Altered networks in bothersome tinnitus: a functional connectivity study.
BACKGROUND
The objective was to examine functional connectivity linked to the auditory system in patients with bothersome tinnitus. Activity was low frequency (< 0.1 Hz), spontaneous blood oxygenation level-dependent (BOLD) responses at rest. The question was whether the experience of chronic bothersome tinnitus induced changes in synaptic efficacy between co-activated components. Functional connectivity for seed regions in auditory, visual, attention, and control networks was computed across all 2 mm(3) brain volumes in 17 patients with moderate-severe bothersome tinnitus (Tinnitus Handicap Index: average 53.5 ± 3.6 (range 38-76)) and 17 age-matched controls.


RESULTS
In bothersome tinnitus, negative correlations reciprocally characterized functional connectivity between auditory and occipital/visual cortex. Negative correlations indicate that when BOLD response magnitudes increased in auditory or visual cortex they decreased in the linked visual or auditory cortex, suggesting reciprocally phase reversed activity between functionally connected locations in tinnitus. Both groups showed similar connectivity with positive correlations within the auditory network. Connectivity for primary visual cortex in tinnitus included extensive negative correlations in the ventral attention temporoparietal junction and in the inferior frontal gyrus and rostral insula - executive control network components. Rostral insula and inferior frontal gyrus connectivity in tinnitus also showed greater negative correlations in occipital cortex.


CONCLUSIONS
These results imply that in bothersome tinnitus there is dissociation between activity in auditory cortex and visual, attention and control networks. The reciprocal negative correlations in connectivity between these networks might be maladaptive or reflect adaptations to reduce phantom noise salience and conflict with attention to non-auditory tasks.
Department of Anatomy & Neurobiology, Washington University School of Medicine, St, Louis, Missouri 63110, USA. harold@pcg.wustl.edu
Harold
H
Burton
Andre
A
Wineland
Mousumi
M
Bhattacharya
Joyce
J
Nicklaus
Keith S
KS
Garcia
Jay F
JF
Piccirillo
D000161:Acoustic Stimulation; D001931:Brain Mapping; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality; D019416:Head Movements; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000473:pathology*; D009434:Neural Pathways / Q000502:physiology; D013223:Statistics as Topic; D014012:Tinnitus / Q000473:pathology* / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation