A Matter of Time: A Web-Based Investigation of Rest and Sleep Effects on Speech Motor Learning.

PURPOSE: Here, we examine the possibility that memory consolidation during a period of postpractice rest or nocturnal sleep can bolster speech motor learning in the absence of additional practice or effort. METHOD: Using web-administered experiments, 74 typical, American English talkers trained in a nonnative vowel contrast then had a 12-hr delay with (SLEEP) or without nocturnal sleep (REST) or proceeded immediately (IMMEDIATE) to a posttraining production assessment. For ecological validity, 51 native Danish talkers perceptually identified the American English talkers' productions. RESULTS: We observed that practice resulted in productions that were more acoustically similar to the Danish target. In addition, we found that rest in the absence of further practice reduced the token-to-token variability of the productions. Last, for vowels produced immediately following training, listeners more accurately identified vowels in the trained context, whereas in the untrained context, listener accuracy improved only for vowels produced by talkers who slept. CONCLUSIONS: A single session of speech motor training promotes observable change to speech production behavior. Specifically, practice facilitates acoustic similarity to the target. Moreover, although a 12-hr postpractice period of rest appears to promote productions that are less variable, only the productions of those who slept are perceived as more accurate by listeners. This may point to sleep's role in contextualizing the acoustic goal of the production to the learner's own vocal tract and its role as a protective mechanism during learning. These results are unaccounted for under existing models and offer potential for future educational and clinical applications to maximize speech motor learning. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.24707442.

Overnight consolidation of speech sounds predicts decoding ability in skilled adult readers.

PURPOSE: Phonological representations are important for reading. In the current work, we examine the relationship between speech-perceptual memory encoding and consolidation to reading ability in skilled adult readers. METHOD: Seventy-three young adults (age 18-24) were first tested in their word and nonword reading ability, and then trained in the late evening to identify an unfamiliar speech sound contrast (Hindi retroflex-dental). Participants were assessed in their ability to perceive the target contrast immediately before training, after training, and 12 hours later. RESULTS: While perceptual performance on the target at any time point was unassociated with reading ability, overnight changes to the post-training perceptual ability over the 12-hour delay was significantly associated with nonword reading (i.e. decoding) ability, but not real-word reading. CONCLUSION: These results provide preliminary support for the hypothesis that individual differences in memory processes that update phonological representations following acoustic-phonetic exposure relate to decoding performance, including in adulthood.

Overnight changes to dual-memory processes reflected in speech-perceptual performance.

Adults' ability to attain and retain nonnative speech sound categories vary substantially among individuals. While we know that speech-perceptual skills play a role, we know less about how consolidation-related changes in acoustic-phonetic memory contribute to perceptual tasks. The goal of this investigation was to examine contributions of memory and perceptual skills to the perceptual performance on a trained nonnative speech contrast over two days. Twenty-one adult participants (ages 18-24) completed four different experiments. Three of these assessed learning and memory: visual statistical learning (implicit), visual object recognition (explicit), and nonnative (Hindi dental-retroflex) speech-sound training. Participants completed the learning tasks around 8 p.m., and performance was measured shortly after learning and again 12 hours later. On a separate day, participants completed a categorical perception task on a native (/a/-/e/) vowel continuum. Nonnative speech perception was associated with implicit learning performance when both were assessed shortly after learning, and associated with the retention of explicit memory when both were assessed after an overnight delay. Native speech-sounds were at least marginally associated with nonnative speech perception performance on both days, but with a stronger association observed with performance assessed on Day 2. These findings provide preliminary support for the interpretation that speech-sounds are encoded by at least two memory systems in parallel, but that perceptual performance may reflect acoustic-phonetic knowledge learned by different memory systems over time since exposure. Moreover, performance on speech perception tasks in both native and nonnative speech-sounds may rely on similar retrieval mechanisms for long-term storage of speech-sound information.

Sufficient sleep attenuates COVID-19 pandemic-related executive dysfunction in late adolescents and young adults.

PURPOSE: To investigate the interaction between (1) sleep and the COVID-19 pandemic; and (2) social cumulative risk and COVID-19 pandemic on executive function (EF). METHODS: Forty late adolescents/young adults (19.25 ± 1.12 y.o.) completed sleep questionnaires and the Behavior Rating Inventory of Executive Function- Adults (BRIEF-A) before and during the COVID-19 pandemic, yielding 80 observations for data analysis. Multilevel random-effects models with interaction terms were used to estimate the associations. RESULTS: Compared to pre-pandemic sleep, participants slept 24 min longer (t = -2.07, p = 0.03) and also had increased sleep latency (t = -1.83, p = 0.07) during COVID-19. Mid-sleep times shifted 40 min later (t = -3.22, p = 0.003), and BRIEF-A scores increased (indicating greater dysfunction), during the pandemic (p < 0.05). The worsening in EF during the pandemic was attenuated by increasing sleep duration (B = -4.38, p = 0.04) and magnified by social cumulative risk (B = 3.19, p = 0.04). Poor sleep quality was independently associated with increase in EF problems (p < 0.05). CONCLUSION: Sufficient sleep may represent a resilience factor against EF decline during this unprecedented crisis.

Declarative Memory Predicts Phonological Processing Abilities in Adulthood.

Individual differences in phonological processing abilities have often been attributed to perceptual factors, rather than to factors relating to learning and memory. Here, we consider the contribution of individual differences in declarative and procedural memory to phonological processing performance in adulthood. We examined the phonological processing, declarative memory, and procedural memory abilities of 79 native English-speaking young adults with typical language and reading abilities. Declarative memory was assessed with a recognition memory task of real and made-up objects. Procedural memory was assessed with a serial reaction time task. For both tasks, learning was assessed shortly after encoding, and again after a 12-h, overnight delay. We regressed phonological processing ability with memory performance on both days. We found that declarative memory, but not procedural memory, was highly predictive of phonological processing abilities. Specifically, declarative memory scores obtained shortly after learning were associated with non-word repetition performance, whereas declarative memory scores obtained after the overnight delay were associated with phonological awareness. Procedural memory was not associated with either of the phonological processing measures. We discuss these findings in the context of adult participants with mature phonological systems. We examine possible implications for the relationship between declarative memory and phonological processing in adulthood.

Deficits of Learning in Procedural Memory and Consolidation in Declarative Memory in Adults With Developmental Language Disorder.

Purpose This study examined procedural and declarative learning and consolidation abilities in adults with developmental language disorder (DLD) relative to their typical language (TD) peers. Method A total of 100 young adults (age 18-24 years) with (n = 21) and without (n = 79) DLD participated across two sites. Performance measures on a recognition memory task and a serial reaction time task were used to assess declarative and procedural memory, respectively. Performance was measured shortly after learning (8 a.m.) and again after a 12-hr, overnight delay (8 a.m.). Results Linear mixed-effects modeling was used to examine the effects of time and group membership on task performance. For the serial reaction time task, there were significant effects of group (TD > DLD) and time (Day 1 > Day 2), but no interaction between them. For the recognition memory task, there was a significant interaction between group and time, driven by overnight gains in the TD group, combined with stable performance across days by those with DLD. Conclusions In procedural memory, adults with DLD demonstrate a learning deficit relative to adults without DLD, but appear to have comparable retention of learned information. In declarative memory, adults with DLD demonstrate a deficit in the overnight enhancement of memory retrieval, despite typical-like learning exhibited when tested shortly after encoding. Supplemental Material https://doi.org/10.23641/asha.13626485.

Literacy-supporting skills in college students with specific reading comprehension deficit and developmental language disorder.

Specific reading comprehension deficit (S-RCD) and developmental language disorder (DLD) are both commonly occurring developmental disorders of language. The ways in which these disorders do and do not overlap during childhood are a matter of debate (Nation & Norbury, 2005). Moreover, in both populations, the challenges faced by individuals in adulthood are understudied. Here, we combined data across cohorts of college students, and classified individuals with only S-RCD (n = 20), only DLD (n = 55), and co-occurring S-RCD and DLD (n = 13). Individuals with good language and reading skills, who matched those with S-RCD on decoding, comprised our typical language and reading group (TD; n = 20). Beyond the measures used for classification, group-level differences were identified in sentence-level reading fluency, phonological processing, verbal working memory, and rapid automatized naming. We found that skill profiles differed across groups; however, we found no evidence of weaknesses beyond the core deficit in reading comprehension observed in those with only S-RCD. In contrast, when S-RCD co-occurs with DLD, weaknesses are observed in phonological processing, as well as reading fluency and verbal working memory. These findings suggest that some adults with S-RCD have co-occurring DLD as a core weakness. These findings, as well as differences between individuals with S-RCD and DLD, are further discussed.

A case for the role of memory consolidation in speech-motor learning.

This review will explore the role of memory consolidation in speech-motor learning. Existing frameworks of speech-motor control account for the protracted time course of building the speech-motor representation. These perspectives converge on the speech-motor representation as a multimodal unit that is comprised of auditory, motor, and linguistic information. Less is known regarding the memory mechanisms that support the emergence of a generalized speech-motor unit from instances of speech production. Here, we consider the broader learning and memory consolidation literature and how it may apply to speech-motor learning. We discuss findings from relevant domains on the stabilization, enhancement, and generalization of learned information. Based on this literature, we provide our predictions for the division of labor between conscious and unconscious memory systems in speech-motor learning, and the subsequent effects of time and sleep to memory consolidation. We identify both the methodological challenges, as well as the practical importance, of advancing this work empirically. This discussion provides a foundation for building a memory-based framework for speech-motor learning.

Learning and Consolidation of Declarative Memory in Good and Poor Readers of English as a Second Language.

Declarative memory abilities may be important for children who are learning to read in a second language. In the present study, we investigated declarative memory in a recognition memory task in 7-to-13-year-old, Kannada native-speaking, good (n = 22) and poor (n = 22) readers of English, in Karnataka, India. Recognition memory was tested shortly (∼10 min) after encoding (day 1) and again on the next (day 2). Analyses revealed that the two groups did not differ in recognition memory performance on day 1. On day 2, the good readers improved from day 1, whereas poor readers did not. A partial correlation analysis suggests that consolidation - the change in performance in recognition memory between the 2 days - is associated with reading skills in good readers, but not in poor readers. Taken together, these results suggest that children who struggle to read in a second language may have deficits in declarative memory consolidation.

Skill Profiles of College Students With a History of Developmental Language Disorder and Developmental Dyslexia.

Developmental language disorder (DLD) and developmental dyslexia (DD) are two prevalent subtypes of Specific Learning Disabilities (SLDs; Diagnostic and Statistical Manual of Mental Disorders [5th ed.; DSM-5]). Yet, little information is available regarding the distinct challenges faced by adults with DLD and/or DD in college. The purpose of the present report is to characterize the relative strengths and challenges of college students with a history of DLD and/or DD, as this information is critical for providing appropriate institutional support. We examined the cognitive skill profiles of 352 college students (ages 18-35 years), using standardized and research-validated measures of reading, spoken language, nonverbal cognition, and self-reported childhood diagnostic history. We classified college students as having DLD (n = 50), and/or DD (n = 40), or as typically developed adults (n = 132) according to procedures described for adults with DLD and DD. A structural equation model determined the cognitive, language, and reading measures predicted by the classification group. Adults with DLD demonstrated poor verbal working memory and speeded sentence-level reading. Adults with DD primarily demonstrated deficits in phonology-based skills. These results indicate that adults with DLD and/or DD continue to face similar challenges as they did during childhood, and thus may benefit from differentially targeted accommodations in college.

The Neurocognition of Developmental Disorders of Language.

Developmental disorders of language include developmental language disorder, dyslexia, and motor-speech disorders such as articulation disorder and stuttering. These disorders have generally been explained by accounts that focus on their behavioral rather than neural characteristics; their processing rather than learning impairments; and each disorder separately rather than together, despite their commonalities and comorbidities. Here we update and review a unifying neurocognitive account-the Procedural circuit Deficit Hypothesis (PDH). The PDH posits that abnormalities of brain structures underlying procedural memory (learning and memory that rely on the basal ganglia and associated circuitry) can explain numerous brain and behavioral characteristics across learning and processing, in multiple disorders, including both commonalities and differences. We describe procedural memory, examine its role in various aspects of language, and then present the PDH and relevant evidence across language-related disorders. The PDH has substantial explanatory power, and both basic research and translational implications.

The impact of expressive language development and the left inferior longitudinal fasciculus on listening and reading comprehension.

BACKGROUND: During the first 3-years of life, as the brain undergoes dramatic growth, children begin to develop speech and language. Hallmarks of this progression are seen when children reach developmental milestones, forming the foundation of language. Expressive language milestones, such as the production of a child's first word, are delayed in 5-8% of children. While for some children delays in reaching these milestones are harbingers of developmental disorders, for others expressive language delays appear to resolve. Regardless of whether or not early language skills appear resolved, difficulty with later comprehension is a likely outcome. Whether this heightened risk for poor comprehension differs based on text features, individual characteristics, or receipt of intervention remains unknown. Moreover, this relationship between expressive language development and comprehension is not yet linked to neurobiology, though the inferior longitudinal fasciculus (ILF) is a potential neurobiological correlate. Therefore, we investigated the impact of, and interactions between, expressive language development, early intervention, and the ILF on comprehension. METHODS: Longitudinal recurrent survival analyses predicted the risk of answering a comprehension question incorrectly. Predictors of comprehension included expressive language development, passage features, participant characteristics, fractional anisotropy, receipt of early intervention, and later diagnosis of speech or language disorders. RESULTS: Children with later expressive language milestones had poorer comprehension. When comprehension text features were examined, children with later milestones had poorer listening and reading comprehension, and poorer narrative and expository comprehension. The left ILF acted as a neurodevelopmental correlate, one that moderated the relationship between expressive language milestones and comprehension. Specifically, the left ILF exacerbated the relationship for those who did not receive early intervention and buffered the relationship for those who received intervention services. Early intervention decreased the risk of poor comprehension by 39% for children later diagnosed with a speech or language disorder. CONCLUSIONS: Early intervention should be provided for children with delayed expressive language milestones, particularly those who are at risk for speech or language disorders. The ILF plays a critical role in the relationship between expressive language development and comprehension, which may be that of a protective factor for children with the most severe early issues with speech and language.

Sleep Facilitates Generalisation of Accent Adaptation to a New Talker.

Lexically-guided phonetic retuning helps listeners adapt to the phonetic "fingerprint" of a talker. Previous findings show that listeners can generalise from one accented talker to another accented talker, but only for phonetically similar talkers. We tested whether sleep-mediated consolidation promotes generalisation across accented talkers who are not phonetically similar. Native-English participants were trained on a Mandarin-accented talker and tested on this talker and an untrained Mandarin talker. Experiment 1 showed adaptation for the trained talker and a weak transfer to the untrained talker. In Experiment 2, participants were trained and tested either in the morning (Same-Day group) or evening (Overnight group), and again after twelve hours. Both groups retained talker-specific learning over the 12-hour delay. Importantly, the Overnight group showed improvements for the untrained talker, whereas the Same-Day group's performance on the untrained talker deteriorated. We suggest that sleep facilitated talker generalisation by helping listeners abstract away from specific acoustic properties of the trained talker.

Adults with Specific Language Impairment fail to consolidate speech sounds during sleep.

Specific Language Impairment (SLI) is a common learning disability that is associated with poor speech sound representations. These differences in representational quality are thought to impose a burden on spoken language processing. The underlying mechanism to account for impoverished speech sound representations remains in debate. Previous findings that implicate sleep as important for building speech representations, combined with reports of atypical sleep in SLI, motivate the current investigation into a potential consolidation mechanism as a source of impoverished representations in SLI. In the current study, we trained individuals with SLI on a new (nonnative) set of speech sounds, and tracked their perceptual accuracy and neural responses to these sounds over two days. Adults with SLI achieved comparable performance to typical controls during training, however demonstrated a distinct lack of overnight gains on the next day. We propose that those with SLI may be impaired in the consolidation of acoustic-phonetic information.

Native phonological processing abilities predict post-consolidation nonnative contrast learning in adults.

This study examined the relationship between native phonological processing ability and the learning outcome of a trained nonnative (Hindi /ɖ/ - / d̪/) contrast. Participants were perceptually trained and assessed in the evening, and reassessed early the next morning. Native phonological processing ability did not predict the learning of the nonnative contrasts on Day 1. However, after a period of post-training sleep, Blending ability predicted nonnative Discrimination performance, and Nonword Repetition predicted nonnative Identification. These findings may point to similarities between processes involved in maintaining native phonological representations and that in the retention of nonnative acoustic-phonetic features in adulthood.

Empirical Implications of Matching Children With Specific Language Impairment to Children With Typical Development on Nonverbal IQ.

This study determined the effect of matching children with specific language impairment (SLI) and their peers with typical development (TD) for nonverbal IQ on the IQ test scores of the resultant groups. Studies published between January 2000 and May 2012 reporting standard nonverbal IQ scores for SLI and age-matched TD controls were categorized into those that matched and did not match children with SLI and TD on nonverbal IQ. We then compared the nonverbal IQ scores across matching criterions within each diagnostic category. In studies that matched children on nonverbal IQ, children with SLI scored significantly higher on nonverbal IQ tests relative to children with SLI in studies that did not match on this criterion. Therefore, it appears that the nonverbal IQ performance of children with SLI is not comparable across studies that do and do not match samples on nonverbal IQ. This suggests that the practice of nonverbal IQ matching may have unintended consequences for the generalization of research findings to the broader SLI population.

Sleep duration predicts behavioral and neural differences in adult speech sound learning.

Sleep is important for memory consolidation and contributes to the formation of new perceptual categories. This study examined sleep as a source of variability in typical learners' ability to form new speech sound categories. We trained monolingual English speakers to identify a set of non-native speech sounds at 8PM, and assessed their ability to identify and discriminate between these sounds immediately after training, and at 8AM on the following day. We tracked sleep duration overnight, and found that light sleep duration predicted gains in identification performance, while total sleep duration predicted gains in discrimination ability. Participants obtained an average of less than 6h of sleep, pointing to the degree of sleep deprivation as a potential factor. Behavioral measures were associated with ERP indexes of neural sensitivity to the learned contrast. These results demonstrate that the relative success in forming new perceptual categories depends on the duration of post-training sleep.

Sleep and native language interference affect non-native speech sound learning.

Adults learning a new language are faced with a significant challenge: non-native speech sounds that are perceptually similar to sounds in one's native language can be very difficult to acquire. Sleep and native language interference, 2 factors that may help to explain this difficulty in acquisition, are addressed in 3 studies. Results of Experiment 1 showed that participants trained on a non-native contrast at night improved in discrimination 24 hr after training, while those trained in the morning showed no such improvement. Experiments 2 and 3 addressed the possibility that incidental exposure to perceptually similar native language speech sounds during the day interfered with maintenance in the morning group. Taken together, results show that the ultimate success of non-native speech sound learning depends not only on the similarity of learned sounds to the native language repertoire, but also to interference from native language sounds before sleep.