What if you could regain the long-gone ability to learn a language, say, as effortlessly as you once did in childhood? You just might be able to... with the help of a relatively commonplace drug. In a new study, researchers found that valproate, an anticonvulsant which is used to treat epilepsy, PTSD, and mood disorders, helped adult volunteers learn to identify pitch significantly better than those who trained in the same program while taking only a placebo. “This study provides the ‘proof-of-concept’ for the possibility to restore [brain] neuroplasticity using a drug,” wrote the authors in the study, published in Frontiers in Systems Neuroscience. “Normal male volunteers performed significantly better on a test of [absolute pitch] after two weeks of [valproate] treatment than after two weeks of placebo.”
Brain Plasticity and Learning Ability
As children, our developing brains are saturated with new information that must be sorted and processed to make sense of the world and so our brains form new connections between cells, strengthen existing ones, and prune others, all part of the learning process, a process referred to by scientists as “synaptic plasticity.” As we age this plasticity or ability for the brain to modify itself is lost — and so too is the ability to effortlessly learn. Our brains have passed beyond the critical period, “a fixed window of time … during which experience has lasting effects on the development of brain function and behavior,” according to the authors of the study who wondered: Could it be possible to reopen a window of critical period in adulthood?
Understanding that critical periods close when a particular enzyme, HDAC, acts as a “brake” on plasticity, the team hypothesized that if a drug, such as valproate, can block the production of those enzymes, might it be capable of reopening the window of critical period? To test their theory, the researchers constructed an experiment whereby the HDAC enzyme-inhibitor valproate was given to adult, non-musician volunteers as they attempted to acquire “perfect” pitch. Because perfect or absolute pitch is usually acquired in childhood, the researchers figured this task would be the perfect measurement of childlike brain plasticity.
The volunteers consisted of 24 healthy, right-handed, monolingual, English-speaking men between the ages of 18 and 27. Half of the participants took valproate, the other half a placebo while they performed over a two week period online tasks meant to train their ears to recognize tone. The researchers believed their hypothesis would be proved if the men taking valproate showed even a small gain in the ability to identify pitch since no known instance of an adult developing the skill exists. Imagine, then, their surprise when they evaluated the men after the two-week training period had elapsed: Those who took valproate scored much higher on pitch tests than those who took a placebo.
“The finding that [valproate] can restore plasticity in a fundamental perceptual system in adulthood provides compelling evidence that one of the modes of action for [valproate] in psychiatric treatment may be to facilitate reorganization and rewiring of otherwise firmly established pathways in the brain,” wrote the authors. “If confirmed by future replications, our study will provide a behavioral paradigm for the assessment of the potential of psychiatric drugs to induce plasticity.” Since pitch is closely tied to language, according to research from UC San Diego, perhaps one day adults wishing to learn, say, Swahili will begin by popping a pill.
Language and Tone
Perfect pitch, an ability once possessed by, it is said, Beethoven, Mozart, and Ella Fitzgerald, is considered rare in the U.S. and Europe, with an estimated prevalence of less than one in every 10,000 people. Yet, a team of researchers led by psychology professor Diana Deutsch of UC San Diego found a strong link between speaking a tone language – such as Vietnamese – and having absolute pitch. “We conclude that the potential to acquire absolute pitch is universally present at birth, and that it can be realized by enabling the infant to associate pitches with verbal labels during the critical period for speech acquisition,” wrote the authors in their study, which appeared in Music Perception: An Interdisciplinary Journal.
Their large-scale, direct-test study of perfect pitch provided evidence that native tone language speakers are almost nine times more likely to have the ability than those whose native language does not depend on tone. Common in Africa, East Asia, and Central America, tone languages use pitch to determine meaning; words, many of which are monosyllabic, take on entirely different definitions depending on the tones in which they are enunciated. In Mandarin, for instance, the word “ma” has four distinct meanings depending on how it is pronounced: “mother,” “hemp,” “horse,” and “scold.” Comparing native speakers of tone and non-tone languages, then, the researchers discovered a clear and important difference. “In Mandarin speakers, perfect pitch appears to be not rare, but rather a readily acquired ability,” Deutsch said in a press release. “We also found a striking effect of age of onset of musical training.”
In both groups of native speakers, the earlier a child began music lessons, the more likely he or she was to acquire perfect pitch. That said, the likelihood was substantially higher in Mandarin speakers. For pupils who began their musical training between the ages of four and five, about 60 percent of the Chinese speakers displayed perfect pitch compared to only 14 percent of nontone language speakers. For students who had begun training between ages six and seven, nearly 55 percent of the Chinese and six percent of the non-tone speaks achieved the mark. And for those beginning between ages eight and nine, just about 42 percent of Chinese acquired the skill --- compared to none among the non-tone language speakers. “Based on these findings, and considering the related literatures on critical periods in speech development, and the neurological underpinnings of lexical tone, we propose … that speakers of tone language naturally acquire this feature during the critical period for speech acquisition,” the researchers wrote in their study.
“We further propose that the acquisition of absolute pitch by rare individuals who speak [a non-tone] language may be associated with a critical period of unusually long duration, so that it encompasses the age at which the child can take music lessons,” the authors concluded. Ella Fitzgerald, Mozart, and Beethoven, then, may have had more plastic brains — or "open-minded" brains — for a longer period of time in childhood than those of us without their musical and tonal abilities.
Sources: Gervain J, Vines BW, Chen LM, et al. Valproate reopens critical-period learning of absolute pitch. Frontiers in Systems Neuroscience. 2013.
Deutsch D, Henthorn T, Dolson M. Absolute Pitch, Speech, and Tone Language: Some Experiments and a posed framework. Music Perception: An Interdisciplinary Journal. 2004.