Language Utilizes Ancient Brain Circuits That Predate Humans

Language acquisition depends on two brain systems that preexist Homo sapiens.

Posted Jan 30, 2018

VLADGRIN/Shutterstock
Source: VLADGRIN/Shutterstock

A new paper by an international team of researchers presents strong evidence that language is learned using two general-purpose brain systems (declarative memory and procedural memory) that are evolutionarily ancient and not language specific. Contrary to popular belief, the researchers found that children learning their native language and adults learning a foreign language do not rely on brain circuitry specifically dedicated to language learning. Instead, language acquisition piggybacks on ancient, general-purpose neurocognitive mechanisms that preexist Homo sapiens.

These findings were published online January 29, 2018, in the journal Proceedings of the National Academy of Sciences (PNAS). For this analysis, the research team statistically synthesized the findings of 16 previous studies that examined language learning via declarative and procedural memory, which are two well-studied brain systems.

What Is the Difference Between Declarative Memory and Procedural Memory?

Declarative memory refers to crystallized knowledge that you could learn while sitting in a chair without having to practice finely-tuned motor coordination. Declarative memories, such as knowing all 50 states and the District of Columbia or memorizing SAT vocab words, can easily be described on a written test. On the flip side, procedural memory encompasses things like playing a musical instrument or riding a bicycle, which everyone must learn by actually performing the task. Over time, procedural memory becomes automatized in unconscious ways through practice, practice, practice. 

Over a decade ago, when I created “The Athlete’s Way” program to optimize sports performance, the foundation of my coaching method was to take a dual-pronged approach that targeted declarative (explicit) memory and procedural (implicit) memory separately. Notably, the discovery that ancient brain circuits are used to learn a language—and are also used to master sports—corroborates that these neurocognitive systems have multiple purposes.

"These brain systems are also found in animals. For example, rats use them when they learn to navigate a maze," co-author Phillip Hamrick of Kent State University in Ohio said in a statement. "Whatever changes these systems might have undergone to support language, the fact that they play an important role in this critical human ability is quite remarkable."

Interestingly, results of this analysis showed that memorizing vocabulary words used in a language relied on declarative memory. However, grammar and syntax, which allow us to fluidly combine words into sentences that follow the rules of a language, relies more on procedural memory.

When acquiring their native language, children utilize procedural memory to master grammar and syntax without necessarily “knowing” the rules. However, when adults begin to learn a second language, grammatical rules are initially memorized using declarative memory. As would be expected, grammar and syntax switch to procedural memory systems at later stages of language acquisition as someone becomes more fluent.

"The findings have broad research, educational, and clinical implications" co-author Jarrad Lum of Deakin University in Melbourne, Australia said in a statement. 

The correlations of these two brain systems were extensive and found consistently across many languages (e.g., English, Finnish, French, and Japanese) and among many language tasks (e.g., reading, listening, and speaking). This suggests that the correlation between learning language and these two ancient brain systems is robust and reliable, according to the researchers.

"Our conclusion that language is learned in such ancient general-purpose systems contrasts with the long-standing theory that language depends on innately-specified language modules found only in humans," the study's senior investigator, Michael T. Ullman, professor of neuroscience at Georgetown University School of Medicine in Washington, D.C., said in a statement.

Declarative and Procedural Memory Use General-Purpose Learning Systems

Because I’ve been teaching people how to apply declarative and procedural memory systems to master sports performance for so many years, this study piqued my curiosity as a neuroscience-based coach. So, I reached out to Michael Ullman in an email yesterday to learn more about his team's research.

I wrote, “Your latest paper, 'Child First Language and Adult Second Language Are Both Tied to General-Purpose Learning Systems,' identifies that language is learned using two different brain circuits (declarative memory and procedural memory) that are not necessarily language specific and predate humans. Can you sum up the real-world significance of these findings for Psychology Today readers?"

Ullman responded via email: "We know much more about certain aspects of the declarative and procedural memory systems than about language, including not only the genetics and biology of these systems and how they actually learn, but also how learning in the systems can be enhanced. Now that evidence suggests that language is indeed learned in these two systems, what we know about the systems should also apply to language.

Most importantly for real-world applications, we know a fair bit about how learning and retaining information and skills in the two systems can be enhanced. For example, pharmacological agents such as memantine, or behavioral approaches such as presenting information so it's spaced out over time, have been shown to improve learning or retention in declarative memory.

Since we've presented evidence that both the words and grammar of a language can be learned in declarative memory, these techniques may also be effective for enhancing language learning in this system, both for second (foreign) language learners, and to improve language problems in disorders such as aphasia, dyslexia, and autism. So our findings could help people trying to learn a second language, and help people with such disorders."

Huge thanks to Karen Teber, Senior Director of Strategic Communications at Georgetown University Medical Center, and Michael Ullman for your quick and thorough response to my inquiries. Much appreciated!

References

Phillip Hamrick, Jarrad Lum, Michael T. Ullman. “Child First Language and Adult Second Language Are Both Tied to General-Purpose Learning Systems” PNAS (Published online ahead of print: January 29, 2018) DOI: 10.1073/pnas.1713975115   

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