Neural network models of tinnitus

Eye movement desensitization and reprocessing as a treatment for tinnitus

OBJECTIVES/HYPOTHESIS

To determine the effectiveness of eye movement desensitization and reprocessing (EMDR) as a treatment for tinnitus.

STUDY DESIGN

Single-site prospective interventional clinical trial at a university hospital in the United Kingdom.

METHODS

Participants were provided with tEMDR. This is a bespoke EMDR protocol that was developed specifically to treat individuals with tinnitus. Participants received a maximum of 10 sessions of tEMDR. Outcome measures including tinnitus questionnaires and mood questionnaires were recorded at baseline, discharge, and at 6 months postdischarge.

RESULTS

Tinnitus Handicap Inventory and Beck Depression Inventory scores demonstrated a statistically significant improvement at discharge after EMDR intervention (P = .0005 and P = .0098, respectively); this improvement was maintained at 6 months postdischarge. There was also a moderate but not significant (P = .0625) improvement in Beck Anxiety Inventory scores.

CONCLUSIONS

This study has demonstrated that the provision of tEMDR has resulted in a clinically and statistically significant improvement in tinnitus symptoms in the majority of those participants who took part. Furthermore, the treatment effect was maintained at 6 months after treatment ceased. This study is of particular interest, as the study protocol was designed to be purposefully inclusive of a diverse range of tinnitus patients. However, as a small uncontrolled study, these results do not consider the significant effects of placebo and therapist interaction. Larger high-quality studies are essential for the verification of these preliminary results.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:2384-2390, 2019.

Examining the short term effects of emotion under an Adaptation Level Theory model of tinnitus perception

OBJECTIVES

Existing evidence suggests a strong relationship between tinnitus and emotion. The objective of this study was to examine the effects of short-term emotional changes along valence and arousal dimensions on tinnitus outcomes. Emotional stimuli were presented in two different modalities: auditory and visual. The authors hypothesized that (1) negative valence (unpleasant) stimuli and/or high arousal stimuli will lead to greater tinnitus loudness and annoyance than positive valence and/or low arousal stimuli, and (2) auditory emotional stimuli, which are in the same modality as the tinnitus, will exhibit a greater effect on tinnitus outcome measures than visual stimuli.

STUDY DESIGN

Auditory and visual emotive stimuli were administered to 22 participants (12 females and 10 males) with chronic tinnitus, recruited via email invitations send out to the University of Auckland Tinnitus Research Volunteer Database. Emotional stimuli used were taken from the International Affective Digital Sounds- Version 2 (IADS-2) and the International Affective Picture System (IAPS) (Bradley and Lang, 2007a, 2007b). The Emotion Regulation Questionnaire (Gross and John, 2003) was administered alongside subjective ratings of tinnitus loudness and annoyance, and psychoacoustic sensation level matches to external sounds.

RESULTS

Males had significantly different emotional regulation scores than females. Negative valence emotional auditory stimuli led to higher tinnitus loudness ratings in males and females and higher annoyance ratings in males only; loudness matches of tinnitus remained unchanged. The visual stimuli did not have an effect on tinnitus ratings. The results are discussed relative to the Adaptation Level Theory Model of Tinnitus.

CONCLUSIONS

The results indicate that the negative valence dimension of emotion is associated with increased tinnitus magnitude judgements and gender effects may also be present, but only when the emotional stimulus is in the auditory modality. Sounds with emotional associations may be used for sound therapy for tinnitus relief; it is of interest to determine whether the emotional component of sound treatments can play a role in reversing the negative responses discussed in this paper.

Increased striatal functional connectivity with auditory cortex in tinnitus

Tinnitus is a common auditory perceptual disorder whose neural substrates are under intense debate. One physiologically based model posits the dorsal striatum to play a key role in gating auditory phantoms to perceptual awareness. Here, we directly test this model along with the roles of auditory and auditory-limbic networks in tinnitus non-invasively by comparing resting-state fMRI functional connectivity patterns in chronic tinnitus patients against matched control subjects without hearing loss. We assess resting-state functional connectivity of the caudate dorsal striatum (area LC), caudate head (CH), nucleus accumbens (NA), and primary auditory cortex (A1) to determine patterns of abnormal connectivity. In chronic tinnitus, increases in ipsilateral striatal–auditory cortical connectivity are found consistently only in area LC. Other patterns of increased connectivity are as follows: (1) right striatal area LC, A1, CH, and NA with parietal cortex, (2) left and right CHs with dorsal pre-frontal cortex, (3) NA and A1 with cerebellum, hippocampus, visual and ventral pre-frontal cortex. Those findings provide further support for a striatal gating model of tinnitus, where dysfunctionally permissive area LC enables auditory phantoms to reach perceptual awareness.

An adaptation level theory of tinnitus audibility

Models of tinnitus suggest roles for auditory, attention, and emotional networks in tinnitus perception. A model of tinnitus audibility based on Helson’s (1964) adaptation level theory (ALT) is hypothesized to explain the relationship between tinnitus audibility, personality, memory, and attention. This theory attempts to describe how tinnitus audibility or detectability might change with experience and context. The basis of ALT and potential role of auditory scene analysis in tinnitus perception are discussed. The proposed psychoacoustic model lends itself to incorporation into existing neurophysiological models of tinnitus perception. It is hoped that the ALT hypothesis will allow for greater empirical investigation of factors influencing tinnitus perception, such as attention and tinnitus sound therapies.

[Tinnitus treatment: neurosurgical management]

Tinnitus is a very frequent symptom affecting 10% of the general population. It corresponds to the perception of an internal noise that can severely impair the quality of life. Tinnitus management requires a multidisciplinary approach in which neuromodulation and neurosurgery tend to play major roles. Classification of tinnitus separates objective tinnitus (i.e., tinnitus that can be heard or recorded) from the more frequent subjective tinnitus (i.e., tinnitus only perceived by the patient). Objective tinnitus is either pulsatile synchronous with heartbeat or asynchronous. In the former, appropriate radiological testing should search for a vascular abnormality as well as other neurological diseases (intracranial hypertension, Arnold-Chiari malformation, vascular loops, etc.). Asynchronous objective tinnitus generally corresponds to muscular contractions that require specific management. The pathophysiology of subjective tinnitus is more complex, showing strong analogies with postamputation pain syndromes. After peripheral middle ear or inner ear damage, auditory deafferentation could result in hyperactivity and/or functional reorganization within central auditory and nonauditory structures. This could explain the persistence of tinnitus after total hearing amputation (e.g., translabyrinthine approach for vestibular schwannoma) and associated symptoms such as hyperacusis or anxiety and depression. This central model finds strong support in animal experiments and in functional neuroimagery (PET, fMRI, MEG). Since no etiologically based therapies are currently available, severe subjective tinnitus management only targets tinnitus tolerance with sound enrichment or cognitive behavior therapy. However, in the near future better knowledge of tinnitus pathophysiology and innovative therapeutic tools could emerge from neuromodulation techniques such as repeated transcranial magnetic or epidural electric stimulation.

Biocybernetics of attention in the tinnitus decompensation: An integrative multiscale modeling approach

Tinnitus is one of the most common symptoms affecting people all over the world. In the absence of an established cure many individuals are not only faced with the need to adjust to the sensation of the tinnitus noise, but also with psychological comorbidities. In recent years, different studies have been directed to elucidate the psychophysiological mechanisms that are involved in the tinnitus decompensation. From these, special emphasis has been placed on studies related to attention and habituation, which accordingly play a crucial role in current tinnitus therapy approaches. In spite of such progress, the relationship between selective attention and the tinnitus decompensation with respect to large-scale neural correlates is still not well understood. In order to address this issue, we propose an integrative multiscale modeling approach for studying neural correlates of auditory selective attention in the tinnitus decompensation. Computational simulations based on our model confirmed electroencephalographic human data of both auditory selective attention and the tinnitus decompensation. It is concluded that the proposed methodology represents a promising approach to give insight into the neurodynamics of auditory selective attention in the tinnitus decompensation.