Monthly Archives: May 2009
Language regions of brain are operative in color perception
The effect of language on the categorical perception of color is stronger for stimuli in the right visual field (RVF) than in the left visual field, but the neural correlates of the behavioral RVF advantage are unknown. Here we present brain activation maps revealing how language is differentially engaged in the discrimination of colored stimuli presented in either visual hemifield. In a rapid, event-related functional MRI study, we measured subjects’ brain activity while they performed a visual search task. Compared with colors from the same lexical category, discrimination of colors from different linguistic categories provoked stronger and faster responses in the left hemisphere language regions, particularly when the colors were presented in the RVF. In addition, activation of visual areas 2/3, responsible for color perception, was much stronger for RVF stimuli from different linguistic categories than for stimuli from the same linguistic category. Notably, the enhanced activity of visual areas 2/3 coincided with the enhanced activity of the left posterior temporoparietal language region, suggesting that this language region may serve as a top-down control source that modulates the activation of the visual cortex. These findings shed light on the brain mechanisms that underlie the hemifield- dependent effect of language on visual perception.
from the Proceedings of the National Academy of Sciences of the United States of America
Segregating the core computational faculty of human language from working memory
In contrast to simple structures in animal vocal behavior, hierarchical structures such as center-embedded sentences manifest the core computational faculty of human language. Previous artificial grammar learning studies found that the left pars opercularis (LPO) subserves the processing of hierarchical structures. However, it is not clear whether this area is activated by the structural complexity per se or by the increased memory load entailed in processing hierarchical structures. To dissociate the effect of structural complexity from the effect of memory cost, we conducted a functional magnetic resonance imaging study of German sentence processing with a 2-way factorial design tapping structural complexity (with/without hierarchical structure, i.e., center-embedding of clauses) and working memory load (long/short distance between syntactically dependent elements; i.e., subject nouns and their respective verbs). Functional imaging data revealed that the processes for structure and memory operate separately but co-operatively in the left inferior frontal gyrus; activities in the LPO increased as a function of structural complexity, whereas activities in the left inferior frontal sulcus (LIFS) were modulated by the distance over which the syntactic information had to be transferred. Diffusion tensor imaging showed that these 2 regions were interconnected through white matter fibers. Moreover, functional coupling between the 2 regions was found to increase during the processing of complex, hierarchically structured sentences. These results suggest a neuroanatomical segregation of syntax-related aspects represented in the LPO from memory-related aspects reflected in the LIFS, which are, however, highly interconnected functionally and anatomically.
from the Proceedings of the National Academy of Sciences of the United States of America
First language transfer and long-term structural priming in comprehension
The present study investigated L1 transfer effects in L2 sentence processing and syntactic priming through comprehension in speakers of German and Italian. L1 and L2 speakers of both languages participated in a syntactic priming experiment that aimed to shift their preferred interpretation of ambiguous relative clause constructions. The results suggested that L1 transfer affects L2 processing but not the strength of structural priming, and therefore does not hinder the acquisition of L2 parsing strategies. We also report evidence that structural priming through comprehension can persist in L1 and L2 speakers over an experimental phase without further exposure to primes. Finally, we observed that priming can occur for what are essentially novel form-meaning pairings for L2 learners, suggesting that adult learners can rapidly associate existing forms with new meanings.
Auditory spatio-temporal brain dynamics and their consequences for multisensory interactions in humans
Recent multisensory research has emphasized the occurrence of early, low-level interactions in humans. As such, it is proving increasingly necessary to also consider the kinds of information likely extracted from the unisensory signals that are available at the time and location of these interaction effects. This review addresses current evidence regarding how the spatio-temporal brain dynamics of auditory information processing likely curtails the information content of multisensory interactions observable in humans at a given latency and within a given brain region. First, we consider the time course of signal propagation as a limitation on when auditory information (of any kind) can impact the responsiveness of a given brain region. Next, we overview the dual pathway model for the treatment of auditory spatial and object information ranging from rudimentary to complex environmental stimuli. These dual pathways are considered an intrinsic feature of auditory information processing, which are not only partially distinct in their associated brain networks, but also (and perhaps more importantly) manifest only after several tens of milliseconds of cortical signal processing. This architecture of auditory functioning would thus pose a constraint on when and in which brain regions specific spatial and object information are available for multisensory interactions. We then separately consider evidence regarding mechanisms and dynamics of spatial and object processing with a particular emphasis on when discriminations along either dimension are likely performed by specific brain regions. We conclude by discussing open issues and directions for future research.
from Hearing Research
Temperamental profiles and linguistic development: Differences in the quality of linguistic production in relation to temperament in children of 28 months
The temperamental constellations that can be found in the infant population may influence the development trajectories of single domains of knowledge, such as that relative to language. The main objective of this study is to identify temperamental profiles to which one associates different levels of linguistic competence and to identify the profile associated with the highest risk for language acquisition. The temperamental characteristics of a sample of 106 children of 28 months attending day-care centres were surveyed and three temperamental profiles were highlighted: a profile typical of the Italian population which grouped most of the children; another made up of easily distractible and not very persistent children, who show a poor capacity to modulate motor activity and finally, the third with children inhibited in new situations. A comparison of the three groups on the basis of the level of linguistic competence revealed important differences regarding certain indices such as the vocabulary size and composition: in particular, the group of “inattentive” children has a more “immature” vocabulary composition, characterised by the presence of more primitive components of the lexical repertory.
Risk of hypertension from exposure to road traffic noise in a population-based sample
Conclusions: The study shows a positive association between residential road traffic noise and hypertension among men, and an exposure–response relationship. While prevalence ratios were increased, findings were more pronounced when incidence was assessed.
Sonotubometry in Children With Otitis Media With Effusion Before and After Insertion of Ventilation Tubes
Conclusions Sonotubometric testing in children with OME reveals a low incidence of eustachian tube opening. Shortly after insertion of ventilation tubes, sonotubometry revealed no difference in eustachian tube ventilatory function compared with measurements in healthy controls. The low incidence of eustachian tube opening before grommet insertion may be attributable to decreased opening or dampening of the sound transmission by the middle ear fluid.
The Clinical Value of the Multiple-Frequency 80-Hz Auditory Steady-State Response in Adults With Normal Hearing and Hearing Loss
Conclusions In adults, the multiple-frequency 80-Hz ASSR technique can be used to determine the degree and configuration of hearing loss. Although air-conduction ASSR thresholds accurately predicted behavioral thresholds in CHL, future research with bone-conduction ASSRs is necessary to establish the type of hearing loss. Furthermore, the applicability of these findings still needs to be confirmed for infants.
Language and academic abilities in children with selective mutism
We examined receptive language and academic abilities in children with selective mutism (SM; n = 30; M age = 8.8 years), anxiety disorders (n = 46; M age = 9.3 years), and community controls (n = 27; M age = 7.8 years). Receptive language and academic abilities were assessed using standardized tests completed in the laboratory. We found a significant group by sex interaction for receptive vocabulary scores such that, within females, the SM and mixed anxiety groups had significantly lower receptive vocabulary scores than community controls. We also found that children with SM and children with anxiety disorders had significantly lower mathematics scores than community controls. Despite these differences in mathematics and receptive vocabulary performance, children with SM and children with anxiety disorders still performed at age-level norms, while more children in the community control group performed above age-level norms. Findings suggest that despite their speaking inhibition in the school setting, children with SM are still able to attain the receptive vocabulary and academic abilities that are expected at their age levels. Copyright © 2009 John Wiley & Sons, Ltd.
Influence of Drilling on the Distortion Product Otoacoustic Emissions in the Non-Operated Ear
Objective: To determine possible changes in the outer hair cell (OHC) function related to drill noise exposure. Methods: Distortion product otoacoustic emissions (DPOAE) were measured at frequencies of f2 = 2, 3, 4 and 5 kHz, and a frequency ratio f1/f2 = 1.22. The f1 and f2 levels were delivered at 65 dB SPL. DPOAE amplitudes were compared in 13 patients both before and after mastoidectomy, and between these patients and 5 patients who underwent tympanoplasty. Results: The DPOAE amplitudes were significantly decreased at 2 and 4 kHz (p = 0.01 and p = 0.013, respectively) immediately after the mastoidectomy, and still differed from the preoperative results at these frequencies on the first post-mastoidectomy day. After the various individual fluctuations, the DPOAE amplitudes remained decreased in some of the patients at the end of the study. Conclusions: Drill-induced noise during mastoidectomy can cause reversible changes in DPOAE in the non-operated ear. OHC function may be diminished during the period after mastoid surgery, and last >1 month.
from ORL -Journal for Oto-Rhino-Laryngology and Its Related Specialties
Early word-learning entails reference, not merely associations
Recent years have witnessed a resurgence of classic tensions concerning the fundamental nature of human knowledge and the processes underlying its acquisition. This tension, especially evident in research on the acquisition of words and concepts, arises when researchers pit one type of content against another (perceptual versus conceptual) and one type of process against another (associative versus theory-based). But these dichotomies are false; they rest upon insufficient consideration of the structure and diversity of the words and concepts that we naturally acquire. As infants and young children establish categories and acquire words to describe them, they take advantage of both perceptual and conceptual information, and relate this to both the (rudimentary) theories they hold and the statistics that they witness.
Acute Cochlear Nucleus Compression Alters Tuning Properties of Inferior Colliculus Neurons
Auditory brainstem implants (ABI) have been used in neurofibromatosis type 2 (NF2) patients in an attempt to restore hearing sensation, with limited clinical success. Factors associated with poor clinical outcomes for NF2 ABI patients include larger tumour size, longer duration of hearing loss, and brainstem distortion and/or deformation caused by tumours that compress the brainstem. The present study investigated changes in tuning properties of inferior colliculus (IC) neurons following compression of the contralateral cochlear nucleus (CN). The left CN in adult rats (n = 8) was exposed and a 32-channel acute recording probe inserted along the tonotopic gradient of the right IC. In 4 animals, an ethylene vinyl acetate bead was applied to the exposed CN. Three recordings were made corresponding to T1 = 0 min (before compression), T2 = 45 min (during compression) and T3 = 225 min (following bead removal/recovery). Recordings consisted of a response area protocol using pure tones of various frequencies and intensities (1-44 kHz; 10-70 dB SPL) to determine the characteristic frequency for each probe site. Compression of the CN led to sharpened tuning curves, decreased spike rate, and increased threshold and characteristic frequency in the IC. Reversal of compression enabled these variables, excluding threshold, to recover to baseline. NF2 patients may have poorer ABI performance due to damage to the physical structure of the CN, resulting in alterations to the tonotopic organisation of the auditory pathway which may complicate ABI implantation and activation.
Scientists reaching consensus on how brain processes speech
Washington, DC – Neuroscientists feel they are much closer to an accepted unified theory about how the brain processes speech and language, according to a scientist at Georgetown University Medical Center who first laid the concepts a decade ago and who has now published a review article confirming the theory.
from EurekAlert.org
Inner ear balance disorders common, associated with falls among older Americans
An estimated 35 percent of U.S. adults age 40 and older have vestibular dysfunction (inner ear balance disorders), and those who do may have a higher risk of falling, according to a report in the May 25 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
from EurekAlert.org
