Sunday, August 31, 2014

Whitman Was Not a Neuroscientist


Do I contradict myself?
Very well then I contradict myself,
(I am large, I contain multitudes.)

-Walt Whitman, "Song of Myself" (from Leaves of Grass)


Science is the search for objective truth based on physical laws of the universe. Scientific theories try to explain the consistent and predictable behavior of natural systems. They are generally reductionist, meaning that complex systems are reduced to simpler and more fundamental elements. The principles of physics, for instance, are expressed in the form of beautiful equations that are the envy of the softer sciences.




The enterprise of explaining how human brains produce complex thought (or how any nervous system produces observable behavior, for that matter) is notably lacking in the realm of grand unifying theories, a topic of discussion recently in the New York Times: “What would a good theory of the brain actually look like?”

But the “search for a general ‘bridging theory’ may be a fruitless one” – like Awaiting a theory of neural weather. The “bridge, some way of connecting two separate scientific languages — those of neuroscience and psychology” may not exist.

I'm not sure why the question, “What would a good theory of the brain actually look like?” was even posed in the first place (or posed in that fashion, like a single theory should be expected to explain “the brain”). Adam Calhoun asked what I think is a more productive question:  Are these the equations of the brain?




English theoretical physicist Paul Dirac said, “A physical law must possess mathematical beauty.” Are these equations beautiful? 1

I cannot say. I am neither physicist nor mathematician. I traffic in matters less sublime. All I can do here is to include this citation from neuroaesthetician Semir Zeki and colleagues (2014), who reported that the neural correlates of perceiving mathematical beauty are the same as those that appreciate fine visual art. To be more precise, ratings of mathematical beauty were parametrically related to BOLD signal in field A1 of the medial orbitofrontal cortex, a part of the brain involved in  emotion, reward, and decision making.

At the phenomenological level of subjective experience, this knowledge of brain activity does no more to explain what it's like to behold Dirac’s wave equation than the Temporal Difference Learning equation describes what it's like to feel this emotionally rewarding experience — the Nagelian conundrum of qualia.

We sail the arctic sea, it is plenty light enough,
Through the clear atmosphere I stretch around on the wonderful beauty,
The enormous masses of ice pass me and I pass them, the scenery is plain in all directions,

-Whitman, ibid


What does any of this have to do with Walt Whitman? Yesterday I saw a pair of articles that encapsulate Whitman's principle of “I am large, I contain multitudes” when applied to neuroimaging studies of unclear psychological phenomena.

“The results obtained suggest that dysfunctional [lower] activation of the SMA [supplementary motor area] for response inhibition is one of the candidate mechanisms of IGD [internet gaming disorder].”

“...adults with IGD have ... greater activation of the fronto-striatal network in order to maintain their response inhibition performance.”

The first study claimed that reduced recruitment of the SMA (a motor control area) could be responsible for the impulsivity seen in individuals with internet gaming disorder (an actual “Condition for Further Study” in the DSM-5). The second study suggested that enhanced activity in the fronto-striatal network (implicated in motor control as well, but also in reward) was necessary for IGD participants to maintain the same restrained behavior as control participants.

So which is it?

These results are not consistent. They contradict themselves. This is not unusual. The greater problem is that the discrepant results were reported by the same lab, each without any reference to the other study.

Do I contradict myself?
Very well then I contradict myself


This world view makes for profound and transcendent poetry, but unacknowledged internal contradiction should not be adopted as the optimum path to scientific enlightenment.

Empirical falsification, on the other hand, is a staple of the scientific method.

I don't mean to single out this particular lab (which is why I did not include in-line citations), but this is a pet peeve of mine, along with a refusal to acknowledge any and all evidence that refutes one's signature theory. There's no shame in obtaining inconsistent results (or at least, there shouldn't be). But at least say so, try to come up with a plausible explanation, and do more experiments.


Clear and sweet is my soul, and clear and sweet is all that is not my soul.

Lack one lacks both, and the unseen is proved by the seen,
Till that becomes unseen and receives proof in its turn.

-Whitman, ibid



Additional Reading

Awaiting a theory of neural weather

Song of Myself

The Beauty of Brain Science

The Trouble With Brain Science


Footnote

1 Do the equations of the brain give insights into its fundamental structure and function? Do they have the power to describe the brain? In the 1993 Dirac Lecture (Freeman, 1994), physicist Daniel Z. Freeman said:
Many quotations remind us of Dirac’s ideas about the beauty of fundamental physical laws. For example, on a blackboard at the University of Moscow where visitors are asked to write a short statement for posterity, Dirac wrote: “A physical law must possess mathematical beauty.” Elsewhere he wrote: “A great deal of my work is just playing with equations and seeing what they give.”. And finally there is the famous statement: “It is more important for our equations to be beautiful than to have them fit experiment.” This last statement is more extreme than I can accept. Nevertheless, as theoretical physicists we have been privileged to encounter in our education and in our research equations which have simplicity and beauty and also the power to describe the real world. It is this privilege that makes scientific life worth living, and it is this and its close association with Dirac that suggested the title for this talk [SOME BEAUTIFUL EQUATIONS OF MATHEMATICAL PHYSICS].


References

Chen, C., Huang, M., Yen, J., Chen, C., Liu, G., Yen, C., & Ko, C. (2014). Brain correlates of response inhibition in Internet gaming disorder. Psychiatry and Clinical Neurosciences DOI: 10.1111/pcn.12224

Daniel Z. Freedman (1994). Some beautiful equations of mathematical physics. CERN-TH.7367/94 arXiv: hep-th/9408175v1

Ko, C., Hsieh, T., Chen, C., Yen, C., Chen, C., Yen, J., Wang, P., & Liu, G. (2014). Altered brain activation during response inhibition and error processing in subjects with Internet gaming disorder: a functional magnetic imaging study. European Archives of Psychiatry and Clinical Neuroscience DOI: 10.1007/s00406-013-0483-3

Zeki, S., Romaya, J., Benincasa, D., & Atiyah, M. (2014). The experience of mathematical beauty and its neural correlates. Frontiers in Human Neuroscience, 8 DOI: 10.3389/fnhum.2014.00068



I bequeath myself to the dirt to grow from the grass I love,
If you want me again look for me under your boot-soles.

You will hardly know who I am or what I mean,
But I shall be good health to you nevertheless,
And filter and fibre your blood.

Failing to fetch me at first keep encouraged,
Missing me one place search another,
I stop somewhere waiting for you

-Whitman, ibid

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4 Comments:

At September 01, 2014 4:34 AM, Anonymous Peter B. Reiner said...

I too am not sure what a theory of the brain would look like, but we will know we have it when people no longer say things like "field A1 of the medial orbitofrontal cortex, a part of the brain in emotion, reward, and decision making." No offence to the author, but that the best we can do at the present time is to say that a part of the brain is "involved" in something - no less three somethings - is a reflection of how rudimentary our understanding still is. When we can move beyond this sort of colour-by-numbers view of the brain, we will have made some progress towards a proper theory of brain function.

 
At September 01, 2014 10:17 AM, Blogger Right Mind Matters said...

Kudos, Neurocritic, for using poetry to explain neuroscience in terms that thrill instead of deaden the soul.

 
At September 03, 2014 11:04 AM, Blogger The Neurocritic said...

Peter B. Reiner - Well then, "a part of the brain involved in emotion, reward, and decision making" is a nice rhetoric device...

Right Mind Matters - Thank you, I appreciate it.

 
At September 03, 2014 4:24 PM, Blogger The Neurocritic said...

Oops, I meant a nice rhetorical device...

 

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