Abstract:  It has been well documented that the spotlight of attention is intrinsically rhythmic, which discretely samples a single or multiple objects. Adopting high resolution behavioral approach, attention oscillation has been revealed. However, neural mechanism of attention oscillation remains poorly understood. In the present study, basing on functional anatomy of the primary visual cortex, we aimed to investigate the role of primary visual cortex (V1) in attention oscillation, by using a modified high temporal resolution cue-target paradigm in a 4AFC task. In the present study, behavioral oscillations in visual attention under ordinary (binocular; not dichoptic) viewing condition (exp. 1) and binocular dichoptic (exp. 2) condition were examined. In experiment 1, 16 paid participants were asked to detect target at either the previously cued (valid condition) or uncued location (invalid condition). The cue-target SOA varied from 0.1 s to 1.08 s in steps of 20 ms. Performances were evaluated in a 4AFC task. If they saw target, they were instructed to judge the location of the target (1 for target on the upper left; 2 for upper right; 4 for lower left; 5 for lower right) on the keypad. While, 16 paid participants were recruited to detect target at either cued or uncued locations under binocular dichoptic condition. Target could occur in the same or different eye of cue stimuli. Amplitude of target contrast decrement was determined with QUEST procedure before cue-target experiment. Except that no cue stimuli were presented, threshold procedure was identical to the cue-target experiment procedure. Results showed that when grating locations were presented under ordinary viewing condition, a theta rhythm was visible. While targets were presented in the same or different eye under binocular dichoptic condition, attention oscillation was clearly seen at 12.5 Hz with antiphase relationship between cued and uncued conditions. The findings under ordinary viewing condition are in general consistent with previous studies. While, under binocular dichoptic condition, attention oscillation increased to a higher frequency. This study indicates that attention oscillation may occur at or beyond primary visual cortex where binocular integration begins.

Key words: attention oscillation, V1, binocular dichoptic, high temporal resolution, cue-target paradigm