Methods: MEG 1 0.0 / 5 ? PsychologyMethods: MEG 1UniversityNone Created by: CanveySamCreated on: 06-05-15 12:08 What does MEG stand for? Magnetoencephalography 1 of 19 What does MEG measure? magnetic fields, generated by the brain 2 of 19 How does MEG differ from EEG? 1) can be measured at a single point 2) no reference point needed 3) no electrical circuit 3 of 19 What are the implications of an MEG not involving electrical circuits? Signal unimpeded by skull, signal less spread out, therefore better spatial resolution 4 of 19 What neurons and potentials are involved? PYRAMIDAL and POSTYNAPTIC potentials (last 20ms) 5 of 19 What is the right hand rule? no - Radial dipole; yes - Tangential dipole 6 of 19 2 methods of noise cancellation? 1) Sensor design 2) Shielded room (Faraday cage) 7 of 19 What does SQUID stand for? Superconducting Quantum Interference Device - high tech and expensive 8 of 19 3 other noise removal methods? 1) filtering e.g. low pass, high pass, 50Hz 2) reference subtracted from SQUID 3) averaging e.g. over 100,000 trials 9 of 19 How many MEG sensors are used? Up to 275 10 of 19 Compare position of sensors between MEG and EEG EEG - stuck but head movements can cause transient artefacts. MEG - loose over so if the head moves the position changes 11 of 19 what does ERF stand for? Event Related Field 12 of 19 what is used to transform data to a time frequency histogram? time-frequency decomposition 13 of 19 Why use MEG for mismatch negativity? Faster, sensitive to source only, many sensors 14 of 19 Compare MEG/EEG for dipoles MEG - only measures tangential dipoles, EEG - measures both tangential and radial dipoles 15 of 19 Is MEG or EEF more spatially precise? MEG 16 of 19 Is MEG or EEG better at picking up spikes? EEG 17 of 19 Is MEG or EEG less sensitive to deep sources? MEG 18 of 19 Is MEG or EEG better at timing? MEG 19 of 19
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