scholarly journals Simultaneous human intracerebral stimulation and HD-EEG: ground-truth for source localization methods

2020 ◽  
Author(s):  
Ezequiel Mikulan ◽  
Simone Russo ◽  
Sara Parmigiani ◽  
Simone Sarasso ◽  
Flavia Maria Zauli ◽  
...  
Keyword(s):  
Brain Activity ◽  
Single Pulse ◽  
Ground Truth ◽  
Brain Regions ◽  
Tissue Conductivity ◽  
Implanted Electrodes ◽  
Multiple Parameters ◽  
Solution Methods ◽  
Drug Resistant Epilepsy

AbstractPrecisely localizing the sources of brain activity as recorded by EEG is a fundamental procedure and a major challenge for both research and clinical practice. Even though many methods and algorithms have been proposed, their relative advantages and limitations are still not well established. Moreover, these methods involve tuning multiple parameters, for which no principled way of selection exists yet. These uncertainties are emphasized due to the lack of ground-truth for their validation and testing. Here we provide the first open dataset that comprises EEG recorded electrical activity originating from precisely known locations inside the brain of living humans. High-density EEG was recorded as single-pulse biphasic currents were delivered at intensities ranging from 0.1 to 5 mA through stereotactically implanted electrodes in diverse brain regions during pre-surgical evaluation of patients with drug-resistant epilepsy. The uses of this dataset range from the estimation of in vivo tissue conductivity to the development, validation and testing of forward and inverse solution methods.

scholarly journals Orientation of Temporal Interference for Non-Invasive Deep Brain Stimulation in Epilepsy

2020 ◽  
Author(s):  
Florian Missey ◽  
Evgeniia Rusina ◽  
Emma Acerbo ◽  
Boris Botzanowski ◽  
Romain Carron ◽  
...  
Keyword(s):  
Electric Fields ◽  
Brain Regions ◽  
Intracranial Stimulation ◽  
Epileptogenic Zone ◽  
Implanted Electrodes ◽  
Non Invasive ◽  
Gamma Range ◽  
Wide Range ◽  
Drug Resistant Epilepsy ◽  
Intracranial Electrodes

AbstractIn patients with focal drug-resistant epilepsy, electrical stimulation from intracranial electrodes is frequently used for the localization of seizure onset zones and related pathological networks. The ability of electrically stimulated tissue to generate beta and gamma range oscillations, called rapid-discharges, is a frequent indication of an epileptogenic zone. However, a limit of intracranial stimulation is the fixed physical location and number of implanted electrodes, leaving numerous clinically and functionally relevant brain regions unexplored. Here, we demonstrate an alternative technique relying exclusively on nonpenetrating surface electrodes, namely an orientation-tunable form of temporally-interfering (TI) electric fields to target the CA3 of the mouse hippocampus which focally evokes seizure-like events (SLEs) having the characteristic frequencies of rapid-discharges, but without the necessity of the implanted electrodes. The orientation of the topical electrodes with respect to the orientation of the hippocampus is demonstrated to strongly control the threshold for evoking SLEs. Additionally, we demonstrate the use of square waves as an alternative to sine waves for TI stimulation. An orientation-dependent analysis of classic implanted electrodes to evoke SLEs in the hippocampus is subsequently utilized to support the results of the minimally-invasive temporally-interfering fields. The principles of orientation-tunable TI stimulation seen here can be generally applicable in a wide range of other excitable tissues and brain regions, overcoming several limitations of fixed electrodes which penetrate tissue.

scholarly journals Brain Tissue Conductivity Measurements with MR-Electrical Properties Tomography: An In Vivo Study

2020 ◽  
Author(s):  
Stefano Mandija ◽  
Petar I. Petrov ◽  
Jord J. T. Vink ◽  
Sebastian F. W. Neggers ◽  
Cornelis A. T. van den Berg
Keyword(s):  
Electrical Properties ◽  
Healthy Subjects ◽  
Ex Vivo ◽  
Simulated Data ◽  
Ground Truth ◽  
In Vivo Study ◽  
Conductivity Measurements ◽  
Tissue Conductivity ◽  
Before And After

AbstractFirst in vivo brain conductivity reconstructions using Helmholtz MR-Electrical Properties Tomography (MR-EPT) have been published. However, a large variation in the reconstructed conductivity values is reported and these values differ from ex vivo conductivity measurements. Given this lack of agreement, we performed an in vivo study on eight healthy subjects to provide reference in vivo brain conductivity values. MR-EPT reconstructions were performed at 3 T for eight healthy subjects. Mean conductivity and standard deviation values in the white matter, gray matter and cerebrospinal fluid (σWM, σGM, and σCSF) were computed for each subject before and after erosion of regions at tissue boundaries, which are affected by typical MR-EPT reconstruction errors. The obtained values were compared to the reported ex vivo literature values. To benchmark the accuracy of in vivo conductivity reconstructions, the same pipeline was applied to simulated data, which allow knowledge of ground truth conductivity. Provided sufficient boundary erosion, the in vivo σWM and σGM values obtained in this study agree for the first time with literature values measured ex vivo. This could not be verified for the CSF due to its limited spatial extension. Conductivity reconstructions from simulated data verified conductivity reconstructions from in vivo data and demonstrated the importance of discarding voxels at tissue boundaries. The presented σWM and σGM values can therefore be used for comparison in future studies employing different MR-EPT techniques.

scholarly journals Investigating Data Cleaning Methods to Improve Performance of Brain–Computer Interfaces Based on Stereo-Electroencephalography

2021 ◽  
Vol 15 ◽  
Author(s):  
Shengjie Liu ◽  
Guangye Li ◽  
Shize Jiang ◽  
Xiaolong Wu ◽  
Jie Hu ◽  
...  
Keyword(s):  
Data Cleaning ◽  
Brain Activity ◽  
Low Frequency ◽  
Reference Electrode ◽  
Brain Regions ◽  
Subcortical Structures ◽  
Implanted Electrodes ◽  
Average Reference ◽  
Depth Electrodes ◽  
Cleaning Methods

Stereo-electroencephalography (SEEG) utilizes localized and penetrating depth electrodes to directly measure electrophysiological brain activity. The implanted electrodes generally provide a sparse sampling of multiple brain regions, including both cortical and subcortical structures, making the SEEG neural recordings a potential source for the brain–computer interface (BCI) purpose in recent years. For SEEG signals, data cleaning is an essential preprocessing step in removing excessive noises for further analysis. However, little is known about what kinds of effect that different data cleaning methods may exert on BCI decoding performance and, moreover, what are the reasons causing the differentiated effects. To address these questions, we adopted five different data cleaning methods, including common average reference, gray–white matter reference, electrode shaft reference, bipolar reference, and Laplacian reference, to process the SEEG data and evaluated the effect of these methods on improving BCI decoding performance. Additionally, we also comparatively investigated the changes of SEEG signals induced by these different methods from multiple-domain (e.g., spatial, spectral, and temporal domain). The results showed that data cleaning methods could improve the accuracy of gesture decoding, where the Laplacian reference produced the best performance. Further analysis revealed that the superiority of the data cleaning method with excellent performance might be attributed to the increased distinguishability in the low-frequency band. The findings of this work highlighted the importance of applying proper data clean methods for SEEG signals and proposed the application of Laplacian reference for SEEG-based BCI.

scholarly journals Seizures are a druggable mechanistic link between TBI and subsequent tauopathy

2020 ◽  
Author(s):  
Hadeel Alyenbaawi ◽  
Richard Kanyo ◽  
Laszlo F. Locskai ◽  
Razieh Kamali-Jamil ◽  
Michèle G. DuVal ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Cell Death ◽  
Brain Injury ◽  
Chronic Traumatic Encephalopathy ◽  
Brain Activity ◽  
Brain Regions ◽  
List Type ◽  
Larval Zebrafish ◽  
Post Traumatic

SummaryTraumatic brain injury (TBI) is a prominent risk factor for neurodegenerative diseases and dementias including chronic traumatic encephalopathy (CTE). TBI and CTE, like all tauopathies, are characterized by accumulation of Tau into aggregates that progressively spread to other brain regions in a prion-like manner. The mechanisms that promote spreading and cellular uptake of tau seeds after TBI are not fully understood, in part due to lack of tractable animal models. Here, we test the putative roles for excess neuronal activity and dynamin-dependent endocytosis in promoting the in vivo spread of tauopathy. We introduce ‘tauopathy reporter’ zebrafish expressing a genetically-encoded fluorescent Tau biosensor that reliably reports accumulation of human tau species when seeded via intra-ventricular brain injections. Subjecting zebrafish larvae to a novel TBI paradigm produced various TBI symptoms including cell death, hemorrhage, blood flow abnormalities, post–traumatic seizures, and Tau inclusions. Bath application of anticonvulsant drugs rescued TBI-induced tauopathy and cell death; these benefits were attributable to inhibition of post-traumatic seizures because co-application of convulsants reversed these beneficial effects. However, one convulsant drug, 4-Aminopyridine, unexpectedly abrogated TBI-induced tauopathy - this was due to its inhibitory action on endocytosis as confirmed via additional dynamin inhibitors. These data suggest a role for seizure activity and dynamin-dependent endocytosis in the prion-like seeding and spreading of tauopathy following TBI. Further work is warranted regarding anti-convulsants that dampen post-traumatic seizures as a route to moderating subsequent tauopathy. Moreover, the data highlight the utility of deploying in vivo Tau biosensor and TBI methods in larval zebrafish, especially regarding drug screening and intervention.Graphical AbstractHighlightsIntroduces first Traumatic Brain Injury (TBI) model in larval zebrafish, and its easyTBI induces clinically relevant cell death, haemorrhage & post-traumatic seizuresCa2+ imaging during TBI reveals spike in brain activity concomitant with seizuresTau-GFP Biosensor allows repeated in vivo measures of prion-like tau aggregationpost-TBI, anticonvulsants stop tauopathies akin to Chronic Traumatic Encephalopathy

scholarly journals Orientation of Temporal Interference for Non-invasive Deep Brain Stimulation in Epilepsy

2021 ◽  
Vol 15 ◽  
Author(s):  
Florian Missey ◽  
Evgeniia Rusina ◽  
Emma Acerbo ◽  
Boris Botzanowski ◽  
Agnès Trébuchon ◽  
...  
Keyword(s):  
Electric Fields ◽  
Pulse Width Modulation ◽  
Brain Regions ◽  
Intracranial Stimulation ◽  
Epileptogenic Zone ◽  
Implanted Electrodes ◽  
Non Invasive ◽  
Gamma Range ◽  
Wide Range ◽  
Drug Resistant Epilepsy

In patients with focal drug-resistant epilepsy, electrical stimulation from intracranial electrodes is frequently used for the localization of seizure onset zones and related pathological networks. The ability of electrically stimulated tissue to generate beta and gamma range oscillations, called rapid-discharges, is a frequent indication of an epileptogenic zone. However, a limit of intracranial stimulation is the fixed physical location and number of implanted electrodes, leaving numerous clinically and functionally relevant brain regions unexplored. Here, we demonstrate an alternative technique relying exclusively on non-penetrating surface electrodes, namely an orientation-tunable form of temporally interfering (TI) electric fields to target the CA3 of the mouse hippocampus which focally evokes seizure-like events (SLEs) having the characteristic frequencies of rapid-discharges, but without the necessity of the implanted electrodes. The orientation of the topical electrodes with respect to the orientation of the hippocampus is demonstrated to strongly control the threshold for evoking SLEs. Additionally, we demonstrate the use of Pulse-width-modulation of square waves as an alternative to sine waves for TI stimulation. An orientation-dependent analysis of classic implanted electrodes to evoke SLEs in the hippocampus is subsequently utilized to support the results of the minimally invasive temporally interfering fields. The principles of orientation-tunable TI stimulation seen here can be generally applicable in a wide range of other excitable tissues and brain regions, overcoming several limitations of fixed electrodes which penetrate tissue and overcoming several limitations of other non-invasive stimulation methods in epilepsy, such as transcranial magnetic stimulation (TMS).

scholarly journals Origin of Slow Spontaneous Resting-State Neuronal Fluctuations in Brain Networks

2017 ◽  
Author(s):  
Giri P. Krishnan ◽  
Oscar C. González ◽  
Maxim Bazhenov
Keyword(s):  
Computational Model ◽  
Resting State ◽  
Large Scale ◽  
Brain Activity ◽  
Brain Regions ◽  
Brain Network ◽  
Ion Concentration ◽  
Brain State ◽  
The Brain

AbstractResting or baseline state low frequency (0.01-0.2 Hz) brain activity has been observed in fMRI, EEG and LFP recordings. These fluctuations were found to be correlated across brain regions, and are thought to reflect neuronal activity fluctuations between functionally connected areas of the brain. However, the origin of these infra-slow fluctuations remains unknown. Here, using a detailed computational model of the brain network, we show that spontaneous infra-slow (< 0.05 Hz) fluctuations could originate due to the ion concentration dynamics. The computational model implemented dynamics for intra and extracellular K+ and Na+ and intracellular Cl- ions, Na+/K+ exchange pump, and KCC2 co-transporter. In the network model representing resting awake-like brain state, we observed slow fluctuations in the extracellular K+ concentration, Na+/K+ pump activation, firing rate of neurons and local field potentials. Holding K+ concentration constant prevented generation of these fluctuations. The amplitude and peak frequency of this activity were modulated by Na+/K+ pump, AMPA/GABA synaptic currents and glial properties. Further, in a large-scale network with long-range connections based on CoCoMac connectivity data, the infra-slow fluctuations became synchronized among remote clusters similar to the resting-state networks observed in vivo. Overall, our study proposes that ion concentration dynamics mediated by neuronal and glial activity may contribute to the generation of very slow spontaneous fluctuations of brain activity that are observed as the resting-state fluctuations in fMRI and EEG recordings.

scholarly journals Concurrent tissue oxymetry and blood flowmetry to assess the effect of drugs on cerebral oxygen metabolism

2020 ◽  
Vol 10 (3) ◽  
pp. 5552-5555
Keyword(s):  
Brain Activity ◽  
Oxygen Metabolism ◽  
Brain Regions ◽  
Cerebral Oxygen ◽  
Cerebral Oxygen Metabolism ◽  
Cns Depressant ◽  
Carbon Dioxide Co2 ◽  
Blood Flowmetry ◽  
The Brain

An Oxylite/LDF system (Oxford Optronix, UK) driven by a sensor made of optical fibres for the tissue oxygen tension (pO2) and for the Laser Doppler Blood Flow (BF) was implemented. This has allowed pO2 and BF real time measurements in discrete brain areas of anaesthetised rats that were then challenged with exogenous oxygen (O2) and carbon dioxide (CO2). The results gathered were compared with data obtained following treatment with drugs that have excitatory influence upon the brain activity such as amphetamine or with a central nervous system (CNS) depressant such as CI-966. Altogether these experiments support the methodology for in vivo investigation of pharmacological effects on cerebral oxygen metabolism and could provide new understandings on the effects of psychostimulants and anticonvulsants on selected brain regions.

Abstract T MP46: Stroke-Related Neuroplasticity During Steering of Human Gait

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Caroline Paquette ◽  
Jean-Paul Soucy
Keyword(s):  
Brain Plasticity ◽  
Brain Activity ◽  
Brain Regions ◽  
Whole Body ◽  
Human Gait ◽  
Stroke Survivors ◽  
Post Stroke ◽  
Positron Emission ◽  
18F Fdg

Background: The risk of falling is higher in stroke survivors than among the general population. These falls are more frequent during walking and transfers or during turning. The neuronal substrates involved in steering of locomotion are poorly understood due to methodological limitations in quantifying brain activations during whole-body movements. Thus, no data is currently available to study the mechanisms of post-stroke brain plasticity for steering of gait. This study tested the hypothesis that stroke-induced neuroplastic changes for steering of gait can be quantified using 18F- fluorodesoxy-glucose (18F-FDG) Positron Emission Tomography (PET) in-vivo in humans Methods: PET imaging with 18F-FDG tracer was used to quantify cerebral glucose metabolism (CMRGlc) during two locomotor tasks (straight walking and turning) measured on separate days. Immediately prior to each walking task, a 5 mCi bolus of 18F-FDG was injected. Subjects walked for 40 minutes (duration of 18F-FDG uptake). Subjects were scanned on an ECAT HR+ scan (20min emission followed by 10min transmission) within 10 minutes of completing the walking task, well within reaching the 2h half-life of 18F. Images obtained during straight walking were subtracted from the ones acquired during steering Results: Subjects post-stroke showed an asymmetrical pattern of CMRGlc in sensorimotor areas and superior parietal lobule where the affected hemisphere shows no increase in CMRGlc. Differences between groups were also observed in the cerebellum where CMRGlc was increased in the vermis for controls, an area predominant for the control of trunk and gait. Stroke subjects, in contrast, showed increased CMRGlc in the hemishperes, associated with goal-directed leg movements. Conclusions: Neuroplasticity in complex locomotor tasks such as steering can be quantified using 18F-FDG PET in subjects post-stroke. This study showed that changes affect several brain regions remote to the infarct. Understanding stroke-related changes in brain activity during steering of locomotion is crucial for improving rehabilitative strategies to minimize falls and injuries in stroke survivors.

scholarly journals Opioidergic Regulation of Emotional Arousal: A Combined PET–fMRI Study

2018 ◽  
Vol 29 (9) ◽  
pp. 4006-4016 ◽  
Author(s):  
Tomi Karjalainen ◽  
Kerttu Seppälä ◽  
Enrico Glerean ◽  
Henry K Karlsson ◽  
Juha M Lahnakoski ◽  
...  
Keyword(s):  
Emotional Processing ◽  
Brain Activity ◽  
Emotional Arousal ◽  
Brain Regions ◽  
Positron Emission ◽  
Fmri Study ◽  
Μ Opioid Receptor ◽  
Positive Correlations ◽  
Arousal And Valence

Abstract Emotions can be characterized by dimensions of arousal and valence (pleasantness). While the functional brain bases of emotional arousal and valence have been actively investigated, the neuromolecular underpinnings remain poorly understood. We tested whether the opioid and dopamine systems involved in reward and motivational processes would be associated with emotional arousal and valence. We used in vivo positron emission tomography to quantify μ-opioid receptor and type 2 dopamine receptor (MOR and D2R, respectively) availability in brains of 35 healthy adult females. During subsequent functional magnetic resonance imaging carried out to monitor hemodynamic activity, the subjects viewed movie scenes of varying emotional content. Arousal and valence were associated with hemodynamic activity in brain regions involved in emotional processing, including amygdala, thalamus, and superior temporal sulcus. Cerebral MOR availability correlated negatively with the hemodynamic responses to arousing scenes in amygdala, hippocampus, thalamus, and hypothalamus, whereas no positive correlations were observed in any brain region. D2R availability—here reliably quantified only in striatum—was not associated with either arousal or valence. These results suggest that emotional arousal is regulated by the MOR system, and that cerebral MOR availability influences brain activity elicited by arousing stimuli.

scholarly journals Joint-Label Fusion Brain Atlases for Dementia Research in Down Syndrome

2020 ◽  
Author(s):  
Nazek Queder ◽  
Michael J. Phelan ◽  
Lisa Taylor ◽  
Nicholas Tustison ◽  
Eric Doran ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Ground Truth ◽  
Disease Status ◽  
Brain Regions ◽  
Motion Artifacts ◽  
Brain Atlas ◽  
Positron Emission ◽  
Dementia Research ◽  
Amyloid Load

AbstractResearch suggests a link between Alzheimer’s Disease in Down Syndrome (DS) and the overexpression of amyloid plaques. Using Positron Emission Tomography (PET) we can assess the in-vivo regional amyloid load using several available ligands. To measure amyloid distributions in specific brain regions, a brain atlas is used. A popular method of creating a brain atlas is to segment a participant’s structural Magnetic Resonance Imaging (MRI) scan. Acquiring an MRI is often challenging in intellectually-imparied populations because of contraindications or data exclusion due to significant motion artifacts or incomplete sequences related to general discomfort. When an MRI cannot be acquired, it is typically replaced with a standardized brain atlas derived from neurotypical populations which may be inappropriate for use in DS. In this project, we create a series of disease and diagnosis-specific (cognitively stable, mild cognitive impairment (MCI-DS), and dementia) probabilistic group atlases of participants with DS and evaluate their accuracy of quantifying regional amyloid load compared to our ground truth individual MRI-based segmentations. Further, we compare the diagnostic-specific atlases with a probabilistic atlas constructed from similar-aged cognitively-stable neurotypical participants. We hypothesized that regional PET signals will best match the ground truth by using DS group atlases that aligns with a participant’s disorder and disease status (e.g. DS and MCI-DS). Our results vary by brain region but generally show that using a disorder-specific atlas in DS better matches the ground truth than using an atlas constructed from cognitively-stable neurotypical participants. We found no additional benefit of using a disease-state specific atlas. All atlases are made publicly available for the research community.AbbreviationsAD, DS, Aβ, DSG, CS-DS, CS-NT, LOOCV, ROI, MSE, MRI, PET, JLF, CS, MCI-DS, DEM.

Sign in / Sign up

Export Citation Format

Share Document