Martin Gajdos

Martin Gajdos
Masaryk University | MUNI · Centre for Neuroscience

About

48
Publications
2,721
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163
Citations
Citations since 2016
39 Research Items
162 Citations
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201620172018201920202021202201020304050

Publications

Publications (48)
Article
Full-text available
Transcranial direct current stimulation (tDCS) has the potential to modulate cognitive training in healthy aging; however, results from various studies have been inconsistent. We hypothesized that inter-individual differences in baseline brain state may contribute to the varied results. We aimed to explore whether baseline resting-state dynamic fun...
Article
Full-text available
The objective was to determine the optimal combination of multimodal imaging methods (IMs) for localizing the epileptogenic zone (EZ) in patients with MR-negative drug-resistant epilepsy. Data from 25 patients with MR-negative focal epilepsy (age 30 ± 10 years, 16M/9F) who underwent surgical resection of the EZ and from 110 healthy controls (age 31...
Article
Full-text available
Introduction Patients with schizophrenia have difficulties in cognitive and affective mentalizing which is manifested by excessive (‘overmentalizing’) or defective (‘undermentalizing’) attribution of mental states. As most of the tests does not differentiate between ‘overmentalizing’ and ‘undermentalizing’, it is not yet clear how are these deficit...
Article
Full-text available
White Matter Lesions (WML) are a radiological finding common in aged subjects. We explored the impact of WML on underlying neurodegenerative processes. We focused on the impact of WML on two neurodegenerative diseases with different pathology. In this cross-sectional study of 137 subjects (78 female, 59 men, mean age 67.2; 43–87 years), we compared...
Article
Full-text available
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 i...
Article
Full-text available
Objectives: Repetitive transcranial magnetic stimulation (rTMS) is an innovative method in the treatment of borderline personality disorder (BPD). We hypothesized that prefrontal rTMS in patients with BPD leads to improved BPD symptoms and that these effects are associated with brain connectivity changes. Methods: Fourteen patients with BPD receive...
Article
Full-text available
We wanted to verify the effect of combining multi‐echo (ME) functional magnetic resonance imaging (fMRI) with slice acceleration in simultaneous multi‐slice acquisition. The aim was to shed light on the benefits of multiple echoes for various acquisition settings, especially for levels of slice acceleration and flip angle. Whole‐brain ME fMRI data...
Article
Full-text available
Many cognitive functions, including working memory, are processed within large-scale brain networks. We targeted the right frontoparietal network (FPN) with one session of transcranial direct current stimulation (tDCS) in an attempt to modulate the cognitive speed of a visual working memory task (WMT) in 27 young healthy subjects using a double-bli...
Article
Full-text available
Arterial spin labeling (ASL) is an MRI technique measuring brain perfusion using magnetically labeled blood as a tracer. The clinical utility of ASL for presurgical evaluation in non-lesional epilepsy as compared with the quantitative analysis of interictal [18F] fluorodeoxyglucose PET (FDG-PET) was studied. In 10 patients (4 female; median age 29...
Article
Full-text available
Drug-resistant epilepsy is a diagnostic and therapeutic challenge, mainly in patients with negative MRI findings. State-of-the-art imaging methods complement standard epilepsy protocols with new information and help epileptologists to increase the reliability of their decisions. In this study, we investigate whether arterial spin labeling (ASL) per...
Article
Full-text available
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 transcrani...
Article
Full-text available
Many methods applied to data acquired by various imaging modalities have been evaluated for their benefit in localizing lesions in magnetic resonance (MR) negative epilepsy patients. No approach has proven to be a stand‐alone method with sufficiently high sensitivity and specificity. The presented study addresses the potential benefit of the automa...
Preprint
Full-text available
Drug-resistant epilepsy is a diagnostic and therapeutic challenge, mainly in patients with negative MRI findings. State-of-the-art imaging methods complement standard epilepsy protocols with new information and help to epileptologists to increase reliability of their decisions. In this study, we investigate if arterial spin labeling (ASL) perfusion...
Article
Purpose: People with eating disorders (EDs) have difficulties understanding their own emotions and recognizing the emotions of others, especially in ambiguous settings. We examined the neuronal mechanisms underlying the emotion processing of ambiguous interpersonal stimuli in EDs and healthy controls (HCs). Methods: The fMRI data were acquired b...
Article
Full-text available
Verbal communication relies heavily upon mutual understanding, or common ground. Inferring the intentional states of our interaction partners is crucial in achieving this, and social neuroscience has begun elucidating the intra- and inter-personal neural processes supporting such inferences. Typically, however, neuroscientific paradigms lack the re...
Article
Full-text available
During social interactions, decision‐making involves mutual reciprocity—each individual's choices are simultaneously a consequence of, and antecedent to those of their interaction partner. Neuroeconomic research has begun to unveil the brain networks underpinning social decision‐making, but we know little about the patterns of neural connectivity w...
Preprint
During social interactions, decision‐making involves mutual reciprocity—each individual's choices are simultaneously a consequence of, and antecedent to those of their interaction partner. Neuroeconomic research has begun to unveil the brain networks underpinning social decision‐making, but we know little about the patterns of neural connectivity w...
Article
Full-text available
Parcellation-based approaches are an important part of functional magnetic resonance imaging data analysis. They are a necessary processing step for sorting data in structurally or functionally homogenous regions. Real functional magnetic resonance imaging datasets usually do not cover the atlas template completely; they are often spatially constra...
Article
Background and objective Repetitive transcranial magnetic stimulation is a promising tool to study and modulate brain plasticity and connectivity. The aim of this study was to investigate the effects of theta burst stimulation (TBS) on the Stroop task (ST) performance and related changes in resting state functional brain connectivity. dorsal attent...
Article
Introduction Smoothing is used to increase SNR. Here we examine it’s effect of smoothing on graph analysis of fMRI data. Methods We used fMRI data of 30 subjects from HCP (Human Connectome Project; 3T; motor task). We preprocessed the data using realign and unwarp, spatial normalization, filtering and smoothing with FWHM = {none, 3, 5, 8 and 11} m...
Article
Full-text available
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 sup...
Article
Introduction: We used a functional MRI paradigm involving conventional vs. unconventional views of objects to assess bottom-up vs. top-down visual processing in Parkinson's disease (PD) with normal cognition, PD with mild cognitive impairment (MCI), and MCI due to Alzheimer's disease (AD) as compared to healthy controls. We particularly aimed at d...
Poster
Full-text available
Impairment in Theory of Mind might be due to insufficient (undermentalizing) or excessive (overmentalizing) inferences about other people’s mental states. Links were found between paranoid thoughts and Theory of mind, but disagreement exists whether it is due to impaired cognitive or affective perspective-taking. Our aim was to develop fMRI compati...
Poster
Full-text available
Introduction Abnormalities in emotional functioning is one of the key features of eating disorders (ED), such as anorexia nervosa (AN) and bulimia nervosa (BN). These patients show increased levels of alexithymia, problems understanding one's own emotion, which has been simultaneously, associated with difficulties in recognizing others emotions. O...
Article
Background and objective: Functional magnetic resonance imaging (fMRI) studies of the human brain are appearing in increasing numbers, providing interesting information about this complex system. Unique information about healthy and diseased brains is inferred using many types of experiments and analyses. In order to obtain reliable information, i...
Article
Objective We performed partial least squares correlation (PLSC) analysis to study functional connectivity in resting-state networks (RSN) in PD patients. Methods We acquired rs-fMRI data in PD patients (18 non-demented and non-depressed males) in the ON and OFF medication conditions and rs-fMRI data in healthy controls (15 males). We chose 2 coord...
Article
Resting-state networks (RSNs) are characterized by organized basal activity during rest and by low-frequency signal fluctuations that can be studied by fMRI. To date, several RSNs have been consistently reported, including the task-positive networks (e.g., the primary motor, visual and auditory network, the left and right fronto-parietal RSNs, and...
Article
Introduction In many fMRI studies of functional connectivity, researchers need to select representative signal of region of interest (ROI). Usual approach is to compute mean or first eigenvector of ROI voxels and use it to calculate Pearson correlation (PC). In this abstract we compare this usual practice with extended technique using more eigenvec...
Conference Paper
Background / Purpose: We studied patients with Parkinson's disease in their on and off medication states. We used graph theoretical approach to evaluate differences in their rs-fMRI functional connectivity. The whole-brain AAL atlas and expert knowledge were used to define regions of interest. Main conclusion: We were able to identify signific...
Conference Paper
Full-text available
Background / Purpose: We have tested if Stephan et al. (2009) methodology for optimisation of effective connectivity estimation via anatomical connectivity, gives similar or the same results used on a different dataset. They used task with visual stimuli, we have used motor task in fMRI data. Main conclusion: Although our optimised results wer...
Article
Introduction In this work we characterize functional magnetic resonance imaging (fMRI) data from event related and block design studies with typical values of several parameters. We use signal to noise ratio (SNR), percent signal change (PSC) and statistical parametric maps, estimated by SPM8 toolbox (beta, con and t-statistic maps). The aim of thi...
Conference Paper
In this paper, the software tool designed for group fMRI analysis - a mask_explorer - is introduced. The purpose of the mask_explorer is to enable user friendly exploration of fMRI dataset and to prevent unwanted data loss. This data loss could be caused by automatic discarding of voxels from analysis, which are not containing the information from...
Article
Full-text available
There are many different methods for evaluation of alertness level of a person. The commonly used questionnaires and some physiological test such as flicker-fusion (FF) test are not objective. Other objective methods based on the analysis of biological signals can be used for validation of these tests. The present study is focused on analysis of sp...

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Project (1)
Project
Identify patterns of activation during social cognition, that are specific for schizophrenia. Special task was developed to consider cognitive and affective aspects of mentalizing as well as dissociation between under and overmentalizing, in relation to self assessed social cognitive abilities, positive and negative symptoms and paranoid thinking.