Monthly Archives: September 2010
The BigCAT: A normative and comparative investigation of the communication attitude of nonstuttering and stuttering adults
The purpose of this investigation was to provide normative and comparative data for the BigCAT, the adult form of the Communication Attitude Test, a sub-test of the Behavior Assessment Battery. The BigCAT, a 35-item self-report test of speech-associated attitude was administered to 96 adults who stutter (PWS) and 216 adults who do not (PWNS). The difference in the extent to which the two groups of participants reported a negative attitude toward their speech and speech ability, as measured by the BigCAT, was statistically significant. Moreover, the overlap in the scores of the PWS and PWNS was minimal, and the effect size attributable to group membership was very large. The BigCAT’s high Cronbach Alpha coefficients, together with the fact that each of its items significantly differentiated PWS from PWNS, indicate that the BigCAT is an internally consistent measure of the attitude that they have about their speech. Gender did not have a significant influence on the attitude toward speech or speech ability of either the PWS or PWNS. Overall, the presented data suggest that the BigCAT holds promise as an aid to clinical decision making that relates to the assessment and treatment of those who stutter.
from the Journal of Communication Disorders
Mensch, bentsh, and balagan: Variation in the American Jewish linguistic repertoire
Based on a large-scale survey, this paper argues that the speech of American Jews should be analyzed not as a separate ethnolect or language variety but as English with a repertoire of distinctive linguistic features stemming from Yiddish, Hebrew, Aramaic, and other sources. Jews make selective use of this repertoire as they index their identities as Jews and as certain types of Jews. Older Jews, Orthodox Jews, and non-Orthodox Jews who are highly engaged in religious life use different Hebrew and Yiddish words and grammatical constructions and different Hebrew pronunciations. Some Jews use distinctive meanings of Yiddish words, regional pronunciations of English words, or discourse styles. These trends are analyzed in relation to ethnolinguistic variation and Jewish languages.
Explicit processing of verbal and spatial features during letter-location binding modulates oscillatory activity of a fronto-parietal network
The present study investigated the binding of verbal and spatial features in immediate memory. In a recent study, we demonstrated incidental and asymmetrical letter-location binding effects when participants attended to letter features (but not when they attended to location features) that were associated with greater oscillatory activity over prefrontal and posterior regions during the retention period. We were interested to investigate whether the patterns of brain activity associated with the incidental binding of letters and locations observed when only the verbal feature is attended differ from those reflecting the binding resulting from the controlled/explicit processing of both verbal and spatial features. To achieve this, neural activity was recorded using magnetoencephalography (MEG) while participants performed two working memory tasks. Both tasks were identical in terms of their perceptual characteristics and only differed with respect to the task instructions. One of the tasks required participants to process both letters and locations. In the other, participants were instructed to memorize only the letters, regardless of their location. Time-frequency representation of MEG data based on the wavelet transform of the signals was calculated on a single trial basis during the maintenance period of both tasks. Critically, despite equivalent behavioural binding effects in both tasks, single and dual feature encoding relied on different neuroanatomical and neural oscillatory correlates. We propose that enhanced activation of an anterior–posterior dorsal network observed in the task requiring the processing of both features reflects the necessity for allocating greater resources to intentionally process verbal and spatial features in this task.
from Neuropsychologia
Effects of Spectral Shifting on Speech Perception in Noise
The present study used eight normal-hearing (NH) subjects, listening to acoustic cochlear implant (CI) simulations, to examine the effects of spectral shifting on speech recognition in noise. Speech recognition was measured using spectrally matched and shifted speech (vowels, consonants, and IEEE sentences), generated by 8-channel, sine-wave vocoder. Measurements were made in quiet and in noise (speech-shaped static noise and speech-babble at 5 dB signal-to-noise ratio). One spectral match condition and four spectral shift conditions were investigated: 2 mm, 3 mm, and 4 mm linear shift, and 3 mm shift with compression, in terms of cochlear distance. Results showed that speech recognition scores dropped because of noise and spectral shifting, and that the interactive effects of spectral shifting and background conditions depended on the degree/type of spectral shift, background conditions, and the speech test materials. There was no significant interaction between spectral shifting and two noise conditions for all speech test materials. However, significant interactions between linear spectral shifts and all background conditions were found in sentence recognition; significant interactions between spectral shift types and all background conditions were found in vowel recognition. Overall, the results suggest that tonotopic mismatch may affect performance of CI users in complex listening environments.
from Hearing Research
Mild traumatic brain injury: Graph-model characterization of brain networks for episodic memory
Episodic memory is among the cognitive functions that can be affected in the acute phase following mild traumatic brain injury (MTBI). The present study used EEG recordings to evaluate global synchronization and network organization of rhythmic activity during the encoding and recognition phases of an episodic memory task varying in stimulus type (kaleidoscope images, pictures, words, and pseudowords). Synchronization of oscillatory activity was assessed using a linear and nonlinear connectivity estimator and network analyses were performed using algorithms derived from graph theory. Twenty five MTBI patients (tested within days post-injury) and healthy volunteers were closely matched on demographic variables, verbal ability, psychological status variables, as well as on overall task performance. Patients demonstrated sub-optimal network organization, as reflected by changes in graph parameters in the theta and alpha bands during both encoding and recognition. There were no group differences in spectral energy during task performance or on network parameters during a control condition (rest). Evidence of less optimally organized functional networks during memory tasks was more prominent for pictorial than for verbal stimuli.
Behavioral/Systems/Cognitive Spatiotemporal Representation of the Pitch of Harmonic Complex Tones in the Auditory Nerve
The pitch of harmonic complex tones plays an important role in speech and music perception and the analysis of auditory scenes, yet traditional rate–place and temporal models for pitch processing provide only an incomplete description of the psychophysical data. To test physiologically a model based on spatiotemporal pitch cues created by the cochlear traveling wave (Shamma, 1985), we recorded from single fibers in the auditory nerve of anesthetized cat in response to harmonic complex tones with missing fundamentals and equal-amplitude harmonics. We used the principle of scaling invariance in cochlear mechanics to infer the spatiotemporal response pattern to a given stimulus from a series of measurements made in a single fiber as a function of fundamental frequency F0. We found that spatiotemporal cues to resolved harmonics are available for F0 values between 350 and 1100 Hz and that these cues are more robust than traditional rate–place cues at high stimulus levels. The lower F0 limit is determined by the limited frequency selectivity of the cochlea, whereas the upper limit is caused by the degradation of phase locking to the stimulus fine structure at high frequencies. The spatiotemporal representation is consistent with the upper F0 limit to the perception of the pitch of complex tones with a missing fundamental, and its effectiveness does not depend on the relative phase between resolved harmonics. The spatiotemporal representation is thus consistent with key trends in human psychophysics.
from the Journal of Neuroscience
Neonatal hearing screening in Benin City
The screening tests suggest a high crude prevalence (6.5%) of bilateral neonatal hearing impairment in Benin City necessitating confirmation and intervention. The study fortifies the need for hearing screening among all new born in developing countries.
from the International Journal of Pediatric Otorhinolaryngology
Reading words; seeing style: The neuropsychology of word; font and handwriting perception
The reading of text is predominantly a left hemisphere function. However, it is also possible to process text for attributes other than word or letter identity, such as style of font or handwriting. Anecdotal observations have suggested that processing the latter may involve the right hemisphere. We devised a test that, using the identical stimuli, required subjects first to match on the basis of word identity and second to match on the basis of script style. We presented two versions, one using various computer fonts, and the other using the handwriting of different individuals. We tested four subjects with unilateral lesions who had been well characterized by neuropsychological testing and structural and/or functional MRI. We found that two prosopagnosic subjects with right lateral fusiform damage eliminating the fusiform face area and likely the right visual word form area were impaired in reading times and/or accuracy when sorting for script style, but performed better when sorting for word identity. In contrast, one alexic subject with left fusiform damage showed normal accuracy for sorting by script style and normal or mildly elevated completion times for sorting by style, but markedly prolonged reading times for sorting by word identity. A prosopagnosic subject with right medial occipitotemporal damage sparing areas in the lateral fusiform gyrus performed well on both tasks. The contrast in the performance of patients with right versus left fusiform damage suggests an important distinction in hemispheric processing that reflects not the type of stimulus but the nature of processing required.
from Neuropsychologia
Neural inhibition enables selection during language processing
Whether grocery shopping or choosing words to express a thought, selecting between options can be challenging, especially for people with anxiety. We investigate the neural mechanisms supporting selection during language processing and its breakdown in anxiety. Our neural network simulations demonstrate a critical role for competitive, inhibitory dynamics supported by GABAergic interneurons. As predicted by our model, we find that anxiety (associated with reduced neural inhibition) impairs selection among options and associated prefrontal cortical activity, even in a simple, nonaffective verb-generation task, and the GABA agonist midazolam (which increases neural inhibition) improves selection, whereas retrieval from semantic memory is unaffected when selection demands are low. Neural inhibition is key to choosing our words.
from the Proceedings of the National Academy of Sciences of the United States of America
Phonological decisions require both the left and right supramarginal gyri
Recent functional imaging studies demonstrated that both the left and right supramarginal gyri (SMG) are activated when healthy right-handed subjects make phonological word decisions. However, lesion studies typically report difficulties with phonological processing after left rather than right hemisphere damage. Here, we used a unique dual-site transcranial magnetic stimulation (TMS) approach to test whether the SMG in the right hemisphere contributes to modality-independent (i.e., auditory and visual) phonological decisions. To test task-specificity, we compared the effect of real or sham TMS during phonological, semantic, and perceptual decisions. To test laterality and anatomical specificity, we compared the effect of TMS over the left, right, or bilateral SMG and angular gyri. The accuracy and reaction times of phonological decisions were selectively disrupted relative to semantic and perceptual decisions when real TMS was applied over the left, right, or bilateral SMG. These effects were not observed for TMS over the angular gyri. A follow-up experiment indicated that the threshold-intensity for inducing a disruptive effect on phonological decisions was identical for unilateral TMS over the right or left SMG. Taken together, these findings provide converging evidence that the right SMG contributes to accurate and efficient phonological decisions in the healthy brain, with no evidence that the left and right SMG can compensate for one another during TMS. Our findings motivate detailed studies of phonological processing in patients with acute or long-term damage of the right SMG.
from the Proceedings of the National Academy of Sciences of the United States of America
Intact first- and second-order implicit sequence learning in secondary-school-aged children with developmental dyslexia
We examined the influence of task complexity on implicit sequence learning in secondary-school-aged children with developmental dyslexia (DD). This was done to determine whether automatization problems in reading extend to the automatization of all skill and depend on the complexity of the to-be-learned skill. A total of 28 dyslexic children between 12 and 15 years and 28 matched control children carried out two serial reaction time tasks using a first-order conditional (FOC) and second-order conditional (SOC) sequence. In both tasks, children incidentally learned a sequence of hidden target positions, but whereas FOC sequence learning could be based on knowledge about the immediate preceding position, SOC sequence learning required more complex knowledge about the previous two positions. The results demonstrated that sequence learning was highly comparable in dyslexic and control children, regardless of the sequence complexity. This shows that implicit sequence learning, as manifested in the present study, is maintained in DD and is unrelated to task complexity. We suggest that previous reports of sequence-learning deficits in DD can be accounted for by attenuated explicit sequence learning, possibly related to malfunctions in prefrontal processing. The present findings indicate that deficits in skill learning and automatization in DD are not general in nature, but task dependent.
from the Journal of Clinical and Experimental Neurophysiology
Verbal memory impairment in severe closed head injury: The role of encoding and consolidation
We applied the item-specific deficit approach (ISDA) to California Verbal Learning Test data obtained from 56 severe, acceleration-deceleration closed head injury (CHI) participants and 62 controls. The CHI group demonstrated deficits on all ISDA indices in comparison to controls. Regression analyses indicated that encoding deficits, followed by consolidation deficits, accounted for most of the variance in delayed recall. Additionally, level of acquisition played a partial role in CHI-associated consolidation difficulties. Finally, CHI encoding deficits were largely driven by low semantic clustering during list learning. These results suggest that encoding (primary) and consolidation (secondary) deficits account for CHI-associated verbal memory impairment.
from the Journal of Clinical and Experimental Neuropsychology
Comparing Speech Perception of Children With Cochlear Implants or Hearing Aids
Cochlear implant (CI) candidacy guidelines continue to evolve as a result of advances in both cochlear implant and hearing aid technology. Empirical studies comparing the speech perception abilities of children using cochlear implants or hearing aids will be reviewed in the context of current device technology and CI candidacy evaluations.
from Perspectives on Hearing and Hearing Disorders in Childhood
For Children With Hearing Loss: The Times They Are A-changin’
Today, children with hearing loss have more opportunities than ever before to use audition and to achieve age-appropriate spoken language and academic outcomes. Several factors are driving these new outcomes, including universal newborn hearing screening and earlier diagnosis of hearing loss, immediate fitting of advanced hearing technology, and enrollment in appropriate early intervention services. For speech-language pathologists and audiologists, these changes mean altering how these children and their families are served, including the types of diagnostic evaluations that are conducted. Specifically, if speech-language pathologists are to remain vital service providers, they must raise their professional expectations for what these children can ultimately achieve.
from Perspectives on Hearing and Hearing Disorders in Childhood
