Multidimensional EEG analysis reveals a transient cortical network in early visual processing L Rosas-Martinez, E Milne, Y Zheng |
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Psychology, University of Sheffield, United Kingdom
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| Functional integration and segregation in visual perception have been mainly studied in severe neurobehavioral deficits, suggesting that brain activation is stimulus-dependent. Primary sensory areas have shown to be hyperactivated when presenting sinusoidal gratings. Conversely, functional integration among such areas is reduced in the presence of complex stimuli. However, the relation between these two cortical properties has been largely overlooked. We aim to investigate whether it is possible to measure functional integration along segregation in early visual areas and the underneath temporal dynamics. Ten participants were presented with sinusoidal gratings at two different spatial frequencies (2.8 and 6 cpd) to elicit steady-state visual evoked potentials (SSVEPs). Wavelet analysis was applied to the SSVEP responses to elucidate the temporal properties of brain rhythms. Our stimuli elicited a frequency-specific local network in parieto-occipital area that arises at stimulus onset and whose intensity diminishes in the steady response. This network is highly dynamic as synchronizes differently in each spectral band. Our results might imply an integration of top-down signals coming down from different areas that contribute to the segregation reported in visual areas. This study provides evidence that the interplay between functional integration and segregation performs an important role in visual perception. |
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