Benedetto Alessandro, Morrone Maria Concetta
Department of Neuroscience, Psychology, Pharmacology and Child Health, University of Florence, 50135 Florence, Italy.
Department of Translational Research on New Technologies in Medicines and Surgery, University of Pisa, 56123 Pisa, Italy.
J Neurosci. 2017 Mar 29;37(13):3661-3670. doi: 10.1523/JNEUROSCI.2390-16.2016. Epub 2017 Mar 7.
Action and perception are intimately coupled systems. One clear case is saccadic suppression, the reduced visibility around the time of saccades, which is important in mediating visual stability; another is the oscillatory modulation of visibility synchronized with hand action. To suppress effectively the spurious retinal motion generated by the eye movements, it is crucial that saccadic suppression and saccadic onset be temporally synchronous. However, the mechanisms that determine this temporal synchrony are unknown. We investigated the effect of saccades on contrast discrimination sensitivity over a long period stretching over >1 s before and after saccade execution. Human subjects made horizontal saccades at will to two stationary saccadic targets separated by 20°. At a random interval, a brief Gabor patch was displayed between the two fixations in either the upper or lower visual field and the subject had to detect its location. Strong saccadic suppression was measured between -50 and 50 ms from saccadic onset. However, the suppression was systematically embedded in a trough of oscillations of contrast sensitivity that fluctuated rhythmically in the delta range (at ∼3 Hz), commencing ∼1 s before saccade execution and lasting for up to 1 s after the saccade. The results show that saccadic preparation and visual sensitivity oscillations are coupled and the coupling might be instrumental in temporally aligning the initiation of the saccade with the visual suppression. Saccades are known to produce a suppression of contrast sensitivity at saccadic onset and an enhancement after saccadic offset. Here, we show that these dynamics are systematically embedded in visual oscillations of contrast sensitivity that fluctuate rhythmically in the delta range (at ∼3 Hz), commencing ∼1 s before saccade execution and lasting for up to 1 s after the saccade. The results show that saccadic preparation and visual sensitivity oscillations are coupled and the coupling might be instrumental in aligning temporally the initiation of the saccade with the visual suppression.
动作与感知是紧密相连的系统。一个明显的例子是扫视抑制，即扫视期间周围视觉清晰度降低，这对调节视觉稳定性很重要；另一个例子是与手部动作同步的视觉清晰度振荡调制。为了有效抑制眼球运动产生的虚假视网膜运动，扫视抑制和扫视起始在时间上同步至关重要。然而，决定这种时间同步的机制尚不清楚。我们研究了扫视对扫视执行前后超过1秒的长时间内对比度辨别敏感度的影响。人类受试者随意进行水平扫视，看向两个相距20°的固定扫视目标。在随机间隔时间，一个简短的伽马校正过的条纹光栅补丁会在上半视野或下半视野的两次注视点之间显示，受试者必须检测其位置。在扫视起始后-50至50毫秒之间测量到强烈的扫视抑制。然而，这种抑制系统性地嵌入在对比度敏感度振荡的波谷中，该振荡在δ频段（约3赫兹）有节奏地波动，在扫视执行前约1秒开始，扫视后持续长达1秒。结果表明，扫视准备与视觉敏感度振荡是耦合的，这种耦合可能有助于在时间上使扫视起始与视觉抑制对齐。已知扫视在起始时会抑制对比度敏感度，在扫视结束后会增强。在此，我们表明这些动态变化系统性地嵌入在对比度敏感度的视觉振荡中，该振荡在δ频段（约3赫兹）有节奏地波动，在扫视执行前约1秒开始，扫视后持续长达1秒。结果表明，扫视准备与视觉敏感度振荡是耦合的，这种耦合可能有助于在时间上使扫视起始与视觉抑制对齐。
