A Clockwork Orange? (A brief musing on the concept of a neural “code”)

I was asked this question on Quora:

Are there many layers of neural codes from the human retina to the optic nerve and the optic nerve to the brain, or are they essentially same signals relayed?

Here’s how I responded:

Here’s a question: in a system composed of clockwork, is there a “code”?

I ask this because I find that the “code” metaphor is often misleading when thinking about biology. Codes are composed of symbols. But it is not clear that neurons communicate using symbols.

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“Are thoughts just a bunch of electrical and chemical signals being tossed around inside the brain, or is there more to it than that?”

“In our world,” said Eustace, “a star is a huge ball of flaming gas.”

“Even in your world, my son, that is not what a star is but only what it is made of…”

The Voyage of the Dawn Treader, CS Lewis

I really like the quote above, which is from the Chronicles of Narnia. It raises a neat little metaphysical question:

Why do we assume that what a thing is made up of is what a thing is?

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Yanny or Laurel? A perspective from the science of mind and brain

I really like the Yanny versus Laurel meme, which exploded yesterday. It helps illustrate some key points about human perception:

  1. In some situations people can differ wildly in their experience of low-level perception.
  2. Active top-down expectations (and other, weirder processes) have a strong effect on low-level perception.

So basically, it’s an auditory version of #ThatDress.

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What are emotions?

What indeed?

My research is on cognitive-emotional interaction, so I suppose I am qualified to answer this question. 🙂

But my answer cannot be the answer, since there is actually no consensus among scientists concerning the definition of emotions.

[Illustration of grief from Charles Darwin’s book The Expression of the Emotions in Man and Animals.]

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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)

220px-dopamine_3d_ball

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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