Amyotrophic lateral sclerosis (ALS) is a progressive and intractable neurodegenerative disease of human motor system characterized by progressive muscular weakness and atrophy. A considerable body of research has demonstrated significant structural and functional abnormalities of the primary motor cortex in patients with ALS. In contrast, much less attention has been paid to the abnormalities of cerebellum in this disease. Using multimodal magnetic resonance imagining data of 60 patients with ALS and 60 healthy controls, we examined changes in gray matter volume (GMV), white matter (WM) fractional anisotropy (FA), and functional connectivity (FC) in patients with ALS. Compared with healthy controls, patients with ALS showed decreased GMV in the left precentral gyrus and increased GMV in bilateral cerebellum, decreased FA in the left corticospinal tract and body of corpus callosum, and decreased FC in multiple brain regions, involving bilateral postcentral gyrus, precentral gyrus and cerebellum anterior lobe, among others. Meanwhile, we found significant intermodal correlations among GMV of left precentral gyrus, FA of altered WM tracts, and FC of left precentral gyrus, and that WM microstructural alterations seem to play important roles in mediating the relationship between GMV and FC of the precentral gyrus, as well as the relationship between GMVs of the precentral gyrus and cerebellum. These findings provided evidence for the precentral degeneration and cerebellar compensation in ALS, and the involvement of WM alterations in mediating the relationship between pathologies of the primary motor cortex and cerebellum, which may contribute to a better understanding of the pathophysiology of ALS.

Objective:To investigate the cortical gyrification changes as well as their relationships with white matter (WM) microstructural abnormalities in the akinetic-rigid (AR) and tremor-dominant (TD) subtypes of Parkinson’s disease (PD).Methods:Sixty-four patients with the AR subtype, 26 patients with the TD subtype and 56 healthy controls (HCs) were included in this study. High-resolution T1-weighted and diffusion-weighted images were acquired for each participant. We computed local gyrification index (LGI) and fractional anisotropy (FA) to identify the cortical gyrification and WM microstructural changes in the AR and TD subtypes.Results:Compared with HCs, patients with the AR subtype showed decreased LGI in the precentral, postcentral, inferior and superior parietal, middle and superior frontal/temporal, anterior and posterior cingulate, orbitofrontal, supramarginal, precuneus, and some visual cortices, and decreased FA in the corticospinal tract, inferior and superior longitudinal fasciculus, inferior fronto-occipital fasciculus, forceps minor/major, and anterior thalamic radiation. Decreases in LGI and FA of the AR subtype were found to be tightly coupled. LGIs of the left inferior and middle frontal gyrus correlated with the mini-mental state examination and the Hoehn and Yahr scores of patients with the AR subtype. Patients with the TD subtype showed no significant change in the LGI and FA compared with patients with the AR subtype and HCs.Conclusions:Our results suggest that cortical gyrification changes in PD are motor phenotype-specific and are possibly mediated by the microstructural abnormalities of the underlying WM tracts.