title: Saccadic Suppression Is Embedded Within Extended Oscillatory Modulation of Sensitivity.
abstract: 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.SIGNIFICANCE STATEMENTSaccades 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.
authors.affiliation: 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.
authors.forename: Alessandro
authors.identifier: 0000-0002-9713-1300
authors.initials: A
authors.lastname: Benedetto
authors.affiliation: Department of Translational Research on New Technologies in Medicines and Surgery, University of Pisa, 56123 Pisa, Italy, concetta@in.cnr.it.|Center for Human Technologies, IIT, 16152 Genova, Italy, and.|Scientific Institute Stella Maris, 56018 Calambrone, Pisa, Italy.
authors.forename: Maria Concetta
authors.identifier: 0000-0002-1025-0316
authors.initials: MC
authors.lastname: Morrone
mesh_terms: D000328:Adult; D001683:Biological Clocks / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008297:Male; D009433:Neural Inhibition / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012438:Saccades / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology*
keywords: action and perception; contrast sensitivity; eye movements; saccadic suppression; sensorimotor integration; visual oscillations