Performing electrophysiological measurements in humans inside Magnetic Resonance Imaging scanners; applications in Epilepsy research and other areas by Louis Lemieux
IRJET- Design and Development of Electroencephalography based Cost Effect...IRJET Journal
This document describes a study on the design and development of a low-cost prosthetic arm controlled by brain waves. Researchers created an electroencephalography (EEG)-based system to read brain signals and control a prosthetic arm. The system detects different brain wave patterns like alpha, beta, gamma, delta and theta waves using EEG sensors. It then processes the signals with an Arduino microcontroller and uses servo motors to move the prosthetic arm. The goal is to make a prosthetic arm that can move similarly to a biological human arm by interpreting the user's thoughts detected through brain waves.
Application of swarm intelligence optimization in biomedical Aboul Ella Hassanien
The document summarizes a presentation on applying swarm intelligence optimization algorithms to biomedical applications. Specifically, it discusses using these algorithms to help predict epileptic seizures by analyzing electroencephalogram (EEG) data. The presentation introduces swarm algorithms and machine learning, describes how EEG data is used to detect epilepsy, and proposes a model for feature engineering of EEG data using swarm intelligence to help classify signals as normal or abnormal and predict seizures.
This document analyzes spectral features extracted from EEG signals to detect brain tumors. Sixteen candidate features were considered from 102 normal subjects and 100 brain tumor patients. Nine of the features showed a statistically significant difference between the two groups. Specifically, power ratio index, relative intensity ratio for different frequency bands, maximum-to-mean power ratio, peak bispectrum, peak bicoherence, and spectral entropy values were extracted from segmented EEG signals and compared between subjects. Statistical testing found that the mean values of nine features were significantly different between brain tumor patients and normal subjects, suggesting quantitative EEG analysis may help in diagnosis of brain tumors.
Neuro-technology aims to restore or improve human nervous system function through electronics. Neuromotor prostheses (NMPs) extract signals from the nervous system to control devices. The goal of NMPs is to convey motor control intent from the central nervous system to drive multi-degree of freedom prosthetic devices for amputees or paralyzed patients. Key challenges are developing neural interfaces that last a lifetime and providing dexterous, natural control of prosthetics. NMP systems involve neural implants to record brain signals, decoding software to translate signals into motor commands, and output devices like prosthetics. Technological advances now allow basic NMP control but further progress is still needed.
Amyotrophic Lateral Sclerosis (ALS) is the most common progressive neurodegenerative disorder reflecting
the degeneration of upper and lower motor neurons. Motor neurons controls the communication between nervous
system and muscles of the body. ALS results in the loss of voluntary control over muscular activities along with the
inability to breathe and the maximum life expectancy of affected individual will be 3-5 years from the onset of
symptoms. But the lifetime of affected people can be extended by early detection of disease. The usual methods for
diagnosis are Electromyography (EMG), Nerve Conduction Study (NCS), Magnetic Resonance Imaging (MRI) and
Magneto-encephalography (MEG). But some of these methods may erroneously result in neuropathy or myopathy
instead of ALS and some do not provide any biomarker. EEG is comparatively least expensive method and it
provides biomarker for ALS detection. ALS is always associated with fronto-temporal dementia (FTD). The spectral
analysis of EEG will reveal the structural and functional connectivity alterations of the underlying neural network
that occurs due to FTD and it can generate potential biomarkers for the early detection of ALS. A novel algorithm
has been developed by exploiting the Dual Tree Complex Wavelet Transform (DTCWT) technique and it can
overcome the short comes of existing methods for the analysis and feature extraction of EEG. Deterministic
biomarkers were obtained from spectral analysis of EEG and the proposed algorithm provided 100% accuracy for all
the test datasets.
Neuroprosthetics involves using brain signals acquired from neurons for various purposes like restoring movement in paralyzed patients. Nanotechnology like nano multi-electrode arrays can be used to receive and transmit brain signals more effectively by increasing electrode conduction and reducing incorrect connections with neurons. Neuroprosthetics has applications in both in vivo and in vitro contexts and can help improve functions like movement, speech, and understanding of drug effects on animal behavior and emotions.
This document describes a smart helmet system that embeds sensors to monitor the wearer's brain activity (EEG) and respiration. The system includes an Arduino microcontroller, GPS module, GSM module for emergency alerts, EEG sensor, respiratory sensor, and power supply. It monitors sensor values and compares them to normal tolerance levels. If any abnormal readings or accidents occur, the system sends an emergency alert message along with GPS location to recovery authorities. The wearer can also manually trigger an emergency message using a button. The document discusses recording EEG and ECG signals from inside the helmet and transmitting data to evaluate feasibility. It aims to monitor physiological signals during activities like sports or military engagements for safety.
Brain-Computer Interface: Rebuilding radically new output of the Human BrainArina Kochetova
This document discusses a brain-computer interface (BCI) research project led by Alexander Kaplan at Lomonosov Moscow State University. The project aims to establish direct communication between the human brain and external devices without using peripheral nerves or muscles. Kaplan's lab uses electroencephalography (EEG) to detect electrical brain activity and translate it into commands for prosthetics and other devices. Challenges include low speed, accuracy and unpredictability of initial "internal type" BCIs that rely on conscious thought control. The project is pursuing an "external type" BCI using unconscious pattern conditioning training to improve speed, accuracy and consistency of thought-driven control.
IRJET- Design and Development of Electroencephalography based Cost Effect...IRJET Journal
This document describes a study on the design and development of a low-cost prosthetic arm controlled by brain waves. Researchers created an electroencephalography (EEG)-based system to read brain signals and control a prosthetic arm. The system detects different brain wave patterns like alpha, beta, gamma, delta and theta waves using EEG sensors. It then processes the signals with an Arduino microcontroller and uses servo motors to move the prosthetic arm. The goal is to make a prosthetic arm that can move similarly to a biological human arm by interpreting the user's thoughts detected through brain waves.
Application of swarm intelligence optimization in biomedical Aboul Ella Hassanien
The document summarizes a presentation on applying swarm intelligence optimization algorithms to biomedical applications. Specifically, it discusses using these algorithms to help predict epileptic seizures by analyzing electroencephalogram (EEG) data. The presentation introduces swarm algorithms and machine learning, describes how EEG data is used to detect epilepsy, and proposes a model for feature engineering of EEG data using swarm intelligence to help classify signals as normal or abnormal and predict seizures.
This document analyzes spectral features extracted from EEG signals to detect brain tumors. Sixteen candidate features were considered from 102 normal subjects and 100 brain tumor patients. Nine of the features showed a statistically significant difference between the two groups. Specifically, power ratio index, relative intensity ratio for different frequency bands, maximum-to-mean power ratio, peak bispectrum, peak bicoherence, and spectral entropy values were extracted from segmented EEG signals and compared between subjects. Statistical testing found that the mean values of nine features were significantly different between brain tumor patients and normal subjects, suggesting quantitative EEG analysis may help in diagnosis of brain tumors.
Neuro-technology aims to restore or improve human nervous system function through electronics. Neuromotor prostheses (NMPs) extract signals from the nervous system to control devices. The goal of NMPs is to convey motor control intent from the central nervous system to drive multi-degree of freedom prosthetic devices for amputees or paralyzed patients. Key challenges are developing neural interfaces that last a lifetime and providing dexterous, natural control of prosthetics. NMP systems involve neural implants to record brain signals, decoding software to translate signals into motor commands, and output devices like prosthetics. Technological advances now allow basic NMP control but further progress is still needed.
Amyotrophic Lateral Sclerosis (ALS) is the most common progressive neurodegenerative disorder reflecting
the degeneration of upper and lower motor neurons. Motor neurons controls the communication between nervous
system and muscles of the body. ALS results in the loss of voluntary control over muscular activities along with the
inability to breathe and the maximum life expectancy of affected individual will be 3-5 years from the onset of
symptoms. But the lifetime of affected people can be extended by early detection of disease. The usual methods for
diagnosis are Electromyography (EMG), Nerve Conduction Study (NCS), Magnetic Resonance Imaging (MRI) and
Magneto-encephalography (MEG). But some of these methods may erroneously result in neuropathy or myopathy
instead of ALS and some do not provide any biomarker. EEG is comparatively least expensive method and it
provides biomarker for ALS detection. ALS is always associated with fronto-temporal dementia (FTD). The spectral
analysis of EEG will reveal the structural and functional connectivity alterations of the underlying neural network
that occurs due to FTD and it can generate potential biomarkers for the early detection of ALS. A novel algorithm
has been developed by exploiting the Dual Tree Complex Wavelet Transform (DTCWT) technique and it can
overcome the short comes of existing methods for the analysis and feature extraction of EEG. Deterministic
biomarkers were obtained from spectral analysis of EEG and the proposed algorithm provided 100% accuracy for all
the test datasets.
Neuroprosthetics involves using brain signals acquired from neurons for various purposes like restoring movement in paralyzed patients. Nanotechnology like nano multi-electrode arrays can be used to receive and transmit brain signals more effectively by increasing electrode conduction and reducing incorrect connections with neurons. Neuroprosthetics has applications in both in vivo and in vitro contexts and can help improve functions like movement, speech, and understanding of drug effects on animal behavior and emotions.
This document describes a smart helmet system that embeds sensors to monitor the wearer's brain activity (EEG) and respiration. The system includes an Arduino microcontroller, GPS module, GSM module for emergency alerts, EEG sensor, respiratory sensor, and power supply. It monitors sensor values and compares them to normal tolerance levels. If any abnormal readings or accidents occur, the system sends an emergency alert message along with GPS location to recovery authorities. The wearer can also manually trigger an emergency message using a button. The document discusses recording EEG and ECG signals from inside the helmet and transmitting data to evaluate feasibility. It aims to monitor physiological signals during activities like sports or military engagements for safety.
Brain-Computer Interface: Rebuilding radically new output of the Human BrainArina Kochetova
This document discusses a brain-computer interface (BCI) research project led by Alexander Kaplan at Lomonosov Moscow State University. The project aims to establish direct communication between the human brain and external devices without using peripheral nerves or muscles. Kaplan's lab uses electroencephalography (EEG) to detect electrical brain activity and translate it into commands for prosthetics and other devices. Challenges include low speed, accuracy and unpredictability of initial "internal type" BCIs that rely on conscious thought control. The project is pursuing an "external type" BCI using unconscious pattern conditioning training to improve speed, accuracy and consistency of thought-driven control.
NEURO-IMAGING IN PSYCHIATRY MAY 2019.pptxssuser7567ef
Neuroimaging techniques such as CT, MRI, fMRI, SPECT, and MRS can be used in psychiatry to diagnose illnesses, develop new treatments, and analyze brain activity and clinically defined patient groups. Structural neuroimaging like CT and MRI are used to identify abnormalities, while functional techniques such as fMRI and SPECT measure brain activity and blood flow. Specific indications include evaluating neurological deficits, dementia, movement disorders, seizures, and investigating organic causes of psychiatric symptoms. Contrast agents may be used to enhance images and reveal abnormalities in vascular permeability. Each technique has advantages and limitations for clinical psychiatric applications.
This document discusses cochlear implants for adults. It covers the components and structure of cochlear implants, including external and internal parts. It discusses various speech processing strategies used by implants, including spectral peak, continuous interleaved sampling, and simultaneous analog strategies. The document also covers candidacy criteria, contraindications, rehabilitation process and potential complications of cochlear implants.
Somatosensory and motor evoked potentials by neelothpalavrkv2007
This document discusses somatosensory and motor evoked potentials. It begins by outlining the topics that will be covered, including the anatomical and physiological basis of sensory and motor evoked potentials, methods of evaluation, measurement and interpretation, clinical applications, and therapeutic applications. It then goes on to provide details on somatosensory evoked potentials, including the anatomical and physiological basis, methods of evaluation such as for median and tibial nerves, measurements, generators, and clinical applications. It similarly provides information on motor evoked potentials, including the physiological anatomy of corticospinal tracts and the physiological basis of motor evoked potentials.
EEG has relatively low sensitivity (25–56%) for diagnosing epilepsy but high specificity (78–98%). Epileptiform discharges are seen in 0.5% of healthy adults on routine EEG but 10-30% in those with brain pathologies. Factors like the location of the epileptogenic zone, seizure frequency, and timing of the EEG affect whether a patient shows interictal epileptiform discharges. Intraoperative electrocorticography directly records cortical potentials during epilepsy surgery to localize the irritative zone, map brain functions, and predict surgical outcomes. It has higher spatial resolution than scalp EEG but recordings are limited by anesthesia effects and duration.
The document discusses bionic eyes and their technological components. It describes how a bionic eye works by having electrodes implanted on the retina that are connected to a camera, video processing unit, and wireless transmitter. The Argus II is highlighted as the most advanced retinal prosthesis currently. It summarizes the key components of a bionic eye like the camera sensor technology, video processing unit, wireless transmission, and microelectrode array. The document also outlines improvements in resolution, material biocompatibility, wireless efficiency, and decreasing costs and size over time as important future opportunities to enhance bionic eye technology.
This case study describes a 54-year-old woman with recurrent epithelial ovarian cancer who was undergoing chemotherapy. After her cancer progressed on multiple lines of chemotherapy including paclitaxel/carboplatin and topotecan, she received ifosfamide. She then developed neurological symptoms and an electroencephalogram showed periodic triphasic waves, indicating ifosfamide-induced encephalopathy. Her chemotherapy was stopped but her encephalopathy worsened and she developed kidney damage from the ifosfamide. She ultimately passed away from her complications within a month.
This case study describes a 54-year-old woman with recurrent epithelial ovarian cancer who was undergoing chemotherapy. After her third round of ifosfamide treatment, she developed neurological symptoms. An electroencephalogram (EEG) detected frequent low-frequency periodic waves across both hemispheres, consistent with ifosfamide-induced encephalopathy. Her chemotherapy was stopped but her condition deteriorated further with worsening encephalopathy and acute kidney injury, and she ultimately passed away within a month.
This document discusses epilepsy surgery evaluation and outcomes. It notes that about one-third of epilepsy patients have seizures that cannot be controlled with medication. For these patients, surgical therapy can be an important treatment option. The goals of presurgical evaluation are to localize the epileptogenic zone and assess risk to brain functions from surgery. Evaluations may include brain imaging, video-EEG monitoring, neuropsychological testing, and in some cases invasive monitoring. Common indications for surgery include mesial temporal lobe epilepsy and lesions. Seizure freedom rates after surgery range from 50-90% depending on the specific diagnosis and evaluation findings. Outcome measures also consider cognitive and quality of life impacts.
This document provides a summary of a presentation on 10-20 EEG placement for polysomnography studies. It begins with an overview of the workshop plan, which focuses on demonstrating the international 10-20 system, the practical steps for setting up a 10-20 EEG montage, and giving participants hands-on experience. The presentation then reviews the basics of the 10-20 system, electrode placement for sleep studies, and preparation including measuring the head, identifying landmarks, and cleaning the skin. Finally, it outlines performing a calibration to check signals and provides references for further reading.
This document discusses a proposed project for an upcoming H2020 call focused on developing adaptive smart working environments to support active and healthy aging. The project would aim to improve data collection methods for monitoring musculoskeletal disorders (MSDs) using miniaturized wearable and implant sensors for real-time posture and load monitoring. Both local processing for early warnings and remote cloud-based analytics of big sensor data using machine learning are proposed. Relevant technologies, stakeholders, and potential partner institutions across Estonia, France, UK are outlined to support the transdisciplinary nature of the project.
Evoked potentials are electrical signals produced by the nervous system in response to external stimuli. The document discusses several types of evoked potentials including brainstem auditory evoked potentials (BAEP), visual evoked potentials (VEP), and somatosensory evoked potentials (SEP). For BAEP, electrodes are placed on the ear and vertex to assess conduction through the auditory pathway up to the midbrain. VEP involves recording potentials from the scalp in response to visual stimuli to evaluate visual function. SEP evaluates sensory pathways from peripheral nerves to the spinal cord and cortex by stimulating nerves like the median and posterior tibial. The document outlines the electrode placement, stimulation parameters, and normal/abnormal findings for these ev
Electroencephalography (EEG) is a technique used to analyze neural activity in the brain. EEG measures electrical activity using electrodes placed on the scalp. It has several uses such as medical diagnosis and research. Some key points are:
- EEG was developed in the early 20th century and works by measuring voltage fluctuations resulting from ionic current flows in neurons.
- It has advantages like being noninvasive and having good temporal resolution, but disadvantages like having poor spatial resolution.
- EEG signals are classified by frequency into different wave types including alpha, beta, theta, delta, and gamma waves which correlate with different brain states.
- Applications include diagnosing brain disorders, brain-computer interfaces,
1. Preperimetric glaucoma is characterized by optic nerve abnormalities detected through imaging and testing, even though standard visual field tests are still normal.
2. Electrophysiological tests like pattern electroretinography (PERG) and multifocal visual-evoked potentials (mfVEP) can detect early ganglion cell damage before visual field loss occurs.
3. Imaging technologies like confocal scanning laser ophthalmoscopy (CSLO), optical coherence tomography (OCT), and scanning laser polarimetry provide structural evaluation of the optic nerve head and retina to diagnose and monitor glaucoma progression.
This document provides a history of optical fiber technology from ancient times to modern applications. It discusses early experiments with light transmission through glass fibers in the 1600-1800s. Major developments include the first demonstrations of signal transmission through fiber bundles in the 1950s and the conception of using single mode fiber for communications in the 1960s. The document outlines the evolution of fiber materials and lasers to reduce losses and enable high-speed digital transmission. It also covers the development of optical amplifiers and WDM to increase network capacity. The document discusses various applications of optical fibers including telecommunications, sensors, and fiber-optic networks.
IRJET- An Efficient Approach for Removal of Ocular Artifacts in EEG-Brain Com...IRJET Journal
This document summarizes a research paper that proposes a method to remove ocular artifacts from electroencephalogram (EEG) signals. Ocular artifacts are contaminants in EEG signals caused by eye blinks and movements that can distort the brain activity being measured. The proposed method uses discrete wavelet transform (DWT) to isolate the ocular artifact components in the frequency domain. It then applies adaptive noise cancellation (ANC) to the wavelet coefficients to remove the artifact components without damaging the underlying brain activity signal. The method is intended to enable more effective analysis of EEG data for applications like diagnosing epilepsy and developing brain-computer interfaces.
High-intensity LEDs are embedded in the flash stimulation pad
The small disc shape and silicone properties of the pad make it both flexible and lightweight
Illuminance can be set up to 20,000 lux, and different light emission times and cycles can be chosen.
A common system for placing electrodes is the “10-20 International System” which is based on measurements of head size (Jasper, 1958).
The mid-occipital electrode location (OZ) is on the midline.
The distance above the inion calculated as 10 % of the distance between the inion and nasion, which is 3-4 cm in most adults
Lateral occipital electrodes are a similar distance off the midline.
To have reliable VEPs, Intraoperatively, the following factors are important
Maintaining normal intraoperative physiological/hemodynamic parameters
Use of TIVA instead of inhalational anesthesia
Better stimulus delivery methods
Recording intraoperative ERG to ensure good retinal stimulation and
Employing optimal recording parameters
Evoked potentials are low amplitude electrical potentials recorded from the brain or peripheral nerves in response to sensory stimuli. They are used to evaluate the function of sensory and motor pathways. There are several types including sensory evoked potentials from visual, auditory and somatosensory stimulation as well as motor evoked potentials. Recording techniques involve signal averaging to detect the low amplitude signals. Evoked potentials provide objective measures for diagnosing various neurological disorders.
AURO-QUANT: Demonstration of a capillary-flow Point of Care (PoC) device "Immuno-CAP" for the measurement of progestrone in bovine milk
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Similar to Performing electrophysiological measurements in humans inside Magnetic Resonance Imaging scanners; applications in Epilepsy research and other areas
NEURO-IMAGING IN PSYCHIATRY MAY 2019.pptxssuser7567ef
Neuroimaging techniques such as CT, MRI, fMRI, SPECT, and MRS can be used in psychiatry to diagnose illnesses, develop new treatments, and analyze brain activity and clinically defined patient groups. Structural neuroimaging like CT and MRI are used to identify abnormalities, while functional techniques such as fMRI and SPECT measure brain activity and blood flow. Specific indications include evaluating neurological deficits, dementia, movement disorders, seizures, and investigating organic causes of psychiatric symptoms. Contrast agents may be used to enhance images and reveal abnormalities in vascular permeability. Each technique has advantages and limitations for clinical psychiatric applications.
This document discusses cochlear implants for adults. It covers the components and structure of cochlear implants, including external and internal parts. It discusses various speech processing strategies used by implants, including spectral peak, continuous interleaved sampling, and simultaneous analog strategies. The document also covers candidacy criteria, contraindications, rehabilitation process and potential complications of cochlear implants.
Somatosensory and motor evoked potentials by neelothpalavrkv2007
This document discusses somatosensory and motor evoked potentials. It begins by outlining the topics that will be covered, including the anatomical and physiological basis of sensory and motor evoked potentials, methods of evaluation, measurement and interpretation, clinical applications, and therapeutic applications. It then goes on to provide details on somatosensory evoked potentials, including the anatomical and physiological basis, methods of evaluation such as for median and tibial nerves, measurements, generators, and clinical applications. It similarly provides information on motor evoked potentials, including the physiological anatomy of corticospinal tracts and the physiological basis of motor evoked potentials.
EEG has relatively low sensitivity (25–56%) for diagnosing epilepsy but high specificity (78–98%). Epileptiform discharges are seen in 0.5% of healthy adults on routine EEG but 10-30% in those with brain pathologies. Factors like the location of the epileptogenic zone, seizure frequency, and timing of the EEG affect whether a patient shows interictal epileptiform discharges. Intraoperative electrocorticography directly records cortical potentials during epilepsy surgery to localize the irritative zone, map brain functions, and predict surgical outcomes. It has higher spatial resolution than scalp EEG but recordings are limited by anesthesia effects and duration.
The document discusses bionic eyes and their technological components. It describes how a bionic eye works by having electrodes implanted on the retina that are connected to a camera, video processing unit, and wireless transmitter. The Argus II is highlighted as the most advanced retinal prosthesis currently. It summarizes the key components of a bionic eye like the camera sensor technology, video processing unit, wireless transmission, and microelectrode array. The document also outlines improvements in resolution, material biocompatibility, wireless efficiency, and decreasing costs and size over time as important future opportunities to enhance bionic eye technology.
This case study describes a 54-year-old woman with recurrent epithelial ovarian cancer who was undergoing chemotherapy. After her cancer progressed on multiple lines of chemotherapy including paclitaxel/carboplatin and topotecan, she received ifosfamide. She then developed neurological symptoms and an electroencephalogram showed periodic triphasic waves, indicating ifosfamide-induced encephalopathy. Her chemotherapy was stopped but her encephalopathy worsened and she developed kidney damage from the ifosfamide. She ultimately passed away from her complications within a month.
This case study describes a 54-year-old woman with recurrent epithelial ovarian cancer who was undergoing chemotherapy. After her third round of ifosfamide treatment, she developed neurological symptoms. An electroencephalogram (EEG) detected frequent low-frequency periodic waves across both hemispheres, consistent with ifosfamide-induced encephalopathy. Her chemotherapy was stopped but her condition deteriorated further with worsening encephalopathy and acute kidney injury, and she ultimately passed away within a month.
This document discusses epilepsy surgery evaluation and outcomes. It notes that about one-third of epilepsy patients have seizures that cannot be controlled with medication. For these patients, surgical therapy can be an important treatment option. The goals of presurgical evaluation are to localize the epileptogenic zone and assess risk to brain functions from surgery. Evaluations may include brain imaging, video-EEG monitoring, neuropsychological testing, and in some cases invasive monitoring. Common indications for surgery include mesial temporal lobe epilepsy and lesions. Seizure freedom rates after surgery range from 50-90% depending on the specific diagnosis and evaluation findings. Outcome measures also consider cognitive and quality of life impacts.
This document provides a summary of a presentation on 10-20 EEG placement for polysomnography studies. It begins with an overview of the workshop plan, which focuses on demonstrating the international 10-20 system, the practical steps for setting up a 10-20 EEG montage, and giving participants hands-on experience. The presentation then reviews the basics of the 10-20 system, electrode placement for sleep studies, and preparation including measuring the head, identifying landmarks, and cleaning the skin. Finally, it outlines performing a calibration to check signals and provides references for further reading.
This document discusses a proposed project for an upcoming H2020 call focused on developing adaptive smart working environments to support active and healthy aging. The project would aim to improve data collection methods for monitoring musculoskeletal disorders (MSDs) using miniaturized wearable and implant sensors for real-time posture and load monitoring. Both local processing for early warnings and remote cloud-based analytics of big sensor data using machine learning are proposed. Relevant technologies, stakeholders, and potential partner institutions across Estonia, France, UK are outlined to support the transdisciplinary nature of the project.
Evoked potentials are electrical signals produced by the nervous system in response to external stimuli. The document discusses several types of evoked potentials including brainstem auditory evoked potentials (BAEP), visual evoked potentials (VEP), and somatosensory evoked potentials (SEP). For BAEP, electrodes are placed on the ear and vertex to assess conduction through the auditory pathway up to the midbrain. VEP involves recording potentials from the scalp in response to visual stimuli to evaluate visual function. SEP evaluates sensory pathways from peripheral nerves to the spinal cord and cortex by stimulating nerves like the median and posterior tibial. The document outlines the electrode placement, stimulation parameters, and normal/abnormal findings for these ev
Electroencephalography (EEG) is a technique used to analyze neural activity in the brain. EEG measures electrical activity using electrodes placed on the scalp. It has several uses such as medical diagnosis and research. Some key points are:
- EEG was developed in the early 20th century and works by measuring voltage fluctuations resulting from ionic current flows in neurons.
- It has advantages like being noninvasive and having good temporal resolution, but disadvantages like having poor spatial resolution.
- EEG signals are classified by frequency into different wave types including alpha, beta, theta, delta, and gamma waves which correlate with different brain states.
- Applications include diagnosing brain disorders, brain-computer interfaces,
1. Preperimetric glaucoma is characterized by optic nerve abnormalities detected through imaging and testing, even though standard visual field tests are still normal.
2. Electrophysiological tests like pattern electroretinography (PERG) and multifocal visual-evoked potentials (mfVEP) can detect early ganglion cell damage before visual field loss occurs.
3. Imaging technologies like confocal scanning laser ophthalmoscopy (CSLO), optical coherence tomography (OCT), and scanning laser polarimetry provide structural evaluation of the optic nerve head and retina to diagnose and monitor glaucoma progression.
This document provides a history of optical fiber technology from ancient times to modern applications. It discusses early experiments with light transmission through glass fibers in the 1600-1800s. Major developments include the first demonstrations of signal transmission through fiber bundles in the 1950s and the conception of using single mode fiber for communications in the 1960s. The document outlines the evolution of fiber materials and lasers to reduce losses and enable high-speed digital transmission. It also covers the development of optical amplifiers and WDM to increase network capacity. The document discusses various applications of optical fibers including telecommunications, sensors, and fiber-optic networks.
IRJET- An Efficient Approach for Removal of Ocular Artifacts in EEG-Brain Com...IRJET Journal
This document summarizes a research paper that proposes a method to remove ocular artifacts from electroencephalogram (EEG) signals. Ocular artifacts are contaminants in EEG signals caused by eye blinks and movements that can distort the brain activity being measured. The proposed method uses discrete wavelet transform (DWT) to isolate the ocular artifact components in the frequency domain. It then applies adaptive noise cancellation (ANC) to the wavelet coefficients to remove the artifact components without damaging the underlying brain activity signal. The method is intended to enable more effective analysis of EEG data for applications like diagnosing epilepsy and developing brain-computer interfaces.
High-intensity LEDs are embedded in the flash stimulation pad
The small disc shape and silicone properties of the pad make it both flexible and lightweight
Illuminance can be set up to 20,000 lux, and different light emission times and cycles can be chosen.
A common system for placing electrodes is the “10-20 International System” which is based on measurements of head size (Jasper, 1958).
The mid-occipital electrode location (OZ) is on the midline.
The distance above the inion calculated as 10 % of the distance between the inion and nasion, which is 3-4 cm in most adults
Lateral occipital electrodes are a similar distance off the midline.
To have reliable VEPs, Intraoperatively, the following factors are important
Maintaining normal intraoperative physiological/hemodynamic parameters
Use of TIVA instead of inhalational anesthesia
Better stimulus delivery methods
Recording intraoperative ERG to ensure good retinal stimulation and
Employing optimal recording parameters
Evoked potentials are low amplitude electrical potentials recorded from the brain or peripheral nerves in response to sensory stimuli. They are used to evaluate the function of sensory and motor pathways. There are several types including sensory evoked potentials from visual, auditory and somatosensory stimulation as well as motor evoked potentials. Recording techniques involve signal averaging to detect the low amplitude signals. Evoked potentials provide objective measures for diagnosing various neurological disorders.
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This document summarizes a presentation on marine chemistry given at Dublin City University. It discusses several topics related to marine chemistry including ocean services, the history of understanding salinity, ocean carbon and acidification, monitoring hazardous substances, and shellfish toxins. Diagrams are included on topics like biogeochemical processes in the oceans, climate change impacts like ocean acidification and nutrients, and types of pollution affecting the oceans.
This document discusses using boronic acid fluorophores for saccharide sensing to enable non-invasive glucose monitoring. It outlines the health issues of diabetes that better glucose monitoring could help address. Current monitoring methods like finger pricking and implanted devices are discussed. The document proposes using boronic acid sensors immobilized on contact lenses as a continuous and non-invasive monitoring platform. It describes synthesizing novel boronic acid sensors and shows their ability to fluorescently detect glucose concentration changes. Future work includes immobilizing the sensors on a lens platform for ocular glucose sensing.
The document discusses the development of point-of-use nanosensors for applications in sustainable agriculture, food safety, and environmental monitoring. It describes the vision for decentralized testing using nanosensors for rapid, on-site detection of important parameters. This would allow for real-time monitoring of events like disease outbreaks or nutrient levels. Examples discussed include nanosensors for disease diagnosis in livestock and label-free detection of viruses. The goals are to develop low-cost, easy-to-use nanosensor systems that can provide rapid, accurate results comparable to laboratory tests and allow for on-farm use.
This document discusses using inertial microfluidics to temporally resolve the receptor activation mechanisms of EGFR. The goal is to preserve reaction intermediates during ligand-induced receptor activation by delivering ligand in milliseconds, providing uniform incubation times, and rapidly quenching the reaction to enable analysis of phosphorylated tyrosine levels. This approach aims to determine the phosphorylation sequence during receptor activation and how it relates to monomer and dimer states of EGFR using inertial focusing in a microfluidic device to control incubation times with millisecond precision.
This document discusses the evolution of microfluidics and biosensors towards systems with revolutionary analytical capabilities. It covers topics such as continuous monitoring sensors, implantable glucose sensors, commercial products like Abbott's Freestyle Libre, Google's contact lens project, and challenges around long-term reliable sensing. The document also examines autonomous platforms for water quality monitoring and reagent-based techniques versus direct sensing approaches.
This document summarizes methods for analyzing oxyhalides using ion chromatography-mass spectrometry (IC-MS). It outlines considerations for coupling IC to MS, including flow rate compatibility and eluent volatility. Two main coupling methods are described: solvent addition, where an organic solvent is added post-column, and direct coupling, with organic solvent added pre-separation. Both methods are shown to achieve low detection limits in the picogram range for oxyhalides like bromate and perchlorate. Direct coupling provides better retention time reproducibility and precision compared to solvent addition. The document concludes by acknowledging contributions and providing information on submitting a poster abstract for a conference on the topic.
This document discusses challenges in method validation from a regulatory laboratory perspective. It begins by defining validation and why it is important. Developing a validation procedure requires following accreditation standards and legislation. Harmonizing the validation approach has advantages like allowing results comparison. Key challenges include a lack of certified analytical standards, validating for multiple matrices, calculating measurement uncertainty, finding proficiency tests, ongoing verification, and determining what constitutes revalidation. The document promotes Eurachem resources on method validation and an upcoming Irish workshop on the topic.
The document discusses trends in the pharmaceutical industry through 2020. It notes ongoing challenges like unmet medical needs, aging populations, and chronic diseases. Future drivers include these aging and underserved populations in developing countries and effects of global warming. The industry will see more integrated value chains between pharma, payers, and providers. Treatment costs are unsustainable so the focus will shift to prevention and pharma providing full healthcare packages with payment for outcomes not just treatment. Pharma business models will change significantly, moving from blockbuster drug sales to more services across the healthcare spectrum. Laboratories of the future will need to develop new capabilities and talent to achieve this changed vision.
This document summarizes Dr. Saidhbhe O'Riordan's research using electrochemical methods to monitor physiological biomarkers in real-time. Specifically, it discusses using sensors to detect hydrogen peroxide levels in rodent brains to study disorders like Parkinson's disease, and oxygen levels to evaluate muscle tissue viability and potentially translate this to human patients. The research aims to further understand disease pathogenesis and provide diagnostic tools. Key findings include characterizing a dual catalase-based sensor for detecting brain hydrogen peroxide levels in freely-moving animals and developing an oxygen sensor with potential for clinical use in monitoring brain and peripheral oxygen levels in rodents and eventually humans.
This document discusses new technologies for single cell detection and analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). It describes a method for labelling T cells with gadolinium for tracking cell-based therapies. A new laser ablation system design is presented that improves speed and sensitivity for single cell analysis by using a small inner chamber and single diameter transport tubing to minimize sample loss. The system enables detection of labelled cells for over 10 days both in vitro and in mouse studies.
This document outlines a presentation on innovative strategies to accelerate drug development. It discusses Pfizer's locations in the UK and facilities for research, manufacturing, and commercial operations. Predictive science approaches using advanced data and technologies are described to enable accelerated development from molecule to medicine. Continuous manufacturing platforms and modular facilities are presented as ways to improve efficiency.
This document discusses prospects for myocardial tissue engineering. It begins by outlining epidemiological data on heart failure mortality rates compared to cancer. It then reviews the number of heart transplants performed globally each year. The document discusses challenges with current continuous-flow ventricular assist devices and INTERMACS registry data. Alternatives to heart transplantation explored include mechanical assist devices, polymers, cell therapy, and tissue engineering. Early cell transplantation studies and limitations are outlined. The unique complexities of engineering myocardial tissue are discussed. Studies generating vascularized cardiac grafts and decellularized heart scaffolds are summarized. Recent work on electrically contractile polymers for augmenting right ventricular function is presented.
This document summarizes Professor Tony Killard's presentation on printed sensor technology for commercialization. It discusses combining advanced functional materials, printing production technology, and bioassay integration to produce point-of-care diagnostic devices. Specifically, it focuses on developing an ammonia breath sensor called AmBeR for applications in monitoring liver and kidney function. The presentation provides details on inkjet printing polyaniline nanoparticle sensors, correlating sensor responses to clinical measurements, and plans for clinical evaluations and mass production to commercialize the AmBeR sensor technology.
This document discusses the use of soft x-ray nanoanalytical tools for studying thin film organic electronics. Specifically, it summarizes research using scanning transmission x-ray microspectroscopy (STXM) and resonant soft x-ray scattering (RSoXS) to characterize the nanoscale morphology, chemical composition, and charge transport properties of organic thin films and devices. STXM provides chemical imaging down to 12 nm resolution while RSoXS can resolve structures below the STXM resolution limit. Together these techniques provide insights into structure-property relationships in organic photovoltaics, field-effect transistors, and other organic electronic materials and devices.
1) Researchers at the University of Manchester isolated graphene in 2004 and were awarded the Nobel Prize in Physics in 2010 for their work.
2) Plans were announced in 2013 and 2014 to build the £61m National Graphene Institute and £60m Graphene Engineering Innovation Centre to further research and commercialize graphene.
3) The document outlines ongoing graphene research at Manchester in areas such as energy storage, membranes, composites, printing, and 2D materials beyond graphene, as well as production methods and potential applications of graphene.
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...Creative-Biolabs
Neutralizing antibodies, pivotal in immune defense, specifically bind and inhibit viral pathogens, thereby playing a crucial role in protecting against and mitigating infectious diseases. In this slide, we will introduce what antibodies and neutralizing antibodies are, the production and regulation of neutralizing antibodies, their mechanisms of action, classification and applications, as well as the challenges they face.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
Signatures of wave erosion in Titan’s coastsSérgio Sacani
The shorelines of Titan’s hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
PPT on Sustainable Land Management presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
Performing electrophysiological measurements in humans inside Magnetic Resonance Imaging scanners; applications in Epilepsy research and other areas
1. Performing electrophysiological
measurements in humans inside Magnetic
Resonance Imaging scanners; applications in
Epilepsy research and other areas
Louis Lemieux
Department of Clinical and Experimental Epilepsy
UCL Institute of Neurology, Queen Square, London
&
MRI Unit, Epilepsy Society
Chalfont St Peter, Buckinghamshire
UK
2. Lemieux – ACES / Europe Dublin 2015
Outline
• Epilepsy
• Multimodal neuroimaging in humans
– EEG and functional MRI (fMRI)
– Mapping epileptic events using scalp EEG-fMRI
• Going deeper: intracranial EEG-fMRI
– Technique implementation
– An epileptic seizure
• Conclusions
3. Lemieux – ACES / Europe Dublin 2015
Epilepsy
• Epilepsy is the most common serious chronic neurological
condition affecting all ages
– 50 million people affected in the world
– Economic costs (~€20 billion/year for Europe).
• 30% of all people with epilepsy have seizures that do not respond to
medical treatment, leading to:
– Cognitive decline
– Poor quality of life
– Significantly increased mortality
– High societal costs
• Need for improved treatment
– Surgery
– Drug delivery
• Need for improved localisation of the epileptogenic areas
4. Lemieux – ACES / Europe Dublin 2015
• fMRI
– Allows tomographic visualisation of haemodynamic changes associated with
brain activity
– Has better temporal resolution than PET (…for epileptic spikes)
– Is non-invasive (BOLD)
• EEG
– Important observable of brain activity in humans
– Reflects neuronal signal generation and synchronisation
– Important clinical tool in epilepsy (epileptic spikes, seizures, etc)
– Non-invasive (scalp) & cheap
Basic principles: EEG & fMRI
5. Lemieux – ACES / Europe Dublin 2015
LF= 0.5 Hz HF= 30 Hz
1 sec.
25 uV
10:36:33 10:36:34 10:36:35 10:36:36
Fp2-F8
F8-T4
T4-T6
T6-O2
Fp1-F7
F7-T3
T3-T5
T5-O1
ECG1-ECG2
Epileptic spikes
• Spatially linked to the epileptic focus
• Brief (<100ms), unpredictable
• Sub-clinical: can only be seen on EEG
• Epileptic spike source localisation
– Inverse problem of EEG…
– Can fMRI better localise epileptic spike
generators?
– Clinical utility?
6. Lemieux – ACES / Europe Dublin 2015
EEG-fMRI in epilepsy
Data acquisition strategy
Subject at rest
Simultaneous EEG-MRI
• fMRI:
− Echo-planar imaging (EPI) fMRI
scanning sequences
− Whole-brain coverage
• EEG:
− 64-channel cap on scalp
− MR-compatible amplifier and digitiser
− Digital signal transmitted to recording
laptop outside the scanner room
7. Lemieux – ACES / Europe Dublin 2015
EEG-fMRI of epileptic spikes
Continuous EEG and fMRI:
EEG-based
GLM
Spike-related BOLD
[Krakow et al, 1999; Lemieux et al, 2001]
1 sec.
25 uV
10:36:33 10:36:34 10:36:35 10:36:36
Fp2-F8
F8-T4
T4-T6
T6-O2
Fp1-F7
F7-T3
T3-T5
T5-O1
ECG1-ECG2
11. Lemieux – ACES / Europe Dublin 2015
Clinical relevance: EEG-fMRI of epileptic spikes in
Focal Cortical Dysplasia
ANN NEUROL 2011;70:822–837
Conclusion:
Scalp EEG-fMRI of epileptic spikes may predict less promising
surgical cases and therefore avoid unnecessary invasive interventions
12. Lemieux – ACES / Europe Dublin 2015
icEEG: Subdural grids and depth electrodes
• Surgically placed on cortex
• Sampling similar to high-density scalp EEG
• Used to map epileptogenic tissue in relation to eloquent
cortex
• 6x8 array of 3mm diameter Pt-Ir disk contacts
[Fried et al, 1999]
• Surgically inserted within brain
• Used to detect epileptogenicity and propagation in deep
cortex/lesions
• Sensitivity profile very different from scalp EEG and grids:
‘tunnel vision’ [see Cosandier et al 2007; Church et al, 1985]
• ‘Spencer probe’ commercial design
• Pt-Ir cylindrical contacts & Ni-Cr terminations and wires
contained in polyurethane
13. Lemieux – ACES / Europe Dublin 2015
[Carmichael et al, 2009; 2012]
•Health hazards
•RF-induced heating
•Induced voltages (stimulation)
•Factors considered:
•Field strength: 1.5T and 3T
•RF transmit coil type: head and body
•Electrodes: depths and grids
•EEG wires
•Geometry and placement
•Length
•Termination
Simultaneous icEEG-fMRI:
Safety tests in phantoms
14. Lemieux – ACES / Europe Dublin 2015
[Carmichael et al, 2009, 2012]
•RF-induced heating greatest health risk
•Excessive heating observed
•Body coil
•3T
•But for certain realistic conditions:
Max ∆T = 0.9ºC (@1.5T, SAR=2.4W/Kg,
6mins)
icEEG-fMRI possible without
excessive additional health risk
under certain conditions
Site-specific assessment necessary
Intra-cranial EEG-fMRI safety study results:
Heating tests
15. Lemieux – ACES / Europe Dublin 2015
1) Use likely safest regime
2) Strict protocol:
- 1.5T Siemens Avanto / head (quad.) Tx/Rx coil
- 90cm cables with 10cm fold along scanner central Z xis
- Foam insert designed for exact positioning
- Position EEG system and cables reproducibly
- Low SAR sequences:
- T1 volume, gradient echo EPI [TE=40ms], B0 map
- 3-4% of 3.2 W/Kg
- max duration 10 minutes
3) Close monitoring and documenting of patient responses,
images, appearance of brain surface, histology
icEEG-fMRI: Implementation
16. Lemieux – ACES / Europe Dublin 2015
icEEG-fMRI image quality:
EPI signal degradation around electrodes
[Carmichael et al, 2012]
17. Lemieux – ACES / Europe Dublin 2015
icEEG-fMRI image quality:
EPI signal degradation around electrodes
[Carmichael et al, 2012]
18. Lemieux – ACES / Europe Dublin 2015
Feasibility study case report:
• Seizures: R hand stiffening
• MRI normal
• No spikes during scalp EEG-fMRI
• icEEG implantation: grids and strips over
left frontal lobe
• Two 10-minute resting-state icEEG-fMRI
sessions:
•100’s of L fronto-central spikes
L
icEEG-fMRI
MEG: IED onset
L
L
MEG: IED propagation
L
L
irritative zone
Demonstration of spike-correlated icEEG-fMRI
[Vulliemoz/Carmichael et al, 2010]
19. Lemieux – ACES / Europe Dublin 2015
Conclusions
EEG-fMRI allows:
• Haemodynamic mapping of events with specific EEG features
• ‘Extends’ EEG: whole-brain coverage, source complexity-independent
Intracranial EEG-fMRI:
• Fascinating, complex data
• Exquisite electrophysiological sensitivity
• Image data quality is an issue:
− Electrode composition is suboptimal for MR imaging
− Clinical impact: Limits ability to locate the electrodes in relation to the
anatomy
− Research impact: Reduces the amount of fMRI signal available for
analysis
20. Lemieux – ACES / Europe Dublin 2015
Team / collaborators / funding
David W. Carmichael
Umair Chaudhary
Ana-Carolina Coan (Campinas)
Alessio De Ciantis (Firenze)
Beate Diehl
John S. Duncan
Madeline Grade
Marco Leite
Andrew McEvoy
Teresa Murta
Irene Pappalardo
Suejen Perani (King’s)
Sofia Markoula (Ioannina)
Roman Rodionov
Catherine Scott
Niraj Sharma
Rachel C. Thornton
André van Graan
Anna Vaudano (Modena)
Matthew C. Walker
Britta Wandschneider
+ The Clinical Neurophysiology and
Neuroradiology teams at the National Hospital
for Neurology and Neurosurgery, Queen Square
K Friston (UCL)
M Guye / F Bartolomei / P Chauvel / JP Ranjeva (Marseille)
S Vulliemoz / C Michel (Geneva)
P Figueiredo (Lisbon)
M Papadopoulou / D Marinazzo (Ghent)
Radhakrishnan A / Chandrasekharan K / Sreedharan S
(Trivandrum)
R Quian Quiroga / C Pedreira (Leicester)
V Kokkinos (Thessaloniki)
S Meletti (Modena)
F Cendes (Campinas)
K Mullinger / R Bowtell (Nottingham)
KR Muller / V Samek / D Blythe (Berlin)
H Laufs (Frankfurt)
J Daunizeau (Paris)
K Whittingstall (Sherbrooke)
E Formisano / F De Martino (Maastricht)
M Torkmani Azar (Konya)
Funding:
Action Medical Research
Brain Research Trust / James Tudor Foundation
NIHR (UK Department of Health)
Medical Research Council
Support in kind:
Brain Products
22. Lemieux – ACES / Europe Dublin 2015
The problem of presurgical test validation
• Validation of localisation tests in epilepsy is fundamentally limited
• Gold standard is not golden:
• Surgical resection localisation and outcome data
• Ictiogenic ‘source’ must be considered a network in most patients a
priori
• Elements of a possible solution
• Improved characterisation / Modelling
• Functional connectivity networks
• Effective connectivity (“DCM”)
• Validation / Interventions:
• Surgical: connection disruptions (functional connectivity sufficient?)
• More sophisticated: stimulation (effective connectivity necessary?)
23. Lemieux – ACES / Europe Dublin 2015
What else the EEG-fMRI can tell us?
Psychophysiologial interaction (PPI)
-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8
-1.5
-1
-0.5
0
0.5
1
1.5
LFdl activity
LFpresponse
Psychophysiologic Interaction
IED
seed ROI
Vaudano et al., 2013-Frontiers in Neurology
2. Connectivity analysis
26. Lemieux – ACES / Europe Dublin 2015
EEG oscillations: their functional roles and brain state
correlates
Classical EEG oscillation bands
• Delta (0.5-3.5Hz):
– deep sleep, learning, motivational processes and reward system
• Theta (4-7 Hz):
– working memory, emotional arousal and fear conditioning
• Alpha (8-12 Hz):
– cortical operations during the awake resting-state in the absence of
sensory inputs, disengagement of task-irrelevant brain areas, working
memory and short-term-memory retention
– Rolandic Alpha / ‘Mu rhythm’ (9-11 Hz)
• Suppressed during task
• Beta (13-30 Hz):
– Vigilence and attention
– Rolandic Beta
• Linked to motor functions
• Inhibited by motor imagery
• Gamma (> 30 Hz):
– feature integration, attention, etc
27. Lemieux – ACES / Europe Dublin 2015
Rolandic Alpha (‘Mu’) and Beta on Scalp EEG
• What are their respective roles?
• They fluctuate similarly but are not perfectly correlated
• Based on MEG, their spatial distributions seem to differ:
• Rolandic Alpha: post-central (primary somatosensory)
• Rolandic Beta: pre-central (primary motor)
• fMRI-based localisation?...
28. Lemieux – ACES / Europe Dublin 2015
fMRI of Rolandic Alpha and Beta on scalp EEG: Ritter
et al, 2009
• Bilateral hand motor task
• 15 healthy subjects
• Two main fMRI models:
• Band/channel
• Blind source separation
Beta – BOLD correlation:
Conclusions
Complex data quality correction and modelling methodology
BOLD of Rolandic alpha and beta rhythms differ: postcentral gyrus
(SI) for alpha and precentral gyrus (MI) for beta;
Negative Rolandic alpha and beta rhythms - BOLD correlation in the
pericentral cortex
29. Lemieux – ACES / Europe Dublin 2015
BOLD Mapping of Rolandic Alpha and Beta
oscillations on ECoG
HRF
Band
Averaging
(around
peak)
0.5mV
M1
S
1
M1
S1
Identification of
patient-specific
band peak
Spatial PCA:
1st PC
[Perani et al, in preparation]
Grid placed over left motor cortex
icEEG-fMRI:
• Rest (epileptic activity mapping)
• Alternating finger tapping task (no rest)
For each band:
Alpha and Beta
30. Lemieux – ACES / Europe Dublin 2015
L
L
L
L
[Perani et al, in preparation]
BOLD Mapping of Rolandic Alpha and Beta on ECoG:
Task data
BOLD increases
BOLD decreases BOLD decreases
BOLD increases
Alpha (Mu) Beta
31. Lemieux – ACES / Europe Dublin 2015
Intra-cranial EEG-fMRI of interictal spikes
Summary BOLD maps across all IZ1 IED
[Chaudhary - submitted]
7 cases had concordant maps:
better outcome (ILAE 1 & 3)
5 cases had discordant maps:
worse outcome (ILAE 4 & 5; 5 cases)
Case # 3 (ILAE class 1)
Case # 13 (ILAE class 4)
SPM{F} contrast across all IZ1 IED-
related effects
Summary measure for comparison:
Relationship of BOLD clusters with
the presumed, icEEG-derived EZ
32. Lemieux – ACES / Europe Dublin 2015
Conclusions (2)
• EEG-fMRI (+video) to have increased importance in neuroscience
• Intracranial EEG-fMRI
• Analysis is complex: additional layer on top of icEEG analysis & interpretation
• Abundance of activity -> more reliable maps than scalp EEG-fMRI
• Interpretation: compare it against what?
• How precious is our ‘gold’ standard?
• Surgical outcome + localisation of resected tissue: what about disruption of
wider networks?
• Effective connectivity: ‘the full multimodal generator model’ (DCM)
• Improved biophysical models of epileptogenic networks being developed
• Applicable to icEEG, then fMRI
33. Lemieux – ACES / Europe Dublin 2015
Seizure propagation in hypothalamic hamartomas (HH)
• Seizures originate in HH, and control of seizures can be achieved by
surgically removing the HH.
• Possible surgical alternative: disconnection of the underlying pathway.
• Different seizure propagation pathways have been described in HH [Leal et
al. Epilepsia 2003; Kahane et al. Epileptic Disord. 2003]:
• Aim: identify the correct seizure propagation pathway in individual
patients using DCM.
1.HH to temporal-
occipital
(posterior, PR)
to frontal lobe
(anterior, AR)
(through the fornix)
2.HH to frontal
(anterior, AR) to
temporal-occipital
(posterior, PR)
lobe
(through the
mammillo-thalamo-
cingulate pathway)
[Murta et al, 2012]
34. Lemieux – ACES / Europe Dublin 2015
Seizure propagation in HH:
Family of DCM models
•HH is the driving region
•All structures consistent with each of 2 propagation hypotheses
•Each connection: uni- or bi-directional (22=4 structures per hypothesis)
•Each connection: linear (black) or bilinear (black and green) (24=8 models per hypothesis)
[Murta et al, 2012]
35. Lemieux – ACES / Europe Dublin 2015
Seizure propagation in HH:
Bayesian model comparison
[Murta et al, 2012]
Most likely model
Model 1:
HH → temp-occ. → frontal
37. Lemieux – ACES / Europe Dublin 2015
• Multi-modal imaging = Combinations of images or
maps
– from different sources (instruments)
or
– that show different aspects (e.g. MR contrasts)
• Fundamental assumption: measurements relate to
the same phenomenon
– Location
– Time
Multi-modal imaging: basics
38. Lemieux – ACES / Europe Dublin 2015
Estimating a network of sources and their dynamics:
Dynamic Causal Modelling
[Friston, 2009; David et al 2006]
Bi-linear model of effective
connectivity
– Effect of activity in one region on
activity in other: equations of motion
– Biophysical generative model
fMRI:EEG/MEG neural mass model:
+ Model comparison (Bayesian)
39. Lemieux – ACES / Europe Dublin 2015
EEGfMRI of GSW - QS 1.5T series
Group analysis
IGE
N=18
Sup Post Par ↓
Front ↓
Post Cing ↓
Thalam ↑
[Hamandi et al., 2006]
Th
Th
40. Lemieux – ACES / Europe Dublin 2015
Dynamic causal models of
effective connectivity in GSW
Centrencephalic
Cortico/corticoreticular
Precuneus model
[Vaudano et al, 2009]
Data:
EEG-fMRI of GSW in 7 patients with IGE
Significant GSW-related BOLD: Thalamus, Precuneus and ventromedial prefrontal
Model of effective connectivity: DCM of fMRI
GSW EEG onsets and offsets modelled as (endogenous) input
3 models:
Best in 5/7 cases
41. Lemieux – ACES / Europe Dublin 2015
Integrate and Fire Neurons
Mean Field Population
Dynamics
DCM of focal seizures
A more realistic biophysical model of (fast) ictal activity
Time (s)
Frequency(Hz)
5 10 15 20 25 30
8
16
32
64
128
Model: Coupled neural population dynamics
[M Leite, unpublished]
42. Lemieux – ACES / Europe Dublin 2015
+10mV
-70mV
E vs. I
Pyr Int
Current(pA)
Phase (%) Phase (%)
Phase (%) Phase (%)
Current(pA)Current(pA)
Current (pA) Current (pA)
Pyr Int
U
[M Leite; unpublished - In collaboration with D Kullmann and D Kuzmin]
LFP + whole cell voltage cla
Vholding = -70mV
A more realistic biophysical model
of (fast) ictal activity: Validation initial results
43. Lemieux – ACES / Europe Dublin 2015
Resting-state BOLD
BOLD increases
BOLD decreases BOLD decreases
BOLD increases
L
L
L
L
[Perani et al, in preparation]
Alpha (Mu) Beta