Monthly Archives: June 2009
Neuroanatomical markers of speaking Chinese
The aim of this study was to identify regional structural differences in the brains of native speakers of a tonal language (Chinese) compared to nontonal (European) language speakers. Our expectation was that there would be differences in regions implicated in pitch perception and production. We therefore compared structural brain images in three groups of participants: 31 who were native Chinese speakers; 7 who were native English speakers who had learnt Chinese in adulthood; and 21 European multilinguals who did not speak Chinese. The results identified two brain regions in the vicinity of the right anterior temporal lobe and the left insula where speakers of Chinese had significantly greater gray and white matter density compared with those who did not speak Chinese. Importantly, the effects were found in both native Chinese speakers and European subjects who learnt Chinese as a non-native language, illustrating that they were language related and not ethnicity effects. On the basis of prior studies, we suggest that the locations of these gray and white matter changes in speakers of a tonal language are consistent with a role in linking the pitch of words to their meaning. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc.
from Human Brain Mapping
Atypical cerebral lateralisation in adults with compensated developmental dyslexia demonstrated using functional transcranial Doppler ultrasound
Functional transcranial Doppler ultrasound (fTCD) is a relatively new and non-invasive technique that assesses cerebral lateralisation through measurements of blood flow velocity in the middle cerebral arteries. In this study fTCD was used to compare functional asymmetry during a word generation task between a group of 30 dyslexic adults and a group of 30 non-dyslexic individuals. In light of previous evidence of atypical laterality in dyslexia, a reduced leftward asymmetry was predicted and confirmed. We know from previous research that most people with atypical language lateralisation have normal language and literacy skills: nevertheless, our results confirm that language laterality is reduced in those with dyslexia. Theoretical explanations for this apparent conundrum are discussed.
from Brain and Language
The sensitivity of the right hemisphere to contextual information in sentences
One explanation for the inconsistencies in research examining the sentence comprehension abilities of the right hemisphere (RH) is the presence of confounding variables that have generally served to disadvantage the processing capacities of the RH. As such, the present study aimed to investigate hemispheric differences in the use of message-level sentential information by removing some of the factors known to be inherently disadvantageous for RH comprehension. Thirty-two right-handed undergraduate university students participated in a computer-based lexical decision task where RT and error rates were recorded. The sensitivity of each hemisphere to the message-level contextual information contained in short versus long sentences was compared, as well as the effect of stimulus modality (visual compared to auditory). The results showed that the RH benefited from increased levels of context to at least the same extent as the LH and that, more importantly, this could not be explained by word-level processes alone. This finding, unusual in behavioral research on normal individuals but consistent with neuropsychological, electrophysiological, and neuroimaging approaches, suggests that the RH plays an important role in sentence comprehension, at least in relation to sentences that conform to a relatively simple structure.
from Brain and Language
Interaction of speech and script in human auditory cortex: Insights from neuro-imaging and effective connectivity
In addition to visual information from the face of the speaker, a less natural, but nowadays extremely important visual component of speech is its representation in script. In this review, neuro-imaging studies are examined which were aimed to understand how speech and script are associated in the adult “literate” brain. The reviewed studies focused on the role of different stimulus and task factors and effective connectivity between different brain regions. The studies will be summarized in a neural mechanism for the integration of speech and script that can serve as a basis for future studies addressing (the failure of) literacy acquisition. In this proposed mechanism, speech sound processing in auditory cortex is modulated by co-presented visual letters, depending on the congruency of the letter–sound pairs. Other factors of influence are temporal correspondence, input quality and task instruction. We present results showing that the modulation of auditory cortex is most likely mediated by feedback from heteromodal areas in the superior temporal cortex, but direct influences from visual cortex are not excluded. The influence of script on speech sound processing occurs automatically and shows extended development during reading acquisition. This review concludes with suggestions to answer currently still open questions to get closer to understanding the neural basis of normal and impaired literacy.
from Hearing Research
Otoacoustic Emission Theories and Behavioral Estimates of Human Basilar Membrane Motion Are Mutually Consistent Journal
When two pure tones (or primaries) of slightly different frequencies (f 1 and f 2) are presented to the ear, new frequency components are generated by nonlinear interaction of the primaries within the cochlea. These new components can be recorded in the ear canal as otoacoustic emissions (OAE). The level of the 2f 1−f 2 OAE component is known as the distortion product otoacoustic emission (DPOAE) and is regarded as an indicator of the physiological state of the cochlea. The current view is that maximal level DPOAEs occur for primaries that produce equal excitation at the f 2 cochlear region, but this notion cannot be directly tested in living humans because it is impossible to record their cochlear responses while monitoring their ear canal DPOAE levels. On the other hand, it has been claimed that the temporal masking curve (TMC) method of inferring human basilar membrane responses allows measurement of the levels of equally effective pure tones at any given cochlear site. The assumptions of this behavioral method, however, lack firm physiological support in humans. Here, the TMC method was applied to test the current notion on the conditions that maximize DPOAE levels in humans. DPOAE and TMC results were mutually consistent for frequencies of 1 and 4 kHz and for levels below around 65 dB sound pressure level. This match supports the current view on the generation of maximal level DPOAEs as well as the assumptions of the behavioral TMC method.
from JARO — Journal of the Association for Research in Otolaryngology
The Effects of Context on the Classroom Discourse Skills of Children With Language Impairment
Purpose: The purpose of this study was to explore the effects of context on the classroom discourse skills of children with language impairment (LI).
Method: Four classroom contexts were audiotaped among 11 children with LI: a journal-writing conference, a small-group lesson, a peer play session, and sharing time.
Results: Context affected the children’s performances on language productivity and complexity measures, self-monitoring strategies, and turn-taking patterns.
Clinical Implications: Classroom discourse as a set of discourse genres is critical in the assessment and intervention of LI. In order to be representative of a given child’s competence, several of such genres must be sampled in language assessment.
Clinical significance of the summating potential-action potential ratio and the action potential latency difference for condensation and rarefaction clicks in Meniere’s disease.
RESULTS: No correlation was found between the SP/AP ratio and the AP con-rar difference. Neither the SP/AP ratio in general nor the AP con-rar difference was correlated with the hearing level. However, enhanced values of the SP/AP ratio (0.35 or higher) were moderately correlated with the hearing level (r = 0.51), and their occurrence rate was 55.2%. An increased AP con-rar difference (0.13 ms or longer) was not correlated with the hearing level, and its occurrence rate was 50.2%; it appeared most frequently at stage 3 (p <0.05). CONCLUSIONS: An enhanced SP/AP ratio might not always indicate the presence of endolymphatic hydrops associated with an increase in endolymphatic pressure. An increased AP con-rar difference might reflect the presence of a biased basilar membrane resulting from an increased endolymphatic pressure, and hence it is diagnostically essential to simultaneously evaluate the SP/AP ratio and the AP con-rar difference.
Influence of blood pressure manometer feedback on the parameters of the vestibular evoked myogenic potential test.
RESULTS: The mean IAD ratio was smaller in the FB+ condition than in the FB- and supine conditions, but the difference was without statistical significance. The upper limits of the normal range of the IAD ratios were 39.5%, 18.3%, and 25.9% for the FB-, FB+, and supine conditions, respectively. The interaural latency difference of p13 was significantly smaller in the supine condition than in the FB- and FB+ conditions. CONCLUSIONS: Although the reduction of the mean IAD ratio did not reach statistical significance by feedback monitoring in our study, feedback using a BP manometer may have some clinical significance, in that a more stable IAD ratio may be obtained with a narrower normal range and a smaller variation.
Mild and variable audiometric and vestibular features in a third DFNA15 family with a novel mutation in POU4F3.
RESULTS: A novel mutation (L223P) in POU4F3 segregated with hearing impairment in the present family. Audiometric analysis generally showed an early-adult to midlife onset of hearing impairment. High-frequency hearing impairment was observed most frequently. Age-related typical audiograms showed a down-sloping configuration at ages of more than 30 years, with the fastest rate of progression at the high frequencies. Vestibular function tests revealed hypofunction of the vestibular labyrinth in 2 mutation carriers (not statistically significant). CONCLUSIONS: The clinical features in the present family with a POU4F3 mutation were fairly similar to those in the 2 previously described DFNA15 families, but the level of hearing impairment was milder, and there was no substantial vestibular dysfunction.
Prothrombotic gene mutations in patients with sudden sensorineural hearing loss and cardiovascular thrombotic disease.
RESULTS: Two patients had 2 mutant alleles, 6 had 3, and 2 had 4. The mean homocysteine, cholesterol, and fibrinogen levels were above the upper limit of normal; the mean folate levels were slightly above the lower limit of normal. Multiple mutations were more frequent in the patient group than in the previously analyzed patients and healthy controls. CONCLUSIONS: The association between inherited and acquired prothrombotic factors in patients with sudden sensorineural hearing loss and thrombotic diseases in other sites suggests that a multifactorial mechanism may underlie microvascular cochlear impairment. Hematologic investigation, including MTHFR, prothrombin, platelet, and V Leiden genotyping, may help to detect patients at potential risk of recurrent hearing loss and multiple microvascular diseases, and could be usefully performed in otherwise idiopathic sudden sensorineural hearing loss.
Use of neuromuscular electrostimulation in the treatment of dysphagia in patients with multiple sclerosis.
RESULTS: After treatment, a significant decrease in pooling of saliva in the pyriform sinuses was seen in 6 patients (p = 0.03), and significantly less aspiration during swallowing of thin liquids (p <0.01) was seen in 9 patients. Overall, the 25 patients reported that their swallowing had improved (p <0.01), and in 20% of the patients,it had become less strenuous. No adverse effects of the treatment were reported. CONCLUSIONS: Our study showed that the treatment of swallowing problems with neuromuscular electrostimulation in patients with multiple sclerosis in this sample was successful in the reduction of pooling of saliva and in the reduction of aspiration.
Speech Target Modulates Speaking Induced Suppression in Auditory Cortex
Results
The present MEG study investigated the effects of utterance rapidity and complexity on SIS: The greatest difference between speak and listen M100 amplitudes (i.e., most SIS) was found in the simple speech task. As the utterances became more rapid and complex, SIS was significantly reduced (p = 0.0003).
Conclusions
These findings are highly consistent with our model of how auditory feedback is processed during speaking, where incoming feedback is compared with an efference-copy derived prediction of expected feedback. Thus, the results provide further insights about how speech motor output is controlled, as well as the computational role of auditory cortex in transforming auditory feedback.
from BMC Neuroscience
Coping responses by adults who stutter: Part I. Protecting the self and others
Using a grounded theory approach, four clusters were identified that represent patterns of coping by adults who stutter. In order to understand the complexities within the coping responses of speakers to the experience of stuttering, this first of two companion papers summarizes the literature on the human coping response to stress and the nature of two of the four main findings identified. These findings describe a coping process that emphasizes strategies of protecting both the speaker and the listener from experiencing discomfort associated with stuttering. The companion paper describes the remaining two main findings that emphasize the characteristics of self- focused and action oriented coping responses.
Children’s understanding of the agent-patient relations in the transitive construction: Cross-linguistic comparisons between Cantonese, German, and English
Cantonese-, German-, and English-speaking children aged 2;6, 3,6, and 4,6 acted out transitive sentences containing novel verbs in three conditions: (1) agent and patient were cued redundantly by both word order and animacy; (2) agent and patient were marked only with word order; and (3) agent and patient were cued in conflicting ways with word order and animacy. All three age groups in all three languages comprehended the redundantly cued sentences. When word order was the only cue, English children showed the earliest comprehension at 2;6, then German, and then Cantonese children at 3;6. When the cues conflicted, none of the 2;6 children in any language comprehended in adult-like ways, whereas all of the children at 3;6 and 4;6 preferred word order over animacy (but with some cross-linguistic differences in performance as well). When animacy contrast changed across sentence types, Cantonese children comprehended the sentences differently at all three age levels, German children did so at the two younger ages, and English children only at the youngest age. The findings correspond well with the informativeness of word order in the three languages, suggesting that children’s learning of the syntactic marking of agent-patient relations is strongly influenced by nature of the language they hear around them.
