Attentional Modulation of Auditory Signal-in-Noise Processing

Trotz der offensichtlichen Relevanz von auditorischer Aufmerksamkeit für die Verarbeitung von akustischen Signalen in Rauschen sind die Effekte und Mechanismen von Aufmerksamkeit auf neuronaler Ebene bislang weitgehend ungeklärt. Die Ergebnisse der drei vorliegenden Magnetenzephalographie-Studien legen diesbezüglich unter Berücksichtigung des aktuellen Forschungsstandes folgende Schlussfolgerungen nahe: (i) der beobachtete schärfende Effekt von auditorischer Aufmerksamkeit spiegelt eine aktive Unterdrückung nichtrelevanter neuronaler Aktivität wider, welche über efferente, inhibitorische Verbindungen vermittelt wird. (ii) Es existiert vermutlich eine grundlegende funktionelle Dominanz der linken Hemisphäre für die Verarbeitung von akustischen Signalen in Rauschen. (iii) Diese generelle funktionelle Dominanz der linken Hemisphäre für die Verarbeitung von akustischen Signalen in Rauschen kann unter ganz bestimmten Bedingungen durch Aufmerksamkeitsprozesse moduliert werden

Short and Intense Tailor-Made Notched Music Training against Tinnitus: The Tinnitus Frequency Matters

Tinnitus is one of the most common diseases in industrialized countries. Here, we developed and evaluated a short-term (5 subsequent days) and intensive (6 hours/day) tailor-made notched music training (TMNMT) for patients suffering from chronic, tonal tinnitus. We evaluated (i) the TMNMT efficacy in terms of behavioral and magnetoencephalographic outcome measures for two matched patient groups with either low (≤8 kHz, N = 10) or high (>8 kHz, N = 10) tinnitus frequencies, and the (ii) persistency of the TMNMT effects over the course of a four weeks post-training phase. The results indicated that the short-term intensive TMNMT took effect in patients with tinnitus frequencies ≤8 kHz: subjective tinnitus loudness, tinnitus-related distress, and tinnitus-related auditory cortex evoked activity were significantly reduced after TMNMT completion. However, in the patients with tinnitus frequencies >8 kHz, significant changes were not observed. Interpreted in their entirety, the results also indicated that the induced changes in auditory cortex evoked neuronal activity and tinnitus loudness were not persistent, encouraging the application of the TMNMT as a longer-term training. The findings are essential in guiding the intended transfer of this neuro-scientific treatment approach into routine clinical practice

Frequency-specific modulation of population-level frequency tuning in human auditory cortex

<p>Abstract</p> <p>Background</p> <p>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 band-eliminated noises during two different stimulus sequencing conditions (constant vs. random) under auditory focused attention by means of magnetoencephalography (MEG).</p> <p>Results</p> <p>In total, we used identical auditory stimuli between conditions, but presented them in a different order, thereby manipulating the neural processing and the auditory performance of the listeners. Constant stimulus sequencing blocks were characterized by the simultaneous presentation of pure tones of <it>identical frequency </it>with band-eliminated noises, whereas random sequencing blocks were characterized by the simultaneous presentation of pure tones of <it>random frequencies </it>and band-eliminated noises. We demonstrated that auditory evoked neural responses were larger in the constant sequencing compared to the random sequencing condition, particularly when the simultaneously presented noises contained narrow stop-bands.</p> <p>Conclusion</p> <p>The present study confirmed that population-level frequency tuning in human auditory cortex can be sharpened in a frequency-specific manner. This frequency-specific sharpening may contribute to improved auditory performance during detection and processing of relevant sound inputs characterized by specific frequency distributions in noisy environments.</p