Presentation
Search Abstracts | Symposia | Slide Sessions | Poster Sessions | Poster Slams
A polysomnographic study of speech-sound memory consolidation in individuals with and without DLD
Poster C24 in Poster Session C, Friday, October 7, 10:15 am - 12:00 pm EDT, Millennium Hall
Rahulkrishna Gurram Thimmugari1, Anne L. van Zelst1, F. Sayako Earle1; 1University of Delaware
Developmental Language Disorder (DLD) is a prevalent, specific learning disability relating to problems with language comprehension and expression beginning in childhood and that cannot be attributed to some other primary condition (Bishop et al., 2017). Prior work has suggested that a period spent in sleep benefits the learning of new speech–sound categories in typical adults (TD) but not in adults with developmental language disorder (DLD) (Earle & Myers, 2015a, 2015b; Earle, Landi & Myers, 2017; 2018). Despite these findings, it remains unclear whether this discrepancy is due to differences in memory consolidation processes that occur during sleep, or if it is epiphenomenal to other factors such as offline time spent in wakeful rest or diurnal effects. To address this, we investigated the effects of a daytime nap on the consolidation of speech-perceptual information in adults with DLD and typical (TD) adults. Twenty-seven native speakers of American English (age 18-25; 10 DLD, 17 TD) were trained to identify the Hindi dental-retroflex contrast. The study consisted of four phases, taking 5-hours in total: pre-nap training, nap, post-nap assessments, and language and reading assessment battery. Participants were fitted with a 32-channel EEG cap pre-positioned in the 10-20 electrode system, two EOG channels, three EMG channels placed on the chin, and two channels placed on each mastoid, as recommended for polysomnography (PSG) by the American Academy of Sleep Medicine (AASM, Berry et al., 2015). Participants were then provided an opportunity to nap for approximately 2.5 hours. PSG was recorded continuously throughout the nap sampling at 500 Hz. later. After removing the cap and electrodes, participants took the post-nap assessment and were administered the language assessment battery used for participant classification (DLD vs. TD). Perceptual performance (discrimination and identification tasks) of the target speech-sound contrast were first converted to d’ scores (MacMillan & Creelman, 2005). PSG recordings were staged via consensus scoring by trained undergraduate research students. EEG signals were segmented to epochs of N2 and SWS sleep and then filtered to retain frequencies representative of sleep spindles (8-16Hz). We are in the process of identifying using a continuous (Morelet) wavelet transform with individual thresholds set to detect visually identified spindles with 95% reliability for the first 10 epochs (Tsanas & Clifford, 2015). Preliminary analyses of our behavioral data suggest that while TD adults improve in performance following a daytime nap, t(16)=3.56, p=.003, adults with DLD do not, t(9)=1.04, p=.323. These results resonate with prior findings of an overnight consolidation deficit for speech-sound learning in individuals with DLD (Earle, Landi, Myers, 2018). We will present the potential sleep mechanisms underlying this behavior by examining group differences in sleep architecture, spindle count, and spectral power.
Topic Areas: Speech Perception, Disorders: Developmental