Search Abstracts | Symposia | Slide Sessions | Poster Sessions
Age-related time-of-day effect on sleep-dependent memory consolidation in language learning: behavioral and fMRI evidence
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Xier Zhao1, Cai Qing1; 1East China Normal University,Shanghai, China
Language learning abilities sharply decline after puberty (Hartshorne et al., 2018), a crucial stage marked by profound neurobiological and hormonal changes (Blakemore & Mills, 2014; Laube et al., 2020). The developmental changes may alter post-learning consolidation process, potentially contributing to age-related differences in language acquisition. Recent studies have shown that adults’ linguistic learning heavily relies on sleep-dependent off-line memory consolidation (Ben-Zion et al., 2022), particularly on the interval between learning and sleep (i.e., the time-of-day effect). Therefore, the present study focuses on the time-of-day effect across pre-pubertal, pubertal and post-pubertal groups to investigate whether language learning undergoes a developmental shift toward greater reliance on sleep-dependent memory consolidation. Additionally, fMRI was used to characterize neural activations associated with the time-of-day effect of language consolidation.An artificial language learning paradigm (Friederici et al., 2002) was employed to assess multiple linguistic domains, involving semantic, syntactic and articulatory performances. To manipulate the interval between learning and sleep, participants were assigned to either morning- or night-training groups. Sixty-eight adults (18-28 years) and 30 adolescents (both prepuberty and puberty, 11-18 years) completed two behavioral assessments separated by 24 hours, involving sentence production in a board game setting. To trace consolidation-related neural dynamics, a subgroup of adult participants additionally underwent multiple fMRI scans during the two days. For each scan, participants completed a comprehension task (i.e., sentence imagery) and an overt production task. Behavioral accuracy changes across two days were analyzed using linear models with age group, training time group, and their interaction as fixed effects. Overall accuracy showed a significant main effect of training group, with adults in the night-training exhibiting greater overnight improvement than those in the morning-training, t(64.64) = -2.23, p = .03. The accuracy changes on grammatical level, a significant age × training time group interaction was observed, F(1, 64.71) = 7.17, p = .001, driven by greater gains in adults trained at night, t(64.71) = -2.49, p = .02. These findings suggest that the time-of-day effect on offline language consolidation becomes more pronounced after puberty. Across three fMRI sessions, neural changes associated with sleep-dependent consolidation emerged in frontoparietal language regions (e.g., left frontal gyrus and left supramarginal gyrus, across both language tasks (cluster-level FDR-corrected at p < .05). Importantly, distinct neural changes across training groups were specifically occurred during off-line consolidation (T2>T1). In the language comprehension task, morning-training participants showed greater activation in visual regions (e.g., cuneus, right inferior temporal gyrus) and cognitive control regions (e.g., middle cingulate cortex), reflecting greater recruitment on perceptual reinstatement and effortful control during language comprehension. In the language production task, night group showed more recruitment in speech motor and language processing areas, involving precentral gyrus, postcentral gyrus, left inferior frontal gyrus and middle frontal gyrus, aligning with greater behavioral off-line gains in sentence production. Together, these findings suggest that time-of-day effect in language consolidation becomes more important after puberty and is accompanied by distinct reorganization of language-related neural systems.
Topic Areas: Language Development/Acquisition, Language Production