Music-induced cortical plasticity and lateral inhibition in the human auditory cortex as foundations for tonal tinnitus treatment

Abstract

Over the past 15 years, we have studied plasticity in the human auditory cortex by means of magnetoencephalography (MEG). Two main topics nurtured our curiosity: the effects of musical training on plasticity in the auditory system, and the effects of lateral inhibition. One of our plasticity studies found that listening to notched music for 3 h inhibited the neuronal activity in the auditory cortex that corresponded to the center-frequency of the notch, suggesting suppression of neural activity by lateral inhibition. Subsequent research on this topic found that suppression was notably dependent upon the notch width employed, that the lower notch-edge induced stronger attenuation of neural activity than the higher notch-edge, and that auditory focused attention strengthened the inhibitory networks. Crucially, the overall effects of lateral inhibition on human auditory cortical activity were stronger than the habituation effects. Based on these results we developed a novel treatment strategy for tonal tinnitus—tailor-made notched music training (TMNMT). By notching the music energy spectrum around the individual tinnitus frequency, we intended to attract lateral inhibition to auditory neurons involved in tinnitus perception. So far, the training strategy has been evaluated in two studies. The results of the initial long-term controlled study (12 months) supported the validity of the treatment concept: subjective tinnitus loudness and annoyance were significantly reduced after TMNMT but not when notching spared the tinnitus frequencies. Correspondingly, tinnitus-related auditory evoked fields (AEFs) were significantly reduced after training. The subsequent short-term (5 days) training study indicated that training was more effective in the case of tinnitus frequencies ≤ 8 kHz compared to tinnitus frequencies >8 kHz, and that training should be employed over a long-term in order to induce more persistent effects. Further development and evaluation of TMNMT therapy are planned. A goal is to transfer this novel, completely non-invasive and low-cost treatment approach for tonal tinnitus into routine clinical practice.

Self-Administered Tinnitus Pitch Matching versus a Conventional Audiometric Procedure

“…Thus, accurate tinnitus pitch matching is an important step for successful sound-based tinnitus treatment [Pantev et al, 2012;Tass et al, 2012]. Tinnitus pitch matching has traditionally been performed as part of audiological evaluations for tinnitus, typically requiring patients to visit hospitals or specialist facilities for audiometry.…”

“…A matched tinnitus pitch can be used as a reference for the selection and fitting of sound therapies that have been gaining popularity and showing increasingly successful results. In particular, tailor-made notched music training was developed to suppress hyperactive-at-resting auditory cortical neurons, which represent the tinnitus frequency, by reinforcing lateral inhibition through listening to music with an octave range centered at the tinnitus frequency filtered out [Okamoto et al, 2010;Teismann et al, 2011;Pantev et al, 2012].…”

Suppression of spontaneous activity in a computational tinnitus DCN model depends on notched-stimulation bandwidth

“…Okamoto, Pantev et al demonstrated recently in a series of studies [1], [2], [3] that tailor-made notched acoustical stimulation can be beneficial in tinnitus therapy. They report a significant reduction in subjectively perceived tinnitus loudness and distress in patients with tailored notched music therapy compared to a control group that received a placebo notched music therapy.…”

Sensory Consciousness is Experienced through Amplification of Sensory Stimuli via Lateral Inhibition

“…Lateral inhibition in audition also: 1) suppresses neighboring responses from stimuli; 2) "broadens tuning curves" [40]; 3) reduces random cortical operation instead of increasing noise [42]; or 4) becomes stronger with the intensity of sound [45].…”

“…Not unlike vision, hearing takes place within the brain (as well as the ears), and the brain must be able to translate and amplify weak signals in order for hearing to occur. Lateral inhibition is likely associated with the same magnification process in hearing as is observed in vision, functioning similarly: the spectral edge of sound stimuli is enhanced in topographical frequency maps, resulting in the improvement of perception of sound [25] [39] R. Jerath et al [40].…”