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Abnormal auditory mismatch response in tinnitus sufferers with high-frequency hearing loss is associated with subjective distress level.

Weisz N, Voss S, Berg P, Elbert T - BMC Neurosci (2004)

Bottom Line: The finding of lesion-edge specific effects and associations with slope of hearing loss corroborates the assumption that hearing loss is the basis for tinnitus development.It is likely that some central reorganization follow a damage to hearing receptors, even though the paradoxical results indicate that they most likely are somewhat different than originally assumed (see Background).A better comprehension of the exact mechanisms leading to the present results could have a broad impact on the understanding and perhaps treatment of tinnitus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Psychology, University of Konstanz, Konstanz, Germany. Nathan.Weisz@uni-konstanz.de

ABSTRACT

Background: Tinnitus is an auditory sensation frequently following hearing loss. After cochlear injury, deafferented neurons become sensitive to neighbouring intact edge-frequencies, guiding an enhanced central representation of these frequencies. As psychoacoustical data 123 indicate enhanced frequency discrimination ability for edge-frequencies that may be related to a reorganization within the auditory cortex, the aim of the present study was twofold: 1) to search for abnormal auditory mismatch responses in tinnitus sufferers and 2) relate these to subjective indicators of tinnitus.

Results: Using EEG-mismatch negativity, we demonstrate abnormalities (N = 15) in tinnitus sufferers that are specific to frequencies located at the audiometrically normal lesion-edge as compared to normal hearing controls (N = 15). Groups also differed with respect to the cortical locations of mismatch responsiveness. Sources in the 90-135 ms latency window were generated in more anterior brain regions in the tinnitus group. Both measures of abnormality correlated with emotional-cognitive distress related to tinnitus (r approximately .76). While these two physiological variables were uncorrelated in the control group, they were correlated in the tinnitus group (r =.72). Concerning relationships with parameters of hearing loss (depth and slope), slope turned out to be an important variable. Generally, the steeper the hearing loss is the less distress related to tinnitus was reported. The associations between slope and the relevant neurophysiological variables are in agreement with this finding.

Conclusions: The present study is the first to show near-to-complete separation of tinnitus sufferers from a normal hearing control group based on neurophysiological variables. The finding of lesion-edge specific effects and associations with slope of hearing loss corroborates the assumption that hearing loss is the basis for tinnitus development. It is likely that some central reorganization follow a damage to hearing receptors, even though the paradoxical results indicate that they most likely are somewhat different than originally assumed (see Background). One partial explanation might lie in the involvement of top-down (presumably frontal-lobe) controlled processes. A better comprehension of the exact mechanisms leading to the present results could have a broad impact on the understanding and perhaps treatment of tinnitus.

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Upper panel: The minimum-norm solution for the difference between the Grand Means of the tinnitus and the control groups indicates a greater prefrontal activity (dark shading) in tinnitus patients following auditory stimulation. The darkest shading corresponds to 100% of the maximum activation (the ligther, the stronger the decrease relative to the maximum). This exploratory analysis was the basis for the post-hoc notion that the source localization in the anterior-posterior direction may be associated with prefrontal activity. Lower Panel: Correlating relative frontal activity (as compared to temporal sources) of each individual with the source location of the regional source results in a quadratic trend that is more pronounced for the right hemisphere.
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Figure 3: Upper panel: The minimum-norm solution for the difference between the Grand Means of the tinnitus and the control groups indicates a greater prefrontal activity (dark shading) in tinnitus patients following auditory stimulation. The darkest shading corresponds to 100% of the maximum activation (the ligther, the stronger the decrease relative to the maximum). This exploratory analysis was the basis for the post-hoc notion that the source localization in the anterior-posterior direction may be associated with prefrontal activity. Lower Panel: Correlating relative frontal activity (as compared to temporal sources) of each individual with the source location of the regional source results in a quadratic trend that is more pronounced for the right hemisphere.

Mentions: We also examined the possibility that the anterior shift of source localization and its considerable variability may be caused by an enhanced frontal activation, relative to the expected temporal activation. This was suggested by the difference in the source distribution between controls and tinnitus subjects using Minimum Norm solution (see Methods), as shown in Figure 3 for the 112 ms latency (maximum difference; upper panel). The results (see Figure 3 lower panel) suggest that a linear relationship exists between the two variables for the majority of cases. However, there is a subset of four patients with the most posterior source localizations. These patients exhibit strong frontal activation, thus causing the overall association to be quadratic. This relationship is statistically significant for the right hemisphere only (F2,14 = 6.32, p < 02). Interestingly, these four patients are exactly the ones who reported the lowest distress values (see Figure 2a).


Abnormal auditory mismatch response in tinnitus sufferers with high-frequency hearing loss is associated with subjective distress level.

Weisz N, Voss S, Berg P, Elbert T - BMC Neurosci (2004)

Upper panel: The minimum-norm solution for the difference between the Grand Means of the tinnitus and the control groups indicates a greater prefrontal activity (dark shading) in tinnitus patients following auditory stimulation. The darkest shading corresponds to 100% of the maximum activation (the ligther, the stronger the decrease relative to the maximum). This exploratory analysis was the basis for the post-hoc notion that the source localization in the anterior-posterior direction may be associated with prefrontal activity. Lower Panel: Correlating relative frontal activity (as compared to temporal sources) of each individual with the source location of the regional source results in a quadratic trend that is more pronounced for the right hemisphere.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC394322&req=5

Figure 3: Upper panel: The minimum-norm solution for the difference between the Grand Means of the tinnitus and the control groups indicates a greater prefrontal activity (dark shading) in tinnitus patients following auditory stimulation. The darkest shading corresponds to 100% of the maximum activation (the ligther, the stronger the decrease relative to the maximum). This exploratory analysis was the basis for the post-hoc notion that the source localization in the anterior-posterior direction may be associated with prefrontal activity. Lower Panel: Correlating relative frontal activity (as compared to temporal sources) of each individual with the source location of the regional source results in a quadratic trend that is more pronounced for the right hemisphere.
Mentions: We also examined the possibility that the anterior shift of source localization and its considerable variability may be caused by an enhanced frontal activation, relative to the expected temporal activation. This was suggested by the difference in the source distribution between controls and tinnitus subjects using Minimum Norm solution (see Methods), as shown in Figure 3 for the 112 ms latency (maximum difference; upper panel). The results (see Figure 3 lower panel) suggest that a linear relationship exists between the two variables for the majority of cases. However, there is a subset of four patients with the most posterior source localizations. These patients exhibit strong frontal activation, thus causing the overall association to be quadratic. This relationship is statistically significant for the right hemisphere only (F2,14 = 6.32, p < 02). Interestingly, these four patients are exactly the ones who reported the lowest distress values (see Figure 2a).

Bottom Line: The finding of lesion-edge specific effects and associations with slope of hearing loss corroborates the assumption that hearing loss is the basis for tinnitus development.It is likely that some central reorganization follow a damage to hearing receptors, even though the paradoxical results indicate that they most likely are somewhat different than originally assumed (see Background).A better comprehension of the exact mechanisms leading to the present results could have a broad impact on the understanding and perhaps treatment of tinnitus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Psychology, University of Konstanz, Konstanz, Germany. Nathan.Weisz@uni-konstanz.de

ABSTRACT

Background: Tinnitus is an auditory sensation frequently following hearing loss. After cochlear injury, deafferented neurons become sensitive to neighbouring intact edge-frequencies, guiding an enhanced central representation of these frequencies. As psychoacoustical data 123 indicate enhanced frequency discrimination ability for edge-frequencies that may be related to a reorganization within the auditory cortex, the aim of the present study was twofold: 1) to search for abnormal auditory mismatch responses in tinnitus sufferers and 2) relate these to subjective indicators of tinnitus.

Results: Using EEG-mismatch negativity, we demonstrate abnormalities (N = 15) in tinnitus sufferers that are specific to frequencies located at the audiometrically normal lesion-edge as compared to normal hearing controls (N = 15). Groups also differed with respect to the cortical locations of mismatch responsiveness. Sources in the 90-135 ms latency window were generated in more anterior brain regions in the tinnitus group. Both measures of abnormality correlated with emotional-cognitive distress related to tinnitus (r approximately .76). While these two physiological variables were uncorrelated in the control group, they were correlated in the tinnitus group (r =.72). Concerning relationships with parameters of hearing loss (depth and slope), slope turned out to be an important variable. Generally, the steeper the hearing loss is the less distress related to tinnitus was reported. The associations between slope and the relevant neurophysiological variables are in agreement with this finding.

Conclusions: The present study is the first to show near-to-complete separation of tinnitus sufferers from a normal hearing control group based on neurophysiological variables. The finding of lesion-edge specific effects and associations with slope of hearing loss corroborates the assumption that hearing loss is the basis for tinnitus development. It is likely that some central reorganization follow a damage to hearing receptors, even though the paradoxical results indicate that they most likely are somewhat different than originally assumed (see Background). One partial explanation might lie in the involvement of top-down (presumably frontal-lobe) controlled processes. A better comprehension of the exact mechanisms leading to the present results could have a broad impact on the understanding and perhaps treatment of tinnitus.

Show MeSH
Related in: MedlinePlus