Department of Hearing & Speech Sciences, Vanderbilt University Medical Center, USA; Department of Medicine, Division of General Internal Medicine & Public Health, Vanderbilt University Medical Center, USA; Center for Health Behavior and Health Education, Vanderbilt University Medical Center, USA.
Department of Medicine, Division of General Internal Medicine & Public Health, Vanderbilt University Medical Center, USA; Center for Health Behavior and Health Education, Vanderbilt University Medical Center, USA.
Neuropsychologia. 2023 Jun 6;184:108518. doi: 10.1016/j.neuropsychologia.2023.108518. Epub 2023 Feb 16.
Word learning is an iterative and dynamic process supported by multiple neural and cognitive systems. Converging evidence from behavioral, cellular, and systems neuroscience highlights sleep as an important support for memory and word learning over time. In many lab-based word learning experiments, participants encode and subsequently retrieve newly learned words in a single session. These designs are inadequate to capture the full dynamic word learning process, making them less ecologically valid. Single timepoint studies also limit investigation of the role of behavioral and lifestyle factors, like sleep, in supporting word learning over time. Adults with a history of traumatic brain injury (TBI), who commonly exhibit deficits in the memory systems that support word learning and report concomitant sleep disturbance, provide a unique opportunity to examine the link between memory, sleep, and word learning. Here we examined word learning over time and the influence of sleep on short- and long-term word recall in 50 adults with chronic moderate-severe TBI and 50 demographically matched neurotypical peers. We used a randomized within-participant crossover design to assess immediate encoding of new words and the consolidation of those words over time across intervals that did or did not involve sleep. Participants completed this study over the course of two weeks in their own homes to capture the iterative, dynamic process of real-world word learning. We also measured sleep in free living conditions using actigraphy throughout the experiment. Participants with TBI exhibited a word learning deficit that began at encoding and persisted across time. Critically, this deficit grew over the course of the week. The performance gap between groups was larger at the 1-week post-test than the immediate post-test, suggesting deficits in both encoding and consolidation of new words in individuals with TBI. Participants with and without TBI remembered more words when they slept after learning. Ecologically valid research designs that examine the relationship between memory, sleep, and word learning over time promise to advance mechanistic accounts of word learning and improve the long-term retention of new words in individuals with and without brain injury.
词汇学习是一个由多个神经认知系统支持的迭代和动态过程。来自行为、细胞和系统神经科学的综合证据强调了睡眠作为记忆和词汇学习随时间推移的重要支持。在许多基于实验室的词汇学习实验中，参与者在单个会话中编码并随后检索新学习的单词。这些设计不足以捕捉完整的动态词汇学习过程，因此不太具有生态有效性。单点研究也限制了对行为和生活方式因素（如睡眠）在支持随时间推移的词汇学习中的作用的研究。有创伤性脑损伤 (TBI) 病史的成年人经常表现出支持词汇学习的记忆系统缺陷，并报告伴随的睡眠障碍，为研究记忆、睡眠和词汇学习之间的联系提供了独特的机会。在这里，我们研究了随时间推移的词汇学习以及睡眠对 50 名慢性中度至重度 TBI 成年人和 50 名年龄匹配的神经典型同龄人短期和长期单词回忆的影响。我们使用随机参与者内交叉设计来评估新单词的即时编码以及在涉及或不涉及睡眠的时间段内随时间推移对这些单词的巩固。参与者在自己的家中分两周完成这项研究，以捕捉现实世界词汇学习的迭代、动态过程。我们还在整个实验过程中使用活动记录仪在自由生活条件下测量睡眠。TBI 参与者表现出从编码开始并随时间推移持续存在的词汇学习缺陷。至关重要的是，这种缺陷在一周内逐渐加剧。与即时后测相比，两组之间的表现差距在 1 周后测更大，这表明 TBI 个体的新单词编码和巩固都存在缺陷。在学习后睡觉的参与者记住了更多的单词。具有生态有效性的研究设计，可随时间研究记忆、睡眠和词汇学习之间的关系，有望推进词汇学习的机制解释，并提高有和无脑损伤个体对新单词的长期保留。
