Dynamic and static spontaneous activity alterations and neurotransmitter coupling in chronic tinnitus

This study combined static and dynamic amplitude of low-frequency fluctuation (sALFF and dALFF) to investigate the abnormalities of local spontaneous brain activity in patients with chronic tinnitus and their relationships with the spatial distributions of multiple neurotransmitters, thereby providing a theoretical basis for understanding the neural mechanisms underlying chronic tinnitus.

This study included 80 patients with chronic tinnitus and 68 healthy controls. Resting-state functional magnetic resonance imaging (rs-fMRI) data were used to calculate sALFF and dALFF metrics in both groups, and between-group differences were subsequently compared. Furthermore, the relationships between ALFF alterations and neurotransmitter distributions in patients with chronic tinnitus were analyzed.

Compared with the healthy control group, the sALFF value in the left superior temporal gyrus of patients with chronic tinnitus was significantly increased, and the dALFF value in the right precuneus was significantly decreased (GRF correction, voxel level P<0.001, cluster level P<0.05). Moreover, the alterations of sALFF correlated with the spatial distribution of serotonin transporter, dopamine, glutamate systems, and GABAergic, and the alterations of dALFF correlated with the spatial distribution of serotonin transporter, dopaminergic, and the vesicular acetylcholine transporter (VAChT).

Chronic tinnitus exhibits not only abnormalities in sALFF, but also aberrant dynamic temporal fluctuations, which spatially correlate with the distribution patterns of different neurotransmitter systems, thereby deepening the understanding of the neural mechanisms underlying chronic tinnitus.