Role of vergence during eye fixation in orienting visual attention

Résumé fourni par la source

Neural mechanisms of attention allow selective sensory information processing. Top-down deployment of visual-spatial attention involves extensive cortical feedback connections from frontal cortical regions to lower sensory areas. Here we provide evidence for a novel circuit in guiding top-down attention. In a series of standard attention paradigms (Solé et al., 2013), subjects fixated on a central spot and were required to indicate the change in orientation of one of eight peripheral bars by pressing a button. In trials where the spatial location of the peripheral target was cued, we found strong eye vergence (convergence) while in non-cued trials vergence was weak. Similarly, for high-salient targets, vergence was strong compared to that recorded after presenting low-salient stimuli. Thus when orienting visual attention, the eyes briefly converge. Correspondingly, we recorded visual evoked responses (vERPs). The results show that vERPs reflecting attention deployment (N2pc) were a function of the eye vergence. Moreover, we provide evidence that vergence correlates with the perception of the target. Eyes briefly converge after a perceived target but not after an unnoticed one. Furthermore, we measured vergence in children diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) while performing a cue/no-cue task and compared the results to age-matched controls. A strong vergence was detected in the control group but not in the ADHD group. The near-triad or accommodation reflex does not appear to be an explanatory factor for the observed vergence. We propose that our findings show a novel role for vergence in visual-spatial attention and provide evidence for a feed-forward, oculomotor circuit in top-down visual attention. Solé Puig M, Pérez Zapata L, Aznar-Casanova JA, Supèr H (2013) A Role of Eye Vergence in Covert Attention. PLoS ONE 8(1): e52955. doi:10.1371/journal.pone.0052955 Meeting abstract presented at VSS 2014

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