This book establishes a dialog between experimental psychology and electrophysiology in the study of infant language development. On the one hand, traditional methods of investigation into language development have reached a high level of refinement despite being confined to observing infants' overt behavioral responses. On the other hand, more recent methods such as neuroimaging and, in particular, event-related potentials provide access to implicit responses from the infant brain while often relying on rather gross experimental contrasts. The aims of this book are both to provide neuroscient.
AbstractThe present study explored the origins of word learning in early infancy. Using event‐related potentials (ERP) we monitored the brain activity of 3‐month‐old infants when they were repeatedly exposed to several initially novel words paired consistently with each the same initially novel objects or inconsistently with different objects. Our results provide strong evidence that these young infants extract statistic regularities in the distribution of the co‐occurrences of objects and words extremely quickly. The data suggest that this ability is based on the rapid formation of associations between the neural representations of objects and words, but that the new associations are not retained in long‐term memory until the next day. The type of brain response moreover indicates that, unlike in older infants, in 3‐month‐olds a semantic processing stage is not involved. Their ability to combine words with meaningful information is caused by a primary learning mechanism that enables the formation of proto‐words and acts as a precursor for the acquisition of genuine words.
AbstractThis study explored the electrophysiology underlying intonational phrase processing at different stages of syntax acquisition. Developmental studies suggest that children's syntactic skills advance significantly between 2 and 3 years of age. Here, children of three age groups were tested on phrase‐level prosodic processing before and after this developmental phase, while their brain activity was recorded. The Closure Positive Shift (CPS), which indexes the perception of intonational phrasing in adults, served as dependent variable. The event‐related brain potentials of 3‐ and 6‐year‐olds, but not of 21‐month‐olds, showed a CPS. These results suggest that prosodic phrase processing, as indicated by the CPS, is established only later during children's development, pointing to a close interaction of prosody and syntax acquisition.
Abstract We examined 7‐month‐old infants' processing of emotionally congruent and incongruent face–voice pairs using ERP measures. Infants watched facial expressions (happy or angry) and, after a delay of 400 ms, heard a word spoken with a prosody that was either emotionally congruent or incongruent with the face being presented. The ERP data revealed that the amplitude of a negative component and a subsequent positive component in infants' ERPs varied as a function of crossmodal emotional congruity. An emotionally incongruent prosody elicited a larger negative component in infants' ERPs than did an emotionally congruent prosody. Conversely, the amplitude of infants' positive component was larger to emotionally congruent than to incongruent prosody. Previous work has shown that an attenuation of the negative component and an enhancement of the later positive component in infants' ERPs reflect the recognition of an item. Thus, the current findings suggest that 7‐month‐olds integrate emotional information across modalities and recognize common affect in the face and voice.
AbstractInfants' ability to learn complex linguistic regularities from early on has been revealed by electrophysiological studies indicating that 3‐month‐olds, but not adults, can automatically detect non‐adjacent dependencies between syllables. While different ERP responses in adults and infants suggest that both linguistic rule learning and its link to basic auditory processing undergo developmental changes, systematic investigations of the developmental trajectories are scarce. In the present study, we assessed 2‐ and 4‐year‐olds' ERP indicators of pitch discrimination and linguistic rule learning in a syllable‐based oddball design. To test for the relation between auditory discrimination and rule learning, ERP responses to pitch changes were used as predictor for potential linguistic rule‐learning effects. Results revealed that 2‐year‐olds, but not 4‐year‐olds, showed ERP markers of rule learning. Although, 2‐year‐olds' rule learning was not dependent on differences in pitch perception, 4‐year‐old children demonstrated a dependency, such that those children who showed more pronounced responses to pitch changes still showed an effect of rule learning. These results narrow down the developmental decline of the ability for automatic linguistic rule learning to the age between 2 and 4 years, and, moreover, point towards a strong modification of this change by auditory processes. At an age when the ability of automatic linguistic rule learning phases out, rule learning can still be observed in children with enhanced auditory responses. The observed interrelations are plausible causes for age‐of‐acquisition effects and inter‐individual differences in language learning.
AbstractSleep spindle activity in infants supports their formation of generalized memories during sleep, indicating that specific sleep processes affect the consolidation of memories early in life. Characteristics of sleep spindles depend on the infant's developmental state and are known to be associated with trait‐like factors such as intelligence. It is, however, largely unknown which state‐like factors affect sleep spindles in infancy. By varying infants' wake experience in a within‐subject design, here we provide evidence for a learning‐ and memory‐dependent modulation of infant spindle activity. In a lexical‐semantic learning session before a nap, 14‐ to 16‐month‐old infants were exposed to unknown words as labels for exemplars of unknown object categories. In a memory test on the next day, generalization to novel category exemplars was tested. In a nonlearning control session preceding a nap on another day, the same infants heard known words as labels for exemplars of already known categories. Central–parietal fast sleep spindles increased after the encoding of unknown object–word pairings compared to known pairings, evidencing that an infant's spindle activity varies depending on its prior knowledge for newly encoded information. Correlations suggest that enhanced spindle activity was particularly triggered, when similar unknown pairings were not generalized immediately during encoding. The spindle increase triggered by previously not generalized object–word pairings, moreover, boosted the formation of generalized memories for these pairings. Overall, the results provide first evidence for a fine‐tuned regulation of infant sleep quality according to current consolidation requirements, which improves the infant long‐term memory for new experiences.
AbstractIntegrating the multisensory features of talking faces is critical to learning and extracting coherent meaning from social signals. While we know much about the development of these capacities at the behavioral level, we know very little about the underlying neural processes. One prominent behavioral milestone of these capacities is the perceptual narrowing of face–voice matching, whereby young infants match faces and voices across species, but older infants do not. In the present study, we provide neurophysiological evidence for developmental decline in cross‐species face–voice matching. We measured event‐related brain potentials (ERPs) while 4‐ and 8‐month‐old infants watched and listened to congruent and incongruent audio‐visual presentations of monkey vocalizations and humans mimicking monkey vocalizations. The ERP results indicated that younger infants distinguished between the congruent and the incongruent faces and voices regardless of species, whereas in older infants, the sensitivity to multisensory congruency was limited to the human face and voice. Furthermore, with development, visual and frontal brain processes and their functional connectivity became more sensitive to the congruence of human faces and voices relative to monkey faces and voices. Our data show the neural correlates of perceptual narrowing in face–voice matching and support the notion that postnatal experience with species identity is associated with neural changes in multisensory processing (Lewkowicz & Ghazanfar, 2009).
AbstractThe ability to represent the mental states of other agents is referred to as Theory of Mind (ToM). A developmental breakthrough in ToM consists of understanding that others can have false beliefs about the world. Recently, infants younger than 2 years of age have been shown to pass novel implicit false belief tasks. However, the processes underlying these tasks and their relation to later‐developing explicit false belief understanding, as well as to other cognitive abilities, are not yet understood. Here, we study a battery of implicit and explicit false belief tasks in 3‐ and 4‐year‐old children, relating their performance to linguistic abilities and executive functions. The present data show a significant developmental change from failing explicit false belief tasks at 3 years of age to passing them at the age of 4, while both age groups pass implicit false belief tasks. This differential developmental trajectory is reflected by the finding that explicit and implicit false belief tasks do not correlate. Further, we demonstrate that explicit false belief tasks correlate with syntactic and executive functions, whereas implicit false belief tasks do not. The study thus indicates that the processes underlying implicit false belief tasks are different from later‐developing explicit false belief understanding. Moreover, our results speak for a critical role of syntactic and executive functions for passing standard explicit false belief tasks in contrast to implicit tasks.
AbstractThe acquisition of the function of case‐marking is a key step in the development of sentence processing for German‐speaking children since case‐marking reveals the relations between sentential arguments. In this study, we investigated the development of the processing of case‐marking and argument structures in children at 3, 4;6 and 6 years of age, as well as its processing in adults. Using EEG, we measured event‐related potentials (ERPs) in response to object‐initial compared to subject‐initial German sentences including transitive verbs and case‐marked noun phrases referring to animate arguments. We also tested children's behavioral competence in a sentence‐picture matching task. Word order and case‐marking were manipulated in German main clauses. Adults' behavioral performance was close to perfect and their ERPs revealed a negativity for the processing of the topicalized accusative marked noun phrase (NP1) and no effect for the second NP (NP2) in the object‐initial structure. Children's behavioral data showed a significant above‐chance outcome in the subject‐initial condition for all age groups, but not for the object‐initial condition. In contrast to adults, the ERPs of 3‐year‐olds showed a positivity at NP1, indicating difficulties in processing the non‐canonical object‐initial structures. Children at the age of 4;6 did not differ in the processing patterns of object‐initial vs. subject‐initial sentences at NP1 but showed a slight positivity at NP2. This positivity at NP2, which implies syntactic integration difficulties, is more pronounced in 6‐year‐olds but is absent in adults. At NP1, however, 6‐year‐olds show the same negativity as adults. In sum, the behavioral and electrophysiological findings demonstrate that children in each age group use different strategies, which are indicative of their developmental stage. While 3‐year‐olds merely detect differences in the two sentence structures without being able to use this information for sentence comprehension, 4;6‐year‐olds proceed to use mainly a word‐order strategy, processing NP1 in both conditions in the same manner, which leads to processing difficulties upon detecting case‐marking cues at NP2. At the age of 6, children are able to use case‐marking cues for comprehension but still show enhanced effort for correct thematic‐role assignment.
AbstractSuccessful communication in everyday life crucially involves the processing of auditory and visual components of speech. Viewing our interlocutor and processing visual components of speech facilitates speech processing by triggering auditory processing. Auditory phoneme processing, analyzed by event‐related brain potentials (ERP), has been shown to be associated with impairments in reading and spelling (i.e. developmental dyslexia), but visual aspects of phoneme processing have not been investigated in individuals with such deficits. The present study analyzed the passive visual Mismatch Response (vMMR) in school children with and without developmental dyslexia in response to video‐recorded mouth movements pronouncing syllables silently. Our results reveal that both groups of children showed processing of visual speech stimuli, but with different scalp distribution. Children without developmental dyslexia showed a vMMR with typical posterior distribution. In contrast, children with developmental dyslexia showed a vMMR with anterior distribution, which was even more pronounced in children with severe phonological deficits and very low spelling abilities. As anterior scalp distributions are typically reported for auditory speech processing, the anterior vMMR of children with developmental dyslexia might suggest an attempt to anticipate potentially upcoming auditory speech information in order to support phonological processing, which has been shown to be deficient in children with developmental dyslexia.
Recently introduced effective connectivity methods allow for the in-vivo investigation of large-scale functional interactions between brain regions. However, dynamic causal modeling, the most widely used technique to date, typically captures only a few predefined regions of interest. In this study, we present an alternative computational approach to infer effective connectivity within the entire connectome and show its performance on a developmental cohort with emerging language capacities. The novel approach provides new opportunities to quantify effective connectivity changes in the human brain. ; G.D. was supported by the ERC Advanced Grant DYSTRUCTURE (n. 295129), the Spanish Research Project PSI2013-42091-P and the FP7-ICT BrainScales (n. 269921). D.M. was supported by a Sir Henry Dale Fellowship of the Wellcome Trust and the Royal Society (n. 101253/Z/13/Z), a Marie Curie Integration Grant of the European Commission (n. 2012-334039), the KU Leuven Special Research Fund (grant C16/15/070), and the Research Foundation Flanders (Pegasus incoming fellowship 12G9417N to MG). MG received funding from the FWO and European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie action (grant 665501). G.D., G.H and A.D. received support from the flagship Human Brain Project (n.604102). A.D was also supported by CNRS, UNIC, the foundation "Voir et Entendre" and Idex (NeuroSaclay). A.D.F. was funded by a grant from the European Research Council (ERC-2010-AdG 20100407, NEUROSYNTAX).
