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Disturbances in the default mode network (DMN) have been described in many neurological and psychiatric disorders including Parkinson's disease (PD). The DMN is characterized by basal activity that increases during rest or passive visual fixation and decreases ("deactivates") during cognitive tasks. The network is believed to be involved in cognitive processes. We examined the DMN in PD patients on dopaminergic medication with normal cognitive performance compared to age- and gender-matched healthy controls (HC) using fMRI and three methodological procedures: independent component analysis of resting-state data, analysis of deactivation during a complex visual scene-encoding task, and seed-based functional connectivity analysis. In the PD group, we also studied the effect of dopaminergic medication on the DMN integrity. We did not find any difference between the PD and HC groups in the DMN, but using the daily levodopa equivalent dose as a covariate, we observed an enhanced functional connectivity of the DMN in the posterior cingulate cortex and decreased activation in the left parahippocampal gyrus during the cognitive task. We conclude that dopaminergic therapy has a specific effect on both the DMN integrity and task-related brain activations in cognitively unimpaired PD patients, and these effects seem to be dose-dependent.

This promotes the view that dystonia results from miscommunication between the basal ganglia and cerebellar loops, thus providing new insights into the brain regions essential for the development of cervical dystonia. © 2017 International Parkinson and Movement Disorder Society.

SUMMARYPurpose: To determine whether changes in gray matter volume (GMV) differ according to the affected side in mesial temporal lobe epilepsy/hippocampal sclerosis (MTLE/HS) syndrome, and moreover to test the hypothesis of more pronounced structural changes in right-sided MTLE/HS. This hypothesis (especially that the contralateral thalamus is more affected in right-sided MTLE/HS) arose from the results of our recent study, wherein more expressed structural and functional changes were observed in a small sample of patients with right-sided MTLE/HS (Brázdil et al., 2009). Methods: Twenty patients with left-sided and 20 with right-sided MTLE/HS and 40 sex-and age-matched healthy controls were included in the study. Voxel-based morphometry (VBM) with a modulation step was applied to magnetic resonance imaging (MRI) brain images. Statistical parametric maps were used to compare structural changes between patients and controls separately for the left-and right-sided MTLE/HS subgroups. We also compared the local GMV of the brain structures (insula and thalamus) between the subgroups of patients. Results: In the subgroup with right-sided MTLE/HS, a reduction of GMV was detected in the mesiotemporal structures and the ipsilateral thalamus (as in left-sided MTLE/HS), but also notably in the ipsilateral insula and contralateral thalamus. A statistical analysis revealed a significantly more extensive reduction of GMV in the ipsilateral/contralateral insula and the contralateral thalaus in the subgroup with right-sided compared to leftsided MTLE/HS. Conclusion: We found asymmetrical morphologic changes in patients with left-and right-sided MTLE/HS syndrome (more pronounced in right-sided MTLE/HS). These differences could be theoretically explained by different neuronal networks and pathophysiologic changes in temporolimbic structures. KEY WORDS: Hippocampal sclerosis, Insula, Mesial temporal lobe epilepsy, Thalamus.Mesial temporal lobe epilepsy (MTLE) is one of the most frequent forms of localization-related epilepsy and the most common human intractable epilepsy. The most common pathologic correlate of MTLE is hippocampal sclerosis (HS), which is histopathologically characterized by gliosis and neuronal loss.Recent studies in patients with MTLE/HS repeatedly revealed structural and functional abnormalities in regions other than the hippocampus. Changes in volume and concentration (gray and white matter) as well as functional changes [electroencephalography (EEG), magnetic resonance spectroscopy (MRS), positron emission tomography (PET), and single photon emission computed tomography (SPECT) studies] were repeatedly shown extending to other brain regions surrounding the hippocampus (the parahippocampal gyrus and the amygdala) and other distant structures (several neocortical regions, the thalamus, the striatal nuclei, the cerebellum, the internal capsule, and the brainstem). The abnormalities were found mainly ipsilateral to the side of the epileptic focus, as described in previous studies (Henry et al

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rTMS enhanced cognitive functions in MCI/AD patients. We demonstrated for the first time that distinct pattern of GM atrophy in MCI/AD diminishes the cognitive effects induced by rTMS of the temporal neocortex.

BackgroundCortical changes associated with cognitive decline in Parkinson's disease (PD) are not fully explored and require investigations with established diagnostic classification criteria.ObjectiveWe used MRI source-based morphometry to evaluate specific differences in grey matter volume patterns across 4 groups of subjects: healthy controls (HC), PD with normal cognition (PD-NC), PD with mild cognitive impairment (MCI-PD) and PD with dementia (PDD).MethodsWe examined 151 consecutive subjects: 25 HC, 75 PD-NC, 29 MCI-PD, and 22 PDD at an Italian and Czech movement disorder centre. Operational diagnostic criteria were applied to classify MCI-PD and PDD. All structural MRI images were processed together in the Czech centre. The spatial independent component analysis was used to assess group differences of local grey matter volume.ResultsWe identified two independent patterns of grey matter volume deviations: a) Reductions in the hippocampus and temporal lobes; b) Decreases in fronto-parietal regions and increases in the midbrain/cerebellum. Both patterns differentiated PDD from all other groups and correlated with visuospatial deficits and letter verbal fluency, respectively. Only the second pattern additionally differentiated PD-NC from HC.ConclusionGrey matter changes in PDD involve areas associated with Alzheimer-like pathology while fronto-parietal abnormalities are possibly an early marker of PD cognitive decline. These findings are consistent with a non-linear cognitive progression in PD.