Stable organization of the early lexical-semantic network in 18- and 24-month-old preterm and full-term infants: an eye-tracker study.

Introduction: An organized mental lexicon determines new information acquisition by orienting attention during language processing. Adult-like lexical-semantic knowledge organization has already been demonstrated in 24-month-olds. However, the outcomes of earlier studies have been contradictory in terms of the organizational capacities of 18-month-olds, thus our aim was to examine lexical-semantic organization in this younger age group. In prematurely born infants, audiovisual integration deficits have been found alongside disruptions in language perception. By including late preterm infants with corrected ages in our study, we aimed to test whether maturational differences influence lexical-semantic organization when vocabulary is growing rapidly. Methods: We tested 47 late preterm and full-term 18- and 24-month-old infants by means of an infant-adapted target-absent task using a slightly modified version of the original visual world paradigm for eye tracker. Results: We found a longer fixation duration for the lexical and semantic distractors compared to the neutral pictures. Neither language proficiency nor age affected the looking time results. We found a dissociation by age between taxonomic and associative semantic relations. Maturational differences were detectable in the initial processing of taxonomic relations, as processing in the preterm group was slightly delayed and qualitatively different in the first half of the looking time. The size and composition of the expressive vocabulary differed only by age. Discussion: In general, our study demonstrated a stable lexical-semantic organization between 18 and 24 months of age, regardless of maturational differences.

The retention of proprioceptive information is suppressed by competing verbal and spatial task.

Proprioceptive information makes us able to perceive the position of our joints from an internal point of view. In the certain cases, proprioceptive information has to be stored in short-term memory, for example, during the learning of new motor skills or the assessment of proprioceptive accuracy. However, there are contradictory findings about the modality-specific storage of proprioceptive information in working memory. In this preregistered study, we applied the interference paradigm, assessing proprioceptive memory capacity in the subdominant elbow joint for 35 young individuals in five different experimental conditions: (a) without competing task/interference (baseline condition), (b) with motor interference, (c) with spatial interference, (d) with visual interference, and (e) with verbal interference. Proprioceptive span was lower in the verbal and spatial interference condition than in the baseline condition, whereas no significant differences were found for the motor and visual conditions. These results indicate that individuals use verbal and spatial strategies to encode proprioceptive information in short-term memory, and, in contrast to our expectation, the motor subsystem of working memory is not substantially involved in this process.

Disrupted or delayed? Stress discrimination among preterm as compared to full-term infants during the first year of life.

BACKGROUND: Several papers pointed out that the language disorders are the most commonly reported cognitive deficits of the preterm (PT) infants. However, neither the exact interpretation (disrupted or delayed) of their language development nor the most powerful perinatal risk factors have been specified yet. AIMS: We aimed to determine whether postnatal development of prosodic processing of PT infants is disrupted or delayed in the first year of life? We also tested the role of Birth Weight (BW) and Gestational Age (GA) regarding the PT and full-term (FT) infants' language perception. METHOD: We registered the mismatch responses (MMR) of 34 PT (at 6 and 12 month of ages) and 33 FT infants (at 4 and 10 month of age) elicited by bisyllabic pseudo-words in two oddball conditions. RESULT: Contrary to their FT peers, younger PT group detected stress changes of the legal stress form only. Analogously, a positive MMR (P-MMR) was found for the legal form discrimination exclusively in PT12 group. Furthermore, the lack of sensitivity to the standard vs. deviant difference was identified in the PT infants. In PT infants, BW explained 21 % of the total variance of the P-MMR. CONCLUSION: Consequently, we argue that the stress sensitivity of the PT infants is unimpaired, but their stress processing seems to be disrupted from the 6th month on. We suggest for further studies to take BW into account in studies using MMR paradigms in PT infants.

The effect of lexical status on prosodic processing in infants learning a fixed stress language.

In speech processing, in the first year of life, prosody and phoneme-relevant aspects serve different functions. Recent studies have assumed that the two aspects become integrated at around 9 months of age. The present study investigates the effect of lexical status on stress processing in a fixed stress language. We hypothesize that lexicality modulates stress processing, and where the stress cue is in conflict with the lexical status (legal deviant condition), we will observe differences in age indicating the stage of integration. We tested 69 6 and 10 month-old infants in an acoustic oddball event-related potential paradigm. A frequent word stimulus (baba) and a pseudoword (bebe) were used with legal versus illegal stress. We systematically swapped the standard and deviant roles of the different stress variants in two conditions. In the illegal deviant condition in the case of the word stimulus, the response pattern typical for the pseudoword (an MMR to the absence of the stress cue) was missing. This implies the suppression effect of lexicality. In the legal deviant condition, negative MMR (N-MMR) in the second time window indicated a facilitation effect of lexicality in both age groups. As only the 6-month-olds produced an N-MMR in the first time window, we concluded that in a fixed stress language, integration starts at 6 months but is only completed by the age of 10 months. Our results show that lexical status modulates stress processing at word level in a highly regularly stressed language in which stable, long-term language-specific stress representation exists from early infancy.

Short-term retention of proprioceptive information.

The Joint Position Reproduction test (JPR), one of the most widely used measurements to estimate proprioceptive accuracy, requires the short term storage of proprioceptive information. It has been suggested that visuospatial sketchpad plays a fundamental role in the memorization of proprioceptive information. The current study aimed to investigate this assumption. To do so, we developed and used a novel JPR protocol to measure the retention capacity with respect to sequences of different positions. Our goal was to develop the original task further to make it comparable with other widely used short-term memory measurements, in which the memory capacity was determined by the number of the items participants retain (memory span). We compared participants' (N=39) performance in this task to that of results of Corsi block-tapping task (capacity of the visuospatial sketchpad) and Digit span task (capacity of the phonological loop). Proprioceptive memory capacity did not correlate either with spatial or verbal memory capacity. The exploratory analysis revealed that proprioceptive span correlated positively with the performance if 5 joint positions had to be retained. Further associations with verbal span for 6 or 7 positions, and spatial span for 5 positions were found. Our findings do not support the idea that visuospatial sketchpad plays a fundamental role in the storage of proprioceptive information. The independence of span measures indicates that proprioceptive information might be stored in a subsystem independent of the visuospatial sketchpad or phonological loop.

Does intra-uterine language experience modulate word stress processing? An ERP study.

BACKGROUND: Preterm birth is associated with various risks, including delayed or atypical language development. The prenatal start of prosodic tuning may affect the processing of word stress, an important suprasegmental feature of spoken utterances. AIM: Our study focused on the expected contribution of intra-uterine experience to word stress processing. We aimed to demonstrate the hypothesized effect of intra-uterine sound exposition on stress sensitivity. METHOD: We recorded ERP responses of 34 preterm infants elicited by bisyllabic pseudo-words in two oddball conditions by switching the stress pattern (legal vs. illegal) and role (standard vs. deviant). RESULTS: The mismatch responses found were synchronized to each syllable of the illegally stressed stimuli with no difference between pre- and full-term infants. However, the clear role of the preterm status was demonstrated by the exaggerated processing of the native stress information. The impact of intra-uterine exposure to prosody was confirmed by our finding that moderate-late preterm infants outperformed the very preterm ones. CONCLUSION: Intra-uterine exposition to prosodic features appears to contribute to the emergence of stable long-term stress representation. When this tuning is missing it is considered a risk for the language acquisition process.

Lexical influence on stress processing in a fixed-stress language.

In the present study, we investigate how lexicality affects the processing of suprasegmental features at the word level. In contrast to earlier studies which analyzed the role of either segmental or suprasegmental feature in language processing our aim was to investigate the effect of the lexical status on the processing of violated stress pattern defined by linguistic rules. We have conducted a passive oddball ERP experiment, presenting a frequent CVCV word with legal (familiar) and illegal (unfamiliar) stress patterns. Former results obtained with pseudo-words in a similar paradigm enabled to assess the influence of lexical information on stress processing. The presence of lexically relevant information resulted in different ERP patterns compared to those obtained with pseudo-words. We obtained two consecutive MMN responses to the illegally stressed words while violating the illegal stress pattern with a legal one the deviant stimulus elicited two consecutive MMN responses as well. In the latter condition lexicality clearly enhanced the comparison of prosodic information between standard and deviant stimuli, as these components very completely missing when presenting pseudo-words. We interpret the results that lexicality acts as a filter since in the absence of lexical familiarity unfamiliar stress patterns are discriminated better. Our results highlight that even when stress is fully predictable, it is taken into account during pre-attentive processing of linguistic input.

Suprasegmental speech cues are automatically processed by the human brain: a mismatch negativity study.

This study investigates the electrical brain activity correlates of the automatic detection of suprasegmental and local speech cues by using a passive oddball paradigm, in which the standard Hungarian word 'banán' ('banana' in English) was contrasted with two deviants: a voiceless phoneme deviant ('panán'), and a stress deviant, where the stress was on the second syllable, instead of the obligatory first one. As a result, we obtained the mismatch negativity component (MMN) of event-related brain potentials in each condition. The stress deviant elicited two MMNs: one as a response to the lack of stress as compared to the standard stimulus, and another to the additional stress. Our results support that the MMN is as valuable in investigating processing characteristics of suprasegmental features as in that of phonemic features. MMN data may provide further insight into pre-attentive processes contributing to spoken word recognition.

Effect of maturation on suprasegmental speech processing in full- and preterm infants: a mismatch negativity study.

Infants born prematurely are at higher risk for later linguistic deficits present in delayed or atypical processing of phonetic and prosodic information. In order to be able to specify the nature of this atypical development, it is important to investigate the role of early experience in language perception. According to the concept of Gonzalez-Gomez and Nazzi (2012) there is a special intrauterine sensitivity to the prosodic features of languages that should have a special role in language acquisition. Therefore, we may also assume that pre- and full-term infants having months difference in intrauterine experience show different maturation patterns of processing prosodic and phonetic information present at word level. The aim of our study was to investigate the effect of these differences on word stress pattern vs. phoneme information processing. Two age groups of infants (6 and 10 month-olds) were included in our study. 21 of 46 of the total of infants investigated were prematurely born with low birth weight. We used the mismatch negativity (MMN) event related brain potential (ERP) component, a widely used electrophysiological correlate of acoustic change detection, for testing the assumed developmental changes of phoneme and word stress discrimination. In a passive oddball paradigm we used a word as standard, a pseudo-word as phoneme deviant, and an illegally uttered word as stress deviant. Our results showed no differences in MMN responses in the phoneme deviant condition between the groups, meaning a relatively intact maturation of phoneme processing of preterm infants as compared to their contemporaries. However, the mismatch responses measured in the stress condition revealed significant between-group differences. These results strengthen the view that the total length of intrauterine experience influences the time of emergence of prosodic processing.