OBJECTIVES: Although white matter hyperintensities (WMHs) are quite commonly found incidentally, their aetiology, structural characteristics, and functional consequences are not entirely known. The purpose of this study was to quantify WMHs in a sample of young, neurologically asymptomatic adults and evaluate the structural and functional correlations of lesion load with changes in brain volume, diffusivity, and functional connectivity. METHODS: MRI brain scan using multimodal protocol was performed in 60 neurologically asymptomatic volunteers (21 men, 39 women, mean age 34.5 years). WMHs were manually segmented in 3D FLAIR images and counted automatically. The number and volume of WMHs were correlated with brain volume, resting-state functional MRI (rs-fMRI), and diffusion tensor imaging (DTI) data. Diffusion parameters measured within WMHs and normally appearing white matter (NAWM) were compared. RESULTS: At least 1 lesion was found in 40 (67%) subjects, median incidence was 1 lesion (interquartile range [IQR] = 4.5), and median volume was 86.82 (IQR = 227.23) mm3. Neither number nor volume of WMHs correlated significantly with total brain volume or volumes of white and grey matter. Mean diffusivity values within WMHs were significantly higher compared with those for NAWM, but none of the diffusion parameters of NAWM were significantly correlated with WMH load. Both the number and volume of WMHs were correlated with the changes of functional connectivity between several regions of the brain, mostly decreased connectivity of the cerebellum. CONCLUSIONS: WMHs are commonly found even in young, neurologically asymptomatic adults. Their presence is not associated with brain atrophy or global changes of diffusivity, but the increasing number and volume of these lesions correlate with changes of brain connectivity, and especially that of the cerebellum. KEY POINTS: • White matter hyperintensities (WMHs) are commonly found in young, neurologically asymptomatic adults. • The presence of WMHs is not associated with brain atrophy or global changes of white matter diffusivity. • The increasing number and volume of WMHs correlate with changes of brain connectivity, and especially with that of the cerebellum.

• Klíčová slova
• Diffusion tensor imaging, Functional magnetic resonance imaging, Healthy volunteers, White matter,
• MeSH
• asymptomatické nemoci MeSH
• bílá hmota patologie   MeSH
• difuzní magnetická rezonance metody   MeSH
• dospělí MeSH
• leukoaraióza diagnóza   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• šedá hmota patologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Jan. Evangelista Purkyně, the most famous among Czech physiologists, was the first who identified and described the largest nerve cells in the cerebellum. The most distinguished researchers of the nervous system then recommended naming these neurons Purkinje cells in his honor. Through experiments by Purkinje and his followers, the function of the cerebellum was properly attributed to the precision of motor movements and skills. This traditional concept was valid until early 1990s, when it was readjusted and replenished with new and important findings. It was discovered that the cerebellar cortex contains more neurons than the cerebral cortex and shortly thereafter was gradually revealed that such enormous numbers of neural cells are not without impact on brain functions. It was shown that the cerebellum, in addition to its traditional role, also participates in higher nervous activity. These new findings were obtained thanks to the introduction of modern methods of examination into the clinical praxis, and experimental procedures using animal models of cerebellar disorders described in this work.

• Klíčová slova
• Animal models, Ataxia, Cerebellar degeneration, Cerebellum, Neurodegeneration, Purkinje cells, SCA models,
• MeSH
• kůra mozečku patofyziologie   MeSH
• lidé MeSH
• modely u zvířat MeSH
• mozeček patofyziologie   MeSH
• nemoci mozečku patofyziologie   MeSH
• Purkyňovy buňky fyziologie   MeSH
• výzkum * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH