Distributed Parallel Processing in the Vestibulo-Oculomotor System

The mechanisms of eye-movement control are among the best understood in motor neurophysiology. Detailed anatomical and physiological data have paved the way for theoretical models that have unified existing knowledge and suggested further experiments. These models have generally taken the form of black-box diagrams (for example, Robinson 1981) representing the flow of hypothetical signals between idealized signal-processing blocks. They approximate overall oculomotor behavior but indicate little about how real eye-movement signals would be carried and processed by real neural networks. Neurons that combine and transmit oculomotor signals, such as those in the vestibular nucleus (VN), actually do so in a diverse, seemingly random way that would be impossible to predict from a block diagram. The purpose of this study is to use a neural-network learning scheme (Rumelhart et al. 1986) to construct parallel, distributed models of the vestibulo-oculomotor system that simulate the diversity of responses recorded experimentally from VN neurons.

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Eye movement evaluation in Multiple Sclerosis and Parkinson’s Disease using a Standardized Oculomotor and Neuro-ophthalmic Disorder Assessment (SONDA)

10.1101/2020.04.20.20072603 ◽

2020 ◽

Author(s):

Alessandro Grillini ◽

Remco J. Renken ◽

Anne C. L. Vrijling ◽

Joost Heutink ◽

Frans W. Cornelissen

Keyword(s):

Multiple Sclerosis ◽

Parkinson’S Disease ◽

Parkinson's Disease ◽

Standardized Tests ◽

Eye Movement ◽

Oculomotor System ◽

Oculomotor Behavior ◽

Non Invasive ◽

Spatio Temporal ◽

Pursuit Gain

AbstractEvaluating the state of the oculomotor system of a patient is one of the fundamental tests done in neuro-ophthalmology. However, up to date, very few quantitative standardized tests of eye movements quality exist, limiting this assessment to confrontational tests reliant on subjective interpretation. Furthermore, quantitative tests relying on eye movement properties such as pursuit gain and saccade dynamics are often insufficient to capture the complexity of the underlying disorders and are often (too) long and tiring. In this study, we present SONDA (Standardised Oculomotor and Neurological Disorder Assessment): this test is based on analyzing eye tracking recorded during a short and intuitive continuous tracking task. We tested patients affected by Multiple Sclerosis (MS) and Parkinson’s Disease (PD) and find that: (1) the saccadic dynamics of the main sequence alone are not sufficient to separate patients from healthy controls; (2) the combination of spatio-temporal and statistical properties of saccades and saccadic dynamics enables an identification of oculomotor abnormalities in both MS and PD patients. We conclude that SONDA constitutes a powerful screening tool that allows an in-depth evaluation of (deviant) oculomotor behavior in a few minutes of non-invasive testing.

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Time course of spatiotopic updating across saccades

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1812210116 ◽

2019 ◽

Vol 116 (6) ◽

pp. 2027-2032 ◽

Cited By ~ 6

Author(s):

Jasper H. Fabius ◽

Alessio Fracasso ◽

Tanja C. W. Nijboer ◽

Stefan Van der Stigchel

Keyword(s):

Eye Movements ◽

Visual System ◽

Eye Movement ◽

Time Course ◽

Saccadic Eye Movements ◽

Oculomotor System ◽

Stimulus Onset ◽

Oculomotor Behavior ◽

Behavioral Studies ◽

The Brain

Humans move their eyes several times per second, yet we perceive the outside world as continuous despite the sudden disruptions created by each eye movement. To date, the mechanism that the brain employs to achieve visual continuity across eye movements remains unclear. While it has been proposed that the oculomotor system quickly updates and informs the visual system about the upcoming eye movement, behavioral studies investigating the time course of this updating suggest the involvement of a slow mechanism, estimated to take more than 500 ms to operate effectively. This is a surprisingly slow estimate, because both the visual system and the oculomotor system process information faster. If spatiotopic updating is indeed this slow, it cannot contribute to perceptual continuity, because it is outside the temporal regime of typical oculomotor behavior. Here, we argue that the behavioral paradigms that have been used previously are suboptimal to measure the speed of spatiotopic updating. In this study, we used a fast gaze-contingent paradigm, using high phi as a continuous stimulus across eye movements. We observed fast spatiotopic updating within 150 ms after stimulus onset. The results suggest the involvement of a fast updating mechanism that predictively influences visual perception after an eye movement. The temporal characteristics of this mechanism are compatible with the rate at which saccadic eye movements are typically observed in natural viewing.

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Pardon the interruption: saccadic inhibition enables the rapid deployment of alternate oculomotor plans

10.1101/285841 ◽

2018 ◽

Cited By ~ 1

Author(s):

Emilio Salinas ◽

Terrence R. Stanford

Keyword(s):

Eye Movement ◽

Visual Information ◽

Oculomotor System ◽

Sudden Onset ◽

Physiological Data ◽

Alternative Plan ◽

New Information ◽

Saccadic Inhibition ◽

Simulation Results ◽

Rapid Deployment

Diverse psychophysical and neurophysiological results show that oculomotor networks are continuously active, such that plans for making the next eye movement are always ongoing. So, when new visual information arrives unexpectedly, how are those plans affected? At what point can the new information start guiding an eye movement, and how? Here, based on modeling and simulation results, we make two observations that are relevant to these questions. First, we note that many experiments, including those investigating the phenomenon known as “saccadic inhibition,” are consistent with the idea that sudden-onset stimuli briefly interrupt the gradual rise in neural activity associated with the preparation of an impending saccade. And second, we show that this stimulus-driven interruption is functionally adaptive, but only if perception is fast. In that case, putting on hold an ongoing saccade plan toward location A allows the oculomotor system to initiate a concurrent, alternative plan toward location B (where a stimulus just appeared), deliberate (briefly) on the priority of each target, and determine which plan should continue. Based on physiological data, we estimate that the actual advantage of this strategy, relative to one in which any plan once initiated must be completed, is of several tens of milliseconds.

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New Perspectives on Serialism and Parallelism in Oculomotor Control During Reading: The Multi-Constituent Unit Hypothesis

Vision ◽

10.3390/vision3040050 ◽

2019 ◽

Vol 3 (4) ◽

pp. 50 ◽

Cited By ~ 1

Author(s):

Chuanli Zang

Keyword(s):

Eye Movement ◽

Computational Models ◽

Lexical Processing ◽

Ambiguous Word ◽

Movement Control ◽

Critical Issue ◽

Oculomotor Control ◽

Oculomotor Behavior ◽

Good Account ◽

Proposed Model

Currently there are several computational models of eye movement control that provide a good account of oculomotor behavior during reading of English and other alphabetic languages. I will provide an overview of two dominant models: E-Z Reader and SWIFT, as well as a recently proposed model: OB1-Reader. I will evaluate a critical issue of controversy among models, namely, whether words are lexically processed serially or in parallel. I will then consider reading in Chinese, a character-based, unspaced language with ambiguous word boundaries. Finally, I will evaluate the concepts of serialism and parallelism of process central to these models, and how these models might function in relation to lexical processing that is operationalized over parafoveal multi-constituent units.

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Nitric oxide facilitates GABAergic neurotransmission in the cat oculomotor system: a physiological mechanism in eye movement control

The Journal of Physiology ◽

10.1113/jphysiol.2001.013308 ◽

2002 ◽

Vol 540 (1) ◽

pp. 295-306 ◽

Cited By ~ 10

Author(s):

Bernardo Moreno‐López ◽

Miguel Escudero ◽

Carmen Estrada

Keyword(s):

Nitric Oxide ◽

Eye Movement ◽

Physiological Mechanism ◽

Movement Control ◽

Oculomotor System ◽

Gabaergic Neurotransmission ◽

Eye Movement Control ◽

System A

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The game of word skipping: Who are the competitors?

Behavioral and Brain Sciences ◽

10.1017/s0140525x03270102 ◽

2003 ◽

Vol 26 (4) ◽

pp. 481-482 ◽

Cited By ~ 2

Author(s):

Ralf Engbert ◽

Reinhold Kliegl

Keyword(s):

Eye Movement ◽

Mathematical Analysis ◽

Computational Models ◽

Word Identification ◽

Movement Control ◽

Oculomotor System ◽

Current Understanding ◽

Saccade Target ◽

Identification System ◽

Word Skipping

Computational models such as E-Z Reader and SWIFT are ideal theoretical tools to test quantitatively our current understanding of eye-movement control in reading. Here we present a mathematical analysis of word skipping in the E-Z Reader model by semianalytic methods, to highlight the differences in current modeling approaches. In E-Z Reader, the word identification system must outperform the oculomotor system to induce word skipping. In SWIFT, there is competition among words to be selected as a saccade target. We conclude that it is the question of competitors in the “game” of word skipping that must be solved in eye movement research.

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COMPLEXITY OF EYE MOVEMENTS IN READING

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127404009491 ◽

2004 ◽

Vol 14 (02) ◽

pp. 493-503 ◽

Cited By ~ 13

Author(s):

R. ENGBERT ◽

R. KLIEGL ◽

A. LONGTIN

Keyword(s):

Eye Movements ◽

Eye Movement ◽

Stochastic Models ◽

Lexical Processing ◽

Movement Control ◽

Oculomotor System ◽

Statistical Features ◽

Symbolic Coding ◽

Random Fluctuations ◽

Erratic Behavior

During reading, our eyes perform complicated sequences of fixations on words. Stochastic models of eye movement control suggest that this seemingly erratic behavior can be attributed to noise in the oculomotor system and random fluctuations in lexical processing. Here, we present a qualitative analysis of a recently published dynamical model [Engbert et al., 2002] and propose that deterministic nonlinear control accounts for much of the observed complexity of eye movement patterns during reading. Based on a symbolic coding technique we analyze robust statistical features of simulated fixation sequences.

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