An fMRI-study on single-sided deafness: Spectral-temporal properties and side of stimulation modulates hemispheric dominance
AuthorHeggdal, Peder Olaf Laugen; Aarstad, Hans Jørgen; Brännström, Jonas; Vassbotn, Flemming; Specht, Karsten
Design: Patients with left- and right single-sided deafness and controls with normal hearing receiving either binaural or monaural stimuli were tested using speech and non-speech auditory stimuli in an event-related fMRI experiment.
Study sample: Twenty-two patients with single-sided deafness after treatment for vestibular schwannoma and 50 normal hearing controls.
Results: Normal hearing persons receiving right side monaural stimuli activate bilateral temporal regions. Activation following left side monaural stimulation is more right lateralized. Persons with single-sided deafness respond similarly to controls to monaural stimulation. Persons with right side single-sided deafness show activation of frontal cortical regions not seen in persons with left side single-sided deafness following speech stimuli. This is possibly related to increased effort and more frequently reported problems with communication. Right side single-sided deafness is related to increased activation of areas usually related to processing of degraded input, including the thalamus.
Conclusion: Hemispheric dominance following monaural auditory stimulation is modulated by the spectral-temporal properties of the stimuli and by which ear is stimulated. Differences between patients with right- and left side deafness suggests that right side deafness is related to increased activation of areas involved in processing of degraded input.