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Magnetoencephalography (MEG) is a neuroscientific technique that can be used to detect brain activity noninvasively with high temporal resolution. Analogously like the EEG, the underlying signal is directly attributable to neuronal activity.
Compared to the EEG, the MEG measures (extremely weak) changes of the magnetic field on the head surface. To achieve this, in addition to a complex magnetic shielding, the use of superconducting sensors (so-called SQUIDs) is necessary. In order to maintain the superconducting state, cooling by means of liquid helium is necessary.
The TRIUX system from Elekta, which is available at the MEG laboratory of the CCNS, has a total of 306 sensors (102 magnetometers and 204 gradiometers) that capture the signal from a total of 102 positions. If required, the deduction can be expanded by 128 EEG electrodes. The sampling rate of the device is up to max. 10kHz.
The laboratory is used by CDK mostly clinically (mainly for epilepsy diagnostics) and by researchers at the PLUS in the context of cognitive neuroscientific studies. For the latter area, a wide range of state-of-the-art stimulation devices (including visual, auditory, somatosensory) allow experimental diversity and flexibility. A special feature are two simultaneous controllable devices for transcranial electrical brain stimulation, the effect of which can be investigated "online" using MEG. The TRIUX system has been installed with a closed helium recovery system, which also saves time as well as eliminating the weekly "refills".
Prof. Dr. Nathan Weisz
The Core Facility MEG supports all interested parties of the Salzburg neuroscientific community to carry out MEG studies at an international top level.
In addition to the provision of the laboratory, it includes the training of users, consultancy, etc.: a) at the design, b) at the implementation by means of the Psychophysics Toolbox, c) at the testing of the experientalscripts (including triggering and timing) and d) at the evaluation. Concerning the latter the core facility team regularly provides well-maintained and tested fieldtrip-based analysis pipelines.
Methods & Expertise for Research Infrastructure
A major advantage of this technique is that, unlike the EEG, the magnetic field penetrates the intervening layers (e.g., skull, scalp) without distortion. This usually results in a "cleaner" signal (better SNR) and easier handling of the modeling of basic generators. Thus, in addition to the time-high resolution, a spatial resolution (theoretically ~ 1 mm) satisfactory for many purposes is possible.
The Elekta TRIUX device allows carrying out investigations in which neuronal activity with high temporal resolution (currently up to a maximum of 10kHz) must be derived. This is highly relevant in many neurocognitive as well as clinical questions.
Apart from the consideration of "evoked" brain responses, an exact timing is also necessary to resolve oscillatory activity on different temporal scales. The use of modern inverse methods (normally in combination with a structural MRI) allows conclusions to be drawn on (probable) generators. Together with methods for the detection of the interaction between these generators, neural network dynamics can be investigated with spatial-temporally high resolution. This approach is becoming increasingly important in neurosciences.
Allocation to Core Facility
Linguistic Department, University of Salzburg
Cell Biology Department, University of Salzburg
Molecular Biology Department, University of Salzburg
Christian-Doppler Klinik (CDK), Salzburg
MED-EL Elektromedizinische Geräte Gesellschaft m.b.H
Win2Con - Brain-state dependent perception: finding the windows to consciousness
ERC - European Research Council
Faith and oscillations recovered: On analyzing EEG/MEG signals during tACS
Neuling, T., Ruhnau, P., Weisz, N., Herrmann, C.S. &, Demarchi, G.
NeuroImage, 147, 960-963
Interpretability of Multivariate Brain Maps in Linear Brain Decoding: Definition, and Heuristic Quantification in Multivariate Analysis of MEG Time-Locked Effects
Kia, S. M., Vega-Pons, S., Weisz, N., & Passerini, A.
Frontiers in Neuroscience, 10(619)
The Tactile Window to Consciousness is Characterized by Frequency-specific Integration and Segregation of the Primary Somatosensory Cortex
Frey, J., Ruhnau, P., Leske, S., Siegel, M., Braun, C., & Weisz, N.
Scientific Reports, 6: 20805
Limbic areas are functionally decoupled and visual cortex takes a more central role during fear conditioning in humans
Lithari, C., Moratti, S., & Weisz, N.
Scientific Reports, 6: 29220
Large-scale network-level processes during entrainment
Lithari C., Sanchez-Garcia, C., Ruhnau, P., & Weisz, N.
Brain Research, 1635, 143–152
Flicker-Driven Responses in Visual Cortex Change during Matched-Frequency Transcranial Alternating Current Stimulation
Ruhnau, P., Keitel, C., Lithari, C., Weisz, N., & Neuling, T.
Frontiers in Human Neuroscience, 10: 184
Eyes wide shut: Transcranial alternating current stimulation drives alpha rhythm in a state dependent manner
Ruhnau, P., Neuling, T., Fusca, M., Herrmann, C.S., Demarchi, G., & Weisz, N.
Scientific Reports, 6: 27138
Cross-modal distractors modulate oscillatory alpha power: the neural basis of impaired task performance
Weise, A., Hartmann, T., Schröger, E., Weisz, N., & Ruhnau, P.
Psychophysiology, 53(11), 1651–1659
Alpha suppression and connectivity modulations in left temporal and parietal cortices index partial awareness of words
Magazzini, L., Ruhnau, P., & Weisz, N.
NeuroImage, 133, 279-287
Spatially resolved time-frequency analysis of odour coding in the insect antennal lobe
Paoli, M., Weisz, N., Antolini, R., & Haase, A.
European Journal of Neuroscience, 44(6), 2387-2395
Beta Band Modulations underlie Action Representations for Movement Planning
Turella, L., Tucciarelli, R., Oosterhof, N.N., Weisz, N., Rumiati, R., & Lingnau, A.
Neuroimage, 136, 197–207
Temporal integration windows in neural processing and perception aligned to saccadic eye movements
Wutz, A., Muschter, E., van Koningsbruggen, M.G., Weisz, N., & Melcher, D.
Current Biology, 26, 1659–1668