Functional and structural connectivity of thalamic subnuclei in major depressive disorder at 7 Tesla

AIMS: Major depressive disorder (MDD) is widely considered to be a mood disorder characterized by altered connectivity. The thalamus plays an important role in MDD by connecting large areas of the brain. Here, we explored thalamic connectivity in MDD at the subnuclear level using ultra-high-field MRI.

METHODS: We combined ultra-high-field functional and diffusion MRI at 7.0 Tesla to map the connectivity of thalamic subnuclei in MDD patients (n = 47) and healthy controls (n = 13). We segmented thalamic subnuclei and calculated the functional and structural connectivity of thalamic subnuclei and tested for group differences and associations with clinical characteristics.

RESULTS: MDD patients showed increased functional connectivity of the right thalamic central lateral nucleus with the right amygdala, bilateral inferior occipital lobe, and right transverse temporal gyrus, which was accompanied by increased structural connectivity between the right thalamic central lateral nucleus and the right inferior occipital lobe. Medicated MDD patients had a greater streamline count of the right thalamic central lateral nucleus-right inferior occipital lobe tract than healthy controls.

CONCLUSIONS: Thalamic subnuclear connectivity with cortical and subcortical brain regions is perturbed in MDD. These results further support increased thalamic connectivity in MDD and suggest that this is related to a specific subnucleus.