Estimation of equivalent current dipoles and the analysis of synthetic aperture magnetmetry on auditory evoked magnetic responses

摘要

We have been studying auditory evoked magnetic fields and dipole analysis. Today synthetic aperture magnetometry (SAM) was applied to the data of auditory evoked responses. Auditory evoked N100 potentials originate in actions of the auditory cortices. The magnetic recordings of this 100-ms response are the major studies. We acquired auditory evoked magnetic fields (AEF) with a whole head array of 64-channel SQUID sensors and averaged whole hundred trials then estimated equivalent current dipoles (BCD) at 100-ms latencies. We analyzed the AEF data from whole channels with dual-state SAM analyze of pseudo-Student's T statistics around 100 ms between each frequency band (alpha: 8-13 Hz, (3: 13-25 Hz,gamma: 25-50 Hz). The resulting ECDs and SAM images are plotted/superimposed into own MR images. SAM images were estimated around the locations of the ECDs in the auditory cortices of the temporal lobes. Synchronization of the electrical activations around 100 ms was observed in all frequency bands. Synchronization of source power revealed by SAM and BCD analyses showed compatible temporal information. The novel technique SAM appears useful for cortical activation in processing perceptual information.