Distinct patterns of spatial attentional modulation of steady‐state visual evoked magnetic fields (SSVEFs) in subdivisions of the human early visual cortex

• Published in: Psychophysiology Vol. 61; no. 2; pp. e14452 - n/a
• Main Authors: Moratti, Stephan, Gundlach, Christopher, Echegaray, Javier, Müller, Matthias M.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.02.2024
• Subjects: Attention task; Cortex (parietal); cortical sources; MEG; spatial attention; steady state visual evoked responses; Temporal cortex; Visual cortex; Visual evoked potentials; spatial attention; cortical sources; steady state visual evoked responses; MEG
• ISSN: 0048-5772; 1469-8986; 1469-8986; 1540-5958
• DOI: 10.1111/psyp.14452

In recent years, steady‐state visual evoked potentials (SSVEPs) became an increasingly valuable tool to investigate neural dynamics of competitive attentional interactions and brain–computer interfaces. This is due to their good signal‐to‐noise ratio, allowing for single‐trial analysis, and their ongoing oscillating nature that enables to analyze temporal dynamics of facilitation and suppression. Given the popularity of SSVEPs, it is surprising that only a few studies looked at the cortical sources of these responses. This is in particular the case when searching for studies that assessed the cortical sources of attentional SSVEP amplitude modulations. To address this issue, we used a typical spatial attention task and recorded neuromagnetic fields (MEG) while presenting frequency‐tagged stimuli in the left and right visual fields, respectively. Importantly, we controlled for attentional deployment in a baseline period before the shifting cue. Subjects either attended to a central fixation cross or to two peripheral stimuli simultaneously. Results clearly showed that signal sources and attention effects were restricted to the early visual cortex: V1, V2, hMT+, precuneus, occipital‐parietal, and inferior‐temporal cortex. When subjects attended to central fixation first, shifting attention to one of the peripheral stimuli resulted in a significant activation increase for the to‐be‐attended stimulus with no activation decrease for the to‐be‐ignored stimulus in hMT+ and inferio‐temporal cortex, but significant SSVEF decreases from V1 to occipito‐parietal cortex. When attention was first deployed to both rings, shifting attention away from one ring basically resulted in a significant activation decrease in all areas for the then‐to‐be‐ignored stimulus. Although the cortical generators of steady‐state visual evoked responses as recorded by EEG or MEG (SSVEPs or SSVEFs, respectively) have been described in humans, how these generators are involved in the modulation of these evoked oscillatory responses by spatial attention is less known. Here, we describe how distinct sub‐divisions of the early human visual cortex contribute differently to the modulation of SSVEFs by spatial attention.