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: These findings suggest that our gamma TFWOI might not have been optimal to find differences between conditions. Thus, we reran our group-level volumetric analysis using a new gamma TFWOI: 50–90 Hz, 100–450 ms (see Fig.6). As before, significant differences were present in right lateral occipital cortex, but this time also extended more anteriorly across the ventral surface of the cortex, extending to the fusiform gyrus (Talaraich coordinates: 35.1, −65.3, −13) around the posterior part of the fusiform face area (FFA). Significant differences were also found in left lateral occipital cortex (Talaraich coordinates: −41.2, −87.3, −7.0). Thus, by optimizing our TFWOI we were able to increase the statistical sensitivity of our analysis and uncover regions of significant difference between conditions that were not present in our initial analysis.
Affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, 70 Park Place, Cardiff, CF10 3AT, Wales, UK.