Spatial Filtering for Gamma Oscillation Detection and Analysis in Auditory Evoked Experiment

摘要

Recently, gamma oscillations have gained much attention as a potential solution to the binding problem. However, it is well known that gamma oscillation recordings have relatively small amplitude and low signal-to-noise ratio (SNR). In this study we investigate the use of adaptive spatial filtering techniques to detect and analyze gamma activity in auditory evoked response experiments, based on the difference in topography of slow auditory evoked response and gamma oscillations. A 37-channel SQUID magnetometer was used to record auditory responses evoked by monaural presentation of base and target tones. Synchronized gamma activity was observed for all subjects and had a spatial pattern distinct from that of the slow auditory evoked response. Preliminary localization results show activation of frontal areas across all subjects studied. Use of this spatial information allows construction of adaptive spatial filters to increase the SNR of the gamma oscillations and to improve the precision of source localization.