Subcallosal brain structure: Correlation with hearing threshold at supra-clinical frequencies (> 8 kHz), but not with tinnitus

Dept. of Otology and Laryngology, Harvard Medical School, Boston MA, USA
Hearing research (Impact Factor: 2.97). 04/2012; 295. DOI: 10.1016/j.heares.2012.03.013
Source: PubMed


This study tested for differences in brain structure between tinnitus and control subjects, focusing on a subcallosal brain region where striking differences have been inconsistently found previously. Voxel-based morphometry (VBM) was used to compare structural MRIs of tinnitus subjects and non-tinnitus controls. Audiograms of all subjects were normal or near-normal at standard clinical frequencies (≤8 kHz). Mean threshold through 14 kHz, age, sex and handedness were matched between groups. There were no definitive differences between tinnitus and control groups in modulated or unmodulated maps of gray matter (GM) probability (i.e., GM volume and concentration, respectively). However, when the image data were tested for correlations with parameters that were either not measured or not matched between the tinnitus and control groups of previous studies, a notable correlation was found: Threshold at supra-clinical frequencies (above 8 kHz) was negatively correlated with modulated GM probability in ventral posterior cingulate cortex, dorsomedial prefrontal cortex, and a subcallosal region that included ventromedial prefrontal cortex and coincided with previously-reported differences between tinnitus and control subjects. The results suggest an explanation for the discrepant findings in subcallosal brain: threshold at supra-clinical frequencies may have differed systematically between tinnitus and control groups in some studies but not others. The observed correlation between (1) brain structure in regions engaged in cognitive and attentional processes and (2) hearing sensitivity at frequencies generally considered unnecessary for normal human auditory behavior is surprising and worthy of follow up.

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    • "Hearing loss is typically comorbid with tinnitus suggesting the tinnitus percept is a direct consequence of maladaptive neuroplastic responses to hearing loss [3]. Current models of tinnitus generation therefore focus on the potential consequences of hearing loss on neuronal activity within the central auditory system [4]–[12], although neuronal structures or networks responsible for tinnitus that are independent of those for hearing loss are yet to be convincingly determined [13]–[16]. "
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    ABSTRACT: BackgroundPrevious studies of frequency discrimination training (FDT) for tinnitus used repetitive task-based training programmes relying on extrinsic factors to motivate participation. Studies reported limited improvement in tinnitus symptoms.PurposeTo evaluate FDT exploiting intrinsic motivations by integrating training with computer-gameplay.MethodsSixty participants were randomly assigned to train on either a conventional task-based training, or one of two interactive game-based training platforms over six weeks. Outcomes included assessment of motivation, tinnitus handicap, and performance on tests of attention.ResultsParticipants reported greater intrinsic motivation to train on the interactive game-based platforms, yet compliance of all three groups was similar (∼70%) and changes in self-reported tinnitus severity were not significant. There was no difference between groups in terms of change in tinnitus severity or performance on measures of attention.ConclusionFDT can be integrated within an intrinsically motivating game. Whilst this may improve participant experience, in this instance it did not translate to additional compliance or therapeutic benefit.Trial NCT02095262
    PLoS ONE 09/2014; 9(9):e107430. DOI:10.1371/journal.pone.0107430 · 3.23 Impact Factor
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    • "Although hearing loss is not supposed to be a predictor for response to rTMS treatment [24], previous studies have shown that hearing loss is an important confounder concerning GM changes in tinnitus patients [14, 60, 61]. To be able to thoroughly interpret research results, future work should try to include pure tone audiogram including high frequency audiogram [14, 60, 61] for all patients. Second, the lacking correlation between treatment outcome and GM changes might have been due to the small treatment effects. "
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    ABSTRACT: Repetitive transcranial magnetic stimulation (rTMS) of the temporal cortex has been used to treat patients with subjective tinnitus. While rTMS is known to induce morphological changes in healthy subjects, no study has investigated yet whether rTMS treatment induces grey matter (GM) changes in tinnitus patients as well, whether these changes are correlated with treatment success, and whether GM at baseline is a useful predictor for treatment outcome. Therefore, we examined magnetic resonance images of 77 tinnitus patients who were treated with rTMS of the left temporal cortex (10 days, 2000 stimuli/day, 1 Hz). At baseline and after the last treatment session high-resolution structural images of the brain were acquired and tinnitus severity was assessed. For a subgroup of 41 patients, additional brain scans were done after a follow-up period of 90 days. GM changes were analysed by means of voxel based morphometry. Transient GM decreases were detectable in several brain regions, especially in the insula and the inferior frontal cortex. These changes were not related to treatment outcome though. Baseline images correlated with change in tinnitus severity in the frontal cortex and the lingual gyrus, suggesting that GM at baseline might hold potential as a possible predictor for treatment outcome.
    Neural Plasticity 06/2014; 2014:132058. DOI:10.1155/2014/132058 · 3.58 Impact Factor
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    • "However, there is mixed anatomical evidence to suggest a difference in the brain of those with and without tinnitus. While some studies report differences in gray matter in the emotional centers (subcallosal area) between those with tinnitus and those without it (e.g., Mü hlau et al, 2006), Melcher et al (2013) demonstrated that this effect could be due to differences in hearing thresholds between subjects, irrespective of the presence or absence of tinnitus. Emotional disturbance generally refers to the " stress response, " which is a constellation of physiological events that occurs in response to some stress-inducing stimulus (Iversen et al, 2000). "
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    ABSTRACT: Background: The authors reviewed practicable options of sound therapy for tinnitus, the evidence base for each option, and the implications of each option for the patient and for clinical practice. Purpose: To provide a general guide to selecting sound therapy options in clinical practice. Intervention: Practicable sound therapy options. Data Collection and Analysis: Where available, peer-reviewed empirical studies, conference proceedings, and review studies were examined. Material relevant to the purpose was summarized in a narrative. Results: The number of peer-reviewed publications pertaining to each sound therapy option reviewed varied significantly (from none to over 10). Overall there is currently insufficient evidence to support or refute the routine use of individual sound therapy options. It is likely, however, that sound therapy combined with education and counseling is generally helpful to patients. Conclusions: Clinicians need to be guided by the patient's point of care, patient motivation and expectations of sound therapy, and the acceptability of the intervention both in terms of the sound stimuli they are to use and whether they are willing to use sound extensively or intermittently. Clinicians should also clarify to patients the role sound therapy is expected to play in the management plan.
    03/2014; 25(1):62-75. DOI:10.3766/jaaa.25.1.5
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