Neuroplasticity doesn’t just mean brain change. It captures the unique kind of change – self-directed and self-perpetuating – that is fundamental to how the brain operates and necessary to the brain’s capacity to learn, to remember, and to shift perspectives. It describes how the fibres connecting brain cells to each other sprout, spread, germinate, retract, and vanish, like vines in a jungle or ivy on a garden wall. It is this plant-like character that allows the brain to restructure itself, naturally, from before birth until the moment of death. All of which is influenced by supplies of nutrients and other molecules, blood flow, physical space limitations, and most of all the relentless brunt of the environment – the world – with which the brain is intimately entrained.
This understanding of brain change has infused neuroscience for decades, and in areas that overlap with brain science, such as developmental psychology, it has been around for over a century. But in his new book The Brain’s Way of Healing, Canadian psychiatrist Norman Doidge uses the term neuroplasticity to mean something more specific: the capability of the brain to restructure itself in response to dysfunction, whether that dysfunction is a product of disease or trauma, as with multiple sclerosis and stroke, or a result of childhood anomalies that lead to ongoing difficulties, such as blindness or autism.
Doidge’s revised definition derives from an interplay between advances in technology and advances in conceptualization, cultivated by a new breed of interventionists he calls neuroplasticians. Throughout its history, neuroscience has advanced through the same sort of tradeoff between new tools and new insights. What’s different now is that our understanding of the brain has crossed a threshold: we can begin to offer effective, targeted treatment to those whose brains aren’t working as they should – a new field coming to be known as guided neuroplasticity.
In this book Doidge continues the chronicle he began in The Brain that Changes Itself. He tells the stories of the pioneers who are pushing the neuroplasticity envelope, the scientists, thinkers, tinkerers, and practitioners who’ve discovered new and better ways to nudge the brain into new patterns of growth. As he emphasizes throughout, the mission of these pioneers is not to change the brain directly, but to perturb it, entice it, or soothe it – through exercises, lasers, filtered sound, or clever visualizations – so that it will begin to change itself, grow new synaptic connections, in a direction that restores function and reduces stress.
And, yes, the brain really does change itself – that’s its principal talent. So the neuroplastician’s job is to oversee and guide, not compel or command, this unique capability.
Doidge’s first book laid the groundwork for understanding guided neuroplasticity. There he introduced unfamiliar concepts such as the versatility of brain regions to do multiple tasks, take over functions from other damaged regions, regrow synapses, and so forth. In this second book, he refines and extends these concepts through a mixture of narrative and scientific explanation.
We learn about a Parkinson’s patient who overcame most of his symptoms by training himself to be conscious of movements that had always been automatic. We discover that lasers can deliver light that restores the health of damaged nerve cells or tunes and soothes inflammations likely to result in physical or cognitive decline. I was intrigued to learn that exercises developed by Moshe Feldenkrais for movement and posture problems could reverse the devastation caused by a stroke or incomplete fetal brain development. And, when mixed with meditation techniques, could restore sight to a man plummeting toward blindness. Through Doidge’s intimate storytelling, we feel we’re in the lab, watching as a tiny grid of stimulators placed on a woman’s tongue reverses the terrible trajectory of multiple sclerosis. This technology was introduced in the previous book, but now we learn of its further development by a team of empathic engineers treating brain-injured people who are losing the ability to stand, walk, speak, sing, or even swallow. These are radically different benefits from a single technology, revealing a general principle of neuroplastic healing.
To discover general principles is vitally important, so Doidge tries to synthesize his burgeoning cluster of facts, stories, hunches, and insights into a model. He moves from the gleeful discovery of new wonders to a sober investigation of causes and effects. Both scientists and practitioners need models – scientists to cement and extend their knowledge, practitioners to identity reliable methods for improving lives.
Toward this end, Doidge makes real progress delimiting the different phases of neuroplastic healing: bringing brain cells back to health: this captures how low-intensity lasers reduce inflammation and scarring following brain surgery, as detailed in one gut-wrenching case history; stimulating neurons starved of inputs because of damage or disuse due to strokes or trauma; helping the traumatized brain modulate itself – to find a balance between over- and under-activation; helping the overwhelmed brain relax, allowing vision to resurface in a man too stressed to see; and encouraging the differentiation of inputs chaotically thrown together, allowing a brain-damaged child to crawl for the first time. Doidge’s parsing of neuroplastic interventions makes sense and offers a useful taxonomy of change.
Yet the challenge of consolidating and systematizing a new field leaves a few rough edges. First, how should we deal with the boundary between speculation and scientific innovation? As a researcher, I know how hard it is to get new ideas published in respectable journals, and new ideas –especially those that can relieve suffering – shouldn’t have to grow old before they’re branded legitimate. Still, the technique outlined in the first chapter, for soothing chronic pain by modifying visual images of one’s brain, seemed implausible to me, especially since the founder of the technique stopped publishing around the time he first introduced it. Second, how should we differentiate neuroplastic change from more general mechanisms of healing? Doidge uses the phrase neuroplastic change too often. Not all brain change embodies the self-modification of neural networks, which is what most of us mean by neuroplasticity. The use of laser light to reduce inflammation of and facilitate cell growth may be a marvelous innovation but one that pertains to healing in general.
I wonder if Doidge’s conceptualization – and his arrival at a more rigorous model – would be improved by a closer acquaintance with developmental psychology. As a psychiatrist, Doidge finds neuroplasticity to be an astonishing innovation, but developmentalists have long assumed that brains are designed to change. The field of cognitive development is founded on the assumption of massive changes in brain wiring, and the primary neuroplastician is considered the child’s environment. If neuroplasticity were contextualized within a developmental framework, certain problems might disappear entirely. For example, Doidge assumes that the idea of localized functions (i.e. specialized brain regions) is incompatible with his emphasis on plastic change. But developmental neuroscience shows how specialized regions require plasticity. And Doidge equates learning with the growth of new synapses. But developmental science teaches us that learning relies on synaptic pruning at least as much.
I’d like to see more substantive dialogue between medicine and developmental science, but the doctor’s first goal is to fix whatever’s gone wrong, and The Brain’s Way of Healing portrays compelling new strategies for doing just that. Neuroplastic healing is a remarkable innovation that fuses scientific insight, intellectual courage, and a heartfelt commitment to ease suffering. For that Dr. Doidge is to be congratulated.
Marc Lewis is the featured speaker at The LRC Presents… Why Addiction is not a Disease on October 20th. For more information and tickets please visit reviewcanada.ca/events.