Acouphène | EPFL Graph Search

Un (du grec ancien , « entendre », et , « apparaître ») est une sensation auditive dont l'origine n'est pas extérieure à l'organisme et qui demeure inaudible par l'entourage du concerné. Le son perçu peut ressembler à un bourdonnement, un sifflement ou même un tintement ressenti dans le crâne ou dans l'oreille, d'un seul ou des deux côtés. Description Les acouphènes sont souvent liés à une pathologie, mais pas systématiquement, d'origine indéterminée et d'intensité qui peut être variable selon l'état de santé ou de fatigue de la personne qui y est sujette. Les acouphènes ne sont pas identiques entre les personnes, ils varient en intensité, en tonalité (grave, aigu) et en quantité (il peut y en avoir plusieurs : graves, aigus, bourdonnements, tintements, chuintements, sifflements, cliquetis, pulsations). Ils peuvent aussi être des voix sans signification ou des musiques (pas agréables car répétitives et lancinantes). Ils peuvent être permanents, intermittents, variable

Neuroimaging of human auditory cortex

Naghmeh Ghazaleh

Modern neuroimaging technologies provide us with non-invasive methods for study- ing structure and function, and plasticity of the human auditory cortex. Here we have acquired high spatial resolution functional magnetic resonance imaging (fMRI) data of the auditory cortex in patients with unilateral hearing loss and tinnitus. Compared to healthy controls, we found evidence of over-representation and hyperactivity in parts of cortical tonotopic map that correspond to low frequencies sounds, irrespective of the hearing loss and tinnitus range, which in most cases affected higher frequencies. These findings suggest that hearing loss has a destabilizing effect on the tonotopic organization in primary auditory cortex that is not restricted to the corresponding frequency range of hearing loss and tinnitus. One of the challenges in tinnitus studies is the high relevance of the hyperacusis con- dition in these patients. The similarity and co-occurrence of these two disorders con- tributes to the debate about the specificity of findings associated with tinnitus alone. For classifying tinnitus patients with and without hyperacusis, we thus implemented partial least square correlation (PLSC) analysis that builds upon the cross-covariance information between audiogram and fMRI data. This method provides us with a multi modal measure to successfully detect the hyperacusis condition in tinnitus patients with 80% cross-validation accuracy, for the first time. The PLSC driven biomarker, also yields the brain area playing a major role in the condition. There is a vast heterogeneity in the anatomy of auditory cortex across subjects, therefore individualized delineation the exact border between primary and secondary auditory cortex is a demanding research topic. Here we established a model of ex- trinsic connectivity of auditory cortex with the two other regions of the brain that have discriminative connectivity with primary and secondary auditory cortices. The resting state fMRI connectivity features are used for segmentation and are performed exploiting two methods as dynamical causal modeling (DCM) of effective connectivity with 74% accuracy and functional connectivity with 71% accuracy. This data-driven segmentation method, not only facilitate the definition of auditory cortex subregions for fundamental research in the normal brain, but also yields a useful tool for following the modification in the functional anatomy of this region as a result of hearing disorders like tinnitus.

EPFL2017

Real-Time fMRI Neurofeedback: Methods and Application to Chronic Tinnitus

Nicolas Gninenko

In the last twenty years, advances in real-time functional magnetic resonance imaging (rt-fMRI) have offered exciting new tools to study the human brain. One of them, termed rt-fMRI neurofeedback (NF), has turned the MRI scanner environment into an interactive brain-computer interface (BCI), allowing to position brain activity as the independent variable in the relationship ranging from brain function to observed behavior. This paradigm immediately gained considerable interest in the fMRI research community, as the idea of grasping volitional control over a precisely targeted brain area suddenly became feasible. Since then, a multitude of studies have used this technique in drastic efforts to normalize pathological brain activity (or connectivity) in a wide range of neurological disorders, ultimately seeking clinical and behavioral improvement.Among these, chronic tinnitus, commonly referred to as "ringing in the ears", has been considered a promising condition for NF interventions. Tinnitus has been linked to wide disruptions in brain functions involving attention, cognition, emotional distress, and auditory and sensory processing, among others. It has also been associated with hyperactivity in the primary auditory cortex after acoustic trauma. Currently, no cure exists for a complete relief of symptoms. A previous proof-of-concept study suggested that learned down-regulation of the auditory cortex slightly improved short-term subjective reports of tinnitus severity in a small group of participants. Here, we present the longest NF clinical trial to date in chronic tinnitus (NeuroTin), in which 60 patients are enrolled across 3 different interventions: electroencephalography NF (EEG NF), fMRI NF, and cognitive behavioral therapy (CBT), nowadays considered as standard care for tinnitus. The aim is to assess whether any of the two NF approaches can outperform standard CBT training for alleviation of tinnitus distress. In this dissertation, we present clinical outcomes and neuroimaging findings for the fMRI NF group.Twenty-one participants learned to down-regulate the activity of their primary auditory cortex over 15 weeks of fMRI NF training. While only a few participants managed to learn down-regulation, we found a significant clinical relief in tinnitus distress lasting up to one year in the fMRI NF group, as opposed to the CBT group. We demonstrate the superiority of fMRI NF training over standard care CBT and show, for the first time, resulting long-term benefits in quality of life. Furthermore, we bring additional evidence regarding the implication of a highly modulated small brain region in tinnitus, bilaterally located in the parietal operculum (OP3). We describe its effective connectivity with regions pertaining to the auditory pathway and discuss its implication in a possibly altered multisensory integration mechanism in tinnitus. Then, using a co-activation patterns analysis, we unveil 4 functional brain networks co-occurring with the deactivation of OP3. We identify them as (1) an auditory-visual network comprising an important node of the auditory pathway (the medial geniculate body), (2) a part of the NF control network, (3) the default mode network, and (4) a somatosensory network likely linked to other sensory integration modalities. Lastly, we characterize the average dynamics of these 4 functional networks and discuss new avenues for fMRI NF interventions and treatments in chronic tinnitus.

EPFL2022

Lateralization of the primary auditory cortex, in patients with unilateral tinnitus

Naghmeh Ghazaleh, Melissa Saenz, Wietske Van der Zwaag

Tinnitus, the chronic perception of ringing or other phantom sounds, is typically associated with hearing loss. The reduction of auditory input that conveys to auditory cortex leads to the changes in the balance of excitatory and inhibitory activation of the corresponding neurons in this area and is possibly the cause of tinnitus. From the other hand a recent study (Gordon et al. Beain 2013) has shown that bilateral input protects the cortex from unilaterally driven reorganization. Based on this finding we could expect that in patient with unilateral hearing loss and tinnitus the input from unimpaired ear has not been transfered sufficiently to the bilateral hemisphere and this loss of input has resulted in reorganization in neuronal activity of the auditory cortex. To test this hypothesis we compare the amplitude of the neuronal activity bold response of the auditory cortex in the ipsilateral and contralateral hemisphere to the hearing ear in response to different frequency tones. Ten tinnitus patients with chronic unilateral hearing loss and tinnitus and age-matched normal controls (ages 26-49) were tested. (Patients had chronic subjective non-pulsatile tinnitus associated with moderate to severe unilateral sensorineural hearing loss in one ear only with at least PTA>40dB on three consecutive frequencies between 1 and 4 KHz; tinnitus duration < 6 months). The recruitment of patients with unilateral hearing loss allowed unimpaired sound delivery via the unimpaired ear, bypassing any abnormal responsiveness at the peripheral level. Our high-resolution functional MRI at 7 Tesla (1.5 mm isotropic voxels) (Da Costa et al. J Neurosci 2011) provides us fine scale tonotopic maps in controls and tinnitus patients and using that we are able to compare the amplitude of the neural activity in the auditory cortex of the unilateral and ipsilateral hemisphere to the hearing ear for each group of different frequency responding neurons. Our first finding shows that the activity difference in tinnitus patient is higher than the activity difference in controls. In more detail the activity amplitude in the contralateral hemisphere to the hearing ear in tinnitus patient is much higher than the activity amplitude in ipsilateral hemisphere, in comparison to controls. This result suggests that the auditory pathway in tinnitus patients is less capable to convey the sound bilaterally and it could be a probable cause of their tinnitus.

2014