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December 26, 2019 - January 2, 2020
we are all born with a far more adaptable, all-purpose, opportunistic brain than we have understood.
It is rare that the person who makes an important discovery is the one with the defect, but there are some exceptions. Barbara Arrowsmith Young is one of these.
junction of three major perceptual areas where the temporal lobe (which normally processes sound and language), the occipital lobe (which normally processes visual images), and the parietal lobe (which normally processes spatial relationships and integrates information from different senses) meet.
We all have some weak brain functions, and such neuroplasticity-based techniques have great potential to help almost everyone. Our weak spots can have a profound effect on our professional success, since most careers require the use of multiple brain functions.
classical education often included rote memorization of long poems in foreign languages, which strengthened the auditory memory (hence thinking in language) and an almost fanatical attention to handwriting, which probably helped strengthen motor capacities and thus not only helped handwriting but added speed and fluency to reading and speaking. Often a great deal of attention was paid to exact
in an immature brain the number of connections among neurons, or synapses, is 50 percent greater than in the adult brain. When we reach adolescence, a massive “pruning back” operation begins in the brain, and synaptic connections and neurons that have not been used extensively suddenly die
Michael Merzenich is a driving force behind scores of neuroplastic innovations and practical inventions,
practicing a new skill, under the right conditions, can change hundreds of millions and possibly billions of the connections between the nerve cells in our brain maps.
current plasticity work helps learning-disabled students improve their cognition and perception. These techniques—his series of plasticity-based computer programs, Fast ForWord—have already helped hundreds of thousands.
“The cerebral cortex,” he says of the thin outer layer of the brain, “is actually selectively refining its processing capacities to fit each task at hand.” It doesn’t simply learn; it is always “learning how to learn.”
each neural system had a different critical period, or window of time, during which it was especially plastic and sensitive to the environment, and during which it had rapid, formative growth.
Language development, for instance, has a critical period that begins in infancy and ends between eight years and puberty. After this critical period closes, a person’s ability to learn a second language without an accent is limited. In fact, second languages learned after the critical period are not processed in the same part of the brain as is the native tongue.
When we say that neurons “rewire” themselves, we mean that alterations occur at the synapse, strengthening and increasing, or weakening and decreasing, the number of connections between the neurons.
The competitive nature of plasticity affects us all. There is an endless war of nerves going on inside each of our brains. If we stop exercising our mental skills, we do not just forget them: the brain map space for those skills is turned over to the skills we practice instead.
Competitive plasticity also explains why our bad habits are so difficult to break or “unlearn.”
when we learn a bad habit, it takes over a brain map, and each time we repeat it, it claims more control of that map and prevents the use of that space for “good” habits. That is why “unlearning” is often a lot harder than learning, and why early childhood education is so important—it’s best to get it right early, before the “bad habit” gets a competitive advantage.
Plasticity is a normal phenomenon, and brain maps are constantly changing.
Hebb proposed that learning linked neurons in new ways. He proposed that when two neurons fire at the same time repeatedly (or when one fires, causing another to fire), chemical changes occur in both, so that the two tend to connect more strongly.
Neurons that fire together wire together.
Neurons that fire apart wire apart—or Neurons out of sync fail to link.
as brain maps get bigger, the individual neurons get more efficient in two stages.
This more efficient use of neurons occurs whenever we become proficient at a skill, and it explains why we don’t quickly run out of map space as we practice or add skills to our repertoire.
as neurons are trained and become more efficient, they can process faster. This means that the speed at which we think is itself plastic.
Finally, Merzenich discovered that paying close attention is essential to long-term plastic change. In numerous experiments he found that lasting changes occurred only when his monkeys paid close attention. When the animals performed tasks automatically, without paying attention, they changed their brain maps, but the changes did not last. We often praise “the ability to multitask.” While you can learn when you divide your attention, divided attention doesn’t lead to abiding change in your brain maps.
“reward” is a crucial feature of the program, because each time the child is rewarded, his brain secretes such neurotransmitters as dopamine and acetylcholine, which help consolidate the map changes he has just made. (Dopamine reinforces the reward, and acetylcholine helps the brain “tune in” and sharpen memories.)
BDNF plays a crucial role in reinforcing plastic changes made in the brain in the critical period.
When we perform an activity that requires specific neurons to fire together, they release BDNF. This growth factor consolidates the connections between those neurons and helps to wire them together so they fire together reliably in the future. BDNF also promotes the growth of the thin fatty coat around every neuron that speeds up the transmission of electrical signals.
That’s why learning a new language in old age is so good for improving and maintaining the memory generally. Because it requires intense focus, studying a new language turns on the control system for plasticity and keeps it in good shape for laying down sharp memories of all kinds.
To keep the mind alive requires learning something truly new with intense focus.
These exercises are now available in thirty independent-living communities and for individuals through the Posit Science Web site.
The Merzenich brain is structured by its constant collaboration with the world, and it is not only the parts of the brain most exposed to the world, such as our senses, that are shaped by experience.
The brain structure that regulates instinctive behaviors, including sex, called the hypothalamus, is plastic, as is the amygdala, the structure that processes emotion and anxiety.
“You cannot have plasticity in isolation…it’s an absolute impossibility.” His experiments have shown that if one brain system changes, those systems connected to it change as well. The same “plastic rules”—use it or lose it, or neurons that fire together wire together—apply throughout.
A single dose of many addictive drugs will produce a protein, called ΔFosB (pronounced “delta Fos B”), that accumulates in the neurons. Each time the drug is used, more ΔFosB accumulates, until it throws a genetic switch, affecting which genes are turned on or off. Flipping this switch causes changes that persist long after the drug is stopped, leading to irreversible damage to the brain’s dopamine system and rendering the animal far more prone to addiction.
we have two separate pleasure systems in our brains, one that has to do with exciting pleasure and one with satisfying pleasure.
lovers looking at photos of their sweethearts show that a part of the brain with great concentrations of dopamine is activated; their brains looked like those of people on cocaine.
lovers can stimulate their dopamine, keeping the high alive, by injecting novelty into their relationship.
When we learn something new, neurons fire together and wire together, and a chemical process occurs at the neuronal level called “long-term potentiation,” or LTP, which strengthens the connections between the neurons. When the brain unlearns associations and disconnects neurons, another chemical process occurs, called “long-term depression,” or LTD
If we only strengthened connections, our neuronal networks would get saturated. Evidence suggests that unlearning existing memories is necessary to make room for new memories in our networks.
In grief, we learn to live without the one we love, but the reason this lesson is so hard is that we first must unlearn the idea that the person exists and can still be relied on.
massive neuronal reorganization occurs at two life stages: when we fall in love and when we begin parenting.
Oxytocin is sometimes called the commitment neuromodulator because it reinforces bonding in mammals.
Whereas dopamine induces excitement, puts us into high gear, and triggers sexual arousal, oxytocin induces a calm, warm mood that increases tender feelings and attachment and may lead us to lower our guard. A recent study shows that oxytocin also triggers trust.
Oxytocin’s “ability” to wipe out learned behavior has led some scientists to call it an amnestic hormone.
Oxytocin, in this theory, does not teach parents to parent. Nor does it make lovers cooperative and kind; rather, it makes it possible for them to learn new patterns.
Plasticity allows us to develop brains so unique—in response to our individual life experiences—that it is often hard to see the world as others do, to want what they want, or to cooperate.
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The brain for Freeman is fundamentally an organ of socialization, and so there must be a mechanism that, from time to time, undoes our tendency to become overly individualized, overly self-involved, and too self-centered.
Based on his work with plasticity, Taub has discovered a number of training principles: training is more effective if the skill closely relates to everyday life; training should be done in increments; and work should be concentrated into a short time, a training technique Taub calls “massed practice,” which he has found far more effective than long-term but less frequent training.
Intelligence predicts, that is its essence; the same intelligence that allows us to plan, hope, imagine, and hypothesize also allows us to worry and anticipate negative outcomes.
The agony of the obsessive worrier is that whenever something bad is remotely possible, it feels inevitable.
