Neural dynamics of selective attention to speech in noise

This thesis investigates how the neural system instantiates selective attention to speech in challenging acoustic conditions, such as spectral degradation and the presence of background noise. Four studies using behavioural measures, magneto- and electroencephalography (M/EEG) recordings were conducted in younger (20–30 years) and older participants (60–80 years). The overall results can be summarized as follows. An EEG experiment demonstrated that slow negative potentials reflect participants’ enhanced allocation of attention when they are faced with more degraded acoustics. This basic mechanism of attention allocation was preserved at an older age. A follow-up experiment in younger listeners indicated that attention allocation can be further enhanced in a context of increased task-relevance through monetary incentives. A subsequent study focused on brain oscillatory dynamics in a demanding speech comprehension task. The power of neural alpha oscillations (~10 Hz) reflected a decrease in demands on attention with increasing acoustic detail and critically also with increasing predictiveness of the upcoming speech content. Older listeners’ behavioural responses and alpha power dynamics were stronger affected by acoustic detail compared with younger listeners, indicating that selective attention at an older age is particularly dependent on the sensory input signal. An additional analysis of listeners’ neural phase-locking to the temporal envelopes of attended speech and unattended background speech revealed that younger and older listeners show a similar segregation of attended and unattended speech on a neural level. A dichotic listening experiment in the MEG aimed at investigating how neural alpha oscillations support selective attention to speech. Lateralized alpha power modulations in parietal and auditory cortex regions predicted listeners’ focus of attention (i.e., left vs right). This suggests that alpha oscillations implement an attentional filter mechanism to enhance the signal and to suppress noise. A final behavioural study asked whether acoustic and semantic aspects of task-irrelevant speech determine how much it interferes with attention to task-relevant speech. Results demonstrated that younger and older adults were more distracted when acoustic detail of irrelevant speech was enhanced, whereas predictiveness of irrelevant speech had no effect. All findings of this thesis are integrated in an initial framework for the role of attention for speech comprehension under demanding acoustic conditions

Acoustic Detail But Not Predictability of Task-Irrelevant Speech Disrupts Working Memory

Attended speech is comprehended better not only if more acoustic detail is available, but also if it is semantically highly predictable. But can more acoustic detail or higher predictability turn into disadvantages and distract a listener if the speech signal is to be ignored? Also, does the degree of distraction increase for older listeners who typically show a decline in attentional control ability? Adopting the irrelevant-speech paradigm, we tested whether younger (age 23–33 years) and older (60–78 years) listeners’ working memory for the serial order of spoken digits would be disrupted by the presentation of task-irrelevant speech varying in its acoustic detail (using noise-vocoding) and its semantic predictability (of sentence endings). More acoustic detail, but not higher predictability, of task-irrelevant speech aggravated memory interference. This pattern of results did not differ between younger and older listeners, despite generally lower performance in older listeners. Our findings suggest that the focus of attention determines how acoustics and predictability affect the processing of speech: First, as more acoustic detail is known to enhance speech comprehension and memory for speech, we here demonstrate that more acoustic detail of ignored speech enhances the degree of distraction. Second, while higher predictability of attended speech is known to also enhance speech comprehension under acoustically adverse conditions, higher predictability of ignored speech is unable to exert any distracting effect upon working memory performance in younger or older listeners. These findings suggest that features that make attended speech easier to comprehend do not necessarily enhance distraction by ignored speech

Orienting auditory attention in time: Lateralized alpha power reflects spatio-temporal filtering

The deployment of neural alpha (8–12 Hz) lateralization in service of spatial attention is well-established: Alpha power increases in the cortical hemisphere ipsilateral to the attended hemifield, and decreases in the contralateral hemisphere, respectively. Much less is known about humans’ ability to deploy such alpha lateralization in time, and to thus exploit alpha power as a spatio-temporal filter. Here we show that spatially lateralized alpha power does signify – beyond the direction of spatial attention – the distribution of attention in time and thereby qualifies as a spatio-temporal attentional filter. Participants (N = 20) selectively listened to spoken numbers presented on one side (left vs right), while competing numbers were presented on the other side. Key to our hypothesis, temporal foreknowledge was manipulated via a visual cue, which was either instructive and indicated the to-be-probed number position (70% valid) or neutral. Temporal foreknowledge did guide participants’ attention, as they recognized numbers from the to-be-attended side more accurately following valid cues. In the magnetoencephalogram (MEG), spatial attention to the left versus right side induced lateralization of alpha power in all temporal cueing conditions. Modulation of alpha lateralization at the 0.8 Hz presentation rate of spoken numbers was stronger following instructive compared to neutral temporal cues. Critically, we found stronger modulation of lateralized alpha power specifically at the onsets of temporally cued numbers. These results suggest that the precisely timed hemispheric lateralization of alpha power qualifies as a spatio-temporal attentional filter mechanism susceptible to top-down behavioural goals

Charakterisierung der Interaktion zwischen Stuhlmikrobiom und autosomal dominanter polyzystischer Nierenerkrankung (ADPKD)

Die autosomal dominante polyzystische Nierenerkrankung (APDKD) ist die häufigste vererbbare chronische Nierenerkrankung1,2. Der unvermeidliche Progress der Erkrankung mit zunehmendem Nierenfunktionsverlust, chronisch, rekurrierenden Schmerzen sowie die potenzielle Übertragung auf Nachkommen stellt für die Betroffenen und ihre Familien eine immense Belastung dar. Eine Identifikation der Einflussfaktoren, welche eine rasche Erkrankungsprogression begünstigen und gegebenenfalls therapeutisch modulierbar sind, ist ein wichtiges Forschungsziel im Feld. Hierbei ist das intestinale Mikrobiom eines der vielversprechendsten neuen Gebiete. Kulturunabhängige Charakterisierungen gewähren mittlerweile einen Einblick in die enorme Diversität, funktionelle Kapazität sowie die durch natürliche Faktoren oder Krankheit bedingte Dynamik des intestinalen Mikrobioms3. Insbesondere Produkte des bakteriellen Metabolismus gewinnen durch ihre gesundheitsförderlichen, als auch schädlichen Effekte zunehmend an Aufmerksamkeit. Diese Arbeit charakterisiert als Pilotstudie das intestinale Mikrobiom sowie Metabolite des bakteriellen Stoffwechsels bei ADPKD-Patient*innen. In den Analysen des Stuhlmikrobioms von Patient*innen mit einer ADPKD, konnten spezifische Veränderungen gefunden werden, die mit nachteiligen Effekten auf die Gesundheit des Wirts assoziiert sind (Enterobacterales, Enterobacteriaceae). Gleichzeitig fand sich eine reduzierte Anzahl von Mikrobiota, die mit vorteilhaften Auswirkungen auf ihren Wirt assoziiert sind (Bifidobacterales, Bifidobacteriaceae). Patient*innen mit einer ADPKD und einem früh aufgetretenem arteriellen Hypertonus wiesen zudem eine Zunahme, überwiegend gesundheitsschädlicher Mikroorganismen (Phylum Proteobacteria) und eine Reduktion der Gesundheit zuträglicher Tannerellaceae auf. Alle untersuchten Urämietoxine (UT) wiesen einen inversen Zusammenhang zur Nierenfunktion auf. Hinsichtlich möglicher Assoziationen der UT, mit den in den Subgruppenanalysen identifizierten abundanten Taxa, konnte nur für die Familie der Peptococcaceae eine direkte Verbindung zu den Serumkonzentrationen des Indoxylsulfats (IS) hergestellt werden. Bislang findet sich nur eine Studie mit Bezug zum intestinalen Mikrobiom bei ADPKD4. In dem hier dargestellten Projekt konnten bereits viele Überschneidungen gefunden werden, sodass ADPKD spezifische Veränderungen des intestinalen Mikrobioms hochwahrscheinlich sind. Hinsichtlich eines Einflusses intestinal gebildeter UT, findet sich zum aktuellen Zeitpunkt keine Studie an Menschen mit einer ADPKD. Vor dem Hintergrund der kleinen Kohorte lassen sich aus dieser Arbeit keine endgültigen, kausalen Schlüsse ableiten. Weiteren Studien des intestinalen Mikrobioms unter Einbeziehung intestinal gebildeter UT kommt nun eine herausragende Bedeutung zu, um Kausalitäten in der Pathogenese der ADPKD und etwaige Einfluss nehmende Faktoren festzustellen. Diese Arbeit stellt eine entsprechende Grundlage zur Verfügung

A new 3D-method to assess the inter implant dimensions in patients ? A pilot study

Complex implant treatments have steadily increased within implant prosthodontics. Based on the lower implant mobility, implant impressions need high accuracy in the model transfer to receive a high passive fit within the final prosthodontic restoration. To analyze the accurate 3-dimensional (3D) inter-implant-positions, a reference point is indispensable. However, there is no reference in the patients mouth, so the aim of the present study was to develop a new method based on a custom-made-measuring-aid (CMA) to assess the inter implant dimensions (InID) in patients. Initially an implant master model (IMM/patient equivalent) was digitized by computed tomography. A CMA was fixed on the impression posts and the inter implant dimensions (InID) were recorded with a coordinate measurement machine (CMM). For comparison to conventional and digital impression techniques, 10 impressions per technique were taken. InIDs for the IMM, the CMA and the two impression techniques were compared. To give a proof of principle, the new 3D-method was applied to three patients as pilot cases. Results for trueness and precision were analyzed by pairwise comparisons (p< .05). All data were subjected to univariate ANOVA. Mean deviation for InID ranged from 10.3±18?m(CMA) to 41.7±36?m(conventional). There were partially significant differences for InID between the CMA and the different impression techniques. There were no significant differences for InID within the CMA. The InID in the in-vivo evaluation ranged from 42.3?m to 376.7?m(digital) and from 58.3?m to 274.0?m(conventional). There were partially significant differences between the techniques. Within the limits of this study, with the developed method using a CMA it is possible to assess the true 3D-InID with a decisive higher accuracy than possible with a conventional or digital implant impression. Overall, the CMA in this study generated results that were deemed clinically useful for the investigated inter implant positions

Accuracy of intraoral and extraoral digital data acquisition for dental restorations

The computer-aided design (CAD) and computer-aided manufacturing (CAM) process chain for dental restorations starts with taking an impression of the clinical situation. For this purpose, either extraoral digitization of gypsum models or intraoral digitization can be used. Despite the increasing use of dental digitizing systems, there are only few studies on their accuracy. Objective This study compared the accuracy of various intraoral and extraoral digitizing systems for dental CAD/CAM technology. Material and Methods An experimental setup for three-dimensional analysis based on 2 prepared ceramic master dies and their corresponding virtual CAD-models was used to assess the accuracy of 10 extraoral and 4 intraoral optical non-contact dental digitizing systems. Depending on the clinical procedure, 10 optical measurements of either 10 duplicate gypsum dies (extraoral digitizing) or directly of the ceramic master dies (intraoral digitizing) were made and compared with the corresponding CAD-models. Results The digitizing systems showed differences in accuracy. However, all topical systems were well within the benchmark of ±20 µm. These results apply to single tooth measurements. Conclusions Study results are limited, since only single teeth were used for comparison. The different preparations represent various angles and steep and parallel opposing tooth surfaces (incisors). For most digitizing systems, the latter are generally the most difficult to capture. Using CAD/CAM technologies, the preparation angles should not be too steep to reduce digitizing errors. Older systems might be limited to a certain height or taper of the prepared tooth, whereas newer systems (extraoral as well as intraoral digitization) do not have these limitations

Strategy disclosures by listed financial services companies: Signalling theory, legitimacy theory and South African integrated reporting practices

This paper investigates the current extent of social-, environmental- and economic- (SEE) related strategy disclosure of companies listed in the financial services sector of the Johannesburg Stock Exchange. It uses signalling and legitimacy theory to analyse the findings from a developed SEE strategy-related disclosure checklist. The paper finds social and environmental strategy-related disclosure is still secondary to economic strategy-related disclosures. This may be due to persistent focus on providers of financial capital and the need to perform financially. Further, the subsector’s business model and how closely the subsector interacts with their customers is seen as a driver of social and environmental strategy-related disclosure to maintain their legitimacy and to reduce information asymmetry, reduce cost of capital and assure investors that these factors are being appropriately managed by the entity. Following from above, the banking, insurance and real estate subsectors presented the most strategy-related disclosure. This was linked to their high public accountability and daily interaction with customers, necessitating the need to manage their legitimacy and address adverse selection. The paper also proposes some areas for future research to understand the potential obstacles to incorporating social and environmental concerns into strategy and related disclosures

Update on shedding and transmission routes of porcine haemotrophic mycoplasmas in naturally and experimentally infected pigs

Horizontal transmission of Mycoplasma suis via parenteral exposure during standard practices or through bites during fightings have been identified as key epidemiological routes. However, as knowledge gaps on other potential shedding and transmission routes exist, the present study combines both laboratory experiments and field surveys to gain new insights into the epidemiology of porcine haemotrophic mycoplasmas. Splenectomised pigs were orally inoculated with a M. suis field strain and investigated for clinical signs related to infectious anaemia of pigs (IAP) and the presence of M. suis in blood, urine and saliva samples by qPCR. All blood samples were negative for M. suis and animals did not show obvious clinical signs of IAP throughout the entire study period. Additionally, urine, nasal and saliva samples from sows of conventional piglet producing farms and semen samples from a boar stud revealed no detection of M. suis and ‘Candidatus Mycoplasma haemosuis’ by qPCR. Thus, the results indicate that blood-independent transmission routes might be of minor relevance under field conditions