Unravelling listening effort in age-related hearing loss using a multimodal neuroimaging approach and simultaneous pupillometry

• Applicant: Dr. Stephanie Rosemann
• Subject Area: Biological Psychology and Cognitive Neuroscience
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 508927989

Age-related hearing loss is one of the most prevalent chronic disorders in the older population and is commonly described as a form of bilateral sensorineural hearing loss affecting higher frequencies. The degraded auditory input leads to difficulties in understanding speech and is associated with an increased listening effort – the mental effort expended in demanding listening conditions, such as the allocation of attentional or cognitive resources in order to increase cognitive control and facilitate the listening process. Consequently, the increase in listening effort may decrease available resources for other cognitive operations. Previous research using functional magnetic resonance imaging (fMRI) has shown increased neural responses in several frontal brain regions when listening is effortful. In age-related hearing loss, changes in neural activity as well as functional connectivity covering auditory, frontal and parietal areas have been observed. Further, there is evidence of a decreased neurotransmitter concentrations (glutamate and gamma-aminobutyric acid (GABA)) in the auditory cortex in age-related hearing loss. However, its implications on neural activity in the frontal cortex along with functional connectivity of the auditory to frontal and parietal areas have not been investigated so far. A different line of research has established the peak pupil dilation response as a sensitive and reliable psychophysical measure of listening effort. However, results in age-related hearing loss has been inconsistent. Hence, in the proposed research project, I want to conduct the first study that uses simultaneous fMRI and pupillometry to assess listening effort in age-related hearing loss. The aim of the project is to investigate the association of neural activity and pupil dilation response under different listening conditions (50% and 80% speech intelligibility) in elderly hard of hearing and normal-hearing participants. Results of this study are of particular relevance as they not only advance our knowledge on neural changes associated with listening effort in hearing impairment, but also might aid in determining the clinical relevance of the pupil dilation response in age-related hearing loss as an objective marker of listening effort. This may play a crucial role in optimizing hearing-aid fitting. The second aim of the proposed project is to investigate changes in GABA and glutamate concentration levels in the auditory cortex and their relation to neural activity and functional connectivity during the different listening conditions in the fMRI task. Decreased GABA and glutamate concentrations in the auditory cortex may reflect a dysfunctional neurotransmission in the auditory system that could serve as a potential treatment target in age-related hearing loss. Importantly, restoring the neurotransmitter imbalance in the auditory cortex might have positive implications on neural activity and connectivity under different listening conditions.

• DFG Programme: Research Grants