Check out the left! Selective modulation of neuronal communication between visual areas by visual spatial attention

Abstract

At all times only a limited part of the sensory information that flows through our brain can be analyzed up to its highest cognitive levels in order to guide behaviour. Within this current conjecture and within the visual domain, spatial attention is able to select and prioritize information from a limited part of the visual field while ignoring the remaining, non-chosen parts. How does this selection process occur and how does it affect the flow of sensory processing within the hierarchically structured networks? How does our brain know which information to discard and which to enhance, and more crucially, in which order to operate these two sides of the selection process? Previous studies in the non-human primate brain have shown how selective spatial attention to a visual target positively modulates overall time-averaged coherence values across electrode groups implanted in the sensory visual cortex. In this study, we focus on the modulation of neural activity, and specifically on neuronal communication between distant networks within visual processing streams within and beyond the human primary visual cortex through the scope of human intracranial recordings performed in epileptic patients. We specifically focus on the temporal profile of the modulation of local oscillatory power responses and distant coherence modulations between recording sites, in a frequency range from theta to high-gamma (4–80 Hz). We show that selectively orienting spatial attention through endogenous cuing (left versus right) on bilateral dynamic gratings may produce a response pattern that in time first actively inhibits long-distant communication in the ipsi-lateral hemisphere, which processes distractor information, before enhancing communication in the contra-lateral hemisphere, which processes the selected target. We show these effects are frequency specific and reveal the underlying mechanism for selectively routing sensory visual information across brain networks.