Emotional processing in tinnitus
Specific aims
In the current study we plan to analyze emotional processing and its relationship to severity of and interference by tinnitus in subacute and chronic tinnitus sufferers. An analysis of the current literature revealed that the topic has so far not been addressed although all current models on the development of tinnitus emphasize the role of emotional processing. We plan to compare the affective processing of positive, negative and neutral visual material of tinnitus sufferers and controls with respect to subjective ratings, peripheral physiological measures and cerebral activation as assessed by functional magnetic resonance imaging and electroencephalography. We hope to learn from this study
a) if emotional processing is altered in tinnitus sufferers,
b) if it affects tinnitus severity and interference,
c) if potentially elevated emotional processing occurs early on or as a long-term consequence of tinnitus and
d) which brain regions mediate this response.
Background
Current models of tinnitus such as the model of Jastreboff (e.g. Jastreboff, 1990) emphasize that a core feature of tinnitus is enhanced emotional and autonomic responding. There is, however, little research that has examined affective components of tinnitus. The available literature has focused on the determination of associated depressive symptoms which seem to be a frequent sequel of tinnitus (e.g. Katon et al., 1993; Sullivan et al., 1988; Tyler & Baker, 1983). In addition, a PET study of tinnitus sufferers’ response to tinnitus-like sounds revealed significant activation in limbic structures (e.g. Mirz et al., 2000). None of these studies has, however, determined to what extent emotional material that is independent of the tinnitus experience is processed differently in people with tinnitus. In this study we use pictures with varying emotional content of a series developed by Lang et al. (1990) to study emotional processing, called the International Affective Picture System IAPS. Lang et al. have provided subjective rating, physiological and imaging baseline data on large samples of healthy controls that can be used as a baseline for the tinnitus group.
Pilotstudies and preliminary results
The designs implemented here are standard designs used in research on emotion and have been tested by us in both healthy controls (e.g. Flor et al., 1996; Hermann et al., 2000) and various patient groups such as social phobia and psychopathy (Birbaumer et al., 1998; Flor et al., in press).
We also have already examined brain regions involved in the cortical reorganization in tinnitus sufferers. We have analyzed the tonotopic map in auditory cortex and found an alteration of the tonotopic map in tinnitus patients (Mühlnickel et al., 1998).
Research plan
We plan to test 16 persons with a duration of tinnitus of less than 3 months, 16 persons with a duration of tinnitus of more than 2 years and 16 healthy controls matched on age and gender. The patients’ tinnitus will be characterized by standard audiological testing performed in cooperation with the Ear,-Nose- and Throat Clinic and the patients will undergo additional testing to determine the type of tinnitus at our psychophysiological laboratory. Testing will include various psychometric instruments like the Symptom Checklist 90-R (german version, Franke, 1995) as well as a standardized tinnitus interview and questionnaire (Göbel, 1994). The patients will take part in two assessment with an inbetween interval of one week. In one session the EEG will be recorded from 32 sites. In addition, heart rate, skin conductance, corrugator electromyograms and the startle response to a mild noise (95 db) will be recorded. These assessments will be made while the subjects watch neutral, negative and positive slides from the International Affective Picture System (see Lang et al., 1990). The slides will be presented in random order for 6 seconds each and they will be separated by a 15-19 second interstimulus interval. In addition, the subjects will rate the affective valence (positive - negative) and the arousal (aroused – calm) of the slides. We expect to find differences between the tinnitus sufferers and healthy controls if the models on emotional involvement are right. The EEG will give us information on the type of information processing used by the patients compared to the controls.
In another session the tinnitus sufferers and controls will participate in a functional magnetic resonance imaging study where they will view a different set of neutral, positive and negative slides from the same picture system. A design will be used with about the same time frame as in the psychophysiological study. The use of the fMRI permits the analysis of brain regions that are active during affective processing in the tinnitus patients and the healthy controls.
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