Not As Plastic As Described
Jun. 24th, 2014 11:25 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
mtvesselJan 2014
The Brain that Changes Itself - Norman Doidge - Penguin, 2008
* *
My grandfather, who died when I was eight, was a scary man, but it wasn't his fault. Some years before I was born he had an operation to remove a blood clot. There were complications, and he had a stroke that left him unable to speak except in inarticulate groans that only my grandmother could understand. The surgeons also had to remove his leg, and the sight of the pink stump where his knee should have been and the weird contraption of his prosthetic leg were both disturbing and fascinating to my childhood eyes.
I tell this story as a corrective to the ones that are in this book. Like How to Win Friends and Influence People, Doidge relies largely on personal anecdotes to make his triumphalist points about how harnessing neuroplasticity and the "power of positive thinking" can transform lives. But there is a reason why scientists do not admit the experiences of individuals as reasonable evidence for knowledge, which is that they differ. My grandfather was an intelligent man, but after his stroke he never managed to learn to speak again. Brain plasticity only goes so far. Sometimes - usually - the damage is too great.
This important corrective is only indirectly hinted at in this book, though, to be fair, as Doidge develops his theme he does indicate that the reality is more complex than his initial statement of it. He starts by describing the individuals such as Paul Bach-y-Rita and Michael Mezernich who dared to challenge the localizationist orthodoxy that specific mental functions map to specialised areas of the brain. Through bizarre experiments such as a chair that converted pictures into tactile sensations for blind people, they demonstrated that this could not be the whole truth - some brain areas could be co-opted for other functions.
The next chapter however, starts to introduce some qualifications. It describes experiments that show that many forms of learning (such has learning languages) have "windows of plasticity" when habits become ingrained, after which it is difficult to unlearn them. Clearly the brain is plastic, but only in specific circumstances.
Unless, apparently, it is to do with sex. Doidge describes the unusual variety of human sexual behaviour and then goes on to inveigh against pornography, claiming that it puts the brain into an unusually plastic state that leads to addiction (really? So do alcohol, tobacco, cocaine and other addictive drugs also make the brain more plastic?). He doesn't cite any evidence for this theory, instead referring to various examples of sexual addiction that he has treated.
And this is the nub of what is wrong with this book. Doidge is a psychiatrist, a profession which eschews the rigours of double blind trials and careful statistical analysis in favour of the creation of personal narrative. I have no problem with this on an individual basis - we all make up stories to get make sense of our lives, and unless they involve harm to others it doesn't really matter whether they are true or not - but when applied to public policy, they can become toxic. A case in point - Doidge describes and praises a program called Fast ForWord that is intended to help children with language problems by training them to distinguish phonemes and other fast parts of speech, and is now approved as a treatment by the Australian government and others. He cites examples of remarkable improvements in individuals. But a systematic meta-analysis of randomised controlled trials shows no evidence of effectiveness compared with active or untreated control groups.
Now don't get me wrong - neuroplasticity is undoubtedly a thing and learning more about it may lead to effective treatments. Following the "use it or lose it" mantra for mental activity later in life is probably also sensible advice. But judging by this book, it is still too easy to make up just-so stories where neuroplasticity is used as the explanation for any interesting neurological phenomenon from the addictive qualities of porn to phantom limb syndrome to talking cures for depression. Doidge does his subject a disservice by taking such an uncritical approach.
For what it's worth, the current consensus is that a connectionist model, in which basic functions are strongly localized but higher-level functions like object recognition, memory, and language arise from associations of different brain areas, is the most likely to be true. If so, some neuroplasticity - and remarkable recoveries from stroke and other brain-damaging conditions - can be expected. But it's all a matter of chance. Some people will be lucky, like those whose stories are told in this book, and some, like my grandfather, won't.
The Brain that Changes Itself - Norman Doidge - Penguin, 2008
* *
My grandfather, who died when I was eight, was a scary man, but it wasn't his fault. Some years before I was born he had an operation to remove a blood clot. There were complications, and he had a stroke that left him unable to speak except in inarticulate groans that only my grandmother could understand. The surgeons also had to remove his leg, and the sight of the pink stump where his knee should have been and the weird contraption of his prosthetic leg were both disturbing and fascinating to my childhood eyes.
I tell this story as a corrective to the ones that are in this book. Like How to Win Friends and Influence People, Doidge relies largely on personal anecdotes to make his triumphalist points about how harnessing neuroplasticity and the "power of positive thinking" can transform lives. But there is a reason why scientists do not admit the experiences of individuals as reasonable evidence for knowledge, which is that they differ. My grandfather was an intelligent man, but after his stroke he never managed to learn to speak again. Brain plasticity only goes so far. Sometimes - usually - the damage is too great.
This important corrective is only indirectly hinted at in this book, though, to be fair, as Doidge develops his theme he does indicate that the reality is more complex than his initial statement of it. He starts by describing the individuals such as Paul Bach-y-Rita and Michael Mezernich who dared to challenge the localizationist orthodoxy that specific mental functions map to specialised areas of the brain. Through bizarre experiments such as a chair that converted pictures into tactile sensations for blind people, they demonstrated that this could not be the whole truth - some brain areas could be co-opted for other functions.
The next chapter however, starts to introduce some qualifications. It describes experiments that show that many forms of learning (such has learning languages) have "windows of plasticity" when habits become ingrained, after which it is difficult to unlearn them. Clearly the brain is plastic, but only in specific circumstances.
Unless, apparently, it is to do with sex. Doidge describes the unusual variety of human sexual behaviour and then goes on to inveigh against pornography, claiming that it puts the brain into an unusually plastic state that leads to addiction (really? So do alcohol, tobacco, cocaine and other addictive drugs also make the brain more plastic?). He doesn't cite any evidence for this theory, instead referring to various examples of sexual addiction that he has treated.
And this is the nub of what is wrong with this book. Doidge is a psychiatrist, a profession which eschews the rigours of double blind trials and careful statistical analysis in favour of the creation of personal narrative. I have no problem with this on an individual basis - we all make up stories to get make sense of our lives, and unless they involve harm to others it doesn't really matter whether they are true or not - but when applied to public policy, they can become toxic. A case in point - Doidge describes and praises a program called Fast ForWord that is intended to help children with language problems by training them to distinguish phonemes and other fast parts of speech, and is now approved as a treatment by the Australian government and others. He cites examples of remarkable improvements in individuals. But a systematic meta-analysis of randomised controlled trials shows no evidence of effectiveness compared with active or untreated control groups.
Now don't get me wrong - neuroplasticity is undoubtedly a thing and learning more about it may lead to effective treatments. Following the "use it or lose it" mantra for mental activity later in life is probably also sensible advice. But judging by this book, it is still too easy to make up just-so stories where neuroplasticity is used as the explanation for any interesting neurological phenomenon from the addictive qualities of porn to phantom limb syndrome to talking cures for depression. Doidge does his subject a disservice by taking such an uncritical approach.
For what it's worth, the current consensus is that a connectionist model, in which basic functions are strongly localized but higher-level functions like object recognition, memory, and language arise from associations of different brain areas, is the most likely to be true. If so, some neuroplasticity - and remarkable recoveries from stroke and other brain-damaging conditions - can be expected. But it's all a matter of chance. Some people will be lucky, like those whose stories are told in this book, and some, like my grandfather, won't.