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After contracting COVID-19, a substantial number of individuals develop a Post-COVID-Condition, marked by neurologic symptoms such as cognitive deficits, olfactory dysfunction, and fatigue. Despite this, biomarkers and pathophysiological understandings of this condition remain limited. Employing magnetic resonance imaging, we conduct a comparative analysis of cerebral microstructure among patients with Post-COVID-Condition, healthy controls, and individuals that contracted COVID-19 without long-term symptoms. We reveal widespread alterations in cerebral microstructure, attributed to a shift in volume from neuronal compartments to free fluid, associated with the severity of the initial infection. Correlating these alterations with cognition, olfaction, and fatigue unveils distinct affected networks, which are in close anatomical-functional relationship with the respective symptoms. After contracting COVID-19, a substantial number of individuals develop a Post-COVID-Condition with neurological symptoms. Here, the authors show symptom-specific brain microstructure alterations in these patients, providing insights into the underlying pathophysiology.

Bilateral cochlear implant (CI) patients exhibit significant limitations in spatial hearing. Their ability to process interaural time differences (ITDs) is often impaired, while their ability to process interaural level differences (ILDs) remains comparatively good. Clinical studies aiming to identify the causes of these limitations are often plagued by confounds and ethical limitations. Recent behavioral work suggests that rats may be a good animal model for studying binaural hearing under neuroprosthetic stimulation, as rats develop excellent ITD sensitivity when provided with suitable CI stimulation. However, their ability to use ILDs has not yet been characterized. Objective of this study is to address this knowledge gap. Neontally deafened rats were bilaterally fitted with CIs, and trained to lateralize binaural stimuli according to ILD. Their behavioral ILD thresholds were measured at pulse rates from 50 to 2400 pps. CI rats exhibited high sensitivity to ILDs with thresholds of a few dB at all tested pulse rates. We conclude that early deafened rats develop good sensitivity, not only to ITDs but also to ILDs, if provided with appropriate CI stimulation. Their generally good performance, in line with expectations from other mammalian species, validates rats as an excellent model for research on binaural auditory prostheses.

In users of a cochlear implant (CI) together with a contralateral hearing aid (HA), so-called bimodal listeners, differences in processing latencies between digital HA and CI up to 9 ms constantly superimpose interaural time differences. In the present study, the effect of this device delay mismatch on sound localization accuracy was investigated. For this purpose, localization accuracy in the frontal horizontal plane was measured with the original and minimized device delay mismatch. The reduction was achieved by delaying the CI stimulation according to the delay of the individually worn HA. For this, a portable, programmable, battery-powered delay line based on a ring buffer running on a microcontroller was designed and assembled. After an acclimatization period to the delayed CI stimulation of 1 hr, the nine bimodal study participants showed a highly significant improvement in localization accuracy of 11.6% compared with the everyday situation without the delay line (p < .01). Concluding, delaying CI stimulation to minimize the device delay mismatch seems to be a promising method to increase sound localization accuracy in bimodal listeners.

The neural mechanisms underlying somatosensory processing in individuals with acquired single-sided deafness (SSD) and potential central neuronal cross-modal reorganization remain largely unexplored. This study investigates the impact of SSD on somatosensory perception and attentional processing. Electrophysiological responses using EEG, and behavioral measures (discrimination thresholds, hit rates and reaction times) were assessed in adults with acquired SSD and normal-hearing (NH) controls for vibrotactile stimulation at two distinct frequencies. Differences in cortical somatosensory evoked potentials between adults with acquired SSD and normal-hearing (NH) controls, focusing on peak amplitudes and peak times of key event-related potential components (P50, N70, P100, N140, and P3b) and their cortical generators were assessed. While both groups exhibited comparable behavioral performance, significant differences emerged in electrophysiological responses. Individuals with SSD showed increased P3b amplitude (albeit non-significant) and significantly delayed P3b peak times, indicating that individuals with acquired SSD exhibit alterations in attentional mechanisms associated with somatosensory perception. In addition, source localization analysis of the P50 component using standardized low-resolution brain electromagnetic tomography (sLORETA) revealed group differences in cortical activation patterns, with SSD individual showing additional recruitment of auditory-related areas, including the superior temporal gyrus, the middle temporal gyrus and the insula. This further supports the notion of compensatory neuroplasticity in auditory pathways following severe to profound unilateral hearing loss. Our results indicate that SSD is associated with neural reorganization in somatosensory and auditory pathways. The observed modifications in both early and late somatosensory responses, coupled with alterations in source activity, suggest that individuals with SSD engage alternative neural mechanisms when processing vibrotactile stimuli, differing from the typical patterns observed in NH individuals. Understanding these changes prior to cochlear implantation will facilitate the development of personalized auditory rehabilitation strategies following cochlear implantation.

Normally hearing humans can localize sound sources quite accurately, with minimum audible angles as small as 1°. To achieve this, these auditory pathways combine information from multiple acoustic cues, including interaural time and interaural level differences (ITDs and ILDs). Patients relying on cochlear implants (CIs) to hear the world do not match normal performance. These deficits are most pronounced in patients with little or no hearing experience early in life, and they appear to result from impaired sensitivity to ITDs, but not to ILDs. However, little is known about how ITD and ILD sensitivities develop and interact in an early deafened auditory system shortly after CI implantation. neonatally deafened rats with bilateral CIs are fitted, and, providing informative ITDs and ILDs from stimulation onset, trained them to lateralize CI stimuli. These animals are exquisitely sensitive to both ILDs and ITDs of CI stimulus pulses, and combined information from both cues in a weighted sum. Importantly, ITDs are weighted heavily in the CI rats, such that only very modest ITDs pointing in one direction can confound quite large ILDs pointing in the opposite direction. This underlines the importance of informative ITDs for maximizing the potential for spatial hearing with CI devices. Differences in timing (ΔT) are weighted heavily compared to differences in loudness (ΔL) in binaural hearing with cochlear implants.

Patients with asymmetric hearing loss show an asymmetry of glucose metabolism of the primary auditory cortex (PAC). We investigated whether this asymmetry could serve as an objective predictor for speech recognition with CI. Nine patients underwent 18 FDG PET prior to CI surgery. Average normalized 18 FDG uptake of 25% of voxels with highest uptake was calculated for the PAC employing a probabilistic atlas and cerebellar cortex as reference. Differences in glucose metabolism of the PAC were assessed by an asymmetry index (AI-PAC). We tested the correlation between outcome of CI surgery (6 months post implantation), AI-PAC and clinical predictors. Pre-operative AI-PAC showed a positive correlation with speech recognition with CI (significant for sentences and numbers; trend for monosyllabic words). With a pre-operative AI-PAC ≥ 4.2%, patients reached good CI outcome in sentence recognition of 59–90% and number recognition of 90–100% and less favorable CI outcome in monosyllabic word recognition of 25–45%. Age at symptom onset was significantly associated with all measures of speech recognition, while deafness duration was only associated with sentence recognition. AI-PAC allows for a reliable and quantitative pre-operative prediction of early improvement in speech recognition after CI. 18 FDG PET may be a valuable addition to the objective pre-operative assessment of CI candidates. Further studies in larger cohorts and with longer follow-up times are needed.

Positron emission tomography (PET) has been successfully used to investigate central nervous processes, including the central auditory pathway. Unlike early water-cooled PET-scanners, novel PET/CT scanners employ air cooling and include a CT system, both of which result in higher background noise levels. In the present study, we describe the background noise generated by two state-of-the-art air-cooled PET/CT scanners. We measured speech recognition in background noise: recorded PET noise and a speech-shaped noise applied in clinical routine to subjects with normal hearing. Background noise produced by air-cooled PET/CT is considerable: 75.1 dB SPL (64.5 dB(A)) for the Philips Gemini TF64 and 76.9 dB SPL (68.4 dB(A)) for the Philips Vereos PET/CT (Philips Healthcare, The Netherlands). Subjects with normal hearing exhibited better speech recognition in recorded PET background noise compared with clinically applied speech-shaped noise. Speech recognition in both background noises correlated significantly. Background noise generated by PET/CT scanners should be considered when PET is used for the investigation of the central auditory pathway. Speech in PET noise is better than in speech-shaped noise because of the minor masking effect of the background noise of the PET/CT.

Thus tuned, imagination equips all protagonists of the con*text*author*reader*discourse polylogue with the agency of in(ter)ventions, i.e. inventions that intervene. These in(ter)ventions display, reflect, and reconfigure moralities. This is what I call p(r)oEthics: a poetics that affirms the search for an ethics of freedom and justice. This p(r)oEthics keeps reflecting the dis*continuity of moralities, reconfiguring them on behalf of freedom and justice in the process. Such p(r)oEthics is, amongst others, displayed in and via imagination; and this is what I wish to exemplify in the following by referring to Imagination and Maafa.

Purpose The aim of this study is to examine the scalar dislocation rate in straight and perimodiolar electrode arrays in relation to cochlear morphology. Furthermore, we aim to analyze the specific dislocation point of electrode arrays depending on their design and shape and to correlate these results to postoperative speech perception. Methods We conducted a comparative analysis of patients (ears: n  = 495) implanted between 2013 and 2018 with inserted perimodiolar or straight electrode arrays from Cochlear™ or MED-EL. CBCT (cone beam computed tomography) was used to determine electrode array position (scalar insertion, intra-cochlear dislocation, point of dislocation and angular insertion depth). Furthermore, cochlear morphology was measured. The postoperative speech discrimination was compared regarding electrode array dislocation, primary scalar insertion and angular insertion depth. Results The electrode array with the highest rate of primary SV insertions was the CA; the electrode array with the highest rate of dislocations out of ST was the Flex Soft . We did not find significantly higher dislocation rates in cochleostomy-inserted arrays. The angle of dislocation was electrode array design-specific. A multivariate nonparametric analysis revealed that the dislocation of the electrode array has no significant influence on postoperative speech perception. Nevertheless, increasing angular insertion depth significantly reduced postoperative speech perception for monosyllables. Conclusion This study demonstrates the significant influence of electrode array design on scalar location, dislocation and the angle of dislocation itself. Straight and perimodiolar electrode arrays differ from each other regarding both the rate and place of dislocation. Insertion via cochleostomy does not lead to increased dislocation rates in any of the included electrode arrays. Furthermore, speech perception is significantly negatively influenced by angular insertion depth.