The authors studied motor behavior and primary motor (M1) and somatosensory (S1) cortical representations of movement during hand motor skill acquisition over 3 weeks. During four functional MRI sessions 1 week apart, subjects performed simple movements of single fingers and wrist, and a sequential movement of the middle three fingers, contrasted with rest. Half of the subjects practiced the sequential movement, whereas the other half practiced a gross motor task (squeezing a sponge). In both groups, motor performance gradually improved both on the practiced sequence and also on unrelated tests of general hand performance. Similarly, gradual expansion of active M1 and S1 areas was observed with the practiced sequence and with the unpracticed single-finger and wrist movements. Motor practice enhanced overlaps and sharing of cortex (significantly more so in the fine-skill group), preserving somatotopy and the overall extent of the hand representations. Even a limited amount of practice on a complex task can thus lead to both specific and nonspecific improvements in behavior and to expansion of M1 and S1 movement representations. Finally, the extent of active M1 and S1 was significantly correlated with out-of-scanner performance on sequential finger movement and may reflect the current motor ability of the individual.
In dystonic and spastic movement disorders, however different in their pathophysiological mechanisms, a similar impairment of sensorimotor control with special emphasis on afferentation is assumed. Peripheral intervention on afferent inputs evokes plastic changes within the central sensorimotor system. Intramuscular application of botulinum toxin type A (BoNT-A) is a standard evidence-based treatment for both conditions. Apart from its peripheral action on muscle spindles, a growing body of evidence suggests that BoNT-A effects could also be mediated by changes at the central level including cerebral cortex. We review recent studies employing electrophysiology and neuroimaging to investigate how intramuscular application of BoNT-A influences cortical reorganization. Based on such data, BoNT-A becomes gradually accepted as a promising tool to correct the maladaptive plastic changes within the sensorimotor cortex. In summary, electrophysiology and especially neuroimaging studies with BoNT-A further our understanding of pathophysiology underlying dystonic and spastic movement disorders and may consequently help develop novel treatment strategies based on neural plasticity.
The objective of this paper was to analyze the temporal and spatial trends in annual and seasonal precipitation in Slovakia utilizing 487 gauging station data collected statewide in the period from 1981 to 2013. The nonparametric Mann–Kendall (MK) statistical test, which has been widely used to assess the significance of trends in hydrological time series, was applied to detect the significant trends. The Theil–Sen (TS) approach was applied to quantify the trend magnitude, and the Sequential Mann–Kendall (SQMK) test was used to detect abrupt temporal trend shifts. In general, precipitation data in the study area have not changed during the last 33 years, and there are no big gaps. However, predominantly increasing trends in precipitation time series were found at most of the gauging stations in Slovakia. The results corroborate previous climatic studies in the area of central Europe. In Slovakia, there is evidence of different rain distribution from the monthly point of view. Decreasing trends were detected in December in the northern part of Slovakia, while the central and southern parts revealed increasing trends. Most of the stations showed increasing summer precipitation trends, especially in July. It is expected that the findings of this comprehensive study of precipitation trends over Slovakia will produce more insights for the understanding of the regional hydrological behavior in Slovakia over the last several decades.
Background and purpose: Non‐myelopathic degenerative cervical spinal cord compression (NMDC) frequently occurs throughout aging and may progress to potentially irreversible degenerative cervical myelopathy (DCM). Whereas standard clinical magnetic resonance imaging (MRI) and electrophysiological measures assess compression severity and neurological dysfunction, respectively, underlying microstructural deficits still have to be established in NMDC and DCM patients. The study aims to establish tract‐specific diffusion MRI markers of electrophysiological deficits to predict the progression of asymptomatic NMDC to symptomatic DCM.Methods: High‐resolution 3 T diffusion MRI was acquired for 103 NMDC and 21 DCM patients compared to 60 healthy controls to reveal diffusion alterations and relationships between tract‐specific diffusion metrics and corresponding electrophysiological measures and compression severity. Relationship between the degree of DCM disability, assessed by the modified Japanese Orthopaedic Association scale, and tract‐specific microstructural changes in DCM patients was also explored.Results: The study identified diffusion‐derived abnormalities in the gray matter, dorsal and lateral tracts congruent with trans‐synaptic degeneration and demyelination in chronic degenerative spinal cord compression with more profound alterations in DCM than NMDC. Diffusion metrics were affected in the C3‐6 area as well as above the compression level at C3 with more profound rostral deficits in DCM than NMDC. Alterations in lateral motor and dorsal sensory tracts correlated with motor and sensory evoked potentials, respectively, whereas electromyography outcomes corresponded with gray matter microstructure. DCM disability corresponded with microstructure alteration in lateral columns.Conclusions: Outcomes imply the necessity of high‐resolution tract‐specific diffusion MRI for monitoring degenerative spinal pathology in longitudinal studies.
Diffusion magnetic resonance imaging (dMRI) proved promising in patients with non-myelopathic degenerative cervical cord compression (NMDCCC), i.e., without clinically manifested myelopathy. Aim of the study is to present a fast multi-shell HARDI-ZOOMit dMRI protocol and validate its usability to detect microstructural myelopathy in NMDCCC patients. In 7 young healthy volunteers, 13 age-comparable healthy controls, 18 patients with mild NMDCCC and 15 patients with severe NMDCCC, the protocol provided higher signal-to-noise ratio, enhanced visualization of white/gray matter structures in microstructural maps, improved dMRI metric reproducibility, preserved sensitivity (SE = 87.88%) and increased specificity (SP = 92.31%) of control-patient group differences when compared to DTI-RESOLVE protocol (SE = 87.88%, SP = 76.92%). Of the 56 tested microstructural parameters, HARDI-ZOOMit yielded significant patient-control differences in 19 parameters, whereas in DTI-RESOLVE data, differences were observed in 10 parameters, with mostly lower robustness. Novel marker the white-gray matter diffusivity gradient demonstrated the highest separation. HARDI-ZOOMit protocol detected larger number of crossing fibers (5–15% of voxels) with physiologically plausible orientations than DTI-RESOLVE protocol (0–8% of voxels). Crossings were detected in areas of dorsal horns and anterior white commissure. HARDI-ZOOMit protocol proved to be a sensitive and practical tool for clinical quantitative spinal cord imaging.