Differences in intersaccadic adaptation transfer between inward and outward adaptation

2011 ◽  
Vol 106 (3) ◽  
pp. 1399-1410 ◽  
Author(s):  
Fabian Schnier ◽  
Markus Lappe
Keyword(s):  
Peak Velocity ◽  
The Other ◽  
Saccade Target ◽  
Control Mechanisms ◽  
Saccadic Adaptation ◽  
Saccade Onset ◽  
Independent Parameters ◽  
Saccade Duration ◽  
Velocity Decrease

Saccadic adaptation is a mechanism to increase or decrease the amplitude gain of subsequent saccades, if a saccade is not on target. Recent research has shown that the mechanism of gain increasing, or outward adaptation, and the mechanism of gain decreasing, or inward adaptation, rely on partly different processes. We investigate how outward and inward adaptation of reactive saccades transfer to other types of saccades, namely scanning, overlap, memory-guided, and gap saccades. Previous research has shown that inward adaptation of reactive saccades transfers only partially to these other saccade types, suggesting differences in the control mechanisms between these saccade categories. We show that outward adaptation transfers stronger to scanning and overlap saccades than inward adaptation, and that the strength of transfer depends on the duration for which the saccade target is visible before saccade onset. Furthermore, we show that this transfer is mainly driven by an increase in saccade duration, which is apparent for all saccade categories. Inward adaptation, in contrast, is accompanied by a decrease in duration and in peak velocity, but only the peak velocity decrease transfers from reactive saccades to other saccade categories, i.e., saccadic duration remains constant or even increases for test saccades of the other categories. Our results, therefore, show that duration and peak velocity are independent parameters of saccadic adaptation and that they are differently involved in the transfer of adaptation between saccade categories. Furthermore, our results add evidence that inward and outward adaptation are different processes.

Effects of Voluntary Blinks on Saccades, Vergence Eye Movements, and Saccade-Vergence Interactions in Humans

2002 ◽  
Vol 88 (3) ◽  
pp. 1220-1233 ◽  
Author(s):  
H. Rambold ◽  
A. Sprenger ◽  
C. Helmchen
Keyword(s):  
Eye Movements ◽  
Peak Velocity ◽  
Saccade Onset ◽  
Vertical Saccades ◽  
Acceleration And Deceleration ◽  
Tightly Coupled ◽  
Measured Effect ◽  
Straight Ahead ◽  
Omnipause Neurons ◽  
Saccade Duration

Blinks are known to change the kinematic properties of horizontal saccades, probably by influencing the saccadic premotor circuit. The neuronal basis of this effect could be explained by changes in the activity of omnipause neurons in the nucleus raphe interpositus or in the saccade-related burst neurons of the superior colliculus. Omnipause neurons cease discharge during both saccades and vergence movements. Because eyelid blinks can influence both sets of neurons, we hypothesized that blinks would influence the kinematic parameters of saccades in all directions, vergence, and saccade-vergence interactions. To test this hypothesis, we investigated binocular eye and lid movements in five normal healthy subjects with the magnetic search coil technique. The subjects performed conjugate horizontal and vertical saccades from gaze straight ahead to targets at 20° up, down, right, or left while either attempting not to blink or voluntarily blinking. While following the same blink instruction, subjects made horizontal vergence eye movements of 7° and combined saccade-vergence movements with a version amplitude of 20°. The movements were performed back and forth from two targets simultaneously presented nearby (38 cm) and more distant (145 cm). Small vertical saccades accompanied most vergence movements. These results show that blinks change the kinematics (saccade duration, peak velocity, peak acceleration, peak deceleration) of not only horizontal but also of vertical saccades, of horizontal vergence eye movements, and of combined saccade-vergence eye movements. Peak velocity, acceleration, and deceleration of eye movements were decreased on the average by 30%, and their duration increased by 43% on the average when they were accompanied by blinks. The blink effect was time dependent with respect to saccade and vergence onset: the greatest effect occurred 100 ms prior to saccade onset, whereas there was no effect when the blink started after saccade onset. The effects of blinks on saccades and vergence, which are tightly coupled to latency, support the hypothesis that blinks cause profound spatiotemporal perturbations of the eye movements by interfering with the normal saccade/vergence premotor circuits. However, the measured effect may to a certain degree but not exclusively be explained by mechanical interference.

The Main Sequence of Human Optokinetic Afternystagmus (OKAN)

2009 ◽  
Vol 101 (6) ◽  
pp. 2889-2897 ◽  
Author(s):  
Andre Kaminiarz ◽  
Kerstin Königs ◽  
Frank Bremmer
Keyword(s):  
Neural Networks ◽  
Eye Movements ◽  
Main Sequence ◽  
Critical Role ◽  
Saccade Target ◽  
Control Mechanisms ◽  
Visually Guided ◽  
Background Characteristics ◽  
Optokinetic Afternystagmus

Different types of fast eye movements, including saccades and fast phases of optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN), are coded by only partially overlapping neural networks. This is a likely cause for the differences that have been reported for the dynamic parameters of fast eye movements. The dependence of two of these parameters—peak velocity and duration—on saccadic amplitude has been termed “main sequence.” The main sequence of OKAN fast phases has not yet been analyzed. These eye movements are unique in that they are generated by purely subcortical control mechanisms and that they occur in complete darkness. In this study, we recorded fast phases of OKAN and OKN as well as visually guided and spontaneous saccades under identical background conditions because background characteristics have been reported to influence the main sequence of saccades. Our data clearly show that fast phases of OKAN and OKN differ with respect to their main sequence. OKAN fast phases were characterized by their lower peak velocities and longer durations compared with those of OKN fast phases. Furthermore we found that the main sequence of spontaneous saccades depends heavily on background characteristics, with saccades in darkness being slower and lasting longer. On the contrary, the main sequence of visually guided saccades depended on background characteristics only very slightly. This implies that the existence of a visual saccade target largely cancels out the effect of background luminance. Our data underline the critical role of environmental conditions (light vs. darkness), behavioral tasks (e.g., spontaneous vs. visually guided), and the underlying neural networks for the exact spatiotemporal characteristics of fast eye movements.

scholarly journals Handedness results from complementary hemispheric dominance, not global hemispheric dominance: evidence from mechanically coupled bilateral movements

2018 ◽  
Vol 120 (2) ◽  
pp. 729-740 ◽  
Author(s):  
Elizabeth J. Woytowicz ◽  
Kelly P. Westlake ◽  
Jill Whitall ◽  
Robert L. Sainburg
Keyword(s):  
Motor Control ◽  
Dynamic Control ◽  
The Other ◽  
Hemispheric Dominance ◽  
Control Mechanisms ◽  
Left Hand ◽  
Right Hand ◽  
Other Hand ◽  
Task Component ◽  
The Right

Two contrasting views of handedness can be described as 1) complementary dominance, in which each hemisphere is specialized for different aspects of motor control, and 2) global dominance, in which the hemisphere contralateral to the dominant arm is specialized for all aspects of motor control. The present study sought to determine which motor lateralization hypothesis best predicts motor performance during common bilateral task of stabilizing an object (e.g., bread) with one hand while applying forces to the object (e.g., slicing) using the other hand. We designed an experimental equivalent of this task, performed in a virtual environment with the unseen arms supported by frictionless air-sleds. The hands were connected by a spring, and the task was to maintain the position of one hand while moving the other hand to a target. Thus the reaching hand was required to take account of the spring load to make smooth and accurate trajectories, while the stabilizer hand was required to impede the spring load to keep a constant position. Right-handed subjects performed two task sessions (right-hand reach and left-hand stabilize; left-hand reach and right-hand stabilize) with the order of the sessions counterbalanced between groups. Our results indicate a hand by task-component interaction such that the right hand showed straighter reaching performance whereas the left hand showed more stable holding performance. These findings provide support for the complementary dominance hypothesis and suggest that the specializations of each cerebral hemisphere for impedance and dynamic control mechanisms are expressed during bilateral interactive tasks. NEW & NOTEWORTHY We provide evidence for interlimb differences in bilateral coordination of reaching and stabilizing functions, demonstrating an advantage for the dominant and nondominant arms for distinct features of control. These results provide the first evidence for complementary specializations of each limb-hemisphere system for different aspects of control within the context of a complementary bilateral task.

Analysis of the Perception of Students about Biometric Identification

2015 ◽  
Vol 10 (3) ◽  
pp. 1-18 ◽  
Author(s):  
Francisco D. Guillén-Gámez ◽  
Iván García-Magariño ◽  
Sonia J. Romero
Keyword(s):  
Experimental Study ◽  
The Other ◽  
Biometric Identification ◽  
Control Mechanisms ◽  
Biometric Authentication ◽  
Ethical Aspects ◽  
Virtual Classrooms ◽  
Quasi Experimental ◽  
Teaching Learning ◽  
The Impact

Currently, there is a demand within distance education of control mechanisms for verifying the identity of students when conducting activities within virtual classrooms. Biometric authentication is one of the tools to meet this demand and prevent fraud. In this line of research, the present work is aimed at analyzing the perceptions of a group of distance students on the impact on the teaching-learning process of a technology of biometric authentication called Smowl. To meet this objective the authors design a quasi-experimental study with two groups of 50 students, one using Smowl technology and the other not. The results show a comparison of the perceptions of both groups, finding that students who have used Smowl are more favorable towards the use of such tools, except in matters relating to the impact on academic performance and ethical aspects of its use, in which no significant differences were found.

Relation Between the Metrics of the Presaccadic Attention Shift and of the Saccade Before and After Saccadic Adaptation

2000 ◽  
Vol 84 (4) ◽  
pp. 1809-1813 ◽  
Author(s):  
J. Ditterich ◽  
T. Eggert ◽  
A. Straube
Keyword(s):  
Hierarchical Level ◽  
Saccade Target ◽  
Eye Position ◽  
Attention Shift ◽  
Short Term ◽  
Saccadic Adaptation ◽  
Attention Focus ◽  
Before And After ◽  
Saccade Size ◽  
Saccade Programming

A shift of the visual attention focus is known to precede saccades. However, how the metrics of both this presaccadic attention shift and the saccade are coupled is still unclear. We altered the saccade size by short-term saccadic adaptation to determine whether the attention focus would still be shifted to the location of the saccade target or to the modified postsaccadic eye position. The results showed that saccadic adaptation had no influence on the presaccadic attention shift. Thus either different processes determine the metrics of the attention shift and of the saccade or saccadic adaptation causes only modifications on a lower hierarchical level of saccade programming, thereby not influencing the metrics of the attention shift.

Competition Between Saccade Goals in the Superior Colliculus Produces Saccade Curvature

2003 ◽  
Vol 89 (5) ◽  
pp. 2577-2590 ◽  
Author(s):  
Robert M. McPeek ◽  
Jae H. Han ◽  
Edward L. Keller
Keyword(s):  
Superior Colliculus ◽  
Search Task ◽  
Visual Target ◽  
Temporal Structure ◽  
Saccade Target ◽  
Stimulation Site ◽  
Electrical Microstimulation ◽  
Saccade Onset ◽  
Significant Difference ◽  
Increased Activity

When saccadic eye movements are made in a search task that requires selecting a target from distractors, the movements show greater curvature in their trajectories than similar saccades made to single stimuli. To test the hypothesis that this increase in curvature arises from competitive interactions between saccade goals occurring near the time of movement onset, we performed single-unit recording and microstimulation experiments in the superior colliculus (SC). We found that saccades that ended near the target but curved toward a distractor were accompanied by increased presaccadic activity of SC neurons coding the distractor site. This increased activity occurred ∼30 ms before saccade onset and was abruptly quenched on saccade initiation. The magnitude of increased activity at the distractor site was correlated with the amount of curvature toward the distractor. In contrast, neurons coding the target location did not show any significant difference in discharge for curved versus straight saccades. To determine whether this pattern of SC discharge is causally related to saccade curvature, we performed a second series of experiments using electrical microstimulation. Monkeys made saccades to single visual stimuli presented without distractors, and we stimulated sites in the SC that would have corresponded to distractor sites in the search task. The stimulation was subthreshold for evoking saccades, but when its temporal structure mimicked the activity recorded for curved saccades in search, the subsequent saccades to the visual target showed curvature toward the location coded by the stimulation site. The effect was larger for higher stimulation frequencies and when the stimulation site was in the same colliculus as the representation of the visual target. These results support the hypothesis that the increased saccade curvature observed in search arises from rivalry between target and distractor goals and are consistent with the idea that the SC is involved in the competitive neural interactions underlying saccade target selection.

scholarly journals The lateral intraparietal area codes the location of saccade targets and not the dimension of the saccades that will be made to acquire them

2013 ◽  
Vol 109 (10) ◽  
pp. 2596-2605 ◽  
Author(s):  
Sara C. Steenrod ◽  
Matthew H. Phillips ◽  
Michael E. Goldberg
Keyword(s):  
Target Location ◽  
Rhesus Macaques ◽  
Oculomotor System ◽  
Saccade Target ◽  
Delayed Response ◽  
Lateral Intraparietal Area ◽  
Saccadic Adaptation ◽  
End Point ◽  
Priority Map ◽  
Response Task

Activity in the lateral intraparietal area (LIP) represents a priority map that can be used to direct attention and guide eye movements. However, it is not known whether this activity represents the location of saccade targets or the actual eye movement made to acquire them. We recorded single neurons from rhesus macaques ( Macaca mulatta) while they performed memory-guided delayed saccades to characterize the response profiles of LIP cells. We then separated the saccade target from the saccade end point by saccadic adaptation, a method that induces a change in the gain of the oculomotor system. We plotted LIP activity for all three epochs of the memory-guided delayed-response task (visual, delay period, and presaccadic responses) as a function of target location and saccade end point. We found that under saccadic adaptation the response profile for all three epochs was unchanged as a function of target location. We conclude that neurons in LIP reliably represent the locations of saccade targets, not the amplitude of the saccade required to acquire those targets. Although LIP transmits target information to the motor system, that information represents the location of the target and not the amplitude of the saccade that the monkey will make.

Eye position effects in saccadic adaptation in macaque monkeys

2012 ◽  
Vol 108 (10) ◽  
pp. 2819-2826 ◽  
Author(s):  
Svenja Wulff ◽  
Annalisa Bosco ◽  
Katharina Havermann ◽  
Giacomo Placenti ◽  
Patrizia Fattori ◽  
...  
Keyword(s):  
Macaca Fascicularis ◽  
Species Differences ◽  
The Other ◽  
Eye Position ◽  
Saccadic Amplitude ◽  
Position Effects ◽  
Starting Position ◽  
Saccadic Adaptation ◽  
Gaussian Profile ◽  
Position Dependence

The saccadic amplitude of humans and monkeys can be adapted using intrasaccadic target steps in the McLaughlin paradigm. It is generally believed that, as a result of a purely retinal reference frame, after adaptation of a saccade of a certain amplitude and direction, saccades of the same amplitude and direction are all adapted to the same extent, independently from the initial eye position. However, recent studies in humans have put the pure retinal coding in doubt by revealing that the initial eye position has an effect on the transfer of adaptation to saccades of different starting points. Since humans and monkeys show some species differences in adaptation, we tested the eye position dependence in monkeys. Two trained Macaca fascicularis performed reactive rightward saccades from five equally horizontally distributed starting positions. All saccades were made to targets with the same retinotopic motor vector. In each session, the saccades that started at one particular initial eye position, the adaptation position, were adapted to shorter amplitude, and the adaptation of the saccades starting at the other four positions was measured. The results show that saccades that started at the other positions were less adapted than saccades that started at the adaptation position. With increasing distance between the starting position of the test saccade and the adaptation position, the amplitude change of the test saccades decreased with a Gaussian profile. We conclude that gain-decreasing saccadic adaptation in macaques is specific to the initial eye position at which the adaptation has been induced.

Articulation and Stress/Juncture Production Under Oral Anesthetization and Masking

1971 ◽  
Vol 14 (2) ◽  
pp. 271-282 ◽  
Author(s):  
Sylvia A. Gammon ◽  
Philip J. Smith ◽  
Raymond G. Daniloff ◽  
Chin W. Kim
Keyword(s):  
Feedback Control ◽  
Oral Cavity ◽  
White Noise ◽  
Speech Production ◽  
Local Anesthesia ◽  
The Other ◽  
Control Mechanisms ◽  
Combined Stress ◽  
Noise Masking ◽  
High Degree

Eight subjects, half of them naive and the other half aware of the purpose of the experiment, spoke 30 pairs of sentences involving the production of intricate stress/juncture patterns along with a passage containing all major consonant phonemes in English in various intraword positions. All subjects spoke all materials under: (1) normal conditions, (2) 110 dB re: 0.0002 ubar white noise masking, (3) extensive local anesthesia of the oral cavity, and (4) masking and anesthesia combined. Stress and juncture patterns were correctly produced despite all feedback disruption, and there was no difference between naive and aware subjects. Noise masking produced a decline in speech quality and a disruption of normal rhythm, both of which were even more seriously affected by anesthesia and anesthesia plus masking. There were no significant vowel misarticulations under any condition, but there was nearly a 20% rate of consonant misartiqulation under anesthesia and anesthesia and noise. Mis-articulation was most severe for fricatives and affricates in the labial and alveolar regions, presumably because these productions demand a high degree of precision of articulate shape and location and hence, intact feedback. Results are discussed in terms of feedback-control mechanisms for speech production.

scholarly journals Control and Coordination of Design-Driven Innovation Processes: Case Evidence from the Automotive Industry

2018 ◽  
Vol 30 (3) ◽  
pp. 75-94 ◽  
Author(s):  
Nico Peter Berhausen ◽  
Sof Thrane
Keyword(s):  
Technological Innovation ◽  
Automotive Industry ◽  
Technological Development ◽  
The Other ◽  
Control Mechanisms ◽  
Aesthetic Value ◽  
Technical Performance ◽  
Separate Control ◽  
Innovation Processes ◽  
Over Time

ABSTRACT The control and coordination of design and technological innovation pose a dilemma for design-driven organizations because the measurability of design and technological innovation differ. On one hand, a product's aesthetic value might increase if its design is separated from technological innovation and if design is controlled by means other than those used in technological innovation. On the other hand, tight integration is warranted because a product's design affects its cost, technical performance, and manufacturability. This dilemma is the focus of the paper. The paper contributes to extant literature in several ways. First, it conceptualizes control as a process that manages design and technological innovation through distinct, separate control mechanisms. Second, it analyzes and develops three modes of convergence through which the potentially contradictory concerns of design and technological development can be compared and evaluated. Finally, the paper suggests that coordination can be achieved through convergence processes that unfold and develop over time.

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