Brain structural and functional differences associated to language learning abilities

Language-related areas within frontal, parietal and temporal cortices are organized in dorsal and ventral segregated but highly interactive streams. Studying individual differences in functional and structural connectivity between those brain regions and how they change during language learning can clarify the function of each of these specific connections in learning dysfunction and inter-individual variability. While the dorsal stream has been related to articulation and production, the ventral stream has been associated to comprehension and semantic processing (Hickok and Poeppel 2007; Rauschecker and Scott 2009; Saur et al 2008). To understand their role in the earliest stages of language learning we have used artificial languages to study the acquisition of word forms from fluent speech with no influence of semantic information. I will present evidence showing that the direct functional and structural connectivity between left frontal and temporal structures is relevant for audio-motor integration and critical for the acquisition of new word forms. Indeed, interference with this audio-motor component required for working memory maintenance of the phonological form disrupts language learning. Other studies highlight the importance of attention orienting associated to the left fronto-parietal network in the extraction of the embedded rules of words. In addition, the data indicate the relevance of the ventral connection between left frontal and temporal areas as a supporting pathway in the early acquisition process even when no semantic information is available.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Names and their meanings: A dual-process account of proper-name encoding and retrieval

The ability to pick out a unique entity with a proper name is an important component of human language. It has been a primary focus of research in the philosophy of language since the nineteenth century. Brain-based evidence has shed new light on this capacity, and an extensive literature indicates the involvement of distinct fronto-temporal and temporo-occipito-parietal association cortices in proper-name retrieval. However, comparatively few efforts have sought to explain how memory encoding processes lead to the later recruitment of these distinct regions at retrieval. Here, we provide a unified account of proper-name encoding and retrieval, reviewing evidence that socio-emotional and unitized encoding subserve the retrieval of proper names via anterior-temporal-prefrontal activations. Meanwhile, non-unitized item-item and item-context encoding support subsequent retrieval, largely dependent on the temporo-occipito-parietal cortex. We contend that this well-established divergence in encoding systems can explain how proper names are later retrieved from distinct neural structures. Furthermore, we explore how evidence reviewed here can inform a century-and-a-half-old debate about proper names and the meanings they pick out

Language Learning Variability within the Dorsal and Ventral Streams as a Cue for Compensatory Mechanisms in Aphasia Recovery

Dorsal and ventral pathways connecting perisylvian language areas have been shown to be functionally and anatomically segregated. Whereas the dorsal pathway integrates the sensory-motor information required for verbal repetition, the ventral pathway has classically been associated with semantic processes. The great individual differences characterizing language learning through life partly correlate with brain structure and function within these dorsal and ventral language networks. Variability and plasticity within these networks also underlie inter-individual differences in the recovery of linguistic abilities in aphasia. Despite the division of labor of the dorsal and ventral streams, studies in healthy individuals have shown how the interaction of them and the redundancy in the areas they connect allow for compensatory strategies in functions that are usually segregated. In this mini-review we highlight the need to examine compensatory mechanisms between streams in healthy individuals as a helpful guide to choosing the most appropriate rehabilitation strategies, using spared functions and targeting preserved compensatory networks for brain plasticity

Contributions to the functional neuroanatomy of morphosyntactic processing in L2

Studies about bilingualism and second language acquisition (SLA) have a long tradition within linguistic and psycholinguistic research. With the global population becoming more and more multilingual and the recent proliferation of research in cognitive neuroscience, an increasing number of studies examining the way our brain is able to learn, represent, and handle more than one language at the same time are currently available. However, few attempts have been made to transpose psycholinguistic models of SLA into functional neuroanatomic models. An important problem that arises when pursuing this goal is partially due to the delay in the development of cognitive neuroscience of language compared to psycholinguistics. In general, neurolinguistic models focus on very broad and general questions about bilingualism, whereas psycholinguistic research is already at the stage of addressing more specific and fine-tuned questions. This Granularity Mismatch Problem (Poeppel & Embick, 2005) in the degree of zooming into this research topic is not exclusive of L2 research, but it is present in language research in general (Hauser & Bever, 2008). In either case, it often becomes difficult to put together the results from these different perspectives into one integrated model

CONTRIBUTIONS TO THE FUNCTIONAL NEUROANATOMY OF MORPHOSYNTACTIC PROCESSING IN L2

2 Studies about bilingualism and second language acquisition have a long tradition within linguistic and psycholinguistic research. With the global population becoming more and more multilingual and the recent proliferation of research in cognitive neuroscience, an increasing number of studies examining the way our brain is able to learn, represent, and handle more than one language at the same time are currently available. But few attempts have been made to transpose psycholinguistic models of second language acquisition (SLA) into functional neuroanatomic models. An important problem that arises when pursuing this goal is partially due to the delay in the development of cognitive neuroscience of language compared to psycholinguistics. In general, neurolinguistic models focus on very broad and general questions about bilingualism, while psycholinguistic research is already at the stage of addressing more specific and fine-tuned questions. This Granularity Mismatch Problem The contributions from psycholinguistic research are crucial to the improvement of neurolinguistic models. This importance stems from the fact that psycholinguistic research is posing more specific questions than those in many current cognitive neuroscience studies. For example, in the present issue we have several examples of the type of questions that psycholinguistic research can raise. In general, most of the work on morphosyntactic research from neuroscience and psycholinguistics has come from studying English, a language that has a relatively simple morphological system. However, the picture becomes more intricate when these models are extended to more complex morphological systems. The contributions in this journal issue embrace the complexity of different languages both in the role of the L1 background and from L2 processing perspective. They describe results in perception an

Brain dynamics sustaining rapid rule extraction from speech

Language acquisition is a complex process that requires the synergic involvement of different cognitive functions, which include extracting and storing the words of the language and their embedded rules for progressive acquisition of grammatical information. As has been shown in other fields that study learning processes, synchronization mechanisms between neuronal assemblies might have a key role during language learning. In particular, studying these dynamics may help uncover whether different oscillatory patterns sustain more item-based learning of words and rule-based learning from speech input. Therefore, we tracked the modulation of oscillatory neural activity during the initial exposure to an artificial language, which contained embedded rules. We analyzed both spectral power variations, as a measure of local neuronal ensemble synchronization, as well as phase coherence patterns, as an index of the long-range coordination of these local groups of neurons. Synchronized activity in the gamma band (2040 Hz), previously reported to be related to the engagement of selective attention, showed a clear dissociation of local power and phase coherence between distant regions. In this frequency range, local synchrony characterized the subjects who were focused on word identification and was accompanied by increased coherence in the theta band (48 Hz). Only those subjects who were able to learn the embedded rules showed increased gamma band phase coherence between frontal, temporal, and parietal regions

Temporal attention as a Scaffold for Language Development

Language is one of the most fascinating abilities that humans possess. Infants demonstrate an amazing repertoire of linguistic abilities from very early on and reach an adult-like form incredibly fast. However, language is not acquired all at once but in an incremental fashion. In this article we propose that the attentional system may be one of the sources for this developmental trajectory in language acquisition. At birth, infants are endowed with an attentional system fully driven by salient stimuli in their environment, such as prosodic information (e.g., rhythm or pitch). Early stages of language acquisition could benefit from this readily available, stimulus-driven attention to simplify the complex speech input and allow word segmentation. At later stages of development, infants are progressively able to selectively attend to specific elements while disregarding others. This attentional ability could allow them to learn distant non-adjacent rules needed for morphosyntactic acquisition. Because non-adjacent dependencies occur at distant moments in time, learning these dependencies may require correctly orienting attention in the temporal domain. Here, we gather evidence uncovering the intimate relationship between the development of attention and language. We aim to provide a novel approach to human development, bridging together temporal attention and language acquisition

Endogenous temporal attention in the absence of stimulus-driven cues emerges in the second year of life

Podeu consultar dades primàries associades a l'article a: http://hdl.handle.net/2445/113258Anticipating both where and when an object will appear is a critical ability for adaptation. Research in the temporal domain in adults indicate that dissociable mechanisms relate to endogenous attention driven by the properties of the stimulus themselves (e.g. rhythmic, sequential, or trajectory cues) and driven by symbolic cues. In infancy, we know that the capacity to endogenously orient attention progressively develops through infancy. However, the above-mentioned distinction has not yet been explored since previous studies involved stimulus-driven cues. The current study tested 12- and 15-month-olds in an adaptation of the anticipatory eye movement procedure to determine whether infants were able to anticipate a specific location and temporal interval predicted only by symbolic pre-cues. In the absence of stimulus-driven cues, results show that only 15-month-olds could show anticipatory behavior based on the temporal information provided by the symbolic cues. Distinguishing stimulus-driven expectations from those driven by symbolic cues allowed dissecting more clearly the developmental progression of temporal endogenous attention

Prosodic cues enhance rule learning by changing speech segmentation mechanisms

Prosody has been claimed to have a critical role in the acquisition of grammatical information from speech. The exact mechanisms by which prosodic cues enhance learning are fully unknown. Rules from language often require the extraction of non-adjacent dependencies (e.g., he plays, he sings, he speaks). It has been proposed that pauses enhance learning because they allow computing non-adjacent relations helping word segmentation by removing the need to compute adjacent computations. So far only indirect evidence from behavioral and electrophysiological measures comparing learning effects after exposure to speech with and without pauses support this claim. By recording event-related potentials during the acquisition process of artificial languages with and without pauses between words with embedded non-adjacent rules we provide direct evidence on how the presence of pauses modifies the way speech is processed during learning to enhance segmentation and rule generalization. The electrophysiological results indicate that pauses as short as 25 ms attenuated the N1 component irrespective of whether learning was possible or not. In addition, a P2 enhancement was present only when learning of non-adjacent dependencies was possible. The overall results support the claim that the simple presence of subtle pauses changed the segmentation mechanism used reflected in an exogenously driven N1 component attenuation and improving segmentation at the behavioral level. This effect can be dissociated from the endogenous P2 enhancement that is observed irrespective of the presence of pauses whenever non-adjacent dependencies are learned

Attentional effects on rule extraction and consolidation from speech.

Incidental learning plays a crucial role in the initial phases of language acquisition. However this knowledge derived from implicit learning, which is based on prediction-based mechanisms, may become explicit. The role that attention plays in the formation of implicit and explicit knowledge of the learned material is unclear. In the present study, we investigated the role that attention plays in the acquisition of non-adjacent rule learning from speech. In addition, we also tested whether the amount of attention during learning changes the representation of the learned material after a 24h delay containing sleep. For that, we developed an experiment run on two consecutive days consisting on the exposure to an artificial language that contained nonadjacent dependencies (rules) between words whereas different conditions were established to manipulate the amount of attention given to the rules (target and non-target conditions). Furthermore, we used both indirect and direct measures of learning that are more sensitive to implicit and explicit knowledge respectively. Whereas the indirect measures indicated that learning of the rules occurred regardless of attention, more explicit judgments after learning showed differences in the type of learning reached under the two attention conditions. 24 hours later, indirect measures showed no further improvements during additional language exposure and explicit judgments indicated that only the information more robustly learned in the previous day was consolidated