Early-life language deprivation affects specific neural mechanisms of semantic representations

Abstract

One signature of the human brain is its ability to derive knowledge from language inputs, in addition to nonlinguistic sensory channels such as vision and touch. How does human language experience specifically modulate the way in which semantic knowledge is stored in the human brain? We investigated this question using a unique early-life language-deprivation human model: early deaf adults who are born to hearing parents and thus had delayed acquisition of any natural human language (speech or sign), with early deaf adults who acquired sign language from birth as nonlinguistic sensory experience controls. Neural responses in a meaning judgment task with 90 written words that were familiar to both groups were measured using fMRI. The early language-deprived group, compared with the deaf control group, showed reduced semantic sensitivity, in both multivariate pattern (semantic structure encoding) and univariate (abstractness effect) analyses, in the left dorsal anterior temporal lobe (dATL). These results provide positive, causal evidence that the neural semantic representation in dATL is specifically supported by language, as a unique mechanism of representing (abstract) semantic space, beyond the sensory-derived semantic representations distributed in the other cortical regions.

Human‐specific insights into candidate genes and boosted discoveries of novel loci illuminate roles of neuroglia in reading disorders

“…In addition, expression of the candidate genes across human brain developmental stages highlighted distinct patterns in early brain development crucial to RD as previously predicted. 11 , 12 These together rendered new approaches to the assessments and discoveries of novel loci for RD.…”

“…2,20 We further showed that unlike those identified from family studies, the GWAS to RD as previously predicted. 11,12 These together rendered new approaches to the assessments and discoveries of novel loci for RD.…”

“…Indeed, there are many processes that had happened before RD becoming evident but were unaccounted for in the genetic association studies, particularly those in early cognition and language development in infancy 11,12 and early childhood 9 . Such processes each may involve complex gene–environment interactions and jointly form the so called development plasticity 12 .…”

“…6 However, genetic studies of RD so far have identified only a handful of candidate genes segregated in families and 42 loci from genomewide association study (GWAS) that jointly provided little clues of the pathophysiology of RD. 1,7,10 Indeed, there are many processes that had happened before RD becoming evident but were unaccounted for in the genetic association studies, particularly those in early cognition and language development in infancy 11,12 and early childhood. 9 Such processes each may involve complex gene-environment interactions and jointly form the so called development plasticity.…”

Social perception in deaf individuals: A meta‐analysis of neuroimaging studies

“…Deaf individuals typically rely on sign language, or hearing devices to interact with other people. Consistent evidence suggests that sign language supports the proper development of language brain circuits in deaf participants (for recent evidence, see Cheng et al, 2023; Wang et al, 2023) and sign language proficiency is associated with higher executive functions (e.g., performance in Go/no‐go task, Simon task; Kotowicz et al, 2023). Although it has been suggested that knowing sign language can help deaf individuals to feel comfortable and less stressed in social contexts (La Grutta et al, 2023), sign language can only be used with other signing individuals and hearing aids and cochlear implants (CIs) may not always work efficiently (e.g., Orji et al, 2020).…”