Radek Mareček

YNIMG Journal 2024 Journal Article

Development of white matter in young adulthood: The speed of brain aging and its relationship with changes in fractional anisotropy

• Martin Jáni
• Radek Mareček
• Klara Mareckova

White matter (WM) development has been studied extensively, but most studies used cross-sectional data, and to the best of our knowledge, none of them considered the possible effects of biological (vs. chronological) age. Therefore, we conducted a longitudinal multimodal study of WM development and studied changes in fractional anisotropy (FA) in the different WM tracts and their relationship with cortical thickness-based measures of brain aging in young adulthood. A total of 105 participants from the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) prenatal birth cohort underwent magnetic resonance imaging (MRI) at the age of 23-24, and the age of 28-30 years. At both time points, FA in the different WM tracts was extracted using the JHU atlas, and brain age gap estimate (BrainAGE) was calculated using the Neuroanatomical Age Prediction using R (NAPR) model based on cortical thickness maps. Changes in FA and the speed of cortical brain aging were calculated as the difference between the respective variables in the late vs. early 20s. We demonstrated tract-specific increases as well as decreases in FA, which indicate that the WM microstructure continues to develop in the third decade of life. Moreover, the significant interaction between the speed of cortical brain aging, tract, and sex on mean FA revealed that a greater speed of cortical brain aging in young adulthood predicted greater decreases in FA in the bilateral cingulum and left superior longitudinal fasciculus in young adult men. Overall, these changes in FA in the WM tracts in young adulthood point out the protracted development of WM microstructure, particularly in men.

YNICL Journal 2017 Journal Article

Large-scale cortico-subcortical functional networks in focal epilepsies: The role of the basal ganglia

• Eva Výtvarová
• Radek Mareček
• Jan Fousek
• Ondřej Strýček
• Ivan Rektor

Objectives The aim was to describe the contribution of basal ganglia (BG) thalamo-cortical circuitry to the whole-brain functional connectivity in focal epilepsies. Methods Interictal resting-state fMRI recordings were acquired in 46 persons with focal epilepsies. Of these 46, 22 had temporal lobe epilepsy: 9 left temporal (LTLE), 13 right temporal (RTLE); 15 had frontal lobe epilepsy (FLE); and 9 had parietal/occipital lobe epilepsy (POLE). There were 20 healthy controls. The complete weighted network was analyzed based on correlation matrices of 90 and 194 regions. The network topology was quantified on a global and regional level by measures based on graph theory, and connection-level changes were analyzed by the partial least square method. Results In all patient groups except RTLE, the shift of the functional network topology away from random was observed (normalized clustering coefficient and characteristic path length were higher in patient groups than in controls). Links contributing to this change were found in the cortico-subcortical connections. Weak connections (low correlations) consistently contributed to this modification of the network. The importance of regions changed: decreases in the subcortical areas and both decreases and increases in the cortical areas were observed in node strength, clustering coefficient and eigenvector centrality in patient groups when compared to controls. Node strength decreases of the basal ganglia, i. e. the putamen, caudate, and pallidum, were displayed in LTLE, FLE, and POLE. The connectivity within the basal ganglia–thalamus circuitry was not disturbed; the disturbance concerned the connectivity between the circuitry and the cortex. Significance Focal epilepsies affect large-scale brain networks beyond the epileptogenic zones. Cortico-subcortical functional connectivity disturbance was displayed in LTLE, FLE, and POLE. Significant changes in the resting-state functional connectivity between cortical and subcortical structures suggest an important role of the BG and thalamus in focal epilepsies.

YNIMG Journal 2013 Journal Article

Superior temporal sulcus and social cognition in dangerous drivers

• Jana Zelinková
• Daniel Joel Shaw
• Radek Mareček
• Michal Mikl
• Tomáš Urbánek
• Lenka Peterková
• Petr Zámečník
• Milan Brázdil

Understanding the neural systems underpinning social cognition is a primary focus of contemporary social neuroscience. Using functional magnetic resonance imaging (fMRI), the present study asked if brain activity reflecting socio-cognitive processes differs between individuals according to their social behavior; namely, between a group of drivers with frequent traffic offenses and a group with none. Socio-cognitive processing was elicited by employing videos from a traffic awareness campaign, consisting of reckless and anti-social driving behavior ending in tragic consequences, and control videos with analogous driving themes but without such catastrophic endings. We investigated whether relative increases in brain function during the observation of these campaign stimuli compared with control videos differed between these two groups. To develop the results of our previous study we focused our analyses on superior temporal sulcus/gyrus (STS/STG). This revealed a bigger increase in brain activity within this region during the campaign stimuli in safe compared with dangerous drivers. Furthermore, by thematically coding drivers' verbal descriptions of the stimuli, we also demonstrate differences in STS reactivity according to drivers' scores on two indices of socio-cognitive processing: subjects' perceived consequences of actors' actions, and their affective evaluation of the clips. Our results demonstrate the influence of social behavior and socio-cognitive processing on STS reactivity to social stimuli, developing considerably our understanding of the role of this region in social cognition.

YNIMG Journal 2009 Journal Article

Neural correlates of affective picture processing — A depth ERP study

• Milan Brázdil
• Robert Roman
• Tomáš Urbánek
• Jan Chládek
• Dalibor Špok
• Radek Mareček
• Michal Mikl
• Pavel Jurák

Using functional neuroimaging techniques (PET and fMRI), various cortical, limbic, and paralimbic structures have been identified in the last decade as neural substrates of human emotion. In this study we used a novel approach (intracerebral recordings of event-related potentials) to add to our knowledge of specific brain regions involved in affective picture processing. Ten intractable epileptic patients undergoing pre-surgical depth electrode recording viewed pleasant, neutral, and unpleasant pictures and intracerebral event-related potentials (ERPs) were recorded. A total of 752 cortical and subcortical sites were investigated. Significant differences in ERPs to unpleasant as compared to neutral or pleasant pictures were frequently and consistently observed in recordings from various brain areas – the mesial temporal cortex (the amygdala, the hippocampus, the temporal pole), the lateral temporal cortex, the mesial prefrontal cortex (ACC and the medial frontal gyrus), and the lateral prefrontal cortex. Interestingly, the mean latencies of responses to emotional stimuli were somewhat shorter in the frontal lobe structures (with evidently earlier activation within lateral prefrontal areas when compared to mesial prefrontal cortex) and longer in the temporal lobe regions. These differences, however, were not significant. Additional clearly positive findings were observed in some rarely investigated regions – in the posterior parietal cortex, the precuneus, and the insula. An approximately equivalent number of positive findings was revealed in the left and right hemisphere structures. These results are in agreement with a multisystem model of human emotion, distributed far beyond the typical limbic system and substantially comprising lateral aspects of both frontal lobes as well.

YNIMG Journal 2007 Journal Article

Effective connectivity in target stimulus processing: A dynamic causal modeling study of visual oddball task

• Milan Brázdil
• Michal Mikl
• Radek Mareček
• Petr Krupa
• Ivan Rektor