Neuroplasticity is not a new discovery

Image from the Wellcome Collection. Click for sourceWe recently discussed how the term ‘neuroplasticity’ is widely used as if it were a precise scientific concept, when, in fact, it is virtually meaningless on its own. Several commenters suggested that while not scientifically meaningful, it serves as a useful reminder that we no longer think the brain is ‘fixed’ as we did ‘about 20 years ago’. This is also part of the neuroplasticity hype, and, as I’ll demonstrate, discussions of neuroplasticity go back as far as the 1800s.

This is not to say that we haven’t discovered new ways in which the brain changes and adapts. But this hasn’t been a sudden discovery, and it hasn’t solely happened in the last few decades. On the contrary, these discoveries have peppered the last century and this knowledge has been slowly accumulating.

So here’s a hastily gathered list of scientific papers from before 1970 in which neuroplasticity was discussed, found with nothing more than Google Scholar and 30 minutes of time:

A 1896 paper from the Journal of Mental Science that discusses cortical plasticity as the basis of insanity, as well as tackling neural regeneration and recovery of function.

A 1897 paper from The American Journal of Psychology that discusses how “intelligence… enables the organism to make better adaptations. Its neural pre-requisite is plasticity”.

A 1932 study from Brain on recovery of function after brain injury.

A recent paper that reviews neuroplasticity in the work of neuroscientist Ramón y Cajal (1852-1934) who argued for fixed circuits but extensive local plasticity both in structure and function.

A 1943 review article from Brain on recovery from three types of nerve injury that discusses regeneration of nerve fibres.

The transcript of the 1950 Royal Society Ferrier Lecture on “Growth and Plasticity in the Nervous System”.

A 1967 paper from Acta Neurologica Scandinavica reviewing findings in sensory plasticity.

I’m sure there are many more examples that you could find for yourselves.

I suspect the neuroplasticity hype was fuelled by two main things: the 1998 discovery that adults humans have a limited ability to regenerate neurons and the growth of functional brain imaging in both science and the media.

In fact, neuron regeneration accounts for very little of our ability to learn and adapt, but after decades of thinking that ‘we are born with all the brain cells we’re ever going to get before we slowly decline’, it perhaps seems very significant to many and is certainly used in that way in popular discourse.

Functional brain imaging scans are often used as ‘visual proof’ that the brain changes. In reality, neuroimaging, almost by definition, relies on mechanisms that we must at least broadly understand already. But as a tool in popular discourse, it has increasingly come to stand for the brain’s flexibility.

I’m also interested by the fact that ‘neuroplasticity’ is often used in two seemingly contradictory ways.

The first is that it highlights ‘hidden potential’, the second that it highlights ‘hidden vulnerability’. These in themselves are not contradictory but often the message is that ‘we now know that your behaviour is now more susceptible to change than before’ but with an implicit message that once the change has taken place it is more permanent than before. Hence the additional risk or benefit. After all, your brain has changed, right?

To be clear, I am not suggesting that the brain is not flexible or that the discoveries about how the brain changes are not important. It’s simply that neuroplasticity has become a rhetorical device that, in itself, tells us nothing without further explanation.

All neuroscience is the science of how the brain changes and if you’re not being told exactly how this change is taking place, someone is likely wasting your time or trying to pull the wool over your eyes.

Link to previous Mind Hacks piece on neuroplasticity hype.

7 Comments

  1. Posted July 6, 2010 at 8:47 pm | Permalink

    Hey Vaughan,
    I’d always thought that Elizabeth Gould had discovered human adult neurogenesis in 1997:
    http://weblamp.princeton.edu/~psych/psychology/research/gould/publications.php
    (but it turns out that her 97 paper refers to neurogenesis in the brains of tree shrews!)
    I think that neurogenesis might be quite important in terms of our ability to learn and adapt though. Consider the fact that there is hippocampal atrophy in the hippocampus in depression for example (which I suspect may be a biological correlate with difficulty in accepting harsh emotional events and moving on from them by forming new memories). Hippocampal neurogenesis is increased by exercise and antidepressant medication, which suggests this is a possible mechanism of causal efficacy of these methods in treating depression.
    I think the real reason for the “plasticity” hype in the media was a previous misconception that any brain area related to an behaviour implied that this behaviour was “hard wired” (another term I hate to hear over-used). The “plasticity” hype is a recognition that the brain rearranges itself according to things we have learned, and that many mental abilities we might have previously considered to be “hard wired” are in fact amenable to change.

  2. Neuroconscience
    Posted July 7, 2010 at 3:11 am | Permalink

    My first comment here! Vaughan, you’ve done a great job with this post. In the first month of my PhD, my supervisor actually handed me a then in-review history of neuroscience paper arguing basically the same thing, with one important tweak. As you highlight, it is true that neuroplasticity has been a topic of a great deal of research for quite a while. Ramon Y Cajal actually stated early in his career that the primary mechanism for learning was likely the plasticity of a single neuron. He later recanted this position, ending his life in line with the anti-plasticity dogma that has pervaded neuroscience for more than a century. For a variety of reasons, the research you highlighted and much more has nearly always failed to find it’s way to acceptance. Although there have been many demonstrations of mammalian adult neuroplasticity, the neuroscientific establishment simply refused to accept these findings into the mainstream.
    I believe this has a lot to do with the highly modernist effort of neuroscience to separate itself from the pseudoscientific endeavors of early psychology, but that’s just conjecture. The important point is that neuroplasticity has been known about for a long time, but it wasn’t until the advent of brain imaging that it finally propelled it’s way into the mainstream of neuroscience. I find it really ironic that many big-name neuroscientists now scoff at the regular stream of MRI/fMRI neuroplasticity papers, usually with the typical remark that ‘well that isn’t interesting, EVERYTHING changes the brain’! So quickly dogma goes from total refusal to trivialization. Anyway, great post!
    One last thought- it’s important to distinguish between levels of analysis and computation. I think that more recent findings regarding the functional plasticity of, for example, visual and auditory cortex, are probably somewhat revolutionary insofar as they appear to challenge a strict localizationist, modular paradigm. It remains an open question whether the kinds of top-down connectivity plasticity we see in fMRI are central computational performance, or function more as epiphenomena.
    TLDR; neuroplasticity isn’t new, but a lack of anti-neuroplasticity dogma is.

  3. Posted July 7, 2010 at 3:21 am | Permalink

    posting again because I totally failed to promote my blog in my last comment. :D

  4. Pedro
    Posted February 17, 2011 at 12:06 am | Permalink

    yep its not new. I read a paper from the 60s that proved it quite extensively. so… not new. but i guess word takes time to get around.

  5. Jett Holland
    Posted June 30, 2011 at 11:13 pm | Permalink

    I would love to get feedback from you all as to how one might apply (if at all) neuroplasticity to behavioral changes necessary to help those who have addition issues. One “New Age” group says that established 12 step programs around the disease of alcoholism are hogwash and if these really non diseased souls would end their quest for “treatment” and embrace; through the application of this non specific science (neuroplasticity) in the cognitive behavioral world, folks that dont really have a disease called alcoholism can be educated into sobriety. I am I lay person so I am here to learn and for feedback. Thank you

    • neurotic ape
      Posted January 23, 2013 at 5:18 pm | Permalink

      Jett, some schools of thought hold that alcoholism is not a disease in itself but a symptom or a coping mechanism of a psychological disorder. There are a number of different psychological disorders that apply here. PTSD is one of them. The thinking is that an individual uses alcohol to give themselves relief from the uncomfortable experiences associated with the underlying disorder. So instead of rewiring the brain to change the behaviour of alcoholism it would be better to “rewire” the underlying disorder that leads to alcoholism. The University of British Columbia has developed a program called Changeways which works to a degree on this premise.

  6. Posted April 4, 2012 at 5:24 pm | Permalink

    Thanks for the history on neuroplasticity. Since it is true why are so many researchers still intent on proving it over and over again? The real question should be how does it occur?
    How does a neuron signal to its neighbor that it needs help? And why would a neuron drop what it currently knows to take on new functionality? This should be fairly easy to figure out, you can use nanowires to listen in on single neurons or lay a grid across the cortex to listen in.
    I see two possibilities, do you believe in good or evil neurons?
    1. One neuron calls for help to neighboring neurons and they altruistically go to help.
    2. One neuron sends out signals that wipe functionality from neighboring neurons and instructs them to copy the sending message.


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