Localizing evoked and induced responses to faces using magnetoencephalography.
Bottom Line: Recently, a number of studies have used magnetoencephalography (MEG) to try to record these responses non-invasively - in many cases using source analysis techniques based on the beamforming method.We localized the gamma-band response to bilateral lateral occipital cortex, and both the gamma-band response and the M170-evoked response to the right fusiform gyrus.These findings help to establish that MEG beamforming can localize face-specific responses in time, frequency and space with good accuracy (when validated against established findings from functional magnetic resonance imaging and intracranial recordings), as well as contributing to the establishment of best methodological practice for the use of the beamformer method to measure face-specific responses.
Affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, 70 Park Place, Cardiff, CF10 3AT, Wales, UK.Show MeSH
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Mentions: Figure4 demonstrates that, while both the face and the scrambled stimuli induce a broadband gamma response extending from around 50 Hz up to at least 150 Hz, there is little difference between conditions for frequencies above 80 Hz. This is confirmed in Fig.5A, which shows the group average amplitude spectrum across the time period 100–400 ms for both conditions. Significant differences between the two spectra were confined to the range of approximately 50–90 Hz – a narrower frequency bandwidth than used in our initial gamma TFWOI.
Affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, 70 Park Place, Cardiff, CF10 3AT, Wales, UK.