scholarly journals LRP predicts smooth pursuit eye movement onset during the ocular tracking of self-generated movements

2016 ◽  
Vol 116 (1) ◽  
pp. 18-29 ◽  
Author(s):  
Jing Chen ◽  
Matteo Valsecchi ◽  
Karl R. Gegenfurtner

Several studies have indicated that human observers are very efficient at tracking self-generated hand movements with their gaze, yet it is not clear whether this is simply a by-product of the predictability of self-generated actions or if it results from a deeper coupling of the somatomotor and oculomotor systems. In a first behavioral experiment we compared pursuit performance as observers either followed their own finger or tracked a dot whose motion was externally generated but mimicked their finger motion. We found that even when the dot motion was completely predictable in terms of both onset time and kinematics, pursuit was not identical to that produced as the observers tracked their finger, as evidenced by increased rate of catch-up saccades and by the fact that in the initial phase of the movement gaze was lagging behind the dot, whereas it was ahead of the finger. In a second experiment we recorded EEG in the attempt to find a direct link between the finger motor preparation, indexed by the lateralized readiness potential (LRP) and the latency of smooth pursuit. After taking into account finger movement onset variability, we observed larger LRP amplitudes associated with earlier smooth pursuit onset across trials. The same held across subjects, where average LRP onset correlated with average eye latency. The evidence from both experiments concurs to indicate that a strong coupling exists between the motor systems leading to eye and finger movements and that simple top-down predictive signals are unlikely to support optimal coordination.

2009 ◽  
Vol 101 (2) ◽  
pp. 934-947 ◽  
Author(s):  
Masafumi Ohki ◽  
Hiromasa Kitazawa ◽  
Takahito Hiramatsu ◽  
Kimitake Kaga ◽  
Taiko Kitamura ◽  
...  

The anatomical connection between the frontal eye field and the cerebellar hemispheric lobule VII (H-VII) suggests a potential role of the hemisphere in voluntary eye movement control. To reveal the involvement of the hemisphere in smooth pursuit and saccade control, we made a unilateral lesion around H-VII and examined its effects in three Macaca fuscata that were trained to pursue visually a small target. To the step (3°)-ramp (5–20°/s) target motion, the monkeys usually showed an initial pursuit eye movement at a latency of 80–140 ms and a small catch-up saccade at 140–220 ms that was followed by a postsaccadic pursuit eye movement that roughly matched the ramp target velocity. After unilateral cerebellar hemispheric lesioning, the initial pursuit eye movements were impaired, and the velocities of the postsaccadic pursuit eye movements decreased. The onsets of 5° visually guided saccades to the stationary target were delayed, and their amplitudes showed a tendency of increased trial-to-trial variability but never became hypo- or hypermetric. Similar tendencies were observed in the onsets and amplitudes of catch-up saccades. The adaptation of open-loop smooth pursuit velocity, tested by a step increase in target velocity for a brief period, was impaired. These lesion effects were recognized in all directions, particularly in the ipsiversive direction. A recovery was observed at 4 wk postlesion for some of these lesion effects. These results suggest that the cerebellar hemispheric region around lobule VII is involved in the control of smooth pursuit and saccadic eye movements.


2020 ◽  
Vol 117 (20) ◽  
pp. 11178-11183
Author(s):  
Natalya Shelchkova ◽  
Martina Poletti

It is known that attention shifts prior to a saccade to start processing the saccade target before it lands in the foveola, the high-resolution region of the retina. Yet, once the target is foveated, microsaccades, tiny saccades maintaining the fixated object within the fovea, continue to occur. What is the link between these eye movements and attention? There is growing evidence that these eye movements are associated with covert shifts of attention in the visual periphery, when the attended stimuli are presented far from the center of gaze. Yet, microsaccades are primarily used to explore complex foveal stimuli and to optimize fine spatial vision in the foveola, suggesting that the influences of microsaccades on attention may predominantly impact vision at this scale. To address this question we tracked gaze position with high precision and briefly presented high-acuity stimuli at predefined foveal locations right before microsaccade execution. Our results show that visual discrimination changes prior to microsaccade onset. An enhancement occurs at the microsaccade target location. This modulation is highly selective and it is coupled with a drastic impairment at the opposite foveal location, just a few arcminutes away. This effect is strongest when stimuli are presented closer to the eye movement onset time. These findings reveal that the link between attention and microsaccades is deeper than previously thought, exerting its strongest effects within the foveola. As a result, during fixation, foveal vision is constantly being reshaped both in space and in time with the occurrence of microsaccades.


eNeuro ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. ENEURO.0196-18.2019
Author(s):  
Omri Nachmani ◽  
Jonathan Coutinho ◽  
Aarlenne Z. Khan ◽  
Philippe Lefèvre ◽  
Gunnar Blohm

2011 ◽  
Vol 106 (5) ◽  
pp. 2675-2687 ◽  
Author(s):  
Yoshiko Izawa ◽  
Hisao Suzuki ◽  
Yoshikazu Shinoda

This study was performed to characterize the properties of the suppression of smooth pursuit eye movement induced by electrical stimulation of the frontal eye field (FEF) in trained monkeys. At the stimulation sites tested, we first determined the threshold for generating electrically evoked saccades (Esacs). We then examined the suppressive effects of stimulation on smooth pursuit at intensities that were below the threshold for eliciting Esacs. We observed that FEF stimulation induced a clear deceleration of pursuit at pursuit initiation and also during the maintenance of pursuit at subthreshold intensities. The suppression of pursuit occurred even in the absence of catch-up saccades during pursuit, indicating that suppression influenced pursuit per se. We mapped the FEF area that was associated with the suppressive effect of stimulation on pursuit. In a wide area in the FEF, suppressive effects were observed for ipsiversive, but not contraversive, pursuit. In contrast, we observed the bilateral suppression of both ipsiversive and contraversive pursuit in a localized area in the FEF. This area coincided with the area in which we have previously shown that stimulation suppressed the generation of saccades in bilateral directions and also where fixation neurons that discharged during fixation were concentrated. On the basis of these results, we compared the FEF suppression of pursuit with that of saccades with regard to several physiological properties and then discussed the role of the FEF in the suppression of both pursuit and saccades, and particularly in the maintenance of visual fixation.


1995 ◽  
Vol 25 (2) ◽  
pp. 387-403 ◽  
Author(s):  
L. Friedman ◽  
J. A. Jesberger ◽  
L. J. Siever ◽  
P. Thompson ◽  
R. Mohs ◽  
...  

SynopsisSmooth pursuit performance in schizophrenia and affective disorders has generally been found to be abnormal using a variety of measures. The purpose of this study was to assess patients with these disorders and normal controls in order to compare the different measures across diagnoses. Smooth pursuit was assessed using quantitative specific measures (gain, catch-up saccade rate and amplitude, square-wave jerk rate, number of anticipatory saccades and total time scored), as well as two global measures: root mean-square error (RMS) and qualitative rating. As previously reported, patients with schizophrenia had low gain, increased catch-up saccade rate and spent less time engaged in scoreable smooth pursuit than normal controls. Patients with affective disorders were not statistically different from controls on any of these measures, and had significantly higher gain than patients with schizophrenia. RMS error and qualitative rating measures were highly correlated (r = 0·87). In linear regression analyses, the quantitative specific measures were highly significant predictors of both RMS error and qualitative ratings (P < 0·0001). Linear regression analyses and a modelling study indicated that one quantitative specific measure, the percent of time engaged in scoreable smooth pursuit (total time scored), was most related to global ratings. However, RMS error and qualitative ratings were less sensitive than total time scored to the difference between controls and patients with schizophrenia. These data indicate two smooth pursuit performance deficits in schizophrenia: patients spend less time engaged in scoreable smooth pursuit and have low gain (accompanied by increased compensatory saccades) when the smooth pursuit is engaged.


2017 ◽  
Author(s):  
Uday K. Jagadisan ◽  
Neeraj J. Gandhi

AbstractThe trigeminal blink reflex can be evoked by delivering an air puff to the eye. If timed appropriately, e.g., during motor preparation, the small, loopy blink-related eye movement (BREM) associated with eyelid closure disinhibits the saccadic system and reduces the reaction time of planned eye movements. The BREM and intended eye movement overlap temporally, thus a mathematical formulation is required to objectively extract saccade features – onset time and velocity profile – from the combined movement. While it has been assumed that the interactions are nonlinear, we show that blink-triggered movements can be modeled as a linear combination of a typical BREM and a normal saccade, crucially, with an imposed delay between the two components. Saccades reconstructed with this approach are largely similar to control movements in their temporal and spatial profiles. Furthermore, activity profiles of saccade-related bursts in superior colliculus neurons for the recovered saccades closely match those for normal saccades. Thus, blink perturbations, if properly accounted for, offer a non-invasive tool to probe the behavioral and neural signatures of sensory-to-motor transformations.New and noteworthyThe trigeminal blink reflex is a brief noninvasive perturbation that disinhibits the saccadic system and provides a behavioral readout of the latent motor preparation process. The saccade, however, is combined with a loopy blink related eye movement. Here, we provide a mathematical formulation to extract the saccade from the combined movement. Thus, blink perturbations, when properly accounted for, offer a non-invasive tool to probe the behavioral and neural signatures of sensory-to-motor transformations.


2015 ◽  
Vol 15 (12) ◽  
pp. 1023
Author(s):  
Stephen Heinen ◽  
Elena Potapchuk ◽  
Scott Watamaniuk
Keyword(s):  

2021 ◽  
Vol 125 (5) ◽  
pp. 1552-1576
Author(s):  
David Souto ◽  
Dirk Kerzel

People’s eyes are directed at objects of interest with the aim of acquiring visual information. However, processing this information is constrained in capacity, requiring task-driven and salience-driven attentional mechanisms to select few among the many available objects. A wealth of behavioral and neurophysiological evidence has demonstrated that visual selection and the motor selection of saccade targets rely on shared mechanisms. This coupling supports the premotor theory of visual attention put forth more than 30 years ago, postulating visual selection as a necessary stage in motor selection. In this review, we examine to which extent the coupling of visual and motor selection observed with saccades is replicated during ocular tracking. Ocular tracking combines catch-up saccades and smooth pursuit to foveate a moving object. We find evidence that ocular tracking requires visual selection of the speed and direction of the moving target, but the position of the motion signal may not coincide with the position of the pursuit target. Further, visual and motor selection can be spatially decoupled when pursuit is initiated (open-loop pursuit). We propose that a main function of coupled visual and motor selection is to serve the coordination of catch-up saccades and pursuit eye movements. A simple race-to-threshold model is proposed to explain the variable coupling of visual selection during pursuit, catch-up and regular saccades, while generating testable predictions. We discuss pending issues, such as disentangling visual selection from preattentive visual processing and response selection, and the pinpointing of visual selection mechanisms, which have begun to be addressed in the neurophysiological literature.


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