Temporal dynamics of saccades explained by a self-paced process

Roy Amit, Dekel Abeles, Izhar Bar-Gad, Shlomit Yuval-Greenberg

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Sensory organs are thought to sample the environment rhythmically thereby providing periodic perceptual input. Whisking and sniffing are governed by oscillators which impose rhythms on the motor-control of sensory acquisition and consequently on sensory input. Saccadic eye movements are the main visual sampling mechanism in primates, and were suggested to constitute part of such a rhythmic exploration system. In this study we characterized saccadic rhythmicity, and examined whether it is consistent with autonomous oscillatory generator or with self-paced generation. Eye movements were tracked while observers were either free-viewing a movie or fixating a static stimulus. We inspected the temporal dynamics of exploratory and fixational saccades and quantified their first-order and high-order dependencies. Data were analyzed using methods derived from spike-train analysis, and tested against mathematical models and simulations. The findings show that saccade timings are explained by first-order dependencies, specifically by their refractory period. Saccade-timings are inconsistent with an autonomous pace-maker but are consistent with a "self-paced" generator, where each saccade is a link in a chain of neural processes that depend on the outcome of the saccade itself. We propose a mathematical model parsimoniously capturing various facets of saccade-timings, and suggest a possible neural mechanism producing the observed dynamics.

Original languageEnglish
Article number886
JournalScientific Reports
Issue number1
StatePublished - 20 Apr 2017

Bibliographical note

Funding Information:
This work was funded by the Israel Science Foundation (ISF) grant 1427/14. We thank Leon Deouell for a thoughtful discussion and helpful advice. We thank Avia Eyal for her help in running experiments, and Itzik Norman and Omer Sharon for fruitful discussions.

Publisher Copyright:
© 2017 The Author(s).


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