Cognitive mechanisms underpinning successful perception of different speech distortions.

Few studies thus far have investigated whether perception of distorted speech is consistent across different types of distortion. This study investigated whether participants show a consistent perceptual profile across three speech distortions: time-compressed, noise-vocoded, and speech in noise. Additionally, this study investigated whether/how individual differences in performance on a battery of audiological and cognitive tasks links to perception. Eighty-eight participants completed a speeded sentence-verification task with increases in accuracy and reductions in response times used to indicate performance. Audiological and cognitive task measures include pure tone audiometry, speech recognition threshold, working memory, vocabulary knowledge, attention switching, and pattern analysis. Despite previous studies suggesting that temporal and spectral/environmental perception require different lexical or phonological mechanisms, this study shows significant positive correlations in accuracy and response time performance across all distortions. Results of a principal component analysis and multiple linear regressions suggest that a component based on vocabulary knowledge and working memory predicted performance in the speech in quiet, time-compressed and speech in noise conditions. These results suggest that listeners employ a similar cognitive strategy to perceive different temporal and spectral/environmental speech distortions and that this mechanism is supported by vocabulary knowledge and working memory.

The Causal Role of Left and Right Superior Temporal Gyri in Speech Perception in Noise: A Transcranial Magnetic Stimulation Study.

Successful perception of speech in everyday listening conditions requires effective listening strategies to overcome common acoustic distortions, such as background noise. Convergent evidence from neuroimaging and clinical studies identify activation within the temporal lobes as key to successful speech perception. However, current neurobiological models disagree on whether the left temporal lobe is sufficient for successful speech perception or whether bilateral processing is required. We addressed this issue using TMS to selectively disrupt processing in either the left or right superior temporal gyrus (STG) of healthy participants to test whether the left temporal lobe is sufficient or whether both left and right STG are essential. Participants repeated keywords from sentences presented in background noise in a speech reception threshold task while receiving online repetitive TMS separately to the left STG, right STG, or vertex or while receiving no TMS. Results show an equal drop in performance following application of TMS to either left or right STG during the task. A separate group of participants performed a visual discrimination threshold task to control for the confounding side effects of TMS. Results show no effect of TMS on the control task, supporting the notion that the results of Experiment 1 can be attributed to modulation of cortical functioning in STG rather than to side effects associated with online TMS. These results indicate that successful speech perception in everyday listening conditions requires both left and right STG and thus have ramifications for our understanding of the neural organization of spoken language processing.

The role of the arcuate and middle longitudinal fasciculi in speech perception in noise in adulthood.

In this article, we used High Angular Resolution Diffusion Imaging (HARDI) with advanced anatomically constrained particle filtering tractography to investigate the role of the arcuate fasciculus (AF) and the middle longitudinal fasciculus (MdLF) in speech perception in noise in younger and older adults. Fourteen young and 15 elderly adults completed a syllable discrimination task in the presence of broadband masking noise. Mediation analyses revealed few effects of age on white matter (WM) in these fascicles but broad effects of WM on speech perception, independently of age, especially in terms of sensitivity and criterion (response bias), after controlling for individual differences in hearing sensitivity and head size. Indirect (mediated) effects of age on speech perception through WM microstructure were also found, after controlling for individual differences in hearing sensitivity and head size, with AF microstructure related to sensitivity, response bias and phonological priming, and MdLF microstructure more strongly related to response bias. These findings suggest that pathways of the perisylvian region contribute to speech processing abilities, with relatively distinct contributions for the AF (sensitivity) and MdLF (response bias), indicative of a complex contribution of both phonological and cognitive processes to age-related speech perception decline. These results provide new and important insights into the roles of these pathways as well as the factors that may contribute to elderly speech perception deficits. They also highlight the need for a greater focus to be placed on studying the role of WM microstructure to understand cognitive aging.

Effects of Coil Orientation on Motor Evoked Potentials From Orbicularis Oris.

This study aimed to characterize effects of coil orientation on the size of Motor Evoked Potentials (MEPs) from both sides of Orbicularis Oris (OO) and both First Dorsal Interosseous (FDI) muscles, following stimulation to left lip and left hand Primary Motor Cortex. Using a 70 mm figure-of-eight coil, we collected MEPs from eight different orientations while recording from contralateral and ipsilateral OO and FDI using a monophasic pulse delivered at 120% active motor threshold. MEPs from OO were evoked consistently for six orientations for contralateral and ipsilateral sites. Contralateral orientations 0°, 45°, 90°, and 315° were found to best elicit OO MEPs with a likely cortical origin. The largest FDI MEPs were recorded for contralateral 45°, invoking a posterior-anterior (PA) current flow. Orientations traditionally used for FDI were also found to be suitable for eliciting OO MEPs. Individuals vary more in their optimal orientation for OO than for FDI. It is recommended that researchers iteratively probe several orientations when eliciting MEPs from OO. Several orientations likely induced direct activation of facial muscles.

Modulation of intra- and inter-hemispheric connectivity between primary and premotor cortex during speech perception.

Primary motor (M1) areas for speech production activate during speechperception. It has been suggested that such activation may be dependent upon modulatory inputs from premotor cortex (PMv). If and how PMv differentially modulates M1 activity during perception of speech that is easy or challenging to understand, however, is unclear. This study aimed to test the link between PMv and M1 during challenging speech perception in two experiments. The first experiment investigated intra-hemispheric connectivity between left hemisphere PMv and left M1 lip area during comprehension of speech under clear and distorted listening conditions. Continuous theta burst stimulation (cTBS) was applied to left PMv in eighteen participants (aged 18-35). Post-cTBS, participants performed a sentence verification task on distorted (imprecisely articulated), and clear speech, whilst also undergoing stimulation of the lip representation in the left M1 to elicit motor evoked potentials (MEPs). In a second, separate experiment, we investigated the role of inter-hemispheric connectivity between right hemisphere PMv and left hemisphere M1 lip area. Dual-coil transcranial magnetic stimulation was applied to right PMv and left M1 lip in fifteen participants (aged 18-35). Results indicated that disruption of PMv during speech perception affects comprehension of distorted speech specifically. Furthermore, our data suggest that listening to distorted speech modulates the balance of intra- and inter-hemispheric interactions, with a larger sensorimotor network implicated during comprehension of distorted speech than when speech perception is optimal. The present results further understanding of PMv-M1 interactions during auditory-motor integration.

The school Lifesavers study-A randomised controlled trial comparing the impact of Lifesaver only, face-to-face training only, and Lifesaver with face-to-face training on CPR knowledge, skills and attitudes in UK school children.

BACKGROUND: Lifesaver (www.life-saver.org.uk) is an immersive, interactive game that can be used for basic life support training. Users 'resuscitate' a victim of cardiac arrest in a filmed scenario and move their device up and down to simulate cardiac compressions. METHODS: Randomised controlled trial of 3 UK schools (81 students) comparing Lifesaver, face-to-face (F2F) training, and a combination of both. Primary outcomes: mean chest compression rate and depth. SECONDARY OUTCOMES: flow fraction, CPR performance, and attitude survey. Outcomes measured immediately, 3 and 6 months. RESULTS: Primary outcomes: Mean chest compression depth was suboptimal in all groups due to body size. F2F performed better than Lifesaver initially (-11.676; 95% CI -18.34 to -5.01; p=0.0001) but no difference at 3 months (p=0.493) and 6 months (p=0.809). No difference in mean compression rates for Lifesaver vs F2F (-11.89; 95% CI -30.39 to -6.61; p=0.280) and combined vs Lifesaver (0.25; 95% CI -17.4 to -17.9; p=0.999). SECONDARY OUTCOMES: all groups had flow fraction >60% after training. Combined group performed better for skills assessment than Lifesaver (4.02; 95% CI 2.81-5.22; p=0.001) and F2F (1.76; 95 CI 0.51-3; p=0.003); and the same at 6 months (1.92; 95% CI 0.19-3.64; p=0.026 and 1.96; 95% CI 0.17-3.75; p=0.029). CONCLUSIONS: Use of Lifesaver by school children, compared to F2F training alone, can lead to comparable learning outcomes for several key elements of successful CPR. Its use can be considered where resources or time do not permit formal F2F training sessions. The true benefits of Lifesaver can be realised if paired with F2F training.

Ensuring patient safety blood transfusision.

Blood transfusion is a relatively common procedure, and is a necessary skill for many nurses working in a range of clinical environments. Blood transfusion carries a degree of risk, and avoidable mistakes can result in serious or fatal consequences. Adverse events are largely associated with human error, so know-ledge and skills are essential. While local and national policies go some way to reducing clinical risk, a comprehensive knowledge of the blood grouping system and compatibility, and the ability to recognise, respond to and report reactions, are also necessary to optimise patient safety. An online Nursing Times Learning unit on safe blood transfusion will be launched next month.

Measuring body temperature.

Body temperature is one of the four main vital signs that must be monitored to ensure safe and effective care. Temperature measurement is recommended by the National Institute of Clinical Excellence a part of the initial assessment in acute illness in adults (NICE, 2007) and by the Scottish Intercollegiate Guidelines Network guidelines for post-operative management in adults (SIGN, 2004). Despite applying in all healthcare environments, wide variations exist on the methods and techniques used to measure body temperature. It is essential to use the most appropriate technique to ensure that temperature is measured accurately. Inaccurate results may influence diagnosis and treatment, lead to a failure to identify patient deterioration and compromise patient safety. This article explains the importance of temperature regulation and compares methods of its measurement.

Care of peripheral venous cannula sites.

Peripheral venous catheters are commonly used in hospitals to deliver intravenous therapy. They are associated with a range of complications that can be damaging to patients' health and increase healthcare costs. In order to minimise the risk of these complications, thorough patient assessment and careful catheter management are essential.

Basic nursing principles of caring for patients with a tracheostomy.

This one-part unit outlines background information to complement a series of Practical Procedures articles, starting in next week's issue, on caring for patients with a tracheostomy. This article outlines general principles of tracheostomy care, while the series details specific procedures such as suction, inner tube change and dressing.