“Highways” in the Brain Help Young Children Form Plurals

The maturation of neural pathways in the brain is linked to children’s ability to form the plural of words 

To the Point

• Plural formation: Young children learn how to form plural forms, but they often make mistakes in the process. For example, they say “Hundes” instead of “Hunde.”
• Study: Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences are investigating how neural pathways in the brain influence plural formation.
• Neural connections: The arcuate fasciculus connects key brain regions responsible for grammar and word meaning. These connections do not mature until later in life.
• Results: In three-year-olds, there was no correlation between neural maturation and plural formation. In four- and five-year-olds, however, it was found that better connectivity of the neural pathways led to more accurate plural formation.

“In adults, we know that very specific nerve fiber connections in the brain are responsible for this,” explains lead author Cheslie C. Klein. “Like highways, they ensure that information travels at lightning speed from one brain region to another, where it can be processed together to form language. The so-called arcuate fascicle plays a key role in this process. It connects the grammar center in the frontal lobe with the temporal lobe, where words and their meanings are integrated with the relevant grammatical rules. Since this connection doesn’t fully mature until relatively late in life, we wanted to find out in our study: Does this neural highway already play a role in the young brain, enabling preschool-aged children to learn the plural forms of words?”

For their study, the researchers examined a total of 120 children aged three to five. To test how well the children could already form plurals, they played fun language games. During these games, the children were shown pictures of single objects or groups (for example, several dogs) and were asked what they could see. Cheslie C. Klein explains: “The key point here is that the children were shown words they already knew, but also completely made-up words—such as a ‘wug.’ This allowed us to check whether the children truly had the plural rule in mind and could apply it to the new words—‘two wugs’—rather than just repeating familiar words by heart.”

In addition, the researchers used magnetic resonance imaging (MRI) to examine the neural connections in the brain. They wanted to know: Is the maturity of these “highways” directly related to how well a child has already mastered the plural rules? “Our findings reveal an intriguing shift in development between the ages of three and four,” explains Charlotte Grosse Wiesmann, head of the research group “Milestones in Early Cognitive Development”. “While no direct correlation between the maturity of the arcuate fascicle and the ability to form plurals was observed in three-year-olds, this changed significantly in four- and five-year-olds. Here, the maturity of this nerve fiber tract was directly correlated with the correct application of plural rules. This means that the better connected this ‘highway’ was, the more confidently the children could apply the rules.”

Last author Angela D. Friederici adds: “Unlike in adults, in preschool children, not only was the part of the arcuate fascicle leading to the language center in the frontal lobe important, but also the part extending into the so-called premotor cortex. In adults, this area is actually more responsible for hearing and repeating words—a skill that may also have helped them imitate the plural form of words rather than deducing it based on abstract grammatical rules. The results thus help us understand how children can seemingly effortlessly reach the milestone of transforming ‘Hund’ into ‘Hunde’”.