Monthly Archives: April 2011
Sustained selective intermodal attention modulates processing of language-like stimuli
Intermodal attention (IA) is assumed to allocate limited neural processing resources to input from one specific sensory modality. We investigated effects of sustained IA on the amplitude of a 40-Hz auditory (ASSR) and a 4.3-Hz visual steady-state response (VSSR). To this end, we concurrently presented amplitude-modulated multi-speech babble and a stream of nonsense letter sets to elicit the respective brain responses. Subjects were cued trialwise to selectively attend to one of the streams for several seconds where they had to perform a lexical decision task on occasionally occurring words and pseudowords. Attention to the auditory stream led to greater ASSR amplitudes than attention to the visual stream. Vice versa, the VSSR amplitude was greater when the visual stream was attended. We demonstrate that IA research by means of frequency tagging can be extended to complex stimuli as used in the current study. Furthermore, we show not only that IA selectively modulates processing of concurrent multisensory input but that this modulation occurs during trial-by-trial cueing of IA. The use of frequency tagging may be suitable to study the role of IA in more naturalistic setups that comprise a larger number of multisensory signals.
Functional MRI evidence for modulation of cerebral activity by grapheme-to-phoneme conversion in French, and by the variable of gender
This fMRI study aims to assess the effect of two variables on the cerebral substrate of phonological processing during visual phoneme detection: (a) the difficulty level (type) of grapheme-to-phoneme conversion (GPC, letter-sound mapping) with two modalities, simple (S) and complex (C); and (b) the gender of participants, females (F) vs. males (M). The behavioral results have shown that simple items were processed more accurately than complex ones. At the cerebral level, phoneme detection activated the left-hemisphere phonological network and several regions of this network were modulated by the GPC type. Specifically, the activity of the superior posterior temporal gyrus was significantly higher for simple grapheme detection and suggests automatic activation of phonological representations; the activity of the inferior temporal gyrus was significantly higher for complex grapheme detection, suggesting greater demands of the integrative processes for solving competitive and inhibitory processes induced by the visual and phonological properties of stimuli. With respect to gender variable, we obtained significant interaction between GPC and gender. This effect showed higher accuracy for simple graphemes in females and suggests that female participants were more proficient than males for detecting simple items. This effect suggests easier and more rapid activation of phonological codes, probably based on a specific visual strategy, different from males. This is supported by the additional activation of the lingual gyrus in females for processing simple graphemes, although the exact explanation of this effect is not clear yet and requires supplementary experimentation and evidence. Overall, our results indicate that the cognitive mechanisms and cerebral correlates of phonological processing may depend on intrinsic and extrinsic variables, such as GPC and gender.
from the Journal of Neurolinguistics
Music, rhythm, rise time perception and developmental dyslexia: Perception of musical meter predicts reading and phonology
Conclusions
The accurate perception of metrical structure may be critical for phonological development and consequently for the development of literacy. Difficulties in metrical processing are associated with basic auditory rise time processing difficulties, suggesting a primary sensory impairment in developmental dyslexia in tracking the lower-frequency modulations in the speech envelope.
from Cortex
Male advantage in sound localization at cocktail parties
Sex differences exist in the structural organization of the human brain and are related to cognitive abilities. Females usually outperform men in verbal fluency, verbal memory, perceptual speed, numerical calculation, and fine motor skills, whereas males are superior in visuospatial abilities, throwing accuracy, and mathematical reasoning. Here we demonstrated a male advantage in spatial abilities for the auditory modality. We employed a sound localization task based on the so-called “cocktail party situation”, requiring extraction of auditory information of a specific sound source when multiple competing sound sources were present. The results indicated better performance of males than females for localizing target sounds in a multi-source sound environment. This finding suggests a sex difference in the attentional mechanisms extracting spatial information of one acoustic event of interest from an auditory scene composed of multiple sound sources. It seems that the known male superiority in spatial abilities may be supramodal, rather than a specificity of the visual modality.
from Cortex
Reduced attentional capacity, but normal processing speed and shifting of attention in developmental dyslexia: Evidence from a serial task
We report the performance of a group of adult dyslexics and matched controls in an array-matching task where two strings of either consonants or symbols are presented side by side and have to be judged to be the same or different. The arrays may differ either in the order or identity of two adjacent characters. This task does not require naming – which has been argued to be the cause of dyslexics’ difficulty in processing visual arrays – but, instead, has a strong serial component as demonstrated by the fact that, in both groups, Reaction times (RTs) increase monotonically with position of a mismatch. The dyslexics are clearly impaired in all conditions and performance in the identity conditions predicts performance across orthographic tasks even after age, performance IQ and phonology are partialled out. Moreover, the shapes of serial position curves are revealing of the underlying impairment. In the dyslexics, RTs increase with position at the same rate as in the controls (lines are parallel) ruling out reduced processing speed or difficulties in shifting attention. Instead, error rates show a catastrophic increase for positions which are either searched later or more subject to interference. These results are consistent with a reduction in the attentional capacity needed in a serial task to bind together identity and positional information. This capacity is best seen as a reduction in the number of spotlights into which attention can be split to process information at different locations rather than as a more generic reduction of resources which would also affect processing the details of single objects.
from Cortex
Are left fronto-temporal brain areas a prerequisite for normal music-syntactic processing?
An increasing number of neuroimaging studies in music cognition research suggest that “language areas” are involved in the processing of musical syntax, but none of these studies clarified whether these areas are a prerequisite for normal syntax processing in music. The present electrophysiological experiment tested whether patients with lesions in Broca’s area (N=6) or in the left anterior temporal lobe (N=7) exhibit deficits in the processing of structure in music compared to matched healthy controls (N=13). A chord sequence paradigm was applied, and the amplitude and scalp topography of the Early Right Anterior Negativity (ERAN) was examined, an electrophysiological marker of musical syntax processing that correlates with activity in Broca’s area and its right hemisphere homotope. Left inferior frontal gyrus (IFG) (but not anterior superior temporal gyrus – aSTG) patients with lesions older than 4 years showed an ERAN with abnormal scalp distribution, and subtle behavioural deficits in detecting music-syntactic irregularities. In one IFG patient tested 7 months post-stroke, the ERAN was extinguished and the behavioural performance remained at chance level. These combined results suggest that the left IFG, known to be crucial for syntax processing in language, plays also a functional role in the processing of musical syntax. Hence, the present findings are consistent with the notion that Broca’s area supports the processing of syntax in a rather domain-general way.
from Cortex
Frontal lobe damage impairs process and content in semantic memory: Evidence from category-specific effects in progressive non-fluent aphasia
Portions of left inferior frontal cortex have been linked to semantic memory both in terms of the content of conceptual representation (e.g., motor aspects in an embodied semantics framework) and the cognitive processes used to access these representations (e.g., response selection). Progressive non-fluent aphasia (PNFA) is a neurodegenerative condition characterized by progressive atrophy of left inferior frontal cortex. PNFA can, therefore, provide a lesion model for examining the impact of frontal lobe damage on semantic processing and content. In the current study we examined picture naming in a cohort of PNFA patients across a variety of semantic categories. An embodied approach to semantic memory holds that sensorimotor features such as self-initiated action may assume differential importance for the representation of manufactured artifacts (e.g., naming hand tools). Embodiment theories might therefore predict that patients with frontal damage would be differentially impaired on manufactured artifacts relative to natural kinds, and this prediction was borne out. We also examined patterns of naming errors across a wide range of semantic categories and found that naming error distributions were heterogeneous. Although PNFA patients performed worse overall on naming manufactured artifacts, there was no reliable relationship between anomia and manipulability across semantic categories. These results add to a growing body of research arguing against a purely sensorimotor account of semantic memory, suggesting instead a more nuanced balance of process and content in how the brain represents conceptual knowledge.
from Cortex
Are left fronto-temporal brain areas a prerequisite for normal music-syntactic processing?
An increasing number of neuroimaging studies in music cognition research suggest that “language areas” are involved in the processing of musical syntax, but none of these studies clarified whether these areas are a prerequisite for normal syntax processing in music. The present electrophysiological experiment tested whether patients with lesions in Broca’s area (N=6) or in the left anterior temporal lobe (N=7) exhibit deficits in the processing of structure in music compared to matched healthy controls (N=13). A chord sequence paradigm was applied, and the amplitude and scalp topography of the Early Right Anterior Negativity (ERAN) was examined, an electrophysiological marker of musical syntax processing that correlates with activity in Broca’s area and its right hemisphere homotope. Left inferior frontal gyrus (IFG) (but not anterior superior temporal gyrus – aSTG) patients with lesions older than 4 years showed an ERAN with abnormal scalp distribution, and subtle behavioural deficits in detecting music-syntactic irregularities. In one IFG patient tested 7 months post-stroke, the ERAN was extinguished and the behavioural performance remained at chance level. These combined results suggest that the left IFG, known to be crucial for syntax processing in language, plays also a functional role in the processing of musical syntax. Hence, the present findings are consistent with the notion that Broca’s area supports the processing of syntax in a rather domain-general way.
from Cortex
Neuroimaging Evidence for Top-Down Maturation of Selective Auditory Attention
This study investigated maturational differences of selective auditory attention effects on transient evoked responses and 40-Hz auditory steady-state responses between children and adults. Magnetoencephalography (MEG) was recorded from children and adults performing a task where they attended to 40-Hz amplitude-modulated (AM) tones of 1,200 Hz while ignoring 40-Hz AM tones of 800 Hz. By using standard dipole-modeling procedures, the N1m of the transient evoked fields and the 40-Hz ASSRs were localized to secondary and primary auditory cortices, respectively. Source waveforms for the transient evoked fields and ASSRs were reconstructed at these locations and compared between attended and unattended tones. Source waveforms revealed attention enhances the sustained negativity of the transient evoked responses in both adults and children around 250 and 400 ms. ASSRs were also found to be enhanced within this time range but only for adults. The results provide evidence for a limited role of attention modification of the 40-Hz ASSRs in children around the age of 12 years old. Because ASSRs are generated in a lower auditory processing stage as compared to the transient auditory evoked responses, findings from the present study could indicate that the maturation of attention progresses in top-to-bottom manner. These findings fit with the notion that as a person gains sensory experience selective gating of relevant from irrelevant information likely occurs at earlier and earlier processing levels in order to become more automatic and efficient.
from Brain Topography
Prevalence of age-related hearing loss in Europe: a review
Populations are becoming progressively older thus presenting symptoms of diminished organ function due to degenerative processes. These may be physiological or caused by additional factors damaging the organ. Presbyacusis refers to the physiological age-related changes of the peripheral and central auditory system leading to hearing impairment and difficulty understanding spoken language. In contrast to epidemiological data of other continents, the prevalence of age-related hearing loss (ARHL) in Europe is not well defined, due in part to the use of different classification systems. We performed a systematic literature review with the aim of gaining a picture of the prevalence of ARHL in Europe. The review included only population and epidemiological studies in English since 1970 with samples in European countries with subjects aged 60 years and above. Nineteen studies met our selection criteria and additional five studies reported self-reported hearing impairment. When these data were crudely averaged and interpolated, roughly 30% of men and 20% of women in Europe were found to have a hearing loss of 30 dB HL or more by age 70 years, and 55% of men and 45% of women by age 80 years. Apparent problems in comparing the available data were the heterogeneity of measures and cut-offs for grades of hearing impairment. Our systematic review of epidemiological data revealed more information gaps than information that would allow gaining a meaningful picture of prevalence of ARHL. The need for standardized procedures when collecting and reporting epidemiological data on hearing loss has become evident. Development of hearing loss over time in conjunction with the increase in life expectancy is a major factor determining strategies of detection and correction of ARHL. Thus, we recommend using the WHO classification of hearing loss strictly and including standard audiometric measures in population-based health surveys.
A tipping point in dialect obsolescence? Change across the generations in Lerwick, Shetland
The dialect spoken in the Shetland Islands is one of the most distinctive in the British Isles. However, there are claims that this variety is rapidly disappearing, with local forms replaced by more standard variants in the younger generations. In this paper we test these claims through a quantitative analysis of variable forms across three generations of speakers from the main town of Lerwick. We target six variables: two lexical, two morphosyntactic and two phonetic/phonological. Our results show that there is decline in use of the local forms across all six variables. Closer analysis of individual use reveals that the older age cohort form a linguistically homogeneous group. In contrast, the younger speakers form a heterogeneous group: half of the younger speakers have high rates of the local forms, while the other half uses the standard variants near-categorically. We suggest that these results may pinpoint the locus of rapid obsolescence in this traditionally relic dialect area.
Contact, the feature pool and the speech community: The emergence of Multicultural London English
In the multilingual centres of Northern Europe’s major cities, new varieties of the host languages are emerging. While some analyse these ‘multiethnolects’ as youth styles, we take a variationist approach to an emerging ‘Multicultural London English’ (MLE), asking: (1) what features characterise MLE; (2) at what age(s) are they acquired; (3) is MLE vernacularised; and (4) when did MLE emerge, and what factors enabled this? We argue that innovations in the diphthongs and the quotative system are generated from the specific sociolinguistics of inner-city London, where at least half the population is undergoing group second-language acquisition and where high linguistic diversity leads to a heterogeneous feature pool to select from. We look for incrementation (Labov 2001) in the acquisition of the features, but find this only for two ‘global’ changes, BE LIKE and goose-fronting, for which adolescents show the highest usage. Community-internal factors explain the age-related variation in the remaining features.
Patterns of linguistic variation among Glaswegian adolescent males
This article presents the results of an ethnographically informed sociolinguistic investigation of Glaswegian Vernacular and examines the intersection between language and identity using data collected from a group of working-class adolescent males, over the course of three years, from a high school in the south side of Glasgow, Scotland, called Banister Academy. Through the fine-grained acoustic analysis of the phonetic variable cat (equivalent to the trap/bath/palm set, Johnston 1997), coupled with ethnographic observations, this article shows how patterns of variation are related to Community of Practice membership, how the members of the Communities of Practice in Banister Academy use linguistic and social resources to differentiate themselves from one another, and how certain patterns of variation acquire social meaning within the peer-group. This article contributes to the under-researched area of adolescent male language use and offers one of the first ethnographically supported accounts of linguistic variation in Glasgow.
from the Journal of Sociolinguistics
Bilingual children’s acquisition of the past tense: a usage-based approach
Bilingual and monolingual children’s (mean age=4;10) elicited production of the past tense in both English and French was examined in order to test predictions from Usage-Based theory regarding the sensitivity of children’s acquisition rates to input factors such as variation in exposure time and the type/token frequency of morphosyntactic structures. Both bilingual and monolingual children were less accurate with irregular than regular past tense forms in both languages. Bilingual children, as a group, were less accurate than monolinguals with the English regular and irregular past tense, and with the French irregular past tense, but not with the French regular past tense. However, bilingual children were as accurate as monolinguals with the past tense in their language of greater exposure, except for English irregular verbs. It is argued that these results support the view that children’s acquisition rates are sensitive to input factors, but with some qualifications.
from the Journal of Child Language
