High-performance brain

Michael Merzenich, professor emeritus at UCSF and a leading pioneer in brain plasticity research, talks about how mental gymnastics can help retrieve abilities lost to aging.

By Karina Toledo  |  Agência FAPESP – Michael Merzenich, professor emeritus at the University of California, San Francisco (UCSF), is a world-renowned neuroscientist and a leading pioneer in brain plasticity research.

Merzenich came to Brazil in early April to deliver a presentation at the 3rd BRAINN Congress organized by the Brazilian Research Institute for Neuroscience and Neurotechnology (BRAINN), one of the Research, Innovation and Dissemination Centers (RIDCs) funded by FAPESP. BRAINN is hosted by the University of Campinas (UNICAMP).

Since the 1960s, when the vast majority of neuroscientists still saw the brain as a static organ hard-wired strictly according to a genetic template, Merzenich has argued that we create new synapses and neural circuits over our entire lifetime in response to stimuli and experiences, resulting in functional change.

The theories on neuroplasticity formulated by Merzenich and others revolutionized the field, opening up new perspectives both for children with learning difficulties and for patients with brain injuries due to stroke, trauma or disease.

In the 1970s and 1980s, Merzenich demonstrated through experiments with animals that neural circuits and synapses changed rapidly according to the activity performed. In one experiment, he rearranged the nerves in a monkey’s hand and found that the cells of the animal’s sensory cortex quickly remapped their representation of the hand.

In the late 1980s, Merzenich led the UCSF team that developed the cochlear implant. In 1996, he founded the Scientific Learning Corporation, which markets and distributes educational software for children based on models of brain plasticity.

In 2004, he was one of the founders of Posit Science, which creates brain-training software based on his research. Its lead product is a brain-training application called BrainHQ.

In recent years, Merzenich has devoted much time and energy to showing how mental gymnastics can help remodel brain functions so that patients can recover the skills lost to disease, injury or aging.

His findings have been described in more than 150 scientific articles, many of which have been published by high-impact journals such as Science and Nature. He has won many academic awards, including the Russ Prize, the Ipsen Prize, and the Zülch Prize.

In his book Soft-Wired: How the New Science of Brain Plasticity Can Change Your Life, published in 2013, Merzenich shows how ordinary people can reverse mental decline with simple exercises, taking control of brain plasticity processes and improving the quality of their lives.

While in Brazil to attend the BRAINN congress, he found time for an interview with Agência FAPESP in which he explained how positive and negative changes can remodel the brain. Highlights of the interview follow.

Agência FAPESP – How would you define the concept of neuroplasticity? 
Michael Merzenich – The brain is built to change in response to lived experience and the ways in which it’s used. This ongoing process is called neuroplasticity. When we work on improving a skill, the brain’s “wiring” changes as the synapses or neural connections develop to select the connections that support the behavior or skill we’re developing. Just as I benefit in many ways from exercising my body and changing the regulation of several biochemical processes, when I exercise my brain, I change the way it functions, the supply of blood and energy to the brain, and the power of its operations. So I don’t just improve a particular skill, I improve the brain’s entire machinery. When I play table tennis for the first time, I’m very clumsy. After practicing intensely for a year, I become highly skilled. I can see and hit the ball with a high degree of accuracy. Through incredibly complex physical and chemical changes, I’ve created a brain with this skill set. My brain and your brain will be different a week from now and even more different a decade from now. It may be a forward or backward change in the sense of gaining or losing skills. That depends on its use.

Agência FAPESP – So training skills creates positive changes. How are negative changes brought about? 
Merzenich – During our lives, we do things that degrade our ability to extract useful information from the world around us. For example, as a modern human, I spend several hours each day looking at a screen, where things happen that are important to me. Everything outside the screen is unimportant, useless, a distraction. I’m systematically training my vision, narrowing my point of view so that only what’s in front of my nose is important. By doing this, I gradually lose the ability to process visual information from what’s around me. The average citizen of my country, and this has been studied there in great detail, has lost approximately 30% of their visual field by age 60 years and more than 50% by the time they reach 80 years. Things happen and they don’t see them because the brain rejects that stimulus. This is one of the reasons why older people have more traffic accidents. They gradually regress to a narrower visual field and, at the same time, when they do succeed in seeing something, they respond to the stimulus more slowly.

Agência FAPESP – But can a person be trained to lose a skill they’ve already acquired, such as understanding speech in a foreign language? 
Merzenich – Yes, I can train someone using modified forms of unarticulated sound that don’t correspond to speech. I train the brain to change its sound-processing ability so that it loses the ability to interpret the elements that change rapidly in the acoustic flow formed by the phonemes, the elementary structure of words. This interpretation is necessary to extract meaning from words. I can refine this skill, but I can also destroy it. I can challenge you to make increasingly accurate distinctions in what you hear, to pick up more details at faster speeds. I can train you to make these distinctions even when the voice is soft or the speech is abnormal and distorted. Or I can do the opposite and degrade your skill, giving you a brain that operates only when things happen slowly. You won’t be able to interpret the details of the sounds at certain frequencies. We’ve done experiments in negative training with monkeys and rats, and we’ve shown that this is possible.

Agência FAPESP – How does aging influence changes in brain function? 
Merzenich – Brain function is very limited in infants. As we get older, the machinery of the brain steadily increases its ability to operate accurately. The various systems become more and more coordinated, and this continues until the prime of life, which, in the average human, is between the ages of 20 and 40 years. High performance persists a little longer in women, but when they reach the menopause, there’s a rapid deterioration due to hormonal changes and they reach the same level as men around 60 or 65 years. So we have this period in our lives, roughly two decades, when our brains operate at high performance levels, and after that they deteriorate. If a person aged 30 years is operating below the average performance level for the population, having reached 100% of their capacity at peak brain function, by the time they’re 60 years old, they’ll have only 16% of their capacity, and when they’re 80 or 85 years old, only 10%. No one wants to be 85 years old with only 10% of their brain capacity. We’ve shown this deterioration to be reversible. Simply put, an older person’s brain is slower to make decisions and less fluent in its operation than when that same person was young because it handles information in a less organized way. Misfortunes occur throughout our lives, causing noise in the brain and potentially accelerating mental decline. It could be falling off your bike and banging your head, getting a brain infection, or being exposed to toxins. But we can train the older person’s brain and make it recover many of its abilities. We’ve studied many different groups and shown that it’s possible to reverse this decline with training.

Agência FAPESP – Could you describe the training program you’ve developed? 
Merzenich – The training program applied by BrainHQ is designed first and foremost to exercise the brain mechanisms that control neuroplasticity. These mechanisms are also plastic and can be underutilized with age or owing to disease. We’ve shown that it’s possible to train someone for 15 or 20 minutes to regulate the machine’s biochemical processes. As a result, everything they learn or do in the next hour will be enhanced. They learn faster, as if they had taken a drug to raise the level of brain activity. Except that unlike what happens with drugs, if I apply this training program every day for two weeks, the change will be long-lasting. The machine’s performance improves, and when you take a look a year later, the brain is still more alert, more alive, more predisposed to change. Furthermore, the program is designed to improve the way in which the brain processes the details of what we see, hear and feel. As the brain gets noisier, it changes the way it processes information, losing the ability to interpret rapidly changing details in a clear and distinct manner. The training program is designed to reverse this negative change because all other brain operations depend on this ability. In any complex mental operation, such as memory, for example, the performance limit will be determined by the clarity with which the brain represents the information. If I’m trying to record information, the more accurately it’s represented in the brain, the easier it will be for me to recall it. The brain is a machine for making predictions. It accumulates information over time and continuously predicts the future and makes associations with the past. I can enhance this capability simply by increasing the clarity of its operations. To do this, we train the brain to manipulate information. If I want to raise the level of its operations, I can give it a task in which it needs to come back not with the right answer but with several possible answers at high speed and fluently. I can train the brain to classify information quickly, to make fast changes to the rules for its operations when environmental conditions so require. All these things are valid practices. What we usually do is to work out for each individual where there are flaws: in attention control, in the ability to record information, in the way the brain represents information in sequence, or in how it handles and organizes complex chains of information. All these things can be trained. The software we use resembles certain games for cell phones. A given task has to be performed in one or two minutes, and a certain number of attempts are allowed. The difficulty increases quickly: as the player completes each level, a more difficult level appears, challenging them to keep enhancing the skill.

Agência FAPESP – Can the training program be used to treat neuropsychiatric diseases, such as Alzheimer’s or schizophrenia? 
Merzenich – We have several studies showing that people with Alzheimer’s, schizophrenia, bipolar disorder and anxiety disorders or depression can benefit. I don’t mean that they can be cured, but the quality of their lives can be enhanced. However, in my country, the law doesn’t allow us to deal directly with medical conditions. In this case, the training must be intermediated by a physician or therapist. We also have studies showing benefits for people with brain injuries caused by stroke or trauma, people exposed to poison or venom, and people with brain infections or stress. We always succeed in obtaining an improvement – in some cases, quite a significant one, although in others, the patient’s progress is more limited because of the severity of the injury. In one study, we applied the training program to a large population of volunteers who had suffered concussion. After two months, their brains returned to normal, whereas the group that did not take the training program continued to present with neurological alterations a year after the injury. We’ve also tested it on healthy people in professions where decision-making may involve life or death issues, such as police personnel and soldiers. Statistics suggest that police personnel in general make bad choices 50% of the time, and this has a significant impact on a city. Our results show that training can improve the decision-making process. In a trial conducted in partnership with an insurance company, we trained 20,000 professional and recreational drivers. The recreational drivers were elderly. We succeeded in cutting the number of traffic accidents by half. To date, we’ve trained a total of some 600,000 people.

Agência FAPESP – Does the brain lose the benefits of training if it’s interrupted, as muscles do? 
Merzenich – We conducted almost 30 clinical trials to measure the duration of the effect and found some significant duration in all cases. But it was much stronger in some domains than in others. If you train and change the way the brain activates attention, that change lasts longer because attention is a skill used in many real-life situations. When you train listening, the benefit can be lost fairly soon afterwards. But certainly if you achieve high performance in a particular skill, some kind of maintenance training will be required to maintain that high level. In some populations where brain function is more likely to deteriorate, such as people with pre-Alzheimer’s or mild cognitive impairment and people with Huntington’s disease, the decline occurs more rapidly when the training is interrupted, and they soon return to the level they would have been at if they’d never trained at all. However, while they’re training, they remain relatively stable, although we can’t be sure for how long. It’s a major challenge because all of the brain’s abilities are at risk, so we have to keep them engaged, and the training has to be intensive.

Agência FAPESP – What can be done to prevent this knowledge from being misused? 
Merzenich – The brain can be trained to operate destructively, and there are potential forms of abuse. Many people could be interested in manipulating brain plasticity for selfish ends. So it’s a challenge to us to think about how this can be controlled and how to be sure that this knowledge will be used for human well-being and not for destruction. For example, it’s possible to take a 10-year-old or 12-year-old boy, a good student, away from home and transform him into an assassin, a monster. What happens in this case is that brain plasticity is channeled toward destruction.

Agência FAPESP – Can the process be reversed in such cases? 
Merzenich – It’s difficult and requires a lot of training, but it can be done, and that’s one of my efforts. We’re treating children with a long history of abuse and neglect, which damage the brain machinery that controls learning. At the same time, because the learning machinery in these children’s brains has been impaired, they have access to an impoverished repertoire that doesn’t prepare them for life. Ultimately, they end up as failures. Unless we do something to help them from a neurological standpoint, there’s no hope for them. But what does society typically do? Blame them for their poor performance. We massively blame children with terrible childhoods for their experiences. That’s really dumb.