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Transient reduction of tinnitus intensity is marked by concomitant reductions of delta band power.

Kahlbrock N, Weisz N - BMC Biol. (2008)

Bottom Line: Previous research found altered patterns of spontaneous brain activity in chronic tinnitus sufferers compared to healthy controls, yet it is unknown whether these abnormal oscillatory patterns are causally related to the tinnitus sensation.A significant reduction of power in the delta (1.3-4.0 Hz) frequency band was observed in temporal regions during RI (p </= 0.001).The current results suggest that changes of tinnitus intensity induced by RI are mediated by alterations in the pathological patterns of spontaneous brain activity, specifically a reduction of delta activity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Psychology, University of Konstanz, Konstanz, Germany. Nina@Kahlbrock.org

ABSTRACT

Background: Tinnitus is an auditory phantom phenomenon characterized by the sensation of sounds without objectively identifiable sound sources. To date, its causes are not well understood. Previous research found altered patterns of spontaneous brain activity in chronic tinnitus sufferers compared to healthy controls, yet it is unknown whether these abnormal oscillatory patterns are causally related to the tinnitus sensation. Partial support for this notion comes from a neurofeedback approach developed by our group, in which significant reductions in tinnitus loudness could be achieved in patients who successfully normalized their patterns of spontaneous brain activity. The current work attempts to complement these studies by scrutinizing how modulations of tinnitus intensity alter ongoing oscillatory activity.

Results: In the present study the relation between tinnitus sensation and spontaneous brain activity was investigated using residual inhibition (RI) to reduce tinnitus intensity and source-space projected magnetencephalographic (MEG) data to index brain activity. RI is the sustained reduction (criteria: 50% for at least 30 s) in tinnitus loudness after cessation of a tonal tinnitus masker. A pilot study (n = 38) identified 10 patients who showed RI. A significant reduction of power in the delta (1.3-4.0 Hz) frequency band was observed in temporal regions during RI (p

Conclusion: The current results suggest that changes of tinnitus intensity induced by RI are mediated by alterations in the pathological patterns of spontaneous brain activity, specifically a reduction of delta activity. Delta activity is a characteristic oscillatory activity generated by deafferented/deprived neuronal networks. This implies that RI effects might reflect the transient reestablishment of balance between excitatory and inhibitory neuronal assemblies, via reafferentation, that have been perturbed (in most tinnitus individuals) by hearing damage. As enhancements have been reported in the delta frequency band for tinnitus at rest, this result conforms to our assumption that a normalization of oscillatory properties of cortical networks is a prerequisite for attenuating the tinnitus sensation. For RI to have therapeutic significance however, this normalization would have to be stabilized.

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Delta band activity at temporal sources pre- and post-stimulation. Normalized amplitude of delta brain activity pre- and post-stimulation for CO and RI condition separately. Each line represents a single subject. The thick grey lines indicate the mean delta band activities over all subjects.
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Figure 3: Delta band activity at temporal sources pre- and post-stimulation. Normalized amplitude of delta brain activity pre- and post-stimulation for CO and RI condition separately. Each line represents a single subject. The thick grey lines indicate the mean delta band activities over all subjects.

Mentions: A condition × time × frequency interaction approached significance (F (3, 21) = 2.926, p = 0.058). As this interaction was in accordance with our hypotheses, further analyses were conducted. In the delta frequency band, an interaction of condition and time was found to approach significance (F (1, 7) = 3.803, p = 0.092). Additionally, a main effect for time could be observed (F (1, 7) = 25.417, p = 0.001). This leads to the assumption that the amplitude of the slow frequency range differed from pre to post but not equally for the conditions. We followed up this question by a planned comparison between pre and post separately for RI and CO conditions in the delta band in temporal regions. A highly significant (t (7) = 6.102, p ≤ 0.001) reduction of delta power was observed for RI, however not for CO (t (7) = 1.731, p = 0.127). Thus, changes in delta can be seen to be specific for the RI condition (Figure 3).


Transient reduction of tinnitus intensity is marked by concomitant reductions of delta band power.

Kahlbrock N, Weisz N - BMC Biol. (2008)

Delta band activity at temporal sources pre- and post-stimulation. Normalized amplitude of delta brain activity pre- and post-stimulation for CO and RI condition separately. Each line represents a single subject. The thick grey lines indicate the mean delta band activities over all subjects.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2254377&req=5

Figure 3: Delta band activity at temporal sources pre- and post-stimulation. Normalized amplitude of delta brain activity pre- and post-stimulation for CO and RI condition separately. Each line represents a single subject. The thick grey lines indicate the mean delta band activities over all subjects.
Mentions: A condition × time × frequency interaction approached significance (F (3, 21) = 2.926, p = 0.058). As this interaction was in accordance with our hypotheses, further analyses were conducted. In the delta frequency band, an interaction of condition and time was found to approach significance (F (1, 7) = 3.803, p = 0.092). Additionally, a main effect for time could be observed (F (1, 7) = 25.417, p = 0.001). This leads to the assumption that the amplitude of the slow frequency range differed from pre to post but not equally for the conditions. We followed up this question by a planned comparison between pre and post separately for RI and CO conditions in the delta band in temporal regions. A highly significant (t (7) = 6.102, p ≤ 0.001) reduction of delta power was observed for RI, however not for CO (t (7) = 1.731, p = 0.127). Thus, changes in delta can be seen to be specific for the RI condition (Figure 3).

Bottom Line: Previous research found altered patterns of spontaneous brain activity in chronic tinnitus sufferers compared to healthy controls, yet it is unknown whether these abnormal oscillatory patterns are causally related to the tinnitus sensation.A significant reduction of power in the delta (1.3-4.0 Hz) frequency band was observed in temporal regions during RI (p </= 0.001).The current results suggest that changes of tinnitus intensity induced by RI are mediated by alterations in the pathological patterns of spontaneous brain activity, specifically a reduction of delta activity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Psychology, University of Konstanz, Konstanz, Germany. Nina@Kahlbrock.org

ABSTRACT

Background: Tinnitus is an auditory phantom phenomenon characterized by the sensation of sounds without objectively identifiable sound sources. To date, its causes are not well understood. Previous research found altered patterns of spontaneous brain activity in chronic tinnitus sufferers compared to healthy controls, yet it is unknown whether these abnormal oscillatory patterns are causally related to the tinnitus sensation. Partial support for this notion comes from a neurofeedback approach developed by our group, in which significant reductions in tinnitus loudness could be achieved in patients who successfully normalized their patterns of spontaneous brain activity. The current work attempts to complement these studies by scrutinizing how modulations of tinnitus intensity alter ongoing oscillatory activity.

Results: In the present study the relation between tinnitus sensation and spontaneous brain activity was investigated using residual inhibition (RI) to reduce tinnitus intensity and source-space projected magnetencephalographic (MEG) data to index brain activity. RI is the sustained reduction (criteria: 50% for at least 30 s) in tinnitus loudness after cessation of a tonal tinnitus masker. A pilot study (n = 38) identified 10 patients who showed RI. A significant reduction of power in the delta (1.3-4.0 Hz) frequency band was observed in temporal regions during RI (p

Conclusion: The current results suggest that changes of tinnitus intensity induced by RI are mediated by alterations in the pathological patterns of spontaneous brain activity, specifically a reduction of delta activity. Delta activity is a characteristic oscillatory activity generated by deafferented/deprived neuronal networks. This implies that RI effects might reflect the transient reestablishment of balance between excitatory and inhibitory neuronal assemblies, via reafferentation, that have been perturbed (in most tinnitus individuals) by hearing damage. As enhancements have been reported in the delta frequency band for tinnitus at rest, this result conforms to our assumption that a normalization of oscillatory properties of cortical networks is a prerequisite for attenuating the tinnitus sensation. For RI to have therapeutic significance however, this normalization would have to be stabilized.

Show MeSH
Related in: MedlinePlus