Maladaptive auditory cortex reorganization may contribute to the generation and maintenance of tinnitus. Because cortical organization can be modified by behavioral training, we attempted to reduce tinnitus loudness by exposing chronic tinnitus patients to self-chosen, enjoyable music, which was modified ("notched") to contain no energy in the frequency range surrounding the individual tinnitus frequency. After 12 months of regular listening, the target patient group (n = 8) showed significantly reduced subjective tinnitus loudness and concomitantly exhibited reduced evoked activity in auditory cortex areas corresponding to the tinnitus frequency compared to patients who had received an analogous placebo notched music treatment (n = 8). These findings indicate that tinnitus loudness can be significantly diminished by an enjoyable, low-cost, customtailored notched music treatment, potentially via reversing maladaptive auditory cortex reorganization.cortical plasticity | human auditory cortex | lateral inhibition | magnetoencephalography | MEG S ubjective tinnitus (1) is among the most prevalent symptoms of hearing disorders in industrialized countries (2, 3). Tinnitus loudness can be considered as the most tangible tinnitus characteristic. In 1-3% of the general population, the tinnitus sensation is loud enough to affect the quality of life (4). Causal treatment strategies for tinnitus are not yet available.The lack of treatment strategies is due to incomplete knowledge concerning the mechanisms of tinnitus generation and maintenance. However, recent neurophysiological studies have shown that tinnitus is presumably caused by maladaptive auditory cortex reorganization (4-6) (similar phenomena were observed also in somatosensory cortex; refs. 7-9). For instance, magnetoencephalography (MEG) studies have demonstrated that auditory cortical map areas corresponding to the tinnitus frequency were distorted; the amount of distortion correlated positively with perceived tinnitus strength (10). Moreover, auditory cortex activity corresponding to the tinnitus frequency was shown to be enhanced and related to perceived tinnitus intrusiveness (11).To date, widely used tinnitus treatment strategies (e.g., tinnitus retraining therapy; ref. 12) are merely symptom management approaches. Therefore, there is a great demand for causal treatment approaches targeting the tinnitus percept more directly. Recent neurophysiological studies indicate that behavioral training can be a powerful means to reverse maladaptive cortical reorganization (7, 13).A previous study (14) demonstrated that listening to spectrally "notched" music can reduce cortical activity corresponding to the notch center frequency, possibly through lateral inhibition. Motivated by this finding, we developed an innovative tinnitus treatment strategy aimed at reducing tinnitus loudness. The treatment regimen consists of regular listening to enjoyable, custom-tailored notched music. Here, we evaluate and report results of the treatment from a longitudinal double-blinded ...

Attention improves auditory performance in noisy environments by either enhancing the processing of task-relevant stimuli ("gain"), suppressing task-irrelevant information ("sharpening"), or both. In the present study, we investigated the effect of focused auditory attention on the population-level frequency tuning in human auditory cortex by means of magnetoencephalography. Using complex stimuli consisting of a test tone superimposed on different band-eliminated noises during active listening or distracted listening conditions, we observed that focused auditory attention caused not only gain, but also sharpening of frequency tuning in human auditory cortex as reflected by the N1m auditory evoked response. This combination of gain and sharpening in the auditory cortex may contribute to better auditory performance during focused auditory attention.

Background: Under natural circumstances, attention plays an important role in extracting relevant auditory signals from simultaneously present, irrelevant noises. Excitatory and inhibitory neural activity, enhanced by attentional processes, seems to sharpen frequency tuning, contributing to improved auditory performance especially in noisy environments. In the present study, we investigated auditory magnetic fields in humans that were evoked by pure tones embedded in bandeliminated noises during two different stimulus sequencing conditions (constant vs. random) under auditory focused attention by means of magnetoencephalography (MEG).

The investigation of functional hemispheric asymmetries regarding auditory processing in the human brain still remains a challenge. Classical lesion and recent neuroimaging studies indicated that speech is dominantly processed in the left hemisphere, whereas music is dominantly processed in the right. However, recent studies demonstrated that the functional hemispheric asymmetries were not limited to the processing of highly cognitive sound signals like speech and music but rather originated from the basic neural processing of elementary sound features, that is, spectral and temporal acoustic features. Here, in contrast to previous studies, we used carefully composed tones and pulse trains as stimuli, balanced the overall physical sound input between spectral and temporal change conditions, and demonstrated the time course of neural activity evoked by spectral versus temporal sound input change by means of magnetoencephalography (MEG). These original findings support the hypothesis that spectral change is dominantly processed in the right hemisphere, whereas temporal change is dominantly processed in the left.

Background: In daily life, we are exposed to different sound inputs simultaneously. During neural encoding in the auditory pathway, neural activities elicited by these different sounds interact with each other. In the present study, we investigated neural interactions elicited by masker and amplitude-modulated test stimulus in primary and non-primary human auditory cortex during ipsilateral and contra-lateral masking by means of magnetoencephalography (MEG).

Both attention and masking sounds can alter auditory neural processes and affect auditory signal perception. In the present study, we investigated the complex effects of auditory-focused attention and the signal-to-noise ratio of sound stimuli on three different auditory evoked field components (auditory steady-state response, N1m, and sustained field) by means of magnetoencephalography. The results indicate that the auditory steady-state response originating in primary auditory cortex reflects the signal-to-noise ratio of physical sound inputs (bottom-up process) rather than the listener's attentional state (top-down process), whereas the sustained field, originating in nonprimary auditory cortex, reflects the attentional state rather than the signal-to-noise ratio. The N1m was substantially influenced by both bottom-up and top-down neural processes. The differential sensitivity of the components to bottom-up and top-down neural processes, contingent on their level in the processing pathway, suggests a stream from bottom-up driven sensory neural processing to top-down driven auditory perception within human auditory cortex.

Chronic tinnitus is a symptom with high prevalence. There is evidence that the tinnitus perception is related to unfavorable cortical plastic changes. In our recent study we have developed and evaluated a customized music training strategy that appears capable of both reducing cortical tinnitus related neuronal activity and alleviating subjective tinnitus perception. We hypothesize that the regular and enjoyable music training reverses unprofitable cortical reorganization to a certain degree by means of the focused strengthening of auditory inhibitory neuronal networks.

The capability of involuntarily tracking certain sound signals during the simultaneous presence of noise is essential in human daily life. Previous studies have demonstrated that top-down auditory focused attention can enhance excitatory and inhibitory neural activity, resulting in sharpening of frequency tuning of auditory neurons. In the present study, we investigated bottom-up driven involuntary neural processing of sound signals in noisy environments by means of magnetoencephalography. We contrasted two sound signal sequencing conditions: "constant sequencing" versus "random sequencing." Based on a pool of 16 different frequencies, either identical (constant sequencing) or pseudorandomly chosen (random sequencing) test frequencies were presented blockwise together with band-eliminated noises to nonattending subjects. The results demonstrated that the auditory evoked fields elicited in the constant sequencing condition were significantly enhanced compared with the random sequencing condition. However, the enhancement was not significantly different between different band-eliminated noise conditions. Thus the present study confirms that by constant sound signal sequencing under nonattentive listening the neural activity in human auditory cortex can be enhanced, but not sharpened. Our results indicate that bottom-up driven involuntary neural processing may mainly amplify excitatory neural networks, but may not effectively enhance inhibitory neural circuits.