How many minds can one organism have? (Answer: One.)

I was asked this question on Quora:

Do the two halves of the brain have wills of their own? Can they dislike each other or fight?

Here’s my answer:

It’s very difficult to define what exactly the will is in neuroscientific terms. It seems best to reserve this word for the whole organism, rather than some part of it.

Some philosophers would say that attributing will to some sub-component of an organism is an example of the “mereological fallacy”. It’s like saying the stomach eats, or the brain thinks, or the legs walk. We use these kinds of phrases as a kind of poetic shorthand, but only a complete organism can be said to eat, think, or walk.

In the case of the two hemispheres, we also know that the left brain right brain story — that one is “rational” and the other “holistic/artistic” — is wildly misguided. Some neural processes are lateralized, but most normal tasks that humans perform require close integration and communication between the hemispheres.

But we do have to make sense of a common experience — being “in two minds” about something. Most people know what it is like to be in a conflicted state — multiple goals or biases seem to be tugging at us. Clearly decision-making involves a sort of “parliamant” in the brain, in which multiple vested interests vie to enact legislation that suits them. 🙂

But the parliament metaphor should not be taken too seriously. There is little to be gained in anthropomorphizing neurons or groups of neurons. Neural ensembles might sometimes seem to behave as if they have a will, but that idea will not really help us understand decision-making, or the subjective feeling of having a will.

So brain areas don’t have likes or dislikes — organisms do, and brain areas mediate the processes by which these likes and disliked become manifest.

For more on the problems with anthropomorphizing neural processes, see these two essays I wrote:

Persons all the way down: On viewing the scientific conception of the self from the inside out | 3 Quarks Daily (This essay is partly a gentle critique of the Pixar movie Inside Out.)

Me and My Brain: What the “Double-Subject Fallacy” reveals about contemporary conceptions of the Self | 3 Quarks Daily (This essay explores the tendency of people, including neuroscientists, to think of the brain is a separate agent from the person as a whole.)

I admit that it is often fun to anthropomorphize neurons, which is what I do in the essay below. I paint a picture of a neural city and a neural economy, complete with start-ups and investors. 🙂

Be Careful What You Wish For: Some Wild Speculation on Goodhart’s Law and its Manifestations in the Brain | 3 Quarks Daily


Further reading

Yohan John’s answer to Is the left brain and right brain concept a myth, or is it true?

Yohan John’s answer to What happens to consciousness when the brain’s two cerebral hemispheres are disconnected?

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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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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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Are mental disorders the same as brain disorders? Maybe not!

I am currently reading an excellent paper that will be published in Behavioral and Brain Sciences soon. It raises some very important issues with popular conceptions of mental illness.

Brain disorders? Not really… Why network structures block reductionism in psychopathology research

These two figures capture some of the key points:

Here is the abstract:

“In the past decades, reductionism has dominated both research directions and funding policies in clinical psychology and psychiatry. However, the intense search for the biological basis of mental disorders has not resulted in conclusive reductionist explanations of psychopathology. Recently, network models have been proposed as an alternative framework for the analysis of mental disorders, in which mental disorders arise from the causal interplay between symptoms. In this paper, we show that this conceptualization can help understand why reductionist approaches in psychiatry and clinical psychology are on the wrong track. First, symptom networks preclude the identification of a common cause of symptomatology with a neurobiological condition, because in symptom networks there is no such common cause. Second, symptom network relations depend on the content of mental states and as such feature intentionality. Third, the strength of network relations is highly likely to partially depend on cultural and historical contexts as well as external mechanisms in the environment. Taken together, these properties suggest that, if mental disorders are indeed networks of causally related symptoms, reductionist accounts cannot achieve the level of success associated with reductionist disease models in modern medicine. As an alternative strategy, we propose to interpret network structures in terms of D. C. Dennett’s (1987) notion of real patterns, and suggest that, instead of being reducible to a biological basis, mental disorders feature biological and psychological factors that are deeply intertwined in feedback loops. This suggests that neither psychological nor biological levels can claim causal or explanatory priority, and that a holistic research strategy is necessary for progress in the study of mental disorders.”

Behavioral and Brain Sciences is one of the premier journals for “big thinking” in cognitive science and neuroscience, so it’s great to see these ideas there.

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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Is the mind a machine?

My latest 3QD essay explores the “mind as machine” metaphor, and metaphors in general.

Putting the “cog” in “cognitive”: on the “mind as machine” metaphor

Here’s an excerpt:

People who study the mind and brain often confront the limits of metaphor. In the essay ‘Brain Metaphor and Brain Theory‘, the vision scientist John Daugman draws our attention to the fact that thinkers throughout history have used the latest material technology as a model for the mind and body. In the Katha Upanishad (which Daugman doesn’t mention), the body is a chariot and the mind is the reins. For the pre-Socratic Greeks, hydraulic metaphors for the psyche were popular: imbalances in the four humors produced particular moods and dispositions. By the 18th and 19th centuries, mechanical metaphors predominated in western thinking: the mind worked like clockwork. The machine metaphor has remained with us in some form or the other since the industrial revolution: for many contemporary scientists and philosophers, the only debate seems to be about what sort of machine the mind really is. Is it an electrical circuit? A cybernetic feedback device? A computing machine that manipulates abstract symbols? Some thinkers so convinced that the mind is a computer that they invite us to abandon the notion that the idea is a metaphor. Daugman quotes the cogntive scientist Zenon Pylyshyn, who claimed that “there is no reason why computation ought to be treated merely as a metaphor for cognition, as opposed to the literal nature of cognition”.

Daugman reacts to this Whiggish attitude with a confession of incredulity that many of us can relate to: “who among us finds any recognizable strand of their personhood or of their experience of others and of the world and its passions, to be significantly illuminated by, or distilled in, the metaphor of computation?.” He concludes his essay with the suggestion that “[w]e should remember than the enthusiastically embraced metaphors of each “new era” can become, like their predecessors, as much the prisonhouse of thought as they at first appeared to represent its liberation.”

Read the rest at 3 Quarks Daily:

Putting the “cog” in “cognitive”: on the “mind as machine” metaphor