Quantitative MRI of skeletal muscle in a cross-sectional cohort of patients with spinal muscular atrophy types 2 and 3

The aim of this study was to document upper leg involvement in spinal muscular atrophy (SMA) with quantitative MRI (qMRI) in a cross-sectional cohort of patients of varying type, disease severity and age. Thirty-one patients with SMA types 2 and 3 (aged 29.6 [7.6-73.9] years) and 20 healthy controls (aged 37.9 [17.7-71.6] years) were evaluated in a 3 T MRI with a protocol consisting of DIXON, T2 mapping and diffusion tensor imaging (DTI). qMRI measures were compared with clinical scores of motor function (Hammersmith Functional Motor Scale Expanded [HFMSE]) and muscle strength. Patients exhibited an increased fat fraction and fractional anisotropy (FA), and decreased mean diffusivity (MD) and T2 compared with controls (all P < .001). DTI parameters FA and MD manifest stronger effects than can be accounted for the effect of fatty replacement. Fat fraction, FA and MD show moderate correlation with muscle strength and motor function: FA is negatively associated with HFMSE and Medical Research Council sum score (τ = -0.56 and -0.59; both P < .001) whereas for fat fraction values are τ = -0.50 and -0.58, respectively (both P < .001). This study shows that DTI parameters correlate with muscle strength and motor function. DTI findings indirectly indicate cell atrophy and act as a measure independently of fat fraction. Combined these data suggest the potential of muscle DTI in monitoring disease progression and to study SMA pathogenesis in muscle

Juggling revisited — A voxel–based morphometry study with expert jugglers

Juggling is a highly interesting tool to investigate neuroplasticity associated with motor-learning. Several brain-imaging studies have reported changes in regional brain morphology in visual association cortices in individuals learning how to juggle a three-ball cascade. However, to our knowledge there are no studies that investigated expert jugglers, looking for specific features in regional brain morphology related to this highly specialized skill. Using T1-weighted images and voxel-based morphometry we investigated in a cross-sectional study design 16 expert jugglers, able to juggle at least five balls and an age- and gender-matched group of non-jugglers. We hypothesized that expert jugglers would show higher gray matter density in regions involved in visual motion perception and eye-hand coordination. Images were pre-processed and analyzed using SPM8. Age was included in the analyses as covariate of no interest. As compared to controls jugglers displayed several clusters of higher, regional gray matter density in the occipital and parietal lobes including the secondary visual cortex, the hMT +/V5 area bilaterally and the intraparietal sulcus bilaterally. Within the jugglers group we also found a correlation between performance and regional gray matter density in the right hMT +/V5 area. Our study provides evidence that expert jugglers show increased gray matter density in brain regions involved in visual motion perception and eye–hand coordination, i.e. brain areas that have previously been shown to undergo dynamic changes in terms of gray matter increases in subjects learning a basic three-ball cascade. The extent to which transient increases in beginners and the differences in experts and non-experts are based on the same neurobiological correlates remains to be fully elucidated