Functional and structural alterations in the migraine cerebellum.

The cerebellum plays an important role in pain processing but its function in headache and specifically in migraine is not known. We therefore compared 54 migraineurs with pairwise matched healthy controls in a magnetic resonance imaging study on neuronal cerebellar activity in response to nociceptive trigeminal sensation and also investigated possible structural alterations. Headache frequency, disease duration, and the proximity to a migraine attack were used as co-factors. Migraine patients showed functional and structural alterations in the posterior part of the cerebellum, namely crus I and crus II. Gray matter volume changes were seen on the right side whereas functional changes were ipsilateral to the stimulation, on the left side. Neuronal activity in the crus in response to trigeminal pain was modulated by migraine severity and the migraine phase. As the crus is strongly interconnected to higher cognitive areas in the temporal, frontal, and parietal part of the cortex our results suggest an specific cerebellar involvement in migraine. This is further supported by our finding of decreased connectivity from the crus to the thalamus and higher cortical areas in the patients. We therefore suggest an abnormally decreased inhibitory involvement of the migraine cerebellum on gating and nociceptive evaluation.

Increased cerebellar-default-mode-network connectivity in drug-naive major depressive disorder at rest.

The default-mode network (DMN) has been implicated in the neurobiology of major depressive disorder (MDD), and the cerebellum is suggested to be involved in high-order cognitive network such as the DMN. However, the specific contribution of the cerebellum to the DMN alterations remains equivocal. This study was conducted to examine the cerebellar-DMN connectivity in drug-naive MDD directly by using the cerebellum Crus I as seeds.Forty-four drug-naive MDD patients and 44 healthy controls participated in the resting-state scan. Functional connectivity (FC) was applied to analyze the images.Significantly increased FCs were observed between the right Crus I and the right inferior frontal cortex (orbital part)/superior temporal pole, bilateral MPFC (orbital part), and left middle temporal gyrus in the patients compared with the controls. There was a significantly positive correlation between the z values of the right Crus I-bilateral MPFC (orbital part) connectivity and the scores of Automatic Thoughts Questionnaire in the patients (r = 0.329, P = 0.029).The findings reveal that depressed patients have increased cerebellar-DMN connectivity with clinical significance, and thus highlight the contribution of the cerebellum to the DMN alterations in neurobiology of MDD.