scholarly journals Simultaneous EEG-fMRI: A novel approach to localize the Seizure Onset Zone

2019 ◽  
pp. 130-139
Author(s):  
Elias Ebrahimzadeh ◽  
Mehran Nikravan ◽  
Maedeh Nikravan ◽  
Mohammad Sajad Manuchehri ◽  
Sana Amoozegar ◽  
...  
Keyword(s):  
Spatial Information ◽  
Cell Activity ◽  
Blood Oxygen Level Dependent ◽  
Temporal Information ◽  
Epileptic Focus ◽  
Blood Oxygen Level ◽  
Daily Lives ◽  
Localization Accuracy ◽  
Novel Approach ◽  
The Brain

Affecting daily lives of millions of people, Epilepsy is a common central nervous system (neurological) disorder where cell activity in brain is disturbed, causing recurrent seizures. Epilepsy can be treated commonly by medications. Be that as it may, medications do not always work as well as one may have hoped, and thus, some patients tend to resort to surgeries. The primary challenge in such surgeries, and by extension any other surgery where some part of brain may need to be disabled, disconnected or removed, is managing to pose no threat to the critical healthy textures adjacent or close to the part being operated on. Therefore, the precise localization of epileptic focus is a matter of vital importance in treating this condition. Various algorithms have been proposed to localize the brain sources and thus to determine the epileptic focus, however, none has yet been able to offer a solution to effectively address this issue. With EEG signal containing temporal information and fMRI carrying spatial information, it is hoped that the combination of the two can yield optimal results. In this case study, we first remove the artifacts caused by EEG gradients, and proceed to study the signal in and outside the scanner by localizing the brain sources. The simultaneous processing of EEG-fMRI enables us to make use of the temporal information in EEG to analyze fMRI. Epileptic foci are finally localized based on GLM method. This study has been conducted on 2 medication-resistant patients with epilepsy whose data was recorded in Iran National Brain Mapping Centre. The results suggest a significant improvement in localization accuracy compared to existing methods in the literature. Keywords: Simultaneous EEG-fMRI; Epilepsy; Independent Component Analysis (ICA); Blood-oxygen-level dependent imaging (BOLD); Generalized Linear Model (GLM)

scholarly journals Measurement of CMRO2 and its relationship with CBF in hypoxia with an extended calibrated BOLD method

2019 ◽  
Vol 40 (10) ◽  
pp. 2066-2080
Author(s):  
Yaoyu Zhang ◽  
Yayan Yin ◽  
Huanjie Li ◽  
Jia-Hong Gao
Keyword(s):  
Cerebral Blood Volume ◽  
Pulse Sequence ◽  
Blood Oxygen Level Dependent ◽  
Extended Model ◽  
Brain Health ◽  
Blood Oxygen Level ◽  
Oxygen Conditions ◽  
Health And Disease ◽  
The Brain ◽  
Mild Hypoxia

Cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) are physiological parameters that not only reflect brain health and disease but also jointly contribute to blood oxygen level-dependent (BOLD) signals. Nevertheless, unsolved issues remain concerning the CBF–CMRO2 relationship in the working brain under various oxygen conditions. In particular, the CMRO2 responses to functional tasks in hypoxia are less studied. We extended the calibrated BOLD model to incorporate CMRO2 measurements in hypoxia. The extended model, which was cross-validated with a multicompartment BOLD model, considers the influences of the reduced arterial saturation level and increased baseline cerebral blood volume (CBV) and deoxyhemoglobin concentration on the changes of BOLD signals in hypoxia. By implementing a pulse sequence to simultaneously acquire the CBV-, CBF- and BOLD-weighted signals, we investigated the effects of mild hypoxia on the CBF and CMRO2 responses to graded visual stimuli. Compared with normoxia, mild hypoxia caused significant alterations in both the amplitude and the trend of the CMRO2 responses but did not impact the corresponding CBF responses. Our observations suggested that the flow-metabolism coupling strategies in the brain during mild hypoxia were different from those during normoxia.

Interhemispheric Integration at Different Spatial Scales: The Evidence From EEG Coherence and fMRI

2006 ◽  
Vol 96 (1) ◽  
pp. 259-275 ◽  
Author(s):  
Maria G. Knyazeva ◽  
Eleonora Fornari ◽  
Reto Meuli ◽  
Philippe Maeder
Keyword(s):  
Spatial Scales ◽  
Neural Substrates ◽  
Blood Oxygen Level Dependent ◽  
Specific Information ◽  
Eeg Coherence ◽  
Blood Oxygen Level ◽  
Spatial Frequencies ◽  
Collateral Sulcus ◽  
Gestalt Grouping ◽  
The Brain

The early visual system processes different spatial frequencies (SFs) separately. To examine where in the brain the scale-specific information is integrated, we mapped the neural assemblies engaged in interhemispheric coupling with electroencephalographic (EEG) coherence and blood-oxygen-level dependent (BOLD) signal. During similar EEG and functional magnetic resonance imaging (fMRI) experiments, our subjects viewed centrally presented bilateral gratings of different SF (0.25–8.0 cpd), which either obeyed Gestalt grouping rules (iso-oriented, IG) or violated them (orthogonally oriented, OG). The IG stimuli (0.5–4.0 cpd) synchronized EEG at discrete beta frequencies (beta1, beta2) and increased BOLD (0.5 and 2.0 cpd tested) in ventral (around collateral sulcus) and dorsal (parieto-occipital fissure) regions compared with OG. At both SF, the beta1 coherence correlated with the ventral activations, whereas the beta2 coherence correlated with the dorsal ones. Thus distributed neural substrates mediated interhemispheric integration at single SF. The relative impact of the ventral versus dorsal networks was modulated by the SF of the stimulus.

Differential neural correlates of reciprocal activation and cocontraction control in dorsal and ventral premotor cortices

2012 ◽  
Vol 107 (1) ◽  
pp. 126-133 ◽  
Author(s):  
Masahiko Haruno ◽  
Gowrishankar Ganesh ◽  
Etienne Burdet ◽  
Mitsuo Kawato
Keyword(s):  
Brain Activity ◽  
Premotor Cortex ◽  
Neural Correlates ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Dorsal Premotor Cortex ◽  
Blood Oxygen Level ◽  
Efficient Control ◽  
Dependent Activity ◽  
The Brain

Efficient control of reciprocal activation and cocontraction of the muscles are critical to perform skillful actions with suitable force and impedance. However, it remains unclear how the brain controls force and impedance while recruiting the same set of muscles as actuators. Does control take place at the single muscle level leading to force and impedance, or are there higher-order centers dedicated to controlling force and impedance? We addressed this question using functional MRI during voluntary isometric wrist contractions with online electromyogram feedback. Comparison of the brain activity between the conditions requiring control of either wrist torque or cocontraction demonstrates that blood oxygen level-dependent activity in the caudo-dorsal premotor cortex (PMd) correlates well with torque, whereas the activity in the ventral premotor cortex (PMv) correlates well with the level of cocontraction. This suggests distinct roles of the PMd and PMv in the voluntary control of reciprocal activation and cocontraction of muscles, respectively.

scholarly journals Resting state fMRI in pre-surgical brain mapping. Literature review

2018 ◽  
pp. 6-13 ◽  
Author(s):  
A. S. Smirnov ◽  
M. G. Sharaev ◽  
T. V. Melnikova-Pitskhelauri ◽  
V. Yu. Zhukov ◽  
A. E. Bikanov ◽  
...  
Keyword(s):  
Brain Mapping ◽  
Resting State ◽  
Preoperative Planning ◽  
Clinical Information ◽  
Complete Information ◽  
Resting State Fmri ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen Level ◽  
Spontaneous Fluctuations ◽  
The Brain

Today, functional magnetic resonance imaging (fMRI) allows to plan surgery based on the topography of functionally important areas of the human brain cortex and tumor. This method can complement the surgical strategy with significant clinical information. The stimulus-dependent fMRI with motor and language paradigms is generally used for preoperative planning. The study outcome depends on the patient's ability to perform tasks paradigm, which is broken in brain tumors. In an attempt to overcome this problem, resting-state fMRI (rs-fMRI) is used for brain mapping. Rs-fMRI is based on the measurement of spontaneous fluctuations of the BOLD signal (blood oxygen level-dependent), representing the functional structure of the brain. In contrast to stimulus-dependent fMRI, rs-fMRI provides more complete information about functional architecture of the brain. rs-fMRI is used in conditions where the results of stimulusdependent fMRI may be falsely positive or in the absence of the possibility of its implementation. In aggregate, both methods significantly expand the efficiency and specificity of preoperative planning.

scholarly journals Neural representations of task context and temporal order during action sequence execution

2020 ◽  
Author(s):  
Danesh Shahnazian ◽  
Mehdi Senoussi ◽  
Ruth M. Krebs ◽  
Tom Verguts ◽  
Clay B. Holroyd
Keyword(s):  
Contextual Information ◽  
Empirical Studies ◽  
Neural Mechanism ◽  
Blood Oxygen Level Dependent ◽  
Temporal Information ◽  
Blood Oxygen Level ◽  
Action Sequence ◽  
Stimulus Response ◽  
Action Sequences ◽  
Data Driven Approach

AbstractSince routine action sequences can share a great deal of similarity in terms of their stimulus response mappings, their correct execution relies crucially on the ability to preserve contextual and temporal information (Lashley, 1951). However, there are few empirical studies on the neural mechanism and the brain areas maintaining such information. To address this gap in the literature, we recently recorded the blood-oxygen level dependent (BOLD) response in a newly developed coffee-tea making task (Holroyd et al., 2018). The task involves the execution of 4 action sequences that each feature 6 decision states. Here we report a reanalysis of this dataset using a data-driven approach, namely multivariate pattern analysis (MVPA), that examines context-dependent neural activity across several predefined regions of interest. Results highlight involvement of the inferior-temporal gyrus and lateral prefrontal cortex in maintaining temporal and contextual information for the execution of hierarchically-organized action sequences. Furthermore, temporal information seems to be more strongly encoded in areas over the left hemisphere.

scholarly journals The processing of color preference in the brain

2018 ◽  
Author(s):  
Chris Racey ◽  
Anna Franklin ◽  
Chris M. Bird
Keyword(s):  
Brain Activity ◽  
Blood Oxygen Level Dependent ◽  
Color Preference ◽  
Blood Oxygen Level ◽  
Neural Basis ◽  
Color Preferences ◽  
Subjective Value ◽  
Value Judgements ◽  
Automatic Encoding ◽  
The Brain

AbstractDecades of research has established that humans have preferences for some colors (e.g., blue) and a dislike of others (e.g., dark chartreuse), with preference varying systematically with variation in hue (e.g., Hurlbert & Owen, 2015). Here, we used functional MRI to investigate why humans have likes and dislikes for simple patches of color, and to understand the neural basis of preference, aesthetics and value judgements more generally. We looked for correlations of a behavioural measure of color preference with the blood oxygen level-dependent (BOLD) response when participants performed an irrelevant orientation judgement task on colored squares. A whole brain analysis found a significant correlation between BOLD activity and color preference in the posterior midline cortex (PMC), centred on the precuneus but extending into the adjacent posterior cingulate and cuneus. These results demonstrate that brain activity is modulated by color preference, even when such preferences are irrelevant to the ongoing task the participants are engaged. They also suggest that color preferences automatically influence our processing of the visual world. Interestingly, the effect in the PMC overlaps with regions identified in neuroimaging studies of preference and value judgements of other types of stimuli. Therefore, our findings extends this literature to show that the PMC is related to automatic encoding of subjective value even for basic visual features such as color.

Low-frequency blood oxygen level-dependent fluctuations in the brain white matter: more than just noise

2017 ◽  
Vol 62 (9) ◽  
pp. 656-657 ◽  
Author(s):  
Gong-Jun Ji ◽  
Wei Liao ◽  
Fang-Fang Chen ◽  
Lei Zhang ◽  
Kai Wang
Keyword(s):  
White Matter ◽  
Low Frequency ◽  
Blood Oxygen Level Dependent ◽  
Blood Oxygen ◽  
Oxygen Level ◽  
Blood Oxygen Level ◽  
Brain White Matter ◽  
The Brain
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