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.
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.
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.
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.
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.
This theory, that novel environments may trigger neurogenesis, is consistent with Merzenich’s discovery that in order to keep the brain fit, we must learn something new, rather than simply replaying already-mastered skills.
This “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.
For people, postmortem examinations have shown that education increases the number of branches among neurons. An increased number of branches drives the neurons farther apart, leading to an increase in the volume and thickness of the brain. The idea that the brain is like a muscle that grows with exercise is not just a metaphor.
Merzenich has started a new company, Posit Science, devoted to helping people preserve the plasticity of their brains as they age and extend their mental lifespans.
Neurons that fire apart wire apart—or Neurons out of sync fail to link.
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.
Most people assume that our genes shape us—our behavior and our brain anatomy. Kandel’s work shows that when we learn our minds also affect which genes in our neurons are transcribed. Thus we can shape our genes, which in turn shape our brain’s microscopic anatomy.
In the Lincoln-Douglas debates of 1858 the debaters would comfortably speak for an hour or more without notes, in extended memorized paragraphs; today many of the most learned among us, raised in our most elite schools since the 1960s, prefer the omnipresent PowerPoint presentation—the ultimate compensation for a weak premotor cortex.
The experiment demonstrated that if the median nerve was cut, other nerves, still brimming with electrical input, would take over the unused map space to process their input. When it came to allocating brain-processing power, brain maps were governed by competition for precious resources and the principle of use it or lose it.
The tongue is what he calls the ideal “brain-machine interface,” an excellent entry point to the brain because it has no insensitive layer of dead skin on it.
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.
Much of the brain is inhibitory, and when we lose that inhibition, unwanted drives and instincts emerge full force, shaming us and devastating our relationships and families.
We must be learning if we are to feel fully alive, and when life, or love, becomes too predictable and it seems like there is little left to learn, we become restless—a protest, perhaps, of the plastic brain when it can no longer perform its essential task.
Unlearning in love allows us to change our image of ourselves—for the better, if we have an adoring partner. But it also helps account for our vulnerability when we fall in love and explains why so many self-possessed young men and women, who fall in love with a manipulative, undermining, or devaluing person, often lose all sense of self and become plagued with self-doubt, from which it may take years to recover.
The first step is for a person having an OCD attack to relabel what is happening to him, so that he realizes that what he is experiencing is not an attack of germs, AIDS, or battery acid but an episode of OCD.