Thread by @drlouisehansen

“The idea that the brain can change its structure and function through thought and activity is, I believe, the most important alteration in our view of the brain since we first sketched out its basic anatomy and the workings of its basic component, the neuron. 1/20 #March4Justice

For four hundred years mainstream medicine and science believed that brain anatomy was fixed. The common wisdom was that after childhood the brain changed only when it began the long process of decline; 2/20

that when brain cells failed to develop properly, or were injured, or died, they could not be replaced. Nor could the brain ever alter its structure and find a new way to function if part of it was damaged. 3/20

The theory of the unchanging brain decreed that people who were born with brain limitations, or who sustained brain damage, would be limited or damaged for life. Scientists who wondered if the healthy brain might be improved or preserved were told not to waste their time, 4/20

A neurological nihilism — a sense that treatment for many brain problems was ineffective or even unwarranted — had taken hold, and it spread through our culture, even stunting our overall view of human nature. 5/20

Since the brain could not change, human nature, which emerges from it, seemed necessarily fixed and unalterable as well. The belief that the brain could not change had three major sources: 6/20

the fact that brain-damaged patients could so rarely make full recoveries; our inability to observe the living brain's microscopic activities; and the idea — dating back to the beginnings of modern science — that the brain is like a glorious machine. 7/20

And while machines do many extraordinary things, they don't change and grow. When patients did not progress psychologically as much as hoped, often the conventional medical wisdom was that their problems were deeply "hardwired" into an unchangeable brain. 8/20

"Hardwiring" was another machine metaphor coming from the idea of the brain as computer hardware, with permanently connected circuits, each designed to perform a specific, unchangeable function. 9/20

A band of brilliant scientists, in the late 1960s or early 1970s, made a series of unexpected discoveries. They showed that the brain changed its very structure with each different activity it performed, perfecting its circuits so it was better suited to the task at hand. 10/20

If certain "parts" failed, other parts could sometimes take over. The machine metaphor, of the brain as an organ with specialized parts, could not fully account for changes the scientists were seeing. They began to call this fundamental brain property "neuroplasticity." 11/20

Neuro is for "neuron," the nerve cells in our brains. Plastic is for "changeable, malleable, modifiable." At first many scientists didn't dare use the word "neuroplasticity" in their publications, and their peers belittled them for promoting a fanciful notion. 12/20

Yet they persisted, slowly overturning the doctrine of the unchanging brain. They showed children are not always stuck with the mental abilities they are born with; that the damaged brain can often reorganize itself so that when one part fails, another can often substitute; 13/20

if brain cells die, they can be replaced; many "circuits", even basic reflexes that we think are hardwired are not; thinking, learning, acting can turn our genes on/off, shaping brain anatomy and behavior — one of the most extraordinary discoveries of the twentieth century. 14/20

Like all revolutions, this one will have profound effects. The neuroplastic revolution has implications for, among other things, our understanding of how love, sex, grief, relationships, learning, addictions, culture, technology, and psychotherapies change our brains. 15/20

All of these disciplines will have to come to terms with the fact of the self-changing brain and with the realization that the architecture of the brain differs from one person to the next and that it changes in the course of our individual lives. 16/20

While the human brain has apparently underestimated itself, neuroplasticity isn't all good news; it renders our brains not only more resourceful but also more vulnerable to outside influences. 17/20

Neuroplasticity has the power to produce more flexible but also more rigid behaviors — "the plastic paradox." Ironically, some of our most stubborn habits and disorders are products of our plasticity. 18/20

Once a particular plastic change occurs in the brain and becomes well established, it can prevent other changes from occurring. It is by understanding both the positive and negative effects of plasticity that we can truly understand the extent of human possibilities.” 19/20

Source: Adapted from The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science. A book on neuroplasticity by psychiatrist and psychoanalyst Dr Norman Doidge. Published in 2007. 20/20