What impact do perinatal lesions have on word learning?

Learning new words is a crucial milestone in child development, but for some children this process can be particularly challenging. This is the case for children who have suffered a perinatal stroke, a brain injury occurring before, during, or shortly after birth, a rare condition but one with significant impact on the developing brain. To understand how such early lesions influence language acquisition, a team led by Clément François and Antoni Rodriguez‑Fornells closely examined how 3.5‑year‑old children learn and recall new words.

The researchers used a classical fast‑mapping task: first, the children had to associate a novel word with an unfamiliar object; then, they were assessed on their ability to recall this association immediately and again a few minutes later. The result was clear: children with perinatal lesions correctly identified the object associated with a new word, just like their peers without lesions, but they had much more difficulty recalling it after some time had passed.

This dissociation is important. It shows that the difficulty does not lie in the learning process itself but rather in retaining the information over time. In other words, these children are able to learn a new word but struggle to consolidate it in memory, a key step for vocabulary to grow consistently. This difficulty appeared particularly among children with left‑hemisphere lesions, precisely where neural pathways crucial for acquiring and consolidating new words, such as the arcuate fasciculus, are located.

Taken together, the study reveals that the language deficits associated with perinatal stroke may be linked to limitations in memory mechanisms rather than to disruptions exclusively within the classical language network. This opens the door to more targeted interventions focused on strengthening verbal memory retention and consolidation, using strategies such as enhanced repetition, multimodal exposure, and practices that support the stabilisation of new learning.

By providing a clearer picture of how the injured brain learns, this work offers valuable insights for supporting the linguistic development of children who face challenges from the very beginning of life, and reminds us of both the remarkable plasticity and the vulnerability of the developing brain. This study was published in the scientific journal Brain and Language, in the article Evidence for a role of memory in novel word-learning after perinatal stroke, as a part of research project 244/14 - Induced brain plasticity after perinatal stroke: Structural and functional connectivity, supported by the Bial Foundation.

ABSTRACT

Children with left perinatal arterial ischemic stroke (PAIS) often exhibit language deficits. However, evaluations of learning abilities are scarce. We compared word-referent associative learning and recall performance using a fast-mapping paradigm in a group of 3.5-year-old children with PAIS and in age-matched controls. The task involved a referent selection phase followed by immediate and delayed recall trials of the novel word-object associations. While no between-group differences were observed in the referent selection and immediate recall, children with PAIS showed lower performance in delayed recall of the newly learned associations. These results suggest that word learning difficulties after PAIS may arise due to a memory retention failure rather than to the process of referent selection through disambiguation involved in the fast mapping task. We discuss these findings in relation to the neural bases of infant language acquisition and their implications for clinical practice, particularly in terms of improving lexical acquisition and retention in children with PAIS.