Dysfunctions of visual and auditory Gestalt perception (amusia) after stroke : Behavioral correlates and functional magnetic resonance imaging

Music is a special and unique part of human nature. Not only actively playing (making music in a group or alone) but also passive listening to music involves a richness of processes to make music the ideal tool to investigate how the human brain works. Acquired amusia denotes the impaired perception of melodies, rhythms, and the associated disability to enjoy music which can occur after a stroke. Many amusia patients also show deficits in visual perception, language, memory, and attention. Hence, the question arises whether amusia actually describes an independent clinical picture or is better described by a general perceptual deficit for auditory, as well as visual, and speech-related material. Additionally, the question in what way impaired abilities in attention and working memory influence the performance in the music perception task remains to be investigated. Behavioral investigations, lesion analysis, and functional magnetic resonance imaging were performed to assess the anatomical and functional correlates of these deficits. A better and more detailed understanding of amusia and connected cognitive deficits is not only relevant in terms of fundamental neuroscience but also from a clinical point of view: symptoms of amusia are rare, mostly undiscovered, and the underlying mechanisms are hitherto insufficiently understood

Effects of age-related hearing loss and hearing aid experience on sentence processing.

Age-related hearing loss typically affects the hearing of high frequencies in older adults. Such hearing loss influences the processing of spoken language, including higher-level processing such as that of complex sentences. Hearing aids may alleviate some of the speech processing disadvantages associated with hearing loss. However, little is known about the relation between hearing loss, hearing aid use, and their effects on higher-level language processes. This neuroimaging (fMRI) study examined these factors by measuring the comprehension and neural processing of simple and complex spoken sentences in hard-of-hearing older adults (n = 39). Neither hearing loss severity nor hearing aid experience influenced sentence comprehension at the behavioral level. In contrast, hearing loss severity was associated with increased activity in left superior frontal areas and the left anterior insula, but only when processing specific complex sentences (i.e. object-before-subject) compared to simple sentences. Longer hearing aid experience in a sub-set of participants (n = 19) was associated with recruitment of several areas outside of the core speech processing network in the right hemisphere, including the cerebellum, the precentral gyrus, and the cingulate cortex, but only when processing complex sentences. Overall, these results indicate that brain activation for language processing is affected by hearing loss as well as subsequent hearing aid use. Crucially, they show that these effects become apparent through investigation of complex but not simple sentences

The Contribution of Cognitive Factors to Individual Differences in Understanding Noise-Vocoded Speech in Young and Older Adults

Noise-vocoded speech is commonly used to simulate the sensation after cochlear implantation as it consists of spectrally degraded speech. High individual variability exists in learning to understand both noise-vocoded speech and speech perceived through a cochlear implant (CI). This variability is partly ascribed to differing cognitive abilities like working memory, verbal skills or attention. Although clinically highly relevant, up to now, no consensus has been achieved about which cognitive factors exactly predict the intelligibility of speech in noise-vocoded situations in healthy subjects or in patients after cochlear implantation. We aimed to establish a test battery that can be used to predict speech understanding in patients prior to receiving a CI. Young and old healthy listeners completed a noise-vocoded speech test in addition to cognitive tests tapping on verbal memory, working memory, lexicon and retrieval skills as well as cognitive flexibility and attention. Partial-least-squares analysis revealed that six variables were important to significantly predict vocoded-speech performance. These were the ability to perceive visually degraded speech tested by the Text Reception Threshold, vocabulary size assessed with the Multiple Choice Word Test, working memory gauged with the Operation Span Test, verbal learning and recall of the Verbal Learning and Retention Test and task switching abilities tested by the Comprehensive Trail-Making Test. Thus, these cognitive abilities explain individual differences in noise-vocoded speech understanding and should be considered when aiming to predict hearing-aid outcome

Neural Mechanisms Underlying the Processing of Complex Sentences: An fMRI Study.

Previous research has shown effects of syntactic complexity on sentence processing. In linguistics, syntactic complexity (caused by different word orders) is traditionally explained by distinct linguistic operations. This study investigates whether different complex word orders indeed result in distinct patterns of neural activity, as would be expected when distinct linguistic operations are applied. Twenty-two older adults performed an auditory sentence processing paradigm in German with and without increased cognitive load. The results show that without increased cognitive load, complex sentences show distinct activation patterns compared with less complex, canonical sentences: complex object-initial sentences show increased activity in the left inferior frontal and temporal regions, whereas complex adjunct-initial sentences show increased activity in occipital and right superior frontal regions. Increased cognitive load seems to affect the processing of different sentence structures differently, increasing neural activity for canonical sentences, but leaving complex sentences relatively unaffected. We discuss these results in the context of the idea that linguistic operations required for processing sentence structures with higher levels of complexity involve distinct brain operations

Tinnitus as a network problem – plasticity in anatomical and functional connectivity

Tinnitus is the phantom perception of sound when there is no external auditory input. This sound is mostly perceived as a whistling, buzzing or hissing in the ear. Chronic tinnitus – the permanent phantom perception – currently affects 10-20% of the population but no reliable treatment has been found so far. One of the peripheral causes for tinnitus is hearing loss due to loud noise exposure or age-related degeneration, leading to plastic changes in auditory and non-auditory brain regions. In this project, we investigate neuroplastic anatomical and functional changes in tinnitus patients compared to control participants

nBack_Hearing_Oldenburg

Visual nback task with normal-hearing (NH; n=19) and hard of hearing (HI; n=19) participants. Uploaded data include logfiles, subject data (group, gender, age) and individual MRI dat

Störungen der visuellen und auditorischen Gestaltwahrnehmung (Amusie) nach Schlaganfall : Verhaltenskorrelate und funktionelle Magnetresonanztomographie

Music is a special and unique part of human nature. Not only actively playing (making music in a group or alone) but also passive listening to music involves a richness of processes to make music the ideal tool to investigate how the human brain works. Acquired amusia denotes the impaired perception of melodies, rhythms, and the associated disability to enjoy music which can occur after a stroke. Many amusia patients also show deficits in visual perception, language, memory, and attention. Hence, the question arises whether amusia actually describes an independent clinical picture or is better described by a general perceptual deficit for auditory, as well as visual, and speech-related material. Additionally, the question in what way impaired abilities in attention and working memory influence the performance in the music perception task remains to be investigated. Behavioral investigations, lesion analysis, and functional magnetic resonance imaging were performed to assess the anatomical and functional correlates of these deficits. A better and more detailed understanding of amusia and connected cognitive deficits is not only relevant in terms of fundamental neuroscience but also from a clinical point of view: symptoms of amusia are rare, mostly undiscovered, and the underlying mechanisms are hitherto insufficiently understood

McGurk in age-related hearing loss

Age-related hearing loss influences functional connectivity of auditory cortex for the McGurk illusio

Investigating white matter morphology and track-weighted functional connectivity in age-related hearing impairment

In summary, the overall aim of the study is to investigate changes in white matter morphology in age-related hearing loss and whether those are related to alterations in resting-state functional connectivity (track-weighted functional connectivity)