Recent findings in the visual system of non-human primates have demonstrated an important role of gamma band activity (40 — 100 Hz) in the feed-forward flow of sensory information, whereas feedback control appears to be dynamically established by oscillations in the alpha (8 — 13 Hz) and beta bands (13 — 18 Hz) (van Kerkoerle et al., 2014; Bastos et al., 2015). It is not clear, however, how alpha oscillations are controlled and how they interact with the flow of visual information mediated by gamma band activity. Using non-invasive human magnetoencephalographic recordings in subjects performing a visuo-spatial attention task, we show that fluctuations in alpha power during a delay period in a spatial attention task preceded subsequent stimulus-driven gamma band activity. Importantly, these interactions correlated with behavioral performance. Using a Granger analysis we further show that the right frontal-eye field (rFEF) exerted feedback control of the visual alpha oscillations. Our findings suggest that alpha oscillations controlled by the FEF route cortical information flow by modulating gamma band activity.
Visual perception relies on a feed-forward flow of information from sensory regions, which is modulated by a feedback drive. We have identified the neuronal dynamics supporting integration of the feed-forward and feedback information. Alpha oscillations in early visual regions reflect feedback control when spatial attention is allocated and this control is exercised by the right frontal eye-field. Importantly the alpha band activity predicted both performance and activity in the gamma band. In particular the gamma activity was modulated by the phase of the alpha oscillations. These findings provide novel insight into how the brain operates as network and suggest that the integration of feed-forward and feedback information is implemented by cross-frequency interactions between slow and fast neuronal oscillations.
The authors declare no competing financial interests.
The contribution of TP was supported by the Netherlands Organization for Scientific Research (NWO) VICI Grant (#453-09-002) awarded to OJ. SK was supported by NIH (RO1-MH64043, RO1-EY017699), NSF (BCS-132827) and the James S. McDonnell Foundation. We thank Yuri Saalmann and Liang Wang for providing a version of the code for the Flanker paradigm. The authors declare no competing conflicts of interests.