Aging populations face significant cognitive challenges, particularly in working memory (WM). Transcranial alternating current stimulation (tACS) offer promising avenues for cognitive enhancement, especially when inspired by brain physiology. This study (NCT04986787) explores the effect of multifocal tACS on WM performance in healthy older adults, focusing on fronto-parietal network modulation. Individualized physiology-inspired tACS applied to the fronto-parietal network was investigated in two blinded cross-over experiments. The first experiment involved monofocal/bifocal theta-tACS to the fronto-parietal network, while in the second experiment cross-frequency theta-gamma interactions between these regions were explored. Participants have done online WM tasks under the stimulation conditions. Network connectivity was assessed via rs-fMRI and multichannel electroencephalography. Prefrontal monofocal theta tACS modestly improved WM accuracy over sham (d = 0.30). Fronto-parietal stimulation enhanced WM task processing speed, with the strongest effects for bifocal in-phase theta tACS (d = 0.41). Cross-frequency stimulations modestly boosted processing speed with or without impairing task accuracy depending on the stimulation protocol. This research adds to the understanding of physiology-inspired brain stimulation for cognitive enhancement in older subjects.

• Klíčová slova
• Cognition, Electric field modelling, Healthy aging, Multifocal, Neuroimaging, Orchestrated brain stimulation, Systems neuroscience, Working memory, tACS,
• Publikační typ
• časopisecké články MeSH

• MeSH
• Alzheimerova nemoc * terapie   MeSH
• kognitivní dysfunkce * terapie   etiologie   MeSH
• lidé MeSH
• přímá transkraniální stimulace mozku metody   MeSH
• transkraniální magnetická stimulace metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH
• zprávy MeSH

Transcranial direct current stimulation combined with cognitive training (tDCS-cog) represents a promising approach to combat cognitive decline among healthy older adults and patients with mild cognitive impairment (MCI). In this 5-day-long double-blinded randomized trial, we investigated the impact of intensified tDCS-cog protocol involving two trains of stimulation per day on working memory (WM) enhancement in 35 amnestic and multidomain amnestic MCI patients. Specifically, we focused to improve WM tasks relying on top-down attentional control and hypothesized that intensified tDCS would enhance performance of visual object matching task (VOMT) immediately after the stimulation regimen and at a 1-month follow-up. Secondarily, we explored whether the stimulation would augment online visual working memory training. Using fMRI, we aimed to elucidate the neural mechanisms underlying the intervention effects by analyzing BOLD activations during VOMT. Our main finding revealed no superior after-effects of tDCS-cog over the sham on VOMT among individuals with MCI as indicated by insignificant immediate and long-lasting after-effects. Additionally, the tDCS-cog did not enhance online training as predicted. The fMRI analysis revealed brain activity alterations in right insula that may be linked to tDCS-cog intervention. In the study we discuss the insignificant behavioral results in the context of the current evidence in tDCS parameter space and opening the discussion of possible interference between trained cognitive tasks.

• MeSH
• dorsolaterální prefrontální kortex MeSH
• dvojitá slepá metoda MeSH
• kognitivní dysfunkce * terapie   MeSH
• krátkodobá paměť fyziologie   MeSH
• lidé MeSH
• mozek diagnostické zobrazování   MeSH
• prefrontální mozková kůra fyziologie   MeSH
• přímá transkraniální stimulace mozku * metody   MeSH
• senioři MeSH
• Check Tag
• lidé MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• randomizované kontrolované studie MeSH

The vertex has been used as a suitable control stimulation site in repetitive transcranial magnetic stimulation studies. The objectives of this study are (1) to assess cognitive performance (CP) after theta burst stimulation (TBS); (2) to evaluate whether clinically relevant cortical areas might be reached by vertex stimulation and how that might influence CP. Twenty young healthy subjects performed a cognitive task prior to and immediately after intermittent TBS (iTBS) and continuous TBS (cTBS) of two active cortical stimulation sites and the vertex. We used the Wilcoxon signed-rank test to compare the pre- and post-stimulation reaction times (RTs) and a mixed ANOVA analysis to evaluate the effect of the stimulation on changes in RTs. A three-dimensional finite-element model (FEM) was used to calculate the vertex TBS-induced electrical field (E-field) in the adjacent regions of interest (ROIs). Correlation analyses were performed between E-fields in the ROIs and cognitive outcomes. We found a significant effect only of the stimulation time factor (F (1,12) = 65.37, p < 0.001) on RT shortening, with no superiority of the active site stimulation compared to the vertex stimulation. In 73.5% of vertex TBS sessions, a significant E-field was induced in at least one ROI. We found a negative association between the magnitude of the iTBS-induced E-fields and RT changes (R = - 0.54, p = 0.04). TBS protocols may lead to changes in CP when applied over the craniometrically targeted vertex. We therefore suggest not using a conventional approach as a vertex targeting method.

• Klíčová slova
• Cognitive, Control condition, SimNIBS, Transcranial magnetic stimulation, Vertex stimulation, rTMS,
• MeSH
• hlava * MeSH
• lidé MeSH
• reakční čas MeSH
• theta rytmus EEG MeSH
• transkraniální magnetická stimulace * metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Enhancing cognitive functions through noninvasive brain stimulation is of enormous public interest, particularly for the aging population in whom processes such as working memory are known to decline. In a randomized double-blind crossover study, we investigated the acute behavioral and neural aftereffects of bifrontal and frontoparietal transcranial direct current stimulation (tDCS) combined with visual working memory (VWM) training on 25 highly educated older adults. Resting-state functional connectivity (rs-FC) analysis was performed prior to and after each stimulation session with a focus on the frontoparietal control network (FPCN). The bifrontal montage with anode over the left dorsolateral prefrontal cortex enhanced VWM accuracy as compared to the sham stimulation. With the rs-FC within the FPCN, we observed significant stimulation × time interaction using bifrontal tDCS. We found no cognitive aftereffects of the frontoparietal tDCS compared to sham stimulation. Our study shows that a single bifrontal tDCS combined with cognitive training may enhance VWM performance and rs-FC within the relevant brain network even in highly educated older adults.

• MeSH
• čelní lalok MeSH
• dvojitá slepá metoda MeSH
• klinické křížové studie MeSH
• kognice * MeSH
• kognitivně behaviorální terapie metody   MeSH
• krátkodobá paměť MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• neuropsychologické testy MeSH
• prefrontální mozková kůra MeSH
• přímá transkraniální stimulace mozku metody   MeSH
• psychomotorický výkon MeSH
• senioři MeSH
• stupeň vzdělání MeSH
• temenní lalok MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• randomizované kontrolované studie MeSH

PURPOSE OF REVIEW: We summarize structural (s)MRI findings of gray matter (GM) atrophy related to cognitive impairment in Alzheimer's disease (AD) and Parkinson's disease (PD) in light of new analytical approaches and recent longitudinal studies results. RECENT FINDINGS: The hippocampus-to-cortex ratio seems to be the best sMRI biomarker to discriminate between various AD subtypes, following the spatial distribution of tau pathology, and predict rate of cognitive decline. PD is clinically far more variable than AD, with heterogeneous underlying brain pathology. Novel multivariate approaches have been used to describe patterns of early subcortical and cortical changes that relate to more malignant courses of PD. New emerging analytical approaches that combine structural MRI data with clinical and other biomarker outcomes hold promise for detecting specific GM changes in the early stages of PD and preclinical AD that may predict mild cognitive impairment and dementia conversion.

• Klíčová slova
• Alzheimer’s disease, Cognition, Gray matter atrophy, Parkinson’s disease, Structural magnetic resonance imaging,
• MeSH
• Alzheimerova nemoc patologie   psychologie   MeSH
• biologické markery MeSH
• kognice * MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• mozek patologie   MeSH
• Parkinsonova nemoc patologie   psychologie   MeSH
• šedá hmota patologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• biologické markery MeSH

To meet the need for Parkinson's disease biomarkers and evidence for amount and distribution of pathological changes, MRI diffusion tensor imaging (DTI) has been explored in a number of previous studies. However, conflicting results warrant further investigations. As tissue microstructure, particularly of the grey matter, is heterogeneous, a more precise diffusion model may benefit tissue characterization. The purpose of this study was to analyze the diffusion-based imaging technique restriction spectrum imaging (RSI) and DTI, and their ability to detect microstructural changes within brain regions associated with motor function in Parkinson's disease. Diffusion weighted (DW) MR images of a total of 100 individuals, (46 Parkinson's disease patients and 54 healthy controls) were collected using b-values of 0-4000s/mm2. Output diffusion-based maps were estimated based on the RSI-model combining the full set of DW-images (Cellular Index (CI), Neurite Density (ND)) and DTI-model combining b = 0 and b = 1000 s/mm2 (fractional anisotropy (FA), Axial-, Mean- and Radial diffusivity (AD, MD, RD)). All parametric maps were analyzed in a voxel-wise group analysis, with focus on typical brain regions associated with Parkinson's disease pathology. CI, ND and DTI diffusivity metrics (AD, MD, RD) demonstrated the ability to differentiate between groups, with strongest performance within the thalamus, prone to pathology in Parkinson's disease. Our results indicate that RSI may improve the predictive power of diffusion-based MRI, and provide additional information when combined with the standard diffusivity measurements. In the absence of major atrophy, diffusion techniques may reveal microstructural pathology. Our results suggest that protocols for MRI diffusion imaging may be adapted to more sensitive detection of pathology at different sites of the central nervous system.

• MeSH
• degenerace nervu diagnóza   diagnostické zobrazování   patologie   MeSH
• diagnostické zobrazování * MeSH
• difuzní magnetická rezonance MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mozkový kmen diagnostické zobrazování   patologie   MeSH
• Parkinsonova nemoc diagnóza   diagnostické zobrazování   patologie   MeSH
• šedá hmota diagnostické zobrazování   patologie   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• substantia nigra diagnostické zobrazování   patologie   MeSH
• thalamus diagnostické zobrazování   patologie   MeSH
• zobrazování difuzních tenzorů * MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We examined effects of theta burst stimulation (TBS) applied over two distinct cortical areas (the right inferior frontal gyrus and the left superior parietal lobule) on the Stroop task performance in 20 young healthy subjects. Neural underpinnings of the behavioral effect were tested using fMRI. A single session of intermittent TBS of the left superior parietal lobule induced certain cognitive speed enhancement and significantly increased resting-state connectivity of the dorsal attention network. This is an exploratory study that prompts further research with multiple-session TBS in subjects with cognitive impairment.

• MeSH
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• náhodné rozdělení MeSH
• nervová síť fyziologie   MeSH
• pozornost fyziologie   MeSH
• psychomotorický výkon fyziologie   MeSH
• Stroopův test MeSH
• temenní lalok fyziologie   MeSH
• theta rytmus EEG fyziologie   MeSH
• transkraniální magnetická stimulace metody   MeSH
• zdraví dobrovolníci pro lékařské studie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH