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Evoked Field
Evoked fields are part of the Magnetoencephalography, magnetoencephalogram. They are brain signals evoked by sensory stimulation, but usually buried by the ongoing brain activity. Repeating the stimulus multiple times and averaging the signals reduces the uncorrelated ongoing activity and reveals the evoked field. Evoked fields are the magnetoencephalographic equivalent to evoked potentials, which are part of the electroencephalography, electroencephalogram. Auditory evoked fields An auditory evoked field (AEF) is a form neural activity that is induced by an auditory stimulus and recorded via magnetoencephalogram, magnetoencephalography, which is an equivalent of auditory evoked potential (AEP) recorded by EEG, electroencephalography. The advantage of AEF over AEP is the powerful spatial resolution provided by magnetic field recording, which AEP lacks. Thus, researchers using AEF often deals with the global responses of the whole brain at the Cerebral cortex, cortical level while fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetoencephalography
Magnetoencephalography (MEG) is a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers. Arrays of SQUIDs (superconducting quantum interference devices) are currently the most common magnetometer, while the SERF (spin exchange relaxation-free) magnetometer is being investigated for future machines. Applications of MEG include basic research into perceptual and cognitive brain processes, localizing regions affected by pathology before surgical removal, determining the function of various parts of the brain, and neurofeedback. This can be applied in a clinical setting to find locations of abnormalities as well as in an experimental setting to simply measure brain activity. History MEG signals were first measured by University of Illinois physicist David Cohen in 1968, before the availability of the SQUID, using a copper induction coil as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |