The plastic ear and perceptual relearning in auditory spatial perception

The auditory system of adult listeners has been shown to accommodate to altered spectral cues to sound location which presumably provides the basis for recalibration to changes in the shape of the ear over a life time. Here we review the role of auditory and non-auditory inputs to the perception of sound location and consider a range of recent experiments looking at the role of non-auditory inputs in the process of accommodation to these altered spectral cues. A number of studies have used small ear moulds to modify the spectral cues that result in significant degradation in localization performance. Following chronic exposure (10-60 days) performance recovers to some extent and recent work has demonstrated that this occurs for both audio-visual and audio-only regions of space. This begs the questions as to the teacher signal for this remarkable functional plasticity in the adult nervous system. Following a brief review of influence of the motor state in auditory localisation, we consider the potential role of auditory-motor learning in the perceptual recalibration of the spectral cues. Several recent studies have considered how multi-modal and sensory-motor feedback might influence accommodation to altered spectral cues produced by ear moulds or through virtual auditory space stimulation using non-individualised spectral cues. The work with ear moulds demonstrates that a relatively short period of training involving sensory-motor feedback (5 – 10 days) significantly improved both the rate and extent of accommodation to altered spectral cues. This has significant implications not only for the mechanisms by which this complex sensory information is encoded to provide a spatial code but also for adaptive training to altered auditory inputs. The review concludes by considering the implications for rehabilitative training with hearing aids and cochlear prosthesis

A Collection of Pseudo-Words to Study Multi-Talker Speech Intelligibility without Shifts of Spatial Attention

A new collection of pseudo-words was recorded from a single female speaker of American English for use in multi-talker speech intelligibility research. The pseudo-words (known as the KARG collection) consist of three groups of single syllable pseudo-words varying only by the initial phoneme. The KARG method allows speech intelligibility to be studied free of the influence of shifts of spatial attention from one loudspeaker location to another in multi-talker contexts. To achieve this, all KARG pseudo-words share the same concluding rimes, with only the first phoneme serving as a distinguishing identifier. This ensures that listeners are unable to correctly identify the target pseudo-word without hearing the initial phoneme. As the duration of all the initial phonemes are brief, much shorter than the time required to spatially shift attention, the KARG method assesses speech intelligibility without the confound of shifting spatial attention. The KARG collection is available free for research purposes

Two-point discrimination in auditory displays

Proceedings of the 9th International Conference on Auditory Display (ICAD), Boston, MA, July 7-9, 2003.In this paper we describe work which characterises the effect of spatial factors on the segregation of concurrent sound sources. The results inform the operational requirements of virtual auditory displays required to render multiple, concurrent sound sources in terms of (i) minimum spacing between sources and (ii) identification of the principal acoustic directional cues exploited by the auditory system for source segregation. Experiments using various broadband sound sources (white noise, click trains, spoken words) indicate that the extent of actual separation required for reliable segregation of concurrent stimuli varies as a function of location. The pattern of location dependence indicates that the auditory system is principally exploiting binaural differences for sound segregation. Monaural spectral cues, while essential for high fidelity spatialisation, seem to play a much less minor role in segregation under these conditions. However, spectral cues are likely to be useful when competing stimuli have distinct temporal structures or are not fully coincident in time

A Mechanism for Detecting Coincidence of Auditory and Visual Spatial Signals

Abstract Information about the world is captured by our separate senses, and must be integrated to yield a unified representation. This raises the issue of which signals should be integrated and which should remain separate, as inappropriate integration will lead to misrepresentation and distortions. One strong cue suggesting that separate signals arise from a single source is coincidence, in space and in time. We measured increment thresholds for discriminating spatial intervals defined by pairs of simultaneously presented targets, one flash and one auditory sound, for various separations. We report a 'dipper function', in which thresholds follow a 'U-shaped' curve, with thresholds initially decreasing with spatial interval, and then increasing for larger separations. The presence of a dip in the audiovisual increment-discrimination function is evidence that the auditory and visual signals both input to a common mechanism encoding spatial separation, and a simple filter model with a sigmoidal transduction function simulated the results well. The function of an audiovisual spatial filter may be to detect coincidence, a fundamental cue guiding whether to integrate or segregate

Boundary Capabilities in MNCs: Knowledge Transformation for Creative Solution Development

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The management of knowledge across country units is critical to multinational corporations (MNCs). Building on the argument that boundary spanning leads to the development of creative problem solving outcomes, this study advances the concept of MNC knowledge transformation and examines its relationship with solution creativity. Using questionnaire data on 67 problem solving projects, we find that opportunity formation is an underlying mechanism linking MNC knowledge transformation to the development of creative solutions. These insights contribute to our understanding of boundary spanning in global organizations by substantiating MNC knowledge transformation and elaborating the relationship between boundary spanning and creative solution development. If successful at knowledge transformation, collaborators from across the MNC can construct previously unimagined opportunities for the generation of creative outcomes.This study was funded by the Irish Research Council with co-funding from the European Commission (Marie-Curie Fellowship). We are very grateful for the insightful comments of Phillip C. Nell, the three reviewers, editors and participants at the paper development workshop at Ivey Business School

Targeted control of pneumolysin production by a mobile genetic element in Streptococcus pneumoniae

Streptococcus pneumoniae is a major human pathogen that can cause severe invasive diseases such as pneumonia, septicaemia and meningitis. Young children are at a particularly high risk, with an estimated 3–4 million cases of severe disease and between 300 000 and 500 000 deaths attributable to pneumococcal disease each year. The haemolytic toxin pneumolysin (Ply) is a primary virulence factor for this bacterium, yet despite its key role in pathogenesis, immune evasion and transmission, the regulation of Ply production is not well defined. Using a genome-wide association approach, we identified a large number of potential affectors of Ply activity, including a gene acquired horizontally on the antibiotic resistance-conferring Integrative and Conjugative Element (ICE) ICESp23FST81. This gene encodes a novel modular protein, ZomB, which has an N-terminal UvrD-like helicase domain followed by two Cas4-like domains with potent ATP-dependent nuclease activity. We found the regulatory effect of ZomB to be specific for the ply operon, potentially mediated by its high affinity for the BOX repeats encoded therein. Using a murine model of pneumococcal colonization, we further demonstrate that a ZomB mutant strain colonizes both the upper respiratory tract and lungs at higher levels when compared to the wild-type strain. While the antibiotic resistance-conferring aspects of ICESp23FST81 are often credited with contributing to the success of the S. pneumoniae lineages that acquire it, its ability to control the expression of a major virulence factor implicated in bacterial transmission is also likely to have played an important role

THE ROLE OF INTERDEPENDENCE IN THE MICRO-FOUNDATIONS OF ORGANIZATION DESIGN: TASK, GOAL, AND KNOWLEDGE INTERDEPENDENCE

Interdependence is a core concept in organization design, yet one that has remained consistently understudied. Current notions of interdependence remain rooted in seminal works, produced at a time when managers’ near-perfect understanding of the task at hand drove the organization design process. In this context, task interdependence was rightly assumed to be exogenously determined by characteristics of the work and the technology. We no longer live in that world, yet our view of interdependence has remained exceedingly task-centric and our treatment of interdependence overly deterministic. As organizations face increasingly unpredictable workstreams and workers co-design the organization alongside managers, our field requires a more comprehensive toolbox that incorporates aspects of agent-based interdependence. In this paper, we synthesize research in organization design, organizational behavior, and other related literatures to examine three types of interdependence that characterize organizations’ workflows: task, goal, and knowledge interdependence. We offer clear definitions for each construct, analyze how each arises endogenously in the design process, explore their interrelations, and pose questions to guide future research

Strategy tools-in-use: A framework for understanding “technologies of rationality” in practice

In response to critiques of strategy tools as unhelpful or potentially dangerous for organizations, we suggest casting a sociological eye on how tools are actually mobilized by strategy makers. In conceptualizing strategy tools as tools-in-use, we offer a framework for examining the ways that the affordances of strategy tools and the agency of strategy makers interact to shape how and when tools are selected and applied. Further, rather than evaluating the ‘correct’ or ‘incorrect’ use of tools, we highlight the variety of outcomes that result, not just for organizations but also for the tools and the individuals who use them. We illustrate this framework with a vignette and propose an agenda and methodological approaches for further scholarship on the use of strategy tools

Characterisation of eppin function: expression and activity in the lung

Eppin is a serine protease inhibitor expressed in male reproductive tissues. In this study we have demonstrated novel sites of eppin expression in myeloid and epithelial cell lines with further confirmation in primary myeloid cell types. Using immunohistochemistry and Western blotting, eppin was detected in the lungs of patients with Acute Respiratory Distress Syndrome and Cystic Fibrosis lung disease. Expression of eppin in monocytic cells was unaffected by stimulation with TLR agonists, cytokine stimulation and hormone receptor agonist stimulation. However, upregulated expression and secretion of eppin was observed following treatment of monocytes with epidermal growth factor (EGF). Incubation of recombinant eppin with monocytic cells resulted in significant inhibition of lipopolysaccharide (LPS)-induced chemokine production. Furthermore, eppin inhibited LPS- induced NF-κB activation by a mechanism which involved accumulation of phosphorylated IκBα. In an in vivo model of lung inflammation induced by LPS, eppin administration resulted in decreased recruitment of neutrophils to the lung with a concomitant reduction in the levels of the neutrophil chemokine MIP-2. Overall, these results suggest a role for eppin outside of the reproductive tract and that eppin may have a role in the innate immuneresponse in the lung