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shows plots derived from SPM data analysis (one-sample t-tests) (standard approach) and 388 plots representing active region sizes using avareged individual data (alternative approach). Visual 389 inspection provides the following observations, among others. The tone with CF=400 Hz produced larger 390 active regions in SNHL than NH in both hemispheres. Size of activation for the 800Hz CF cortical 391 representations were similar in both groups. For the 1600 Hz CF stimulation, the region sizes were smaller 392 in patients, especially with the standard SPM approach and at lower statistical thresholds. In addition, 393 for 1600 Hz CF , the curve representing the relationship between the t-value and the activation size sloped 394 very rapidly at low t-thresholds until there was no activation detected in SNHL for the t-value 395 corresponding to p=0.05 FWE. Furthermore, some activation was detected in the patient group for high396 frequency stimulation (3200 Hz CF and 6400 Hz CF ) only when averaged activation sizes were looked at. 397 This shows that there were few patients in the group who were able to hear the sounds. This effect was 398 not present when the standard one-sample t-test was used as implemented in SPM, as only group 399 overlapping areas are revealed here. Also in both approaches very similar areas were revealed for pairs 400 of tones, i.e. 400 Hz CF and 800 Hz CF , 1600 Hz CF and 3200 Hz CF in NH. In SNHL, however, the 401 representations of these pairs of sounds were not overlapping in neither approach. 402 403
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Although the tonotopic organisation of the human primary auditory cortex (PAC) has already been studied, the question how its responses are affected in sensorineural hearing loss remains open. Twenty six patients (aged 38.1 ± 9.1 years; 12 men) with symmetrical sloping sensorineural hearing loss (SNHL) and 32 age- and gender-matched controls (NH) p...
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Currently, clinical characterization of hearing deficits for hearing-aid fitting is based on the pure-tone audiogram. Implicitly, this assumes that the audiogram can predict performance in complex, supra-threshold tasks. Sanchez-Lopez et al. (2018) hypothesized that the hearing deficits of a given listener, both at threshold and supra-threshold lev...
Citations
... Given that ARHL begins in the high-frequency region of the auditory spectrum and spreads toward the low-frequency regions with age (Wang and Puel, 2020), the steep slope of the hearing threshold at high frequency is a very typical characteristic of patients with ARHL (Wolak et al., 2017). Accordingly, we used frequency division and the "steepness" of the audiogram to further refine the high-frequency region in this study. ...
... Previous study has found that patients with sensorineural hearing loss showed significantly reduced functional connectivity in the cingulate gyrus (Xu et al., 2019). Meanwhile, it has also been found that the hearing threshold of patients with ARHL began to decline rapidly at 2-4 kHz (Wolak et al., 2017). In addition, we found a significant positive correlation between the GMV of MCC and anxiety scores. ...
Age-related hearing loss (ARHL) is a kind of symmetrical and slow sensorineural hearing loss, which is a common condition in older adults. The characteristic of ARHL is hearing loss beginning in the high-frequency region and spreading toward low-frequency with age. Previous studies have linked it to anxiety, suggesting that brain structure may be involved in compensatory plasticity after partial hearing deprivation. However, the neural mechanisms of underlying ARHL-related anxiety remain unclear. The purpose of this cross-sectional study was to explore the interactions among high-frequency hearing loss and anxiety as well as brain structure in older adults. Sixty-seven ARHL patients and 68 normal hearing (NH) controls participated in this study, and the inclusion criterion of ARHL group was four-frequency (0.5, 1, 2, and 4 kHz) pure tone average (PTA) > 25 decibels hearing level of the better hearing ear. All participants performed three-dimensional T1-weighted magnetic resonance imaging (MRI), pure tone audiometry tests, anxiety and depression scales. Our results found gray matter volume (GMV) decreased in 20 brain regions in the ARHL group compared with the NH group, and a positive correlation existed between high-frequency pure tone audiometry (H-PT) and anxiety scores in the ARHL group. Among 20 brain regions, we also found the GMVs of the middle cingulate cortex (MCC), and the hippocampal/parahippocampal (H-P) regions were associated with H-PT and anxiety scores in all participants separately. However, the depressive symptoms indicated no relationship with hearing assessment or GMVs. Our findings revealed that the crucial role of MCC and H-P in a link of anxiety and hearing loss in older adults.
... Due to the increased SNR and spatial resolution at 7T, fMRI studies focusing on each of the auditory relays separately have consistently reported that the cochlear frequency decomposition is conveyed as a clear, specific frequency gradient ranging from low to high frequencies in all the different subcortical auditory structures (collicular nuclei and Superior Olivary Complex: [1], inferior colliculi: [3,10] and medial geniculate bodies: [3]), until the auditory cortices. In hearing impaired humans, the damages concomitant with hearing loss or Meniere's disease at the level of the cochlea has been reported to induce a broadening of the auditory filters at the cochlear level and then an enlargement of the cortical representations near the "lesionedge" frequency (i.e. the frequency lost at the cochlear level) [9,11]. However, none of the aforementioned studies above investigated simultaneously the tonotopic gradient reorganization within the other auditory relays. ...
... Note that the functional results presented here are only descriptive, as the scope of this study was to evaluate the functional activation within all relays simultaneously using the pTx system and not their individual frequency mappings. Nevertheless, the results indicate potential for clinical applications as functional activations of the auditory pathway in less than 12 min were measured, compared to classical fMRI sessions ranging from 24 min [11] to~80 min [3]. Further studies will have to (a) adapt the MR sequences to match SAR requirements, (b) improve the anatomical localization of the subcortical regions using finer alignments with post mortem data or with functional atlases from other studies, (c) acquire a larger group of healthy subjects to quantify individual variability with specific analysis, and (d) compare the results between different auditory stimuli (pure tones vs. natural sounds) and different clinical populations. ...
Purpose
The aim of the present study is to show a MR procedure for the evaluation of simultaneous left and right auditory functions with functional MRI, and high-resolution acquisition of anatomical auditory pathway using parallel-transmit (pTx) methods at 7T.
Methods
The time-efficient MR acquisition included two steps: RF weights were optimized for the regions-of-interest and high-resolution MR images of the inner-ear were acquired for the first 30 min (400 μm-iso resolution) followed by functional MRI acquisitions along the whole auditory pathway during the next 20 minutes. Data was processed with a linear cross-correlation analysis to define frequency preferences for each voxel in the auditory relays.
Results
Tonotopic maps revealed ordered bilateral frequency gradients in the auditory relays whereas at the level of the cochlear nuclei and superior olivary complexes the frequency gradients were less evident. A 21% increase in transmit-field efficiency was achieved over the left/right inner-ear regions and thus its main structures were clearly discernible using the pTx methods, compared to a single transmit RF coil.
Conclusion
Using 7T pTx allows a fast (less than 60 min in total) and qualitative evaluation of the simultaneous left and right auditory response along the entire auditory pathway, together with high-resolution anatomical images of the inner-ear. This could be further used for patient examination at 7T.
... Decreased frequency-modulation detection, in turn, is associated with reduced speech-in-noise perception (Holmes and Griffiths 2019;Parthasarathy et al. 2020). Moreover, it has been reported that severe hearing loss leads to tonotopic map reorganization in human auditory cortex (Wolak et al. 2017;Koops et al. 2020); however, this finding is not consistent across studies (Saenz and Langers 2014;Ouda et al. 2015). Tonotopic map reorganization (Mühlnickel et al. 1998) and broadened frequency-tuning (Sekiya et al. 2017) have also been observed in individuals with tinnitus (albeit inconsistently; e.g., Koops et al. 2020). ...
Many aging adults experience some form of hearing problems that may arise from auditory peripheral damage. However, it has been increasingly acknowledged that hearing loss is not only a dysfunction of the auditory periphery but also results from changes within the entire auditory system, from periphery to cortex. Damage to the auditory periphery is associated with an increase in neural activity at various stages throughout the auditory pathway. Here, we review neurophysiological evidence of hyperactivity, auditory perceptual difficulties that may result from hyperactivity, and outline open conceptual and methodological questions related to the study of hyperactivity. We suggest that hyperactivity alters all aspects of hearing—including spectral, temporal, spatial hearing—and, in turn, impairs speech comprehension when background sound is present. By focusing on the perceptual consequences of hyperactivity and the potential challenges of investigating hyperactivity in humans, we hope to bring animal and human electrophysiologists closer together to better understand hearing problems in older adulthood.
... One example of a spectacular use of the fMRI technique is to gauge the tonotopic organisation of the auditory cortex ( Figure 4). The frequency-specific organisation of the cortex has been shown to exactly mirror sound frequency encoding in the cochlea [69][70][71][72][73][74][75][87][88][89][90]. ...
In this review we describe several methods that can be used to study auditory processing in the cerebral cortex, including functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), electroencephalography (EEG), functional near-infrared spectroscopy (fNIRS), and positron emission tomography (PET). We explain the principles of each technique and list the characteristics that make them suitable for certain research applications. For each method we give a broad range of examples that have already helped uncover various aspects of cortical auditory processing. We compare and summarise the characteristics of each method in order to help the reader choose one that is best suited to answer a specific research question. We also give perspectives on multimodal imaging – collecting functional brain data with two or more techniques during one study – as a means for overcoming the limitations of each method alone by examining complementary information. This article aims to be a short introductory guide and source of reference for researchers in the field of auditory neuroimaging.
... Thus, it is possible that the differences observed by Koops et al. between hearing-impaired subjects with and without tinnitus (2020) reflect differences in the peripheral pattern of the hearing loss (Tan et al., 2013) rather than changes arising centrally as a consequence of hearing loss. Consistent with this idea, earlier studies, which used constant stimulus levels, found either no changes in cortical responses associated with hearing loss (Ghazaleh et al., 2017;Lanting et al., 2008;Wolak et al., 2017) or increased responses at lower frequencies (Ghazaleh et al., 2017), opposite to the findings of Koops et al. (2020). Importantly, research in humans is complicated by the heterogeneity of tinnitus presentation, and likely also of the underlying causes and mechanisms (reviewed in Cederroth et al., 2019). ...
Sensory input has profound effects on neuronal organization and sensory maps in the brain. The mechanisms regulating plasticity of the auditory pathway have been revealed by examining the consequences of altered auditory input during both developmental critical periods—when plasticity facilitates the optimization of neural circuits in concert with the external environment—and in adulthood—when hearing loss is linked to the generation of tinnitus. In this review, we summarize research identifying the molecular, cellular, and circuit-level mechanisms regulating neuronal organization and tonotopic map plasticity during developmental critical periods and in adulthood. These mechanisms are shared in both the juvenile and adult brain and along the length of the auditory pathway and serve to regulate disinhibitory networks, synaptic structure and function, as well as structural barriers to plasticity. Regulation of plasticity also involves both neuromodulatory circuits, which link plasticity with learning and attention, as well as ascending and descending auditory circuits, which link the auditory cortex and lower structures. Further work identifying the interplay of molecular and cellular mechanisms associating hearing loss induced plasticity with brain changes observed as part of tinnitus should advance strategies to treat tinnitus by molecularly modulating plasticity.
... Ferrucci, 2011) and a higher risk for developing dementia and neurodegenerative disorders (Gates et al., 2010;Golub, 2017;Lin et al., 2011). Previous blood oxygen level dependent (BOLD) functional MRI (fMRI) studies have shown a reduced cortical activation in response to tonal stimulation in the tonotopic areas of the auditory cortex (Langers, van Dijk, Schoenmaker, & Backes, 2007;Zhang, Geng, Zhang, Li, & Zhang, 2006), especially at middle and higher frequencies (3.2 and 6.4 kHz) (Wolak et al., 2017), substantially mirroring the peripheral impairment of HL patients onto the auditory central perception. More recently, BOLD-fMRI studies conducted without stimulations (resting state; see, e.g., Chen et al., 2018) have similarly highlighted a significant reduction of spontaneous neural activity in the primary and secondary auditory cortex of HL patients which correlated with the reduced cognitive performances (including, e.g., language processing). ...
... The steeply sloping high frequency loss is a highly typical audiological pattern of the age-related HL condition, which is sometimes also called "sloping" sensori-neural HL (see, e.g., Wolak et al., 2017). ...
Age‐related hearing loss (HL) can be related to brain dysfunction or structural damage and may result in cerebral metabolic/perfusion abnormalities. Arterial spin labeling (ASL) magnetic resonance imaging (MRI) allows investigating noninvasively brain perfusion changes. Pseudocontinuous ASL and T1‐weighted MRI (at 3 T) and neuropsychological testing (Montreal Cognitive Assessment) were performed in 31 HL (age range = 47–77 years, mean age ± SD = 63.4 ± 8.4 years, pure‐tone average [PTA] HL > 50 dB) and 28 normal hearing (NH; age range = 48–78 years, mean age ± SD = 59.7 ± 7.4 years) subjects. Cerebral blood flow (CBF) and gray matter volume (GMV) were analyzed in the cortical volume to assess perfusion and structural group differences. Two HL subjects showing cognitive impairment were excluded from group comparisons. No significant differences in either global or local atrophy were detected between groups but the HL group exhibited significant regional effects of reduced perfusion within the bilateral primary auditory cortex, with maximal CBF difference (−17.2%) in the right lateral Heschl's gyrus. For the whole sample of HL and NH subjects (n = 59 = 31 HL + 28 NH), the regional CBF was correlated positively to the regional GMV (p = 0.020). In HL subjects (n = 31), the regional CBF was correlated negatively to the audiogram steepness (frequency range: 2–4 kHz, right ear: p = 0.022, left ear: p = 0.015). The observed cortical pattern of perfusion reduction suggests that neuronal metabolism can be related to HL before the recognition of brain structural damage. This also illustrates the potential of ASL‐MRI to contribute early functional markers of reduced central processing associated with HL.
... SŁOWA KLUCZOWE: czynnościowy rezonans magnetyczny, kora słuchowa, intensywność dźwięku BACKGROUND Functional magnetic resonance imaging (fMRI) has proven a valuable tool for studying central mechanisms of auditory perception. A number of works have been published which use this method to examine the relationship between sound parameters, including frequency and intensity, and activation patterns in the auditory cortex [1][2][3]. Notably, it has been shown that tonotopic organisation is preserved throughout the whole auditory system. This means that the systematic tuning of the basilar membrane in the inner ear, with filters tuned sequentially in frequency, is also reflected in the auditory cortex. ...
... Similar outcomes have been presented in fMRI studies by Hart and collaborators (2002) [6] and Sigalovsky and Melcher (2006) [9] who showed the same location of activity for a given frequency range at increased intensity levels with simultaneous spatial expansion of active regions. The high-frequency gradient forming a Vshape around the HG, revealed here for intensities 60 dB and 80 dB, has been reported in numerous papers using the fMRI technique to study auditory cortical responses [1,2,14,18,19,24,25,[27][28][29][30][31]. ...
Background
Despite rapid developments in fMRI, there is still ongoing debate on the optimal paradigm for evaluating the level of auditory cortex activation.
Material and Methods
A number of modern neuroimaging methods can be used to assess brain responses to acoustic stimulation, but new paradigms are still needed. Here the sparse fMRI approach is used to examine frequency-specific activation in auditory cortex in 12 normal hearing individuals.
Results
The size of activation expanded with increasing sound intensity and decreasing sound frequency. At the same time, the main site of frequency-specific activation remained the same across intensities, indicating fixed tonotopic organization. The findings of the study are explained in terms of basilar membrane phenomena such as the travelling wave pattern and spread of activation.
Conclusions
Stimulation levels of at least 60 dB are necessary in order to obtain robust maps of group activation in auditory cortex.
Hearing loss is common among normally aging adults and often arises from damage to auditory peripheral structures, including cochlear hair cell loss and a degradation of synapses connecting hair cells to auditory nerves. However, it has become increasingly clear that age-related hearing loss involves dysfunction of the entire auditory system, including cortex. Peripheral damage induces neuroplastic changes in auditory cortex, most drastically reflected in a loss of neural inhibition that occurs in addition to a broader age-related decrease in inhibition. Here we review the impact of this combined loss of inhibition in auditory cortex on auditory processing. We discuss how reduced inhibition leads to hyperexcitability, reduced neural adaptation, altered periodicity processing, and changes in spectral and spatial tuning. We suggest that these functional changes, resulting from a loss of inhibition, underlie the hearing difficulties commonly experienced by older people, such as tinnitus, hyperacusis, and impaired speech understanding in noisy environments.
Background
Sensory deprivation, such as hearing loss, has been demonstrated to change the intrinsic functional connectivity (FC) of the brain, as measured with resting-state functional magnetic resonance imaging (rs-fMRI). Patients with sloping sensorineural hearing loss (SNHL) are a unique population among the hearing impaired, as they have all been exposed to some auditory input throughout their lifespan and all use spoken language.
Materials and Methods
Twenty patients with SNHL and 21 control subjects participated in a rs-fMRI study. Whole-brain seed-driven FC maps were obtained, with audiological scores of patients, including hearing loss severity and speech performance, used as covariates.
Results
Most profound differences in FC were found between patients with prelingual (before language development, PRE) vs. postlingual onset (after language development, POST) of SNHL. An early onset was related to enhancement in long-range network connections, including the default-mode network, the dorsal-attention network and the fronto-parietal network, as well as in local sensory networks, the visual and the sensorimotor. A number of multisensory brain regions in frontal and parietal cortices, as well as the cerebellum, were also more internally connected. We interpret these effects as top-down mechanisms serving optimization of multisensory experience in SNHL with a prelingual onset. At the same time, POST patients showed enhanced FC between the salience network and multisensory parietal areas, as well as with the hippocampus, when they were compared to those with PRE hearing loss. Signal in several cortex regions subserving visual processing was also more intra-correlated in POST vs. PRE patients. This outcome might point to more attention resources directed to multisensory as well as memory experience. Finally, audiological scores correlated with FC in several sensory and high-order brain regions in all patients.
Conclusion
The results show that a sloping hearing loss is related to altered resting-state brain organization. Effects were shown in attention and cognitive control networks, as well as visual and sensorimotor regions. Specifically, we found that even in a partial hearing deficit (affecting only some of the hearing frequency ranges), the age at the onset affects the brain function differently, pointing to the role of sensitive periods in brain development.
