July 1, 2013 Departments

From the Journals: July 2013

Catch up on the latest findings by researchers in communication sciences and disorders in this roundup of study results.

To Understand Bilingual Clients' Speech Perception, First Consider Their Attitudes

To fully understand bilingual clients' perception of English speech, hearing professionals should consider their attitudes about language in addition to language background, according to a study published in the December 2012 issue of the American Journal of Audiology.

Hypothesizing that linguistic variables alone cannot fully account for bilingual listeners' perception of English running speech, the authors investigated how the combination of linguistic factors and attitude affect bilingual processing of temporally degraded English passages.

Thirty-six bilinguals participated in the study. Bilingual people completed questionnaires to assess their language backgrounds, willingness to communicate, and self-perceived communication competency in English. Participants listened to English passage pairs from the Connected Speech Test, presented at 45 dB HL at three rates—unprocessed, expanded, compressed—in quiet and in noise.

The most significant linguistic variables were language proficiency measures, accounting for the largest amount of variance in performance across most conditions. Willingness to communicate and self-perceived communication competency both were associated with performance and contributed to regression models. Performance in noise was more difficult to predict than in quiet.

Greater Understanding of Families' Language Use Leads to Better Support

Communication between parents and children is a complex matter, unique to each family. So practitioners need to be better informed about intergenerational language practices in minority-language families, says a study in the February 2013 issue of the American Journal of Speech-Language Pathology. Parents need practitioners' support to make language-use decisions that are self-enhancing and congruent with their family's needs.

The author investigated the language practices of 10 bilingual, Chinese/English-speaking, immigrant mothers with their children with autism spectrum disorders. Her aim was to understand the nature of the language practices, their constraints and their impact. She used in-depth phenomenological interviews with thematic and narrative analyses to yield themes.

Interviewees reported that they adopted the language practices they perceived to be most advantageous for acquiring services and maintaining wellness. They valued Chinese language, but did not pursue its use if they thought it would hinder the children's overall English acquisition. All the mothers believed bilingualism made learning more challenging, and many believed it caused confusion or exacerbated disabilities. Their deficit views of bilingualism commonly were reinforced by professionals. All the mothers were motivated to help their children learn English, but had no assistance to do so. Practices were sustainable only when they were aligned with families' preferred communication patterns.

Do Sentence Length and Syntactic Complexity Influence Speech Motor Control?

Some children who stutter exhibit more variable speech motor coordination during fluent speech production than typically developing children, according to a study in the February 2013 issue of the Journal of Speech, Language, and Hearing Research. Sentence length and complexity did not disproportionately affect the coordination variability and duration of children who stutter, but the authors observed considerable individual differences in performance.

To investigate the potential effects of increased sentence length and syntactic complexity on the speech motor control of children who stutter, researchers had participants repeat sentences of varied length and syntactic complexity. Then they analyzed kinematic measures of articulatory coordination variability and movement duration during perceptually fluent speech for 16 children who stutter and 16 typically developing children ages 4–6. The authors also examined behavioral data from a larger pool of children.

For both groups, articulatory coordination variability increased with sentence length, and movement duration was greater for syntactically complex—as opposed to simple—sentences. For sentences with simple syntax, the children who stuttered had higher coordination variability than typically developing peers. There was no group difference in coordination variability for complex sentences. But coordination variability increased significantly with complexity for typically developing children, whereas that of children who stutter remained at the high level they also demonstrated for simple sentences. Overall, the children who stuttered tended toward higher coordination variability compared with the typically developing children.

Target Natural and AAC Speech Simultaneously to Reach Goals

Simultaneously targeting natural speech and augmentative and alternative communication speech—using a novel, integrated multimodal approach—was linked to positive changes in both communication and speech production goals for three children.

The findings, published in the April 2013 issue of Language, Speech, and Hearing Services in Schools, suggest that integrating multimodal speech-generating AAC with traditional speech intervention can be effective in supporting children's natural speech production.

The study introduces Integrated Multimodal Intervention—an activity-based intervention—and examines its effectiveness for treating persistent and severe speech sound disorders in young children. The IMI focuses simultaneously on increasing the quantity of a child's meaningful productions of target words and providing supports to shape the quality of natural speech productions of target sounds. This is achieved by systematically incorporating the full range of each child's communicative repertoire, including AAC systems and natural speech and language.

The authors used a multiple-probe single-subject research design to assess the effectiveness of the IMI for three boys ages 4–8 with moderate to severe speech sound disorders, all of whom used speech-generating AAC. All three participants produced more speech than previously, with greater production accuracy of their target speech sounds.

Scientists Find Tinnitus Cause, Preventive Drug

An epilepsy drug shows promise in an animal model at preventing tinnitus from developing after exposure to loud noise, according to a new study by researchers at the University of Pittsburgh School of Medicine.

The findings, reported in the early online version of the Proceedings of the National Academy of Sciences, reveal for the first time the reason the chronic and sometimes debilitating condition occurs.

Previous research revealed that tinnitus is associated with hyperactivity of DCN cells—they fire impulses even when there is no actual sound to perceive. For the new experiments, researchers took a close look at the biophysical properties of tiny channels, called KCNQ channels, through which potassium ions travel in and out of the cell, and which act as effective "brakes" to reduce the activity of neuronal cells. Researchers believe a reduction in KCNQ activity leads to tinnitus.

After using noise to induce tinnitus in mice, researchers tested whether an FDA-approved epilepsy drug called retigabine—which specifically enhances KCNQ channel activity—could prevent them from developing tinnitus. Thirty minutes into the noise exposure and twice daily for the next five days, researchers injected half of the exposed group with retigabine.

The researchers found that the mice treated with retigabine immediately after noise exposure did not develop tinnitus. Consistent with previous studies, half of the noise-exposed mice that were not treated with the drug exhibited behavioral signs of the condition.

Scientists Derive Mature Brain Cells From Skin

Using stem cells, scientists have devised a method to generate neurons—mature brain cells—by reprogramming a patient's skin cells. The research, to be published in the September 2013 issue of Stem Cell Research, opens new, non-invasive avenues for brain treatment. Researchers believe the method could lead to customized treatments for patients based on their genetic and cellular information, and hope that difficult-to-study diseases such as Alzheimer's, schizophrenia and autism now can be probed more safely and effectively.

The team found a way to differentiate unspecialized or undifferentiated pluripotent stem cells into mature human neurons much more effectively, generating cells that behave similarly to neurons in the brain. In the brain, neurons are always found in proximity to star-shaped cells called astrocytes, which are abundant in the brain and help neurons to function properly. Scientists predicted that this direct physical contact might be an integral part of neuronal growth and health.

To test this hypothesis, researchers cultured neural stem cells, which are stem cells that have the potential to become neurons. These cells were cultured on top of a one-cell-thick layer of astrocytes so that the two cell types were physically touching each other. This direct contact seemed to spur the cells into differentiating into neurons.

To demonstrate the superiority of the neurons grown next to astrocytes, the team used an electrophysiology recording technique to show that the cells grown on astrocytes had many more synaptic events—signals sent out from one nerve cell to the others. In another experiment, after growing the neural stem cells next to astrocytes for just one week, the newly differentiated neurons started to fire action potentials—the rapid electrical excitation signal that occurs in all neurons in the brain. In a final test, the team members added human neural stem cells to a mixture with mouse neurons. They found "cross-talk"—one neuron contacting its neighbors and releasing a neurotransmitter to modulate its neighbor's activity—between the mouse neurons and the human neurons.


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