our brains? Could you put certain molecules in someones head and give them an exact memory that you had?

Short answer: No.


Modern science has shown that every thing is an arrangement of atoms: neurons, apples, tables, rockets, asteroids, aardvarks… they are all made up of atoms.

The question now is this: is a memory a thing?

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No New Neurons? No Problem!

This answer was written in response to the following Quora question:

New research has found no neurogenesis in human adults, could this mean there is none or could it mean that neural stem cells are undetectable with the used techniques? What are your thoughts on this?

It’s good that you’re thinking of such things, since that is exactly what researchers themselves have to do, and what reviewers do. In order to show that the method works, there have to be adequate controls as part of the experiment.

And this is in fact the case. The paper would not have been published without controls.

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Why can’t we perceive cells? Or atoms?

I was asked the following question on Quora:

Why can’t we see, touch, hear and smell on a cellular level? And what happens if we can?

Here’s what I wrote:

Essentially, we perceive the visible world in the way that we do because of our overall size, the shape of our eyes, and the sizes of objects in the world that are relevant to our voluntary behavior.

This question might seem silly, but a closely related question can serve as a springboard for us to think very deeply about physical scale, and how it relates to biological life and to the very concept of a scientific law.


But first lets deal with the basic question.

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