Friday, September 27, 2013

Now we know the brain is "neuroplastic"... in the 19th century

Until recently, scientists believed our brains were fixed, their circuits formed and finalised in childhood, or "hardwired". Now we know the brain is "neuroplastic", and not only can it change, but that it works by changing its structure in response to repeated mental experience.

-Norman Doidge, M.D. (2013). Brain scans of porn addicts: what's wrong with this picture?


Wow! I never knew that! You mean the brain can actually learn? And it changes with experience? Really?? Thank you, Norman Doidge, for that brilliant insight, and for many other gems in your wonderful Comment is Free piece on porn addiction in the Guardian.

Let's see what physicians and psychologists of yesteryear have to say about these newly discovered "neuroplastic" brains.


Here it may be asked whether the organs [of the brain] increase by exercise? This may certainly happen in the brain as well as in the muscles; nay, it seems more than probable, because the blood is carried in greater abundance to the parts which are excited, and nutrition is performed by the blood. In order however, to be able to answer this question positively, we ought to observe the same persons when exercised and when not exercised; or at least observe many persons who are, and many others who are not, exercised during all periods of life.

-J.G. Spurzheim (1815). The physiognomical system of Drs. Gall and Spurzheim; founded on an anatomical and physiological examination of the nervous system in general, and of the brain in particular; and indicating the dispositions and manifestations of the mind.


The question is not whether neural events change the status of the tissue in which they occur. The only question which may still be debated is: whether such changes as do undoubtedly occur have the permanence and those other properties which we must attribute to memory-traces. According to our present knowledge the primary effect which nerve impulses produce in ganglionic layers is chemical activity. . .

-Wolfgang Köhler (1938), The Place Of Value In A World Of Facts.

These quotes were taken from a 1964 review paper by Edward L. Bennett, Marian C. Diamond, David Krech, and Mark R. Rosenzweig. The title? Chemical and Anatomical Plasticity of Brain.

Changes in brain through experience, demanded by learning theories, are found in experiments with rats.



Fig. 1 (Bennett et al., 1964). Animals in Environmental Complexity and Training Cage.


The authors compared the brains of rats exposed to complex, enriched environments to those housed in isolated cages. They found increases in cortical thickness, increases in cortical tissue weight (not related to overall brain or body size), and in increases acetylcholinesterase activity in rats who had lived in the fun and social cages. The project was launched 60 years ago, in 1953... so it's a bit disingenuous for Dr. to call neuroplasticity a "recent" discovery.

Furthermore, Doidge's Freudian interpretation of porn would be rather quaint, if it weren't so disturbing:
Porn sites are also filled with the complexes Freud described: "Milf" ("mothers I'd like to fuck") sites show us the Oedipus complex is alive; spanking sites sexualise a childhood trauma; and many other oral and anal fixations. All these features indicate that porn's dirty little secret is that what distinguishes "adult sites" is how "infantile," they are, in terms how much power they derive from our infantile complexes and forms of sexuality and aggression. Porn doesn't "cause" these complexes, but it can strengthen them, by wiring them into the reward system.

And of course, reward = dopamine. And we all know that "dopamine is the ultimate feminist chemical in the female brain."  Oh wait...

Guess Doidge hasn't watched any feminist porn.


Further Reading

Feminist Dopamine, Conscious Vaginas, and the Goddess Array

Is There Any Evidence for the "Porn-Addicted Brain"?

Neuroplasticity is a dirty word

Neuroplasticity is not a new discovery


Reference

BENNETT EL, DIAMOND MC, KRECH D, & ROSENZWEIG MR (1964). CHEMICAL AND ANATOMICAL PLASTICITY of BRAIN. Science, 146 (3644), 610-9 PMID: 14191699




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8 Comments:

At September 27, 2013 2:22 AM, Blogger Thomas Raab said...

Not to mention the "Plastizitätslehre" of Albrecht Bethe (1872-1954): „Jede Erregung, welche dem Nervensystem zufließt, ist imstande eine geringe Veränderung auf dem ganzen Wege zu hinterlassen, ... kehrt derselbe Reiz ausgehend von demselben Objekt immer wieder, so hinterläßt er auf seinem Wege im Nervensystem eine merkliche Änderung derart, daß beim Wiederkehren desselben Reizes die Wahrnehmung sehr viel leichter anspricht als zuvor". (1898)

 
At September 27, 2013 1:42 PM, Anonymous Anonymous said...

What was the point of your post, anyhow? To take a swipe at Doidge? His book has been around for a while, you know. Maybe ppset that the article was about porn, and that studies are being done that find porn addiction could indeed exist?

 
At September 27, 2013 2:49 PM, Blogger The Neurocritic said...

Thomas Raab - Thanks very much for the additional 19th century quote.

Anonymous - The major point of the post is to correct the record on neuroplasticity. Doidge continues to ignore the history of neuroscience. Yes, I know his book has been around for a while (since 2007), yet he repeats the same tired "Until recently, scientists believed our brains were fixed..." claim. I linked to two excellent Mind Hacks posts which discuss in depth these bizarre ahistorical statements about neuroplasticity (and also that pop notions about "neuroplasticity" are rather vague).

The functional neuroanatomical bases for behavioral addictions, and whether overconsumption of porn can be considered an addiction (or a compulsion or an impulse control disorder), is beyond the scope of the post. The article's claim for a physical change in the brain's "reward centre" is based on an unpublished study. Images from this study appeared in British tabloid, but Neuroskeptic has pointed out that the activations in this study have an usual square shape.

Finally, I believe Doidge has opened himself up to rebuttal of his Freudian claims about porn. Comment is free, after all.

 
At September 27, 2013 4:35 PM, Anonymous Anonymous said...

It's me again.
Yeah I agree with you on the Freudian part of the article. As far as the Cambridge study - it had 19 age/gender matched controls, and there was a significant difference between the two groups. The usual "square shape" doesn't cut it as a rebuttal.

Neuroskeptic simply dislikes the idea of behavioral addictions.

 
At September 27, 2013 5:43 PM, Blogger The Neurocritic said...

Thanks for stopping in again. I'll look forward to reading the paper.

I don't doubt that extremely excessive porn use can be problematic in some people (like many things in excess), and that there's some neural correlate involved (as there is for everything). To say "'Porn addicts' show same brain activity as alcoholics and drug addicts" (as did the Mail Online) seems misleading though. Are the so-called behavioral addictions actually 'addictions' or are they more like compulsions and/or impulse control disorders? Will fMRI studies be able to shed light on the distinction? Why do different people get hooked on different drugs or activities, while other heavy users do not?

Then there's the social implications, or rather the moralistic misuse of neuroscience data to further some agenda, like the incredibly hypocritical Mail Online. On the same page where they rail against obscenity, blathering, "The Daily Mail has vigorously campaigned for an automatic block on online adult videos and images, which would mean over-18s having to opt in to be able to see them." -- we learn that Adele Exarchopoulos has bared her soul in graphic nude sex scenes.

Researchers who work in this area should be acutely aware of the use and misuse of their data, and how the research is covered in the media. Faulty interpretations seem like the rule, rather than the exception.

 
At September 27, 2013 5:49 PM, Blogger The Neurocritic said...

Oops, I meant an UNUSUAL square shape for the brain activations in the unpublished study...

 
At October 03, 2013 8:10 AM, Blogger TheCellularScale said...

I hate when I read "until recently, scientists thought..." statements when my first thought is that I've never met a scientist who thought that. It's especially awful when the textbooks I've learned from don't claim that. If it's already correct in a textbook, then scientists did not "recently think" the opposite.

 
At October 06, 2013 5:06 PM, Blogger The Neurocritic said...

Such statements are a way to sell a book or product or service as more novel than it is. Even graduate students in the 1960s were learning about the rat studies.

 

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