Elisabeth Glass’s research while affiliated with Ludwig-Maximilians-Universität in Munich and other places

Deficits in auditory short-term memory are thought to underlie developmental language disorders and dyslexia. There is, however, a lack of systematic studies of short-term memory in children at a young age. The aim of this study was to probe the duration of auditory sensory memory using objective methods in young children. 37 two-year-old and 52 six-year-old normally developing children were included in the study. Event-related potentials (ERPs) were elicited in a passive auditory oddball paradigm with variable interstimulus intervals (ISIs of 0.5-5 s, depending on the subgroup). For shorter ISIs, a prominent mismatch negativity (MMN) and late discriminative negativity (LDN) were found, while a distinct P3a occurred particularly for longer ISIs. Statistical significance was proven for the dependence of MMN and LDN amplitudes on the ISI. The change in the structure of the ERP components occurred at a longer ISI for the six-year-olds than for the 2-year-olds. The points where MMN and LDN disappear with increasing ISI suggest that the duration of auditory sensory memory lies between 1 and 2 s in two-year-old children and between 3 and 5 s in six-year-olds. The occurrence of a P3a beyond the point where MMN and LDN can no longer be elicited, however, provides evidence that several different mechanisms with different durations of memory representations are involved in short-term storage of auditory information.

Children with specific language impairment (SLI) experience great difficulties in language comprehension and/or production whereby the majority of these children have particular problems in acquiring syntactic rules. In the speech stream boundaries of major syntactic constituents are reliably marked by prosodic cues. Therefore, prosodic information provides an important cue for discovering the syntactic structure of a language [Jusczyk, P.W., 2002. How infants adapt speech-processing capacities to native language structure. Curr. Dir. Psychol. Sci. 11, 15-18.]. Following this, the question is, whether children with SLI differ in the processing of syntactic information from normally developing children and to what extent this is related to the processing of the inherent prosodic information. Children heard either correct sentences or sentences with a word category violation (syntactic level) and a joined prosodic incongruity (prosodic level) while event-related brain potentials (ERPs) were recorded. Judging the sentence's correctness, control children performed better than children with SLI for all types of sentences. With respect to the ERPs, control children showed a bilateral early starting anterior negativity sustaining into a late anterior negativity and a P600 in posterior regions in response to incorrect sentences. Children with SLI showed a comparable P600 but unlike the control children there was only a late, clearly left lateralized anterior negativity. The complete absence of a right anterior negativity in children with SLI suggests that they may not access prosodic information in the same way normal children do. The differences in prosodic processing may in turn hamper the development of syntactic processing skills as indicated by the absence of the syntax-related early left anterior negativity.

Fragestellung: Defizite im auditiven Kurzzeitgedachtnis werden als Ursache u. a. fur Sprachentwicklungs- und Lese-Rechtschreibstorungen diskutiert. Fur die ersten Lebensjahre fehlen bislang jedoch aussagefahige Untersuchungen zum Kurzzeitgedachtnis. Ziel der vorliegenden Studie war es, bei jungeren Kindern die Dauer des auditiven sensorischen Gedachtnisses mit objektiven Methoden zu bestimmen. Methodik: In Gruppen unauffallig entwickelter, zwei- (n = 37) bzw. sechsjahriger (n = 52) Kinder wurden mit einem passiven auditiven Oddball-Paradigma und variablem Interstimulusintervall (ISI: 0.5–5 s, je nach Gruppe) ereigniskorrelierte Potenziale (EKP) abgeleitet. Ergebnisse: Bei kurzem ISI waren eine Mismatch Negativity (MMN) und eine Late Discriminative Negativity (LDN) und bei langem ISI eine P3a zu beobachten. Eine ISI-Abhangigkeit war fur die MMN und LDN statistisch zu belegen. Die Anderung der EKP-Komponentenstruktur trat bei den sechsjahrigen Kindern bei einem deutlich langeren ISI als bei den zweijahrigen...

Short-term storage of auditory information is thought to be a precondition for cognitive development, and deficits in short-term memory are believed to underlie learning disabilities and specific language disorders. We examined the development of the duration of auditory sensory memory in normally developing children between the ages of 2 and 6 years. To probe the lifetime of auditory sensory memory we elicited the mismatch negativity (MMN), a component of the late auditory evoked potential, with tone stimuli of two different frequencies presented with various interstimulus intervals between 500 and 5,000 ms. Our findings suggest that memory traces for tone characteristics have a duration of 1-2 s in 2- and 3-year-old children, more than 2 s in 4-year-olds and 3-5 s in 6-year-olds. The results provide insights into the maturational processes involved in auditory sensory memory during the sensitive period of cognitive development.

Auditory sensory memory is assumed to play an important role in cognitive development, but little is known about it in young children. The aim of this study was to estimate the duration of auditory sensory memory in 2-year-old children. We recorded the mismatch negativity in response to tone stimuli presented with different interstimulus intervals. Our findings suggest that in 2-year-old children the memory representation of the standard tone remains in the sensory memory store for at least 1 s but for less than 2 s. Recording the mismatch negativity with stimuli presented at various interstimulus intervals seems to be a useful method for studying the relationship between auditory sensory memory and normal and disturbed cognitive development.

The current study used event-related brain potentials to investigate lexical-semantic processing of words in sentences spoken by children with specific language impairment and children with normal language development. Children heard correct sentences and sentences with a violation of the selectional restriction of the verb. Control children showed an N400 effect followed by a late positivity for the incorrect sentences. In contrast, children with specific language impairment showed no N400 effect but did show a late, broadly distributed positivity. This absence of the N400 effect is due to a relatively large negativity for correct sentences, suggesting weaker lexical-semantic representations of the verbs and their selectional restrictions in children with specific language impairment.

In the present study, event-related brain potentials (ERPs) were used to compare auditory sentence comprehension in 16 children with developmental dyslexia (age 9–12 years) and unimpaired controls matched on age, sex, and nonverbal intelligence. Passive sentences were presented, which were either correct or contained a syntactic violation (phrase structure) or a semantic violation (selectional restriction). In an overall sentence correctness judgment task, both control and dyslexic children performed well. In the ERPs, control children and dyslexic children demonstrated a similar N400 component for the semantic violation. For the syntactic violation, control children demonstrated a combined pattern, consisting of an early starting bilaterally distributed anterior negativity and a late centro-parietal positivity (P600). Dyslexic children showed a different pattern that is characterized by a delayed left lateralized anterior negativity, followed by a P600. These data indicate that dyslexic children do not differ from unimpaired controls with respect to semantic integration processes (N400) or controlled processes of syntactic reanalyses (P600) during auditory sentence comprehension. However, early and presumably highly automatic processes of phrase structure building reflected in the anterior negativity are delayed in dyslexic children. Moreover, the differences in hemispheric distribution of the syntactic negativity indicate different underlying processes in dyslexic children and controls. The bilateral distribution in controls suggests an involvement of right hemispherically established prosodic processes in addition to the left hemispherically localized syntactic processes, supporting the view that prosodic information may be used to facilitate syntactic processing during normal comprehension. The left hemispheric distribution observed for dyslexic children, in contrast, suggests that these children do not rely on information about the prosodic contour during auditory sentence comprehension as much as controls do. This finding points toward a phonological impairment in dyslexic children that might hamper the development of syntactic processes.