1. Überprüfen Sie System-Tuning und Datenqualität <ol><li> Überprüfen Sie die Stimmung der MEG-System. Verwenden Sie die Tuning-und Lärmmessungen Software mit dem MEG-System zur Verfügung gestellt, um zu überprüfen, dass alle Kanäle richtig eingestellt sind und dass der durchschnittliche Lärmpegel liegt unter 3 fT / cm oder 3 fT auf planaren Gradiometer und Magnetometer MEG Kanälen. </li><li> Sammeln Sie ein Segment des leeren Raumes Daten. Erfassung von Daten mit dem abgeschirmten Raum void Subjekt für 5 Minuten für die Qualitätssicherung und Störgeräuschschätzung. </li></ol> 2. Richten Sie die Reize und Datenerfassung Parameter. <ol><li> Richten Sie die somatosensorische, auditive und visuelle Reize mit einem Stimulus Computer, Projektor außerhalb des Schildes Raum installiert, und eine somatosensorische elektrischen Stimulator (Grass Modell S88). </li></ol> 3. Betreff Vorbereitung <ol><li> Bevor ein MEG / EEG-Studie, muss jedes Fach füllen mehrere Formen in Bezug auf Sicherheit und Zustimmung. </li><li> Überprüfen Sie, dass Thema ist frei von magnetischen Materialien. Bringen Sie das Thema in den abgeschirmten Raum und beginnen MEG Datenerfassung zu prüfen, ob die Daten nicht enthalten Zeichen der magnetischen Artefakte. Wenn nötig, verwenden Sie einen Degausser, um Artefakte aus magnetischen Gegenstände in den Körper wie zahnärztliche Arbeit zu reduzieren. </li><li> Setzen Sie auf EEG-Haube, injizieren leitenden Gel, und überprüfen Sie die Impedanzen. Die Impedanzen sollten unter 10 kOhm sein. </li><li> Setzen Sie auf EOG-Elektroden und der Referenzelektrode. </li><li> Setzen Sie auf Kopf-Stellungsanzeige (HPI) Spulen. Position der vier HPI Spulen, so dass sie unter dem von der MEG-Sensor-Array und weit voneinander entfernt abgedeckt wird. </li><li> Digitalisieren fiducial Sehenswürdigkeiten, HPI Spulen, EEG-Elektroden und Kopfform. </li><li> Verschieben Sie das Motiv in den Scanner. </li></ol> 4. Die Datenerfassung für jede Sinnesmodalität <ol><li> Set up Stimulationsprotokolle auf den Reiz Computer. Für die somatosensorische Median-Nervenstimulation, bringen Sie die Elektroden auf der linken und rechten Handgelenk und schrittweise Erhöhung der Reizintensität, so dass der Reiz Niveau über den Motor Schwelle. Für die auditive Stimulation, die Ohrhörer einlegen und prüfen, ob der Reiz Niveau angemessen ist. Für die visuelle Stimulation, positionieren Sie den Back-Leinwand vor dem Thema und prüfen Sie, ob der Stimulus korrekt dargestellt wird. </li><li> Starten Sie die Datenerfassung und Kontrolle der Datenqualität. Auf der Rohdaten-Display, ob alle Kanäle richtig funktionieren und enthalten keine Artefakte. </li><li> Messen Sie die Kopfposition. Rufen Sie die Kopfposition Messung aus dem Erwerb Konsole und prüfen Sie, ob die Ergebnisse den Vorgaben der Software verhängt erfüllen. </li><li> Sparen Sie von Rohdaten und Online-Mittelung. </li><li> Starten Reiz Lieferung </li><li> Sobald alle Stimuli präsentiert wurden, speichern Rohdaten und on-line-Durchschnitt. </li></ol> 5. Datenanalyse In der Datenanalyse werden wir anatomischen MRT-Daten für die Visualisierung der Ergebnisse zu verwenden, für die Bestimmung der Formen von Gewebe Fächer für uns Modellierung und zum Einschränken der lMEG / EEG-Daten, um die kortikale Oberfläche. Wir nutzen sowohl die aktuelle Dipol-Modell und eine verteilte kortikal eingeschränkt Minimum-Norm-Lösung in der Analyse. Der Ablauf der verteilten Quellcode-Analyse ist in Abbildung 1 dargestellt. <img src="/files/ftp_upload/1668/1668fig1.jpg" alt="Abbildung 1" /> Abbildung 1. Insgesamt Workflow für die Analyse von MEG / EEG mit kortikal-constrained Minimum-Norm-Schätzungen.

<ol>
	<li>H&#228;m&#228;l&#228;inen, M., Hari, R., Ilmoniemi, R., Knuutila, J., Lounasmaa, O. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetoencephalography+-+theory,+instrumentation,+and+applications+to+noninvasive+studies+of+the+working+human+brain.">Magnetoencephalography - theory, instrumentation, and applications to noninvasive studies of the working human brain.</a> Reviews of Modern Physics. 65, 413-497 (1993).</li><li>H&#228;m&#228;l&#228;inen, M., Hari, R., Toga, A. W., Mazziotta, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Brain Mapping, The Methods. , 227-253 (2002).</li><li>Sharon, D., H&#228;m&#228;l&#228;inen, M., Tootell, R. B., Halgren, E., Belliveau, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+advantage+of+combining+MEG+and+EEG:+Comparison+to+fMRI+in+focally+stimulated+visual+cortex.">The advantage of combining MEG and EEG: Comparison to fMRI in focally stimulated visual cortex.</a> Neuroimage. 36, 1225-1235 (2007).</li><li>M&#228;kel&#228;, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+integration+of+brain+anatomy+and+function+to+facilitate+intraoperative+navigation+around+the+sensorimotor+strip.">Three-dimensional integration of brain anatomy and function to facilitate intraoperative navigation around the sensorimotor strip.</a> Human Brain Mapping. 12, 180-192 (2001).</li></ol>

Magnetenzephalographie (MEG) und Elektroenzephalographie (EEG) sind die einzigen nicht-invasive Methoden, um die Gehirnaktivität mit einer feinen zeitlichen Auflösung aufzuzeichnen. MEG ist besonders gut für die Untersuchung kortikaler Aktivität geeignet. Dieser Artikel zeigt, kombiniert MEG / EEG Datenerfassung und-analyse zu bestimmen Hirnaktivität mit der Bearbeitung von einfachen sensorischen Stimuli assoziiert. Diese Art von Experimenten sind sowohl in der Grundlagenforschung Neurowissenschaften und klinischen Studien verwendet. Wenn das Gehirn-Aktivierung ist Schwerpunkt gilt der aktuelle Dipol-Modell und den Ort der Aktivität kann mit einer Genauigkeit von etwa 5 mm bestimmt werden. In komplexeren Situationen kann kortikal-constrained Quelle schätzt, eingesetzt, um die räumlich-zeitlichen Muster der Aktivierung zu enthüllen. Diese Modelle beschäftigen anatomischen MRT-Daten für die Visualisierung, die Bestimmung der Geometrie der Gewebegruppen für Vorwärts-Modellierung und für die kortikale Lage und Orientierung Einschränkungen.

functional mapping with simultaneous meg and eeg

Wir verwenden Magnetenzephalographie (MEG) und Elektroenzephalographie (EEG) zu lokalisieren und zu bestimmen, die zeitliche Entwicklung in Hirnareale bei der Verarbeitung von einfachen sensorischen Stimuli beteiligt. Wir verwenden somatosensorische Reize an die Hand somatosensorischen Bereiche zu lokalisieren, auditive Reize, die auditiven Kortex, visuelle Reize in vier Quadranten des Gesichtsfeldes zu finden, um den frühen visuellen Arealen zu finden. Diese Art von Experimenten sind für die funktionelle Zuordnung in epileptischen und Hirntumorpatienten zur eloquenten Kortex zu lokalisieren. In der Grundlagenforschung Neurowissenschaften ähnlichen experimentellen Protokolle werden verwendet, um die Orchestrierung von kortikale Aktivität zu untersuchen. Die Übernahme-Protokoll enthält Verfahren zur Qualitätssicherung, vorbehaltlich Vorbereitung für den kombinierten MEG / EEG-Studie, und den Erwerb von evozierten-Response-Daten mit somatosensorischen, auditive und visuelle Reize. Wir zeigen auch, Analyse der Daten mit den entsprechenden aktuellen Dipol-Modell und kortikal-constrained Minimum-Norm-Schätzungen. Anatomische MRT-Daten in die Analyse zur Visualisierung und zur Ableitung von Grenzen des Gewebes Grenzen für Vorwärts-Modellierung und kortikalen Lage und Orientierung Einschränkungen für die Minimum-Norm Schätzungen angestellt.

Watch this Scientific Journal Video about Functional Mapping with Simultaneous MEG and EEG at JoVE.com

Functional Mapping with Simultaneous MEG and EEG

Wir verwenden Magnetenzephalographie (MEG) und Elektroenzephalographie (EEG) zu Hirnareale bei der Verarbeitung von einfachen sensorischen Stimuli beteiligt Karte.

Functional Mapping mit Simultaneous MEG und EEG

We use magnetoencephalography (MEG) and electroencephalography (EEG) to locate and determine the temporal evolution in brain areas involved in the ...

functional-mapping-with-simultaneous-meg-and-eeg

Nanyang Technological University

Research

JoVE Journal

Neuroscience

17.8K Aufrufe.  MGH - Massachusetts General Hospital. Wir verwenden Magnetenzephalographie (MEG) und Elektroenzephalographie (EEG) zu Hirnareale bei der Verarbeitung von einfachen sensorischen Stimuli beteiligt Karte.

Serie: Functional Mapping with Simultaneous MEG and EEG

Combining Computer Game-Based Behavioural Experiments With High-Density EEG and Infrared Gaze Tracking

Experimental paradigms are valuable insofar as the timing and other parameters of their stimuli are well specified and controlled, and insofar as they yield data relevant to the cognitive processing that occurs under ecologically valid conditions. These two goals often are at odds, since well controlled stimuli often are too repetitive to sustain subjects' motivation. Studies employing electroencephalography (EEG) are often especially sensitive to this dilemma between ecological validity and experimental control: attaining sufficient signal-to-noise in physiological averages demands large numbers of repeated trials within lengthy recording sessions, limiting the subject pool to individuals with the ability and patience to perform a set task over and over again. This constraint severely limits researchers' ability to investigate younger populations as well as clinical populations associated with heightened anxiety or attentional abnormalities. Even adult, non-clinical subjects may not be able to achieve their typical levels of performance or cognitive engagement: an unmotivated subject for whom an experimental task is little more than a chore is not the same, behaviourally, cognitively, or neurally, as a subject who is intrinsically motivated and engaged with the task. A growing body of literature demonstrates that embedding experiments within video games may provide a way between the horns of this dilemma between experimental control and ecological validity. The narrative of a game provides a more realistic context in which tasks occur, enhancing their ecological validity (Chaytor &amp; Schmitter-Edgecombe, 2003). Moreover, this context provides motivation to complete tasks. In our game, subjects perform various missions to collect resources, fend off pirates, intercept communications or facilitate diplomatic relations. In so doing, they also perform an array of cognitive tasks, including a Posner attention-shifting paradigm (Posner, 1980), a go/no-go test of motor inhibition, a psychophysical motion coherence threshold task, the Embedded Figures Test (Witkin, 1950, 1954) and a theory-of-mind (Wimmer &amp; Perner, 1983) task. The game software automatically registers game stimuli and subjects' actions and responses in a log file, and sends event codes to synchronise with physiological data recorders. Thus the game can be combined with physiological measures such as EEG or fMRI, and with moment-to-moment tracking of gaze. Gaze tracking can verify subjects' compliance with behavioural tasks (e.g. fixation) and overt attention to experimental stimuli, and also physiological arousal as reflected in pupil dilation (Bradley et al., 2008). At great enough sampling frequencies, gaze tracking may also help assess covert attention as reflected in microsaccades - eye movements that are too small to foveate a new object, but are as rapid in onset and have the same relationship between angular distance and peak velocity as do saccades that traverse greater distances. The distribution of directions of microsaccades correlates with the (otherwise) covert direction of attention (Hafed &amp; Clark, 2002).

Procedures for recording high-density EEG and gaze data during computer game-based cognitive tasks are described. Using a video game to present cognitive tasks enhances ecological validity without sacrificing experimental control.

Die Kombination Computer Game-Based Behavioural Experimente mit High-Density EEG-und Infrarot-Tracking-Gaze

Experimental paradigms are valuable insofar as the timing and other parameters of their stimuli are well specified and controlled, and insofar as they ...

Forschung

Neurowissenschaften

Single Cell Measurement of Dopamine Release with Simultaneous Voltage-clamp and Amperometry

After its release into the synaptic cleft, dopamine exerts its biological properties via its pre- and post-synaptic targets1. The dopamine signal is terminated by diffusion2-3, extracellular enzymes4, and membrane transporters5. The dopamine transporter, located in the peri-synaptic cleft of dopamine neurons clears the released amines through an inward dopamine flux (uptake). The dopamine transporter can also work in reverse direction to release amines from inside to outside in a process called outward transport or efflux of dopamine5. More than 20 years ago Sulzer et al. reported the dopamine transporter can operate in two modes of activity: forward (uptake) and reverse (efflux)5. The neurotransmitter released via efflux through the transporter can move a large amount of dopamine to the extracellular space, and has been shown to play a major regulatory role in extracellular dopamine homeostasis6. Here we describe how simultaneous patch clamp and amperometry recording can be used to measure released dopamine via the efflux mechanism with millisecond time resolution when the membrane potential is controlled. For this, whole-cell current and oxidative (amperometric) signals are measured simultaneously using an Axopatch 200B amplifier (Molecular Devices, with a low-pass Bessel filter set at 1,000 Hz for whole-cell current recording). For amperometry recording a carbon fiber electrode is connected to a second amplifier (Axopatch 200B) and is placed adjacent to the plasma membrane and held at +700 mV. The whole-cell and oxidative (amperometric) currents can be recorded and the current-voltage relationship can be generated using a voltage step protocol. Unlike the usual amperometric calibration, which requires conversion to concentration, the current is reported directly without considering the effective volume7. Thus, the resulting data represent a lower limit to dopamine efflux because some transmitter is lost to the bulk solution.

The amperometric technique measures dopamine release from a single cell by detecting the oxidative current produced by spontaneous dopamine oxidization. Simultaneous voltage clamp and amperometry methodology reveal the mechanistic relationship between the overall "activity" of dopamine transporter and the regulatory role of this activity on the reverse transport of dopamine.

Single Cell Messung der Freisetzung von Dopamin mit gleichzeitiger Voltage-Clamp-und Amperometry

After its release into the synaptic cleft, dopamine exerts its biological properties via its pre- and post-synaptic targets1. The dopamine signal is ...

Recording Human Electrocorticographic (ECoG) Signals for Neuroscientific Research and Real-time Functional Cortical Mapping

Neuroimaging studies of human cognitive, sensory, and motor processes are usually based on noninvasive techniques such as electroencephalography (EEG), magnetoencephalography or functional magnetic-resonance imaging. These techniques have either inherently low temporal or low spatial resolution, and suffer from low signal-to-noise ratio and/or poor high-frequency sensitivity. Thus, they are suboptimal for exploring the short-lived spatio-temporal dynamics of many of the underlying brain processes. In contrast, the invasive technique of electrocorticography (ECoG) provides brain signals that have an exceptionally high signal-to-noise ratio, less susceptibility to artifacts than EEG, and a high spatial and temporal resolution (i.e., &lt;1 cm/&lt;1 millisecond, respectively). ECoG involves measurement of electrical brain signals using electrodes that are implanted subdurally on the surface of the brain. Recent studies have shown that ECoG amplitudes in certain frequency bands carry substantial information about task-related activity, such as motor execution and planning1, auditory processing2 and visual-spatial attention3. Most of this information is captured in the high gamma range (around 70-110 Hz). Thus, gamma activity has been proposed as a robust and general indicator of local cortical function1-5. ECoG can also reveal functional connectivity and resolve finer task-related spatial-temporal dynamics, thereby advancing our understanding of large-scale cortical processes. It has especially proven useful for advancing brain-computer interfacing (BCI) technology for decoding a user's intentions to enhance or improve communication6 and control7. Nevertheless, human ECoG data are often hard to obtain because of the risks and limitations of the invasive procedures involved, and the need to record within the constraints of clinical settings. Still, clinical monitoring to localize epileptic foci offers a unique and valuable opportunity to collect human ECoG data. We describe our methods for collecting recording ECoG, and demonstrate how to use these signals for important real-time applications such as clinical mapping and brain-computer interfacing. Our example uses the BCI2000 software platform8,9 and the SIGFRIED10 method, an application for real-time mapping of brain functions. This procedure yields information that clinicians can subsequently use to guide the complex and laborious process of functional mapping by electrical stimulation.
Prerequisites and Planning:
Patients with drug-resistant partial epilepsy may be candidates for resective surgery of an epileptic focus to minimize the frequency of seizures. Prior to resection, the patients undergo monitoring using subdural electrodes for two purposes: first, to localize the epileptic focus, and second, to identify nearby critical brain areas (i.e., eloquent cortex) where resection could result in long-term functional deficits. To implant electrodes, a craniotomy is performed to open the skull. Then, electrode grids and/or strips are placed on the cortex, usually beneath the dura. A typical grid has a set of 8 x 8 platinum-iridium electrodes of 4 mm diameter (2.3 mm exposed surface) embedded in silicon with an inter-electrode distance of 1cm. A strip typically contains 4 or 6 such electrodes in a single line. The locations for these grids/strips are planned by a team of neurologists and neurosurgeons, and are based on previous EEG monitoring, on a structural MRI of the patient's brain, and on relevant factors of the patient's history. Continuous recording over a period of 5-12 days serves to localize epileptic foci, and electrical stimulation via the implanted electrodes allows clinicians to map eloquent cortex. At the end of the monitoring period, explantation of the electrodes and therapeutic resection are performed together in one procedure.
In addition to its primary clinical purpose, invasive monitoring also provides a unique opportunity to acquire human ECoG data for neuroscientific research. The decision to include a prospective patient in the research is based on the planned location of their electrodes, on the patient's performance scores on neuropsychological assessments, and on their informed consent, which is predicated on their understanding that participation in research is optional and is not related to their treatment. As with all research involving human subjects, the research protocol must be approved by the hospital's institutional review board. The decision to perform individual experimental tasks is made day-by-day, and is contingent on the patient's endurance and willingness to participate. Some or all of the experiments may be prevented by problems with the clinical state of the patient, such as post-operative facial swelling, temporary aphasia, frequent seizures, post-ictal fatigue and confusion, and more general pain or discomfort.
At the Epilepsy Monitoring Unit at Albany Medical Center in Albany, New York, clinical monitoring is implemented around the clock using a 192-channel Nihon-Kohden Neurofax monitoring system. Research recordings are made in collaboration with the Wadsworth Center of the New York State Department of Health in Albany. Signals from the ECoG electrodes are fed simultaneously to the research and the clinical systems via splitter connectors. To ensure that the clinical and research systems do not interfere with each other, the two systems typically use separate grounds. In fact, an epidural strip of electrodes is sometimes implanted to provide a ground for the clinical system. Whether research or clinical recording system, the grounding electrode is chosen to be distant from the predicted epileptic focus and from cortical areas of interest for the research. Our research system consists of eight synchronized 16-channel g.USBamp amplifier/digitizer units (g.tec, Graz, Austria). These were chosen because they are safety-rated and FDA-approved for invasive recordings, they have a very low noise-floor in the high-frequency range in which the signals of interest are found, and they come with an SDK that allows them to be integrated with custom-written research software. In order to capture the high-gamma signal accurately, we acquire signals at 1200Hz sampling rate-considerably higher than that of the typical EEG experiment or that of many clinical monitoring systems. A built-in low-pass filter automatically prevents aliasing of signals higher than the digitizer can capture. The patient's eye gaze is tracked using a monitor with a built-in Tobii T-60 eye-tracking system (Tobii Tech., Stockholm, Sweden). Additional accessories such as joystick, bluetooth Wiimote (Nintendo Co.), data-glove (5th Dimension Technologies), keyboard, microphone, headphones, or video camera are connected depending on the requirements of the particular experiment.
Data collection, stimulus presentation, synchronization with the different input/output accessories, and real-time analysis and visualization are accomplished using our BCI2000 software8,9. BCI2000 is a freely available general-purpose software system for real-time biosignal data acquisition, processing and feedback. It includes an array of pre-built modules that can be flexibly configured for many different purposes, and that can be extended by researchers' own code in C++, MATLAB or Python. BCI2000 consists of four modules that communicate with each other via a network-capable protocol: a Source module that handles the acquisition of brain signals from one of 19 different hardware systems from different manufacturers; a Signal Processing module that extracts relevant ECoG features and translates them into output signals; an Application module that delivers stimuli and feedback to the subject; and the Operator module that provides a graphical interface to the investigator.
A number of different experiments may be conducted with any given patient. The priority of experiments will be determined by the location of the particular patient's electrodes. However, we usually begin our experimentation using the SIGFRIED (SIGnal modeling For Realtime Identification and Event Detection) mapping method, which detects and displays significant task-related activity in real time. The resulting functional map allows us to further tailor subsequent experimental protocols and may also prove as a useful starting point for traditional mapping by electrocortical stimulation (ECS).
Although ECS mapping remains the gold standard for predicting the clinical outcome of resection, the process of ECS mapping is time consuming and also has other problems, such as after-discharges or seizures. Thus, a passive functional mapping technique may prove valuable in providing an initial estimate of the locus of eloquent cortex, which may then be confirmed and refined by ECS. The results from our passive SIGFRIED mapping technique have been shown to exhibit substantial concurrence with the results derived using ECS mapping10.
The protocol described in this paper establishes a general methodology for gathering human ECoG data, before proceeding to illustrate how experiments can be initiated using the BCI2000 software platform. Finally, as a specific example, we describe how to perform passive functional mapping using the BCI2000-based SIGFRIED system.

Recording Human Electrocorticographic ECoG Signals for Neuroscientific Research and Real-time Functional Cortical Mapping

We present a method for collecting electrocorticographic signals for research purposes from humans who are undergoing invasive epilepsy monitoring. We show how to use the BCI2000 software platform for data collection, signal processing and stimulus presentation. Specifically, we demonstrate SIGFRIED, a BCI2000-based tool for real-time functional brain mapping.

Aufnahme Menschliche Electrocorticographic (ECoG) Signale für neurowissenschaftliche Forschung und Real-time Funktionelle kortikale Mapping

Neuroimaging studies of human cognitive, sensory, and motor processes are usually based on noninvasive techniques such as electroencephalography (EEG), ...

Mapping Cortical Dynamics Using Simultaneous MEG/EEG and Anatomically-constrained Minimum-norm Estimates: an Auditory Attention Example

Magneto- and electroencephalography (MEG/EEG) are neuroimaging techniques that provide a high temporal resolution particularly suitable to investigate the cortical networks involved in dynamical perceptual and cognitive tasks, such as attending to different sounds in a cocktail party. Many past studies have employed data recorded at the sensor level only, i.e., the magnetic fields or the electric potentials recorded outside and on the scalp, and have usually focused on activity that is time-locked to the stimulus presentation. This type of event-related field / potential analysis is particularly useful when there are only a small number of distinct dipolar patterns that can be isolated and identified in space and time. Alternatively, by utilizing anatomical information, these distinct field patterns can be localized as current sources on the cortex. However, for a more sustained response that may not be time-locked to a specific stimulus (e.g., in preparation for listening to one of the two simultaneously presented spoken digits based on the cued auditory feature) or may be distributed across multiple spatial locations unknown a priori, the recruitment of a distributed cortical network may not be adequately captured by using a limited number of focal sources.
Here, we describe a procedure that employs individual anatomical MRI data to establish a relationship between the sensor information and the dipole activation on the cortex through the use of minimum-norm estimates (MNE). This inverse imaging approach provides us a tool for distributed source analysis. For illustrative purposes, we will describe all procedures using FreeSurfer and MNE software, both freely available. We will summarize the MRI sequences and analysis steps required to produce a forward model that enables us to relate the expected field pattern caused by the dipoles distributed on the cortex onto the M/EEG sensors. Next, we will step through the necessary processes that facilitate us in denoising the sensor data from environmental and physiological contaminants. We will then outline the procedure for combining and mapping MEG/EEG sensor data onto the cortical space, thereby producing a family of time-series of cortical dipole activation on the brain surface (or "brain movies") related to each experimental condition. Finally, we will highlight a few statistical techniques that enable us to make scientific inference across a subject population (i.e., perform group-level analysis) based on a common cortical coordinate space.

We use magneto- and electroencephalography (MEG/EEG), combined with anatomical information captured by magnetic resonance imaging (MRI), to map the dynamics of the cortical network associated with auditory attention.

Mapping Kortikale Dynamics Mit Simultaneous MEG / EEG und anatomisch eingeschränkt Minimum-Norm Schätzungen: ein Auditory Achtung Beispiel

Magneto- and electroencephalography (MEG/EEG) are neuroimaging techniques that provide a high temporal resolution particularly suitable to investigate the ...

Functional Interrogation of Adult Hypothalamic Neurogenesis with Focal Radiological Inhibition

The functional characterization of adult-born neurons remains a significant challenge. Approaches to inhibit adult neurogenesis via invasive viral delivery or transgenic animals have potential confounds that make interpretation of results from these studies difficult. New radiological tools are emerging, however, that allow one to noninvasively investigate the function of select groups of adult-born neurons through accurate and precise anatomical targeting in small animals. Focal ionizing radiation inhibits the birth and differentiation of new neurons, and allows targeting of specific neural progenitor regions. In order to illuminate the potential functional role that adult hypothalamic neurogenesis plays in the regulation of physiological processes, we developed a noninvasive focal irradiation technique to selectively inhibit the birth of adult-born neurons in the hypothalamic median eminence. We describe a method for Computer tomography-guided focal irradiation (CFIR) delivery to enable precise and accurate anatomical targeting in small animals. CFIR uses three-dimensional volumetric image guidance for localization and targeting of the radiation dose, minimizes radiation exposure to nontargeted brain regions, and allows for conformal dose distribution with sharp beam boundaries. This protocol allows one to ask questions regarding the function of adult-born neurons, but also opens areas to questions in areas of radiobiology, tumor biology, and immunology. These radiological tools will facilitate the translation of discoveries at the bench to the bedside.

The function of adult-born mammalian neurons remains an active area of investigation. Ionizing radiation inhibits the birth of new neurons. Using computer tomography-guided focal irradiation (CFIR), three-dimensional anatomical targeting of specific neural progenitor populations can now be used to assess the functional role of adult neurogenesis.

Funktionelle Abfrage der Erotik Hypothalamus Neurogenese mit Brennradiologische Hemmung

The functional characterization of adult-born neurons remains a significant challenge. Approaches to inhibit adult neurogenesis via invasive viral ...

Functional Imaging of Auditory Cortex in Adult Cats using High-field fMRI

Current knowledge of sensory processing in the mammalian auditory system is mainly derived from electrophysiological studies in a variety of animal models, including monkeys, ferrets, bats, rodents, and cats. In order to draw suitable parallels between human and animal models of auditory function, it is important to establish a bridge between human functional imaging studies and animal electrophysiological studies. Functional magnetic resonance imaging (fMRI) is an established, minimally invasive method of measuring broad patterns of hemodynamic activity across different regions of the cerebral cortex. This technique is widely used to probe sensory function in the human brain, is a useful tool in linking studies of auditory processing in both humans and animals and has been successfully used to investigate auditory function in monkeys and rodents. The following protocol describes an experimental procedure for investigating auditory function in anesthetized adult cats by measuring stimulus-evoked hemodynamic changes in auditory cortex using fMRI. This method facilitates comparison of the hemodynamic responses across different models of auditory function thus leading to a better understanding of species-independent features of the mammalian auditory cortex.

Functional studies of the auditory system in mammals have traditionally been conducted using spatially-focused techniques such as electrophysiological recordings. The following protocol describes a method of visualizing large-scale patterns of evoked hemodynamic activity in the cat auditory cortex using functional magnetic resonance imaging.

Funktionelle Bildgebung Auditory Cortex bei erwachsenen Katzen mit Hochfeld-fMRI

Current knowledge of sensory processing in the mammalian auditory system is mainly derived from electrophysiological studies in a variety of animal ...

Deep Brain Stimulation with Simultaneous fMRI in Rodents

In order to visualize the global and downstream neuronal responses to deep brain stimulation (DBS) at various targets, we have developed a protocol for using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) to image rodents with simultaneous DBS. DBS fMRI presents a number of technical challenges, including accuracy of electrode implantation, MR artifacts created by the electrode, choice of anesthesia and paralytic to minimize any neuronal effects while simultaneously eliminating animal motion, and maintenance of physiological parameters, deviation from which can confound the BOLD signal.&#160;Our laboratory has developed a set of procedures that are capable of overcoming most of these possible issues. For electrical stimulation, a homemade tungsten bipolar microelectrode is used, inserted stereotactically at the stimulation site in the anesthetized subject. In preparation for imaging, rodents are fixed on a plastic headpiece and transferred to the magnet bore. For sedation and paralysis during scanning, a cocktail of dexmedetomidine and pancuronium is continuously infused, along with a minimal dose of isoflurane; this preparation minimizes the BOLD ceiling effect of volatile anesthetics. In this example experiment, stimulation of the subthalamic nucleus (STN) produces BOLD responses which are observed primarily in ipsilateral cortical regions, centered in motor cortex. Simultaneous DBS and fMRI allows the unambiguous modulation of neural circuits dependent on stimulation location and stimulation parameters, and permits observation of neuronal modulations free of regional bias. This technique may be used to explore the downstream effects of modulating neural circuitry at nearly any brain region, with implications for both experimental and clinical DBS.

This protocol describes a standard method for simultaneous functional magnetic resonance imaging and deep brain stimulation in the rodent. The combined use of these experimental tools allows for the exploration of global downstream activity in response to electrical stimulation at virtually any brain target.

Deep Brain Stimulation mit gleichzeitiger fMRT in Nagetiere

In order to visualize the global and downstream neuronal responses to deep brain stimulation (DBS) at various targets, we have developed a protocol for ...

Simultaneous ex vivo Functional Testing of Two Retinas by in vivo Electroretinogram System

An In vivo electroretinogram (ERG) signal is composed of several overlapping components originating from different retinal cell types, as well as noise from extra-retinal sources. Ex vivo ERG provides an efficient method to dissect the function of retinal cells directly from an intact isolated retina of animals or donor eyes. In addition, ex vivo ERG can be used to test the efficacy and safety of potential therapeutic agents on retina tissue from animals or humans. We show here how commercially available in vivo ERG systems can be used to conduct ex vivo ERG recordings from isolated mouse retinas. We combine the light stimulation, electronic and heating units of a standard in vivo system with custom-designed specimen holder, gravity-controlled perfusion system and electromagnetic noise shielding to record low-noise ex vivo ERG signals simultaneously from two retinas with the acquisition software included in commercial in vivo systems. Further, we demonstrate how to use this method in combination with pharmacological treatments that remove specific ERG components in order to dissect the function of certain retinal cell types.

Simultaneous ex vivo Functional Testing of Two Retinas by in vivo Electroretinogram System

Ex vivo ERG can be used to record electrical activity of retinal cells directly from isolated intact retinas of animals or humans. We demonstrate here how common in vivo ERG systems can be adapted for ex vivo ERG recordings in order to dissect the electrical activity of retinal cells.

Gleichzeitig<em&gt; Ex vivo</em&gt; Funktionsprüfung von zwei Netzhäute von<em&gt; In vivo</em&gt; Elektroretinogramm-System

An In vivo electroretinogram (ERG) signal is composed of several overlapping components originating from different retinal cell types, as well as noise ...

Non-restraining EEG Radiotelemetry: Epidural and Deep Intracerebral Stereotaxic EEG Electrode Placement

Implantable EEG radiotelemetry is of central relevance in the neurological characterization of transgenic mouse models of neuropsychiatric and neurodegenerative diseases as well as epilepsies. This powerful technique does not only provide valuable insights into the underlying pathophysiological mechanisms, i.e., the etiopathogenesis of CNS related diseases, it also facilitates the development of new translational, i.e., therapeutic approaches. Whereas competing techniques that make use of recorder systems used in jackets or tethered systems suffer from their unphysiological restraining to semi-restraining character, radiotelemetric EEG recordings overcome these disadvantages. Technically, implantable EEG radiotelemetry allows for precise and highly sensitive measurement of epidural and deep, intracerebral EEGs under various physiological and pathophysiological conditions. First, we present a detailed protocol of a straight forward, successful, quick and efficient technique for epidural (surface) EEG recordings resulting in high-quality electrocorticograms. Second, we demonstrate how to implant deep, intracerebral EEG electrodes, e.g., in the hippocampus (electrohippocampogram). For both approaches, a computerized 3D stereotaxic electrode implantation system is used. The radiofrequency transmitter itself is implanted into a subcutaneous pouch in both mice and rats. Special attention also has to be paid to pre-, peri- and postoperative treatment of the experimental animals. Preoperative preparation of mice and rats, suitable anesthesia as well as postoperative treatment and pain management are described in detail.

Non-restraining EEG radiotelemetry is a valuable methodological approach to record in vivo long-term electroencephalograms from freely moving rodents. This detailed protocol describes stereotaxic epidural and deep intracerebral electrode placement in different brain regions in order to obtain reliable recordings of CNS rhythmicity and CNS related behavioral stages.

Nicht beschränkende EEG Radiotelemetrie: epidurale und Deep Intrazerebrale Stereotaktische EEG Elektrodenplatzierung

Implantable EEG radiotelemetry is of central relevance in the neurological characterization of transgenic mouse models of neuropsychiatric and ...

Analyzing Neural Activity and Connectivity Using Intracranial EEG Data with SPM Software

Measuring neural activity and connectivity associated with cognitive functions at high spatial and temporal resolutions is an important goal in cognitive neuroscience. Intracranial electroencephalography (EEG) can directly record electrical neural activity and has the unique potential to accomplish this goal. Traditionally, averaging analysis has been applied to analyze intracranial EEG data; however, several new techniques are available for depicting neural activity and intra- and inter-regional connectivity. Here, we introduce two analytical protocols we recently applied to analyze intracranial EEG data using the Statistical Parametric Mapping (SPM) software: time-frequency SPM analysis for neural activity and dynamic causal modeling of induced responses for intra- and inter-regional connectivity. We report our analysis of intracranial EEG data during the observation of faces as representative results. The results revealed that the inferior occipital gyrus (IOG) showed gamma-band activity at very early stages (110 ms) in response to faces, and both the IOG and amygdala showed rapid intra- and inter-regional connectivity using various types of oscillations. These analytical protocols have the potential to identify the neural mechanisms underlying cognitive functions with high spatial and temporal profiles.

We present two analytical protocols that can be used to analyze intracranial electroencephalography data using the Statistical Parametric Mapping (SPM) software: time-frequency statistical parametric mapping analysis for neural activity, and dynamic causal modeling of induced responses for intra- and inter-regional connectivity.

Analyse der neuronalen Aktivität und Konnektivität mit intrakraniellen EEG-Daten mit SPM-Software

Measuring neural activity and connectivity associated with cognitive functions at high spatial and temporal resolutions is an important goal in cognitive ...