Are Interaural Time and Level Differences Represented by Independent or Integrated Codes in the Human Auditory Cortex?

Sound localization is important for orienting and focusing attention and for segregating sounds from different sources in the environment. In humans, horizontal sound localization mainly relies on interaural differences in sound arrival time and sound level. Despite their perceptual importance, the neural processing of interaural time and level differences (ITDs and ILDs) remains poorly understood. Animal studies suggest that, in the brainstem, ITDs and ILDs are processed independently by different specialized circuits. The aim of the current study was to investigate whether, at higher processing levels, they remain independent or are integrated into a common code of sound laterality. For that, we measured late auditory cortical potentials in response to changes in sound lateralization elicited by perceptually matched changes in ITD and/or ILD. The responses to the ITD and ILD changes exhibited significant morphological differences. At the same time, however, they originated from overlapping areas of the cortex and showed clear evidence for functional coupling. These results suggest that the auditory cortex contains an integrated code of sound laterality, but also retains independent information about ITD and ILD cues. This cue-related information might be used to assess how consistent the cues are, and thus, how likely they would have arisen from the same source

Guideline for UK midwives/health visitors to use with parents of infants at risk of developing childhood overweight/obesity

A guideline for members of the health visiting team to use with parents of infants at risk of overweight/obesity has been developed. The guideline contains recommendations about identification of infants at risk as well as a number of strategies that could be used for prevention of overweight/obesity. The guideline needs to be applied alongside health visitors’ professional judgement. It is not intended to replace normal UK clinical practice which is guided by the Healthy Child Programme and complements existing guidance such as the Framework for Action for tackling obesity

Systematic review of randomised controlled trials of interventions that aim to reduce the risk, either directly or indirectly, of overweight and obesity in infancy and early childhood

The risk factors for childhood overweight and obesity are known and can be identified antenatally or during infancy, however, the majority of effective interventions are designed for older children. This review identified interventions designed to reduce the risk of overweight/obesity that were delivered antenatally or during the first 2 years of life, with outcomes reported from birth to 7 years of age. Six electronic databases were searched for papers reporting randomised controlled trials of interventions published from January 1990 to September 2013. A total of 35 eligible studies were identified, describing 27 unique trials of which 24 were behavioural and three were non-behavioural. The 24 behavioural trials were categorised by type of intervention: (1) nutritional and/or responsive feeding interventions targeted at parents of infants, which improved feeding practices and had some impact on child weight (n = 12); (2) breastfeeding promotion and lactation support for mothers, which had a positive effect on breastfeeding but not child weight (n = 5); (3) parenting and family lifestyle (n = 4); and (4) maternal health (n = 3) interventions that had some impact on feeding practices but not child weight. The non-behavioural trials comprised interventions manipulating formula milk composition (n = 3). Of these, lower/hydrolysed protein formula milk had a positive effect on weight outcomes. Interventions that aim to improve diet and parental responsiveness to infant cues showed most promise in terms of self-reported behavioural change. Despite the known risk factors, there were very few intervention studies for pregnant women that continue during infancy which should be a priority for future research

Speech perception from monaural and binaural information

Two experiments explored the concept of the binaural spectrogram [Culling and Colburn, J. Acoust. Soc. Am. 107, 517-527 (2000)] and its relationship to monaurally derived information. In each experiment, speech was added to noise at an adverse signal-to-noise ratio in the NoS pi binaural configuration. The resulting monaural and binaural cues were analyzed within an array of spectro-temporal bins and then these cues were resynthesized by modulating the intensity and/or interaural correlation of freshly generated noise. Experiment 1 measured the intelligibility of the resynthesized stimuli and compared them with the original NoSo and NoS pi stimuli at a fixed signal-to-noise ratio. While NoS pi stimuli were approximately equal to 50% intelligible, each cue in isolation produced similar (very low) intelligibility to the NoSo condition. The resynthesized combination produced approximately equal to 25% intelligibility. Modulation of interaural correlation below 1.2 kHz and of amplitude above 1.2 kHz was not as effective as their combination across all frequencies. Experiment 2 measured three-point psychometric functions in which the signal-to-noise ratio of the original NoS pi stimulus was increased in 3-dB steps from the level used in experiment 1. Modulation of interaural correlation alone proved to have a flat psychometric function. The functions for NoS pi and for combined monaural and binaural cues appeared similar in slope, but shifted horizontally. The results indicate that for sentence materials, neither fluctuations in interaural correlation nor in monaural intensity are sufficient to support speech recognition at signal-to-noise ratios where 50% intelligibility is achieved in the NoS pi configuration; listeners appear to synergistically combine monaural and binaural information in this task, to some extent within the same frequency region

Systematic review of randomised controlled trials of interventions that aim to reduce the risk, either directly or indirectly, of overweight and obesity in infancy and early childhood

The risk factors for childhood overweight and obesity are known and can be identified antenatally or during infancy, however, the majority of effective interventions are designed for older children. This review identified interventions designed to reduce the risk of overweight/obesity that were delivered antenatally or during the first 2 years of life, with outcomes reported from birth to 7 years of age. Six electronic databases were searched for papers reporting randomised controlled trials of interventions published from January 1990 to September 2013. A total of 35 eligible studies were identified, describing 27 unique trials of which 24 were behavioural and three were non-behavioural. The 24 behavioural trials were categorised by type of intervention: (1) nutritional and/or responsive feeding interventions targeted at parents of infants, which improved feeding practices and had some impact on child weight (n = 12); (2) breastfeeding promotion and lactation support for mothers, which had a positive effect on breastfeeding but not child weight (n = 5); (3) parenting and family lifestyle (n = 4); and (4) maternal health (n = 3) interventions that had some impact on feeding practices but not child weight. The non-behavioural trials comprised interventions manipulating formula milk composition (n = 3). Of these, lower/hydrolysed protein formula milk had a positive effect on weight outcomes. Interventions that aim to improve diet and parental responsiveness to infant cues showed most promise in terms of self-reported behavioural change. Despite the known risk factors, there were very few intervention studies for pregnant women that continue during infancy which should be a priority for future research

A systematic review of studies measuring and reporting hearing aid usage in older adults since 1999: a descriptive summary of measurement tools

Objective: A systematic review was conducted to identify and quality assess how studies published since 1999 have measured and reported the usage of hearing aids in older adults. The relationship between usage and other dimensions of hearing aid outcome, age and hearing loss are summarised. Data sources: Articles were identified through systematic searches in PubMed/MEDLINE, The University of Nottingham Online Catalogue, Web of Science and through reference checking. Study eligibility criteria: (1) participants aged fifty years or over with sensori-neural hearing loss, (2) provision of an air conduction hearing aid, (3) inclusion of hearing aid usage measure(s) and (4) published between 1999 and 2011. Results: Of the initial 1933 papers obtained from the searches, a total of 64 were found eligible for review and were quality assessed on six dimensions: study design, choice of outcome instruments, level of reporting (usage, age, and audiometry) and cross validation of usage measures. Five papers were rated as being of high quality (scoring 10–12), 35 papers were rated as being of moderate quality (scoring 7–9), 22 as low quality (scoring 4–6) and two as very low quality (scoring 0–2). Fifteen different methods were identified for assessing the usage of hearing aids. Conclusions: Generally, the usage data reviewed was not well specified. There was a lack of consistency and robustness in the way that usage of hearing aids was assessed and categorised. There is a need for more standardised level of reporting of hearing aid usage data to further understand the relationship between usage and hearing aid outcomes

Human Decision Making Based on Variations in Internal Noise: An EEG Study

Perceptual decision making is prone to errors, especially near threshold. Physiological, behavioural and modeling studies suggest this is due to the intrinsic or ‘internal’ noise in neural systems, which derives from a mixture of bottom-up and top-down sources. We show here that internal noise can form the basis of perceptual decision making when the external signal lacks the required information for the decision. We recorded electroencephalographic (EEG) activity in listeners attempting to discriminate between identical tones. Since the acoustic signal was constant, bottom-up and top-down influences were under experimental control. We found that early cortical responses to the identical stimuli varied in global field power and topography according to the perceptual decision made, and activity preceding stimulus presentation could predict both later activity and behavioural decision. Our results suggest that activity variations induced by internal noise of both sensory and cognitive origin are sufficient to drive discrimination judgments

Sensitivity to temporal fine structure and hearing-aid outcomes in older adults

Objective: to investigate the effect of sensitivity to temporal fine structure on subjective measures of hearing aid outcome.Design: Prior to receiving hearing aids, participants completed a test to assess sensitivity to temporal fine structure (TFS), the Glasgow Hearing Aid Benefit Profile (GHABP), and the Speech, Spatial and Qualities of hearing (SSQ-A). Follow-up appointments, comprised the GHABP, the SSQ-B , and the International Outcome Inventory for Hearing Aid Outcomes (IOI-HA).Study sample: 75 adults were recruited from direct referral clinics. Results: Two thirds of participants were found to have good sensitivity to TFS; listeners with good sensitivity to TFS rated their hearing abilities higher at pre-fitting (SSQ-A) than those with poor sensitivity to TFS. At follow-up, participants with good sensitivity to TFS showed a small improvement on SSQ-B over listeners with poor sensitivity to TFS. Conclusions: The clinical identification of a patient’s ability to process TFS information at an early stage in the treatment pathway could prove useful in managing expectations about hearing aid outcomes

Reported instances of outcome and usage instruments.

<p>Panel A shows the top ten most used outcomes measures. Panel B shows the range of methods employed for assessing hearing aid usage. White bars indicate standardised questionnaires; grey bars indicate non-standardised methods. Abbreviations: <b>IOI-HA</b> International Outcome Inventory - Hearing Aids <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Cox1" target="_blank">[32]</a>, <b>APHAB</b> Abbreviated Profile of Haring Aid Benefit <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Cox6" target="_blank">[57]</a>, <b>SADL</b> Satisfaction with Amplification in Daily Life <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Cox3" target="_blank">[34]</a>, <b>GHABP</b> Glasgow Hearing Aid Benefit Profile <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Gatehouse1" target="_blank">[15]</a>, <b>HHIE</b> Hearing Handicap Inventory for the Elderly <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Weinstein1" target="_blank">[59]</a>, <b>CST</b> Connected Speech Test <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Cox4" target="_blank">[36]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Cox5" target="_blank">[56]</a>, <b>HHIE-S</b> screening version <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Wechsler1" target="_blank">[62]</a>, <b>HAPI</b> Hearing Aid Performance Inventory <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Walden1" target="_blank">[54]</a>, <b>MarkeTrak </b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Kochkin1" target="_blank">[63]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Kochkin2" target="_blank">[64]</a> and <b>HAUQ</b> Hearing Aid Users Questionnaire <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Forster1" target="_blank">[55]</a>, <b>EAR</b> Effectiveness of Auditory Rehabilitation <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Yueh1" target="_blank">[60]</a>, <b>HASQ</b> Hearing Aid Status Questionnaire <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Boothroyd1" target="_blank">[58]</a>, <b>HDABI</b> Hearing Disability and Aided Benefit Interview <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Gatehouse1" target="_blank">[15]</a>, <b>SAC-Hx</b> Self-Assessment of Communication <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Ivory1" target="_blank">[40]</a> and <b>DOSO</b> Device Oriented Subjective Outcome Scale <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031831#pone.0031831-Cox7" target="_blank">[61]</a>.</p

Differences between chosen and non-chosen responses in the final stimulus interval.

<div><p>(A) ERP waveforms for chosen (magenta) and non-chosen (blue) stimuli in interval 3. Each trace represents an electrode channel. The colored underlays match the statistical maps in B and C.</p> <p>(B) Global field potential (GFP) for chosen and non-chosen stimuli in interval 3. The grey patches demarcate regions where the contrast exceeds the criterion t-value calculated using the permutation test to control for multiple comparisons.</p> <p>(C) Topographic dissimilarity for the chosen vs. non-chosen contrast in interval 3. The pink patch demarcates consecutive significance over ≥10 ms.</p> <p>(D) Topographic plots of chosen (top) and non-chosen (bottom) average activity at selected time-points. The color bar shows potential in microvolts.</p></div