Sensory Development and Motor Control in Infants and Children
Mark De Ste Croix, Thomas Korff in Paediatric Biomechanics and Motor Control, 2013
The eye also contains a set of six extraocular muscles (Figure 2.1b), which can move the eye vertically, horizontally and torsionally (Aslin 1987). When looking directly at an object, the visual image falls on the fovea, which is a small area of the retina containing only cones. Both head and body muscles can be used to foveate, but for rapid foveation the extraocular muscles are needed. They are also used for slow pursuit tracking of objects. In smooth pursuit tracking, the eyes can match the velocity of the moving stimulus. The extraocular muscles are also needed for binocular fixation, that is, moving both eyes to look directly at an object. The lack of binocular fixation can produce a double image (diplopia) or result in a loss of binocular depth perception or stereopsis (Aslin 1987).
Can Cognitive Theories Help to Understand Motor Dysfunction in Autism Spectrum Disorder?
Elizabeth B. Torres, Caroline Whyatt in Autism, 2017
Eye movements serve to maintain objects of interest on the fovea, the region of the retina that provides the greatest acuity and color detection (Leigh and Zee 2015). Accurate eye movements are essential for on-line regulation of fine and gross motor accuracy, in addition to proprioceptive signals, and also for providing visual feedback to refine movement accuracy over the long term. Saccades are semiballistic eye movements that shift the eye toward an object of interest, while smooth pursuit eye movements help us to track moving objects, while either an object or ourselves (or both) are in motion (Leigh and Zee 2015). These two main types of eye movements help us to plan actions and coordinate our whole-body movements, and give us visual information about our changing environment to enable us to adapt our actions on the fly. There are a number of known visual processing and ocular motor disturbances in ASD that are likely to impact these processes, which include impaired motion detection (Manning et al. 2013; Takarae et al. 2014), inaccurate eye movements (Takarae et al. 2004a, 2004b; Johnson et al. 2012; Schmitt et al. 2014), and inefficient timing of ocular motor with fine motor actions (Crippa et al. 2013).
Dynamic Control of Primary Eye Position as a Function of Head Orientation Relative to Gravity
Michael Fetter, Thomas Haslwanter, Hubert Misslisch, Douglas Tweed in Three-Dimensional Kinematics of Eye, Head and Limb Movements, 2020
It has been pointed out by several investigators that the vestibulo-ocular reflexes can not simply comply with the powerful kinematic constraints which Listing’s law imposes on saccades or smooth pursuit movements (Haslwanter et al., 1991; Tweed et al., 1992) since the vestibular input has to determine direction and speed of slow phase eye velocity as a function of head velocity independent of current orbital eye position. On the other hand, based on smoothness and continuity in parametric eye movement control one would expect that gravity which is so important in regulating the orientation of Listing’s plane has a significant impact on the spatial aspects of vestibulo-ocular reflex movements. This interaction could, for example, confine vestibularly driven nystagmus slow phases to certain relaxation positions that follow Listing’s law in the static limit of motion.
The Effect of Target Velocity on the Fast Corrective Response during Reaching Movement
Published in Journal of Motor Behavior, 2022
Kosuke Numasawa, Tomohiro Kizuka, Seiji Ono
In our experiment, participants were required to track the target motion, unlike the MFR. When we look at a small moving object, smooth pursuit eye movements are used to hold the target image on the fovea (Krauzlis, 2004; Lisberger, 2010; Ono, 2015). Smooth pursuit eye movements are driven by retinal slip signals generated from the difference between actual target motion and eye velocity. In particular, retinal slip information carried in the MT/MST plays an important role in the initial part of smooth pursuit (Dursteler & Wurtz, 1988; Newsome et al., 1985). As mentioned above, since arm movements responding to visual motion are associated with neuronal activity in the MT/MST, we speculate that the fast corrective response shares the same visual motion processing as smooth pursuit eye movements. Indeed, our results indicate that the initial amplitude (first 50 ms) of the corrective response increases according to the target velocity. However, a previous study has reported that the initial part of smooth pursuit (open-loop period) is not dependent on target velocity (Lisberger & Westbrook, 1985). Thus, one possible explanation is that the initiation of arm movement is generated differently from the eye movement, even though they both share a common retinal slip signal. Indeed, Saijo et al. (2005) have suggested that the MFR and the eye movements elicited by the large-field visual motion are separated even they are processed by the same visual information in parallel (Saijo et al., 2005).
Neuroanatomy and Imaging Assessment in Traumatic Brain Injury
Published in Journal of Binocular Vision and Ocular Motility, 2020
Mitchell Strominger
Smooth pursuit movements are driven through the horizontal gaze center. They require attention, anticipation, and working memory. The pathways are not known completely. Visual areas in the parietal and occipital lobes provide sensory information that is essential for the initiation and guidance of smooth pursuit movements. These areas also generate a slow phase of optokinetic nystagmus. Smooth pursuit of a predictive target is programmed by the cerebellum. This assists in tracking a target moving in a circle at a fixed rate and anticipates where the object will be located if extinguished, i.e. closing the eyes or having the object disappear. Patients with traumatic brain injury demonstrate decreased target position, increased eye position error with variability of eye position, and more abnormal findings when the target is temporarily extinguished. Our hunter then might have more difficulty tracking the flock of birds if they flew behind trees and anticipating where they would re-appear.
Traumatic Brain Injury in Children: Do the Eyes Have It? The Orthoptic Evaluation of Traumatic Brain Injury
Published in Journal of Binocular Vision and Ocular Motility, 2020
Kyle Arnoldi
Like saccades, accurate smooth pursuit requires executive brain functions such as attention, working memory, and the ability to anticipate target movement. Studies have reported that mTBI patients demonstrate deficits in predictive smooth pursuit, eye position error, and reduced velocity.1,7,10,15 Though deficiencies of smooth pursuit are thought to be a highly sensitive biomarker for mTBI, typically only gross defects can be detected with the naked eye, and only then by a skilled professional such as an orthoptist. The most clinically obvious pursuit dysfunction is decreased velocity resulting in a low gain response. This is confirmed clinically by the need for “catch-up” saccades while visually pursuing a moving target. These are small amplitude saccades in the direction of the target movement, generated by the target’s image slipping off of the fovea, and result in a “cogwheel” type of ocular movement. In mTBI, this “saccadic pursuit” may be observed with both volitional and reflexive pursuit tasks.
Related Knowledge Centers
- Eye
- Eye Movement
- Eye Tracking
- Fixation
- Saccade
- Psychophysics
- Vision Science
- Gaze
- Vestibulo–Ocular Reflex
- Search Coil Magnetometer