Wednesday, May 09, 2007

Can Our Minds Change Our Brains?

By: Michael J. Friedlander

In Sharon Begley's new book, the interface of Western science and Buddhist philosophy provides the context for considering the implications of lifelong neuroplasticity.

In October 2004, Wall Street Journal science editor Sharon Begley attended a meeting in an improbable location on a seemingly equally improbable topic.  At the Dalai Lama’s private compound in Dharamsala, India, leading neuroscientists and Buddhist philosophers met to consider “neuroplasticity.”  The conference was organized by the Mind and Life Institute as part of a series of meetings, beginning in 1987, for brain researchers and Buddhist scholars to share insights into the workings of the mind and brain. The 2004 meeting set out to answer two questions: “Does the brain have the ability to change, and what is the power of the mind to change it?”  

In Train Your Mind, Change Your Brain: How a New Science Reveals Our Extraordinary Potential to Transform Ourselves, Begley reveals the results of that unlikely meeting, while making accessible the rapidly emerging science of neuroplasticity.  Although the title might suggest otherwise, Begley’s book is not a manual on brain exercises or the power of positive thought. Instead, it is a lively, largely scientifically accurate, and eminently readable view into the brain’s capacity for malleability.  Moreover, the book makes it obvious why the two seemingly disparate cultures of neuroscience and Buddhism share a mutual interest, as well as have much to learn from each other.

Neuroplasticity encompasses all of the things that nerve cells can do (or that can be done to them) to change the structure and/or function of the organ in which they are embedded, the brain.  Examples include the brain’s ability to Begley takes readers on a journey through how neuroscience’s view of the brain’s capacity for functional reorganization has evolved. add new nerve cells (neurogenesis), change the efficiency by which one neuron talks to another at sites of chemical communication (synaptic plasticity), and remap functional connections to allow for the outputs (axons) of one set of neurons to invade territory vacated by another set of axons.  All of these processes, which take place in full force while the brain is initially assembled in utero and during the early years of life, are now known also to occur, to some degree, throughout the life span.  This latter type of neuroplasticity is at the heart of the meeting held in Dharamsala and of Begley’s book—not just the nuts and bolts of how brains effect this plasticity, but its implications for who we are today (vs. yesterday) and our potential to become something else tomorrow.  

Discovering Neuroplasticity

The interface of Western science and Buddhist philosophy provides the context for considering these implications.  In order to build a bridge between the two disciplines, Begley takes readers on a journey through how neuroscience’s view of the brain’s capacity for functional reorganization has evolved. She highlights the theories and discoveries of many of the field’s leading investigators. Included are the famous late-nineteenth-century psychologist William James; the father of cellular anatomy of the nervous system, Santiago Ramón y Cajal; and modern experimental neuroscientists such as Nobel laureates David H. Hubel, M.D., and Torsten N. Wiesel, M.D., who elegantly demonstrated the sensitivity of cerebral cortical neurons to visual experience during “critical periods” of early brain development.  Begley implicitly makes the point that the emphasis on such limited windows of opportunity for functional brain reorganization may have contributed to researchers’ initial reluctance to embrace the growing body of evidence for neuroplasticity in the mature brain. 

But then she goes on to describe a growing list of research that demonstrates this neuroplasticity, such as the discovery by Michael Merzenich, Ph.D., and Jon Kaas, Ph.D., that the part of the cerebral cortex that processes tactile information is altered after training or when sensory input from a part of the body is removed. The case for lifelong neuroplasticity becomes even more compelling as Begley reports the identification by Fred H. Gage, Ph.D., of neurogenesis in the brains of adult mammals. The reader will be intrigued to learn that many of the insights into the capacity for adult neuroplasticity came from unexpected quarters. For example, lifelong neuronal renewal was first established in songbirds, and the initial observations of human adult neurogenesis came from cancer patients who underwent chemotherapy with drugs that serendipitously allowed visualization of newly generated neurons when their brains were examined by microscope upon autopsy.

These and other discoveries complete the plasticity circle: not only can the brain change the functional efficiency of synaptic connections, sprout new connections, and refine existing connections, but it also can essentially substitute or replace at least some of its component parts, not just in the early stages of development but in adulthood as well. We learn through Begley’s narrative how the sands of the collective contemporary scientific wisdom shift, grudgingly at first but then decisively under the weight of increasing evidence. 

Can Our Minds Change Our Brains?

All the while, the case for adult neuroplasticity leads us back to the larger questions raised in Dharamsala, ones that have challenged philosophers for millennia. A long-standing question to which Begley introduces readers is the concept that the mind can be viewed as a result of the processes that brains carry out. But a new question brought by modern The reader of Begley’s book learns about the Dalai Lama’s lifelong personal fascination with science, Buddhism’s goal of insight, and its rich consonances with neuroscience. neuroscience is: Are we the same person after we reconfigure our brain hardware?  What does the stuff of brain mean for our mind?  If the outer world can change our brains (through sensory experience, injury, exercise), can we change our brains through internal commands—that is, can we will our mind to change the very matter on which the mind runs?  Even though parts may come and go, the processes and operations performed by the parts have a history (memory), with lifelong plasticity being part of who we are. 

This plasticity sheds new light on the interplay between nature and nurture. Begley weaves the harrowing story of the children in Romanian orphanages under the Ceausescu regime together with studies by Michael Meaney, Ph.D., at McGill University on how maternal attention affects gene expression and behavior in rat pups:

"By the time the children were six, a 2004 study of Romanian children adopted by British families concluded, there were major persistent deficits in a substantial minority of them.  The scientists attributed that to some form of early biological programming or neural damage stemming from institutional deprivation.  It may seem a long way from Romania’s abandoned children to the rats in cages at McGill University in Montreal.  But neuroscientist Michael Meaney begs to differ. . . . The brains of rats born to neglectful mothers but raised by high licking attentive ones had as many glucocorticoid receptors as rats born to and raised by high licking mothers. . . .The mother rats literally groom their offspring to have the adult temperaments and mothering styles they do. . . . Score another point for nurture over nature. The genes of the mellow rats are identical to the genes of the neurotic rats, at least in terms of how genetics traditionally defines “identical”—the sequence of molecules that were the holy grail of the Human Genome Project.  But this sequence doses not represent nature’s orders.  It’s more like a suggestion.  Depending on what sort of world a creature finds itself in, that sequence might be silenced or amplified, its music played or muted, with diametrically different effects on behavior and temperament."

So how is all of this fascinating information about the interplay between behavior, genes, and neuroplasticity connected to the questions posed by the Buddhist philosophers about who we are and how our minds might affect our brains?  At the November 2005 annual meeting of the Society for Neuroscience, thousands of attendees at a lecture on the neuroscience of meditation asked that same question as they listened to the Dalai Lama discuss how Buddhism can interface with the study of the human condition.  The connection becomes clearer as the reader of Begley’s book learns about the Dalai Lama’s lifelong personal fascination with science, Buddhism’s goal of insight, and its rich consonances with neuroscience. Begley explores how Buddhism may both learn from and inform the search for answers to the great questions about the human condition.  

Scientists are now clear that sensory input from the outside world can change the organization of synaptic networks within the brain (often called bottom-up plasticity). Interestingly, when active attention or motor behavior is coupled with that sensory input, functional reorganization, including synaptic plasticity, is enhanced. But what about processes generated entirely within our brains, without any physical interaction with the environment, such as sensory input or motor output? Can such processes alone physically change the very brains in which they are operating (top-down plasticity, or “mind over matter”)?  This question is of great importance to neuroscientists, to psychiatrists and their patients, and to followers and scholars of Buddhism. 

Is simply imagining the desired outcome, for example mental rehearsal by an athlete or musician, sufficient to induce plasticity?  Might this ability be used to help fix a malfunction in the brain of someone with a psychiatric disorder such as depression?  In Train Your Mind, Change Your Brain, Begley makes the case for bidirectional interaction. This raises the intriguing issue of whether internal training—including Buddhist meditation—might trigger the biological processes of plasticity, perhaps making wholesale changes in neuronal architecture, triggering neurogenesis, or healing our own injured or diseased brain. 

This part of the book motivates the reader to confront big issues, including the uniformity versus duality of the mind/brain.  Begley observes that some scientists argue for the mind being more than the brain’s physical activity, but that the corollary of this argument—that the mind can change the brain—is particularly interesting.  However, she goes Overall, Begley provides a clear light along the scientific trail from immutable brains to lifelong neuroplasticity. on to write that “A mental state, be it a sense of the color red or the sound of B-sharp or the emotion of sadness or the feel of pain, is more than its neural correlates.”  But even though we are still woefully uninformed as to the nature of those processes of mentation, including perception and consciousness, we have plenty of opportunity for biological exploration of these processes’ physical nature.  This exploration eventually will go beyond the capability of current tools, such as analysis of patterns of nerve impulses and blood oxygen signals, in order to discover the physical processes that may very well be the computational operations of mind.

Overall, Begley provides a clear light along the scientific trail from immutable brains to lifelong neuroplasticity.  This history is presented accurately and fairly, while being melded with the big questions of mind as engaged by a major philosophy, Buddhism.  The otherwise informative and well-framed thesis is somewhat weakened, however, by a perhaps overly optimistic picture of the expression of neuroplasticity throughout life.  The reader who is not aware of the current controversies in this field may come away with the mistaken impression that plasticity in the adult nervous system is equal to that early in life and perhaps not mechanistically constrained.  

For example, after a raging controversy over whether the capacity for adult neurogenesis is ubiquitous, the process is currently understood as manifesting only in select brain regions (particularly the dentate gyrus and olfactory bulb, but not in the neocortex).  In a similar vein, training-induced changes in the sensory and motor map organization of the cerebral cortex are more robust in young brains.  Moreover, the capacity for fairly rapid functional reorganization of the adult visual cortex after retinal injury has recently been challenged.  In some cases, Begley points out differences between young and mature brains, but the jury is still out on the degree of adult plasticity that can occur in some of these systems.  

In general, though, the author’s points regarding life-long neuroplasticity are accurate, cleverly described for a broad base of readers, and woven into an at once entertaining and informative book.  Begley takes us on a journey that will open readers’ eyes to the enormous adaptive capacity of our brains. Train Your Mind, Change Your Brain provides a firm foundation for a continuing and expanded dialogue between people who usually look at the world through very different lenses.



About Cerebrum

 
Bill Glovin, editor
Carolyn Asbury, Ph.D., consultant

Scientific Advisory Board
Joseph T. Coyle, M.D., Harvard Medical School
Kay Redfield Jamison, Ph.D., The Johns Hopkins University School of Medicine
Pierre J. Magistretti, M.D., Ph.D., University of Lausanne Medical School and Hospital
Robert Malenka, M.D., Ph.D., Stanford University School of Medicine
Bruce S. McEwen, Ph.D., The Rockefeller University
Donald Price, M.D., The Johns Hopkins University School of Medicine

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