One afternoon, at ten past two, Clive Wearing wrote "This time properly awake" in his journal. At 2:14 he wrote "this time finally awake." At 2:35 it was "this time completely awake." In March 1985, the virus that usually causes cold sores had reached his brain. He was in his mid-forties, a conductor and an expert on early music. The infection left him with a memory that lasted only seconds. It also wiped out almost his entire past.
His music survived. He was still in hospital when his wife found out. She held up a score and began to sing one of its lines, and he joined in on the tenor part. He could still play the organ, hands and feet together. In the summer of 2005, the neurologist and writer Oliver Sacks came to visit. Two volumes of Bach's preludes and fugues sat on Clive's piano, and Sacks asked him to play one. Clive told him he'd never played a single one of them. Then he played the Prelude in E major, and said, "I remember this one."
Sacks explains it with two kinds of memory. One holds the events of your life, and that's the kind the virus destroyed. The other holds how to do things. It runs through other parts of the brain, and it can survive damage that wipes out the first. Clive didn't remember ever playing that prelude. His hands did. Years at the keyboard had left something behind that wasn't a memory of practicing. What was it, and where?
The last lecture's sea lion kept time better at fifteen than at three. This lecture asks the same of people. What do years of practice do to a human brain? And does it matter when you start?
A hand will carry us through it. A string player's left hand comes first, and what years of playing do to its place in the brain. Next come children at a keyboard, scanned before their first lesson and again fifteen months later, to see whether the practice made the difference. Then comes the case that starting young counts for more. Last is a famous pianist whose right hand stopped obeying him.
Practice leaves its mark on maps. You've met one already: the first lecture's place map, which lays out sounds from low to high, in the ear and again in the hearing cortex. The brain keeps a map of the body too, for touch. Each part of the body has its own patch in the brain's outer layer. The fingers lie in order, from thumb to little finger.
Thomas Elbert worked in the psychology department at the University of Konstanz, in Germany. In 1995 his group measured the touch map in string players. On a violin or a cello, the left hand does the fine work. Its four fingers press the strings, and the thumb grips the neck, shifting a little now and then. The right hand holds the bow, and its fingers move much less on their own. The team tested nine string players, along with six people who had never played a string instrument. An air-driven device pressed lightly on the thumb and, in separate runs, on the little finger, a thousand times each. Recordings of the brain's magnetic signals showed where on the touch map each press arrived, and how strongly.
In the string players, a touch on the left hand drew a stronger response than in the others. The team read that as more of the map given over to those fingers. The little finger had gained the most. The thumb is used less, and it had gained less. And the right hand, the bow hand, was no different from the non-players'. The map had grown where the practice landed.
Why would a map grow? The answer these researchers give goes back to Donald Hebb, a Canadian psychologist, in 1949. Hebb proposed a rule: when one nerve cell keeps helping to make another fire, the link between them grows stronger. The usual slogan for it is "Cells that fire together, wire together." It seems to have been coined around 1992 by neuroscientists studying how vision develops, though papers sometimes credit it to Hebb.
Experiments on monkeys show the rule redrawing the touch map. Some monkeys were trained to hold two fingertips against a spinning disc with a rough surface. Each time, they were rewarded with banana-flavored chips. After about six hundred of these touches, the researchers mapped the hand. The patches for those two fingertips had grown. Timing matters as well as use. In monkeys whose two fingers were joined by surgery, the two patches merged into one. In people whose joined fingers were separated by surgery, the patches moved apart. Signals that keep arriving together may end up sharing a patch, and signals that arrive apart may keep separate ones. And it seems to take touches that matter to the animal. Touch that it merely receives seems to change little.
The mark shows up beyond touch. A group in Boston scanned eighty men: professional keyboard players, amateurs who practiced about half as much, and men who had never played. In areas for movement and for hearing, and in one used for reading music at sight, the professionals had the most grey matter. The amateurs came next, then the men who had never played. Grey matter is brain tissue, and in rats trained in acrobatics, it gains connections between nerve cells.
Hearing changes too. A team in Münster led by Christo Pantev recorded the hearing cortex of musicians and non-musicians as they heard piano notes and pure tones. A pure tone is a plain sound that no musician practices with. The musicians' responses to piano notes were about a quarter larger than the non-musicians'. For pure tones, the two groups were alike. Among the musicians, how much music they had only listened to made no detectable difference. The team concluded that it seems to take active practice.
Does that mean the practice built those brains? Elbert's team raised the other possibility themselves. People born with a bigger map for the left hand's fingers might make better string players. They'd be more likely to keep at it. The Boston group said the same of its eighty men. They wrote that some of the differences could be inborn. Every comparison of grown musicians runs into this problem, because musicians chose to become musicians. To tell what practice does from what people bring to it, you have to see a brain before the practice starts.
The Boston group set out to do that with children. The study followed thirty-one children, about six years old, from public schools around Boston. None had had music lessons. Fifteen were starting weekly half-hour private lessons on a keyboard. The other sixteen had only a weekly music class at school, with songs, drums and bells. Every child had a brain scan at the start, and another fifteen months later. Every child also took a finger test, pressing number keys in a sequence like five-two-four-three-five, as fast and as accurately as they could. And every child heard pairs of short tunes and said whether the two were the same.
At the start, the two groups' brains showed no differences. Fifteen months later, they did. Several places had grown more in the lesson group, and three of them matter here. One was the hand's patch in the area that becomes active when the body moves. The patch that grew was on the right side, which serves the left hand. The second place was a stretch of the bridge between the brain's left and right halves. The bridge is the band of nerve fibers that joins them. The third was a patch of hearing cortex on the right side, though the evidence for that one was weaker.
The growth also tracked the skills. The hand patch and the bridge grew most in the children whose left hands improved most on the finger test. The hearing patch grew most in those who improved most on the tunes. That's a step past the comparisons of grown musicians. The team concluded that the differences seen in adult musicians are more likely the product of training.
It still wasn't a clean experiment, because the families chose the lessons. The lesson children came from homes where the parents had more education. They were also about five months older. The results the team reports already allow for both. Glenn Schellenberg studies what music lessons do for children, and he reads the study more coldly. The project began with seventy children, and only thirty-one ended up in the brain analysis. Back then, before any lessons, the children about to start had scored higher on all seven tests they took. No single gap was large, but all seven pointed the same way. He argues that children who take lessons already differ from other children, in ability, family background and personality. He suggests that a head start like that could have grown over fifteen months until it showed in the scans. The team's own case rests on the scans, which matched at the start. I'm persuaded the study narrows the gap between training and talent. It doesn't close it.
On this evidence, practice leaves its mark where the work lands, and the children suggest it does more than reveal a brain that was already there. Two questions remain. Does the age you start count on its own? And can the same rule go too far?
Elbert's string players held a second surprise, about age. You might expect the map to follow the hours of practice. It didn't. The size of the little finger's response tracked the age a player had started, and not the hours. Those who began before about twelve had the strongest responses. Those who began after thirteen had weaker ones, though still stronger than the non-players'. In Pantev's study of piano notes, the dividing line fell at about nine. An effect of age like this would point to a sensitive period. That's a window in childhood when what you do leaves an unusually lasting mark on the brain.
A team in Montreal spotted a snag in that kind of evidence. Early starters usually end up with more years of training than late ones. Any difference might come from the extra years.
So the Montreal team matched them. It tested thirty-six highly trained musicians, half of whom had started before seven and half after. The two groups had the same years of lessons, the same years of playing and the same hours of practice each week. A third group had barely played at all. Everyone tapped a key in time with a pattern of short and long flashes on a screen. Everyone also had a scan that traces the brain's wiring, its bundles of nerve fibers.
The early starters kept time with the flashes more precisely. In them, one stretch of the bridge between the brain's halves was better connected. Its fibers link the two sides' areas for touch and movement. The later someone had started, the weaker that stretch. What about the late starters, with all their years of training? In that stretch of the bridge, they looked no different from the people who had barely played.
Why would age matter? Playing an instrument takes two hands working together. The two halves of the brain coordinate the hands across that bridge. That stretch of the bridge also changes a great deal between the ages of six and eight. The early starters began their training while it was still developing. The team's idea is that early training lays down wiring that later practice builds on.
These were still adults who had started at different ages, for reasons nobody controlled. The authors say only an experiment that assigned children at random, or followed them for years, could test a sensitive period directly. The studies don't agree on an age, either. Elbert's fingers pointed to about twelve, and Pantev's piano notes to about nine. The Montreal bridge pointed to seven, and each was measured a different way. And all of these studies are small. The largest had eighty people, and most had a few dozen or fewer. My reading is that an early start probably counts for something. How much, and up to what age, no study here can say.
The same rule may have a darker side. Leon Fleisher was an American pianist who took over his family's piano at the age of four. At sixteen he made his debut at Carnegie Hall. In 1965 he was due to tour the Soviet Union with the Cleveland Orchestra. By then his right hand was failing him. Its fourth and fifth fingers curled under, and he couldn't stop them. He later wrote of "a feeling that my fingers weren't doing what I wanted them to do." In his case, practicing harder only made it worse. He didn't go on the tour, and he began cancelling concerts. He was thirty-six. Eventually the problem got a name: focal dystonia.
Focal dystonia is a painless loss of control over a skilled movement that used to go well. In musicians, fingers start moving together against the player's will. It tends to strike the movements a musician practices most, in the hand that does the hardest work. Pianists and guitarists usually lose control in the right hand, and players of bowed strings in the left. For pianists it's most often the fourth and fifth fingers. A 2013 review suggests the reason: those two fingers carry the melody. For string players, too, it's most often the fourth and fifth, and the little finger is the one whose patch grew most in Elbert's string players. But it can strike any finger. Estimates run from one musician in two hundred to about one professional in a hundred.
Elbert's group suspected the rule itself. A professional musician moves several fingers together, fast and over and over, for hours a day across many years. Monkeys made to repeat the same grasp for a long time developed trouble moving their hands. On their touch maps, the borders between the fingers broke down. In healthy volunteers, repeated touches to several fingertips at once made their patches begin to merge. The volunteers started mistaking which finger had been touched.
Elbert's group went looking for that merging in musicians with dystonia. In 1998 they measured the maps of seven professionals with the condition, among them guitarists, a pianist and an organist. They also measured healthy musicians who played the same instruments, and people who didn't play. The air-driven device pressed each fingertip in turn. The fingers' patches for the affected hand sat closer together than in the people who didn't play. They were still in order, from thumb to little finger. But they had run together. The healthy musicians' patches were spaced normally. In four of the seven, the map for the other hand had drawn together too.
That fits the rule, but one round of measurements can't say which came first. Merged patches might cause the dystonia. The dystonia might merge the patches. Or a third thing might cause both, perhaps a fault in the basal ganglia, the deep timing machinery from the last lecture. A 2015 review of the studies, most of middling or poor quality, judges intensive playing to be one cause, along with an inherited tendency. Plenty of musicians presumably practice as hard and never get it. Elbert's group raises the possibility that those who do had patches prone to merging from the start.
The rule also suggested a treatment. In a small study, Elbert's group had musicians practice with a therapist while splints held some of their other fingers still. That way the affected finger had to move independently of its neighbors. The pianists and guitarists improved, judged by how they played their own pieces, and their maps looked more normal afterwards. The wind players went through the same routine and didn't improve much. The team counted them as, in effect, a placebo group: going through the routine wasn't enough on its own. In a later study of a related training, eight of eleven musicians improved after a week of daily practice. Other treatments include retraining at slow speeds, and injections of botulinum toxin. The 2013 review is plain about the evidence. The splinting and similar retraining rest on case reports and small case series. Slow-speed retraining comes from a larger series of 145 musicians, and after two years about a quarter had better control. Treatment brings relief to some musicians, and some get back to their old level. But symptoms rarely go away completely, and reviews disagree about how many musicians keep their careers.
Fleisher spent the next decades teaching, conducting and playing music written for the left hand alone. In the 1990s, some control slowly came back to his right hand, after treatments that included Botox injections. One man's recovery can't tell us what helped. In 2003 he made a triumphant return to Carnegie Hall, and in 2004 he released an album called Two Hands.
A rule about timing runs through most of this lecture. In the slogan's words, cells that fire together wire together, at least when the activity matters. So years of practice redraw the brain's maps, and the fingers and sounds you work hardest get the most room. A string player's busy left fingers take more of the touch map than a non-player's do. In a few musicians whose hands stopped obeying, the fingers' patches had run together. That may be the same rule overshooting, though which came first is unknown, and it's one suspect among several.
Grown musicians can't show what caused their differences, because they chose to play. Children scanned before their first lesson came closer, though their families chose too. Starting before about seven goes with a better-connected bridge between the brain's halves, even with the years of practice matched, but that is still a comparison.
The Boston children also took tests of reasoning and vocabulary. Whether lessons reach any further than the hands and ears is the next lecture's question. Put plainly, does music make you smarter?
The rule doesn't need you to remember the lesson. Clive Wearing's hands kept the memory for how to play. Sacks places that kind of memory in older, deeper parts of the brain, among them the basal ganglia. A memory researcher wrote to Sacks that every case of amnesia is different, so Clive's is his own. That kind of memory can still take in new things. Clive can make coffee, finding the cups, the milk and the sugar, though he can't say where they're kept. What he can't do is practice on his own. He has no memory of yesterday's session, so the idea of practicing never comes to him. Someone has to put the music in front of him.