Properties of Saccadic Responses in Monkey When Multiple Competing Visual Stimuli Are Present

2004 ◽  
Vol 91 (2) ◽  
pp. 890-900 ◽  
Author(s):  
Kuniharu Arai ◽  
Robert M. McPeek ◽  
Edward L. Keller
Keyword(s):  
Search Task ◽  
Target Selection ◽  
Visual Stimuli ◽  
Experimental Manipulation ◽  
Movement Trajectory ◽  
Movement Trajectories ◽  
Neural Organization ◽  
Single Target ◽  
Stereotyped Movement ◽  
Saccadic Responses

Important insights into the neural organization of the saccadic system have been gained when the usually stereotyped movement trajectories of saccades have been altered by experimental manipulation. In the present study we produced trajectory variability in monkeys by using a visual search task in which both the location and color of an odd-colored target were changed randomly trial by trial, and the number of distractors was varied on each trial. We wished to determine whether increasing the number of distractors also increased the movement trajectory variation, i.e., the amount of initial directional deviation, endpoint deviation (averaging), and curvature of saccades. Overall, saccade latencies and the proportion of saccades directed to distractors decreased as the number of homogenous distractors increased. We also found that saccades have much more dispersion in their initial direction when distractors are present in comparison to the case when only a single target without distractors appears. However, initial dispersion decreases systematically as the number of distractors increases. The percentage of averaging saccades produced in the search task was not consistently dependent on the number of distractors. A significant fraction of averaging saccades still occurred for much wider spatial separations of stimuli than in previous studies using two visual stimuli with no specified target. The curvature of saccade trajectories increased dramatically when distractors were present, but the amount of curvature was not systematically affected by the number of distractors. Errors present in saccade trajectory in the search task were only poorly compensated. We conclude that these variable saccade trajectories result from incomplete or inaccurate specification of the target when competing stimuli are present and that a smaller number of more widely spread distractors facilitate saccade variability, perhaps due to the greater difficulty of target selection.

scholarly journals Mind-wandering Is Accompanied by Both Local Sleep and Enhanced Processes of Spatial Attention Allocation

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Christian Wienke ◽  
Mandy V Bartsch ◽  
Lena Vogelgesang ◽  
Christoph Reichert ◽  
Hermann Hinrichs ◽  
...  
Keyword(s):  
Search Task ◽  
Brain Activity ◽  
Target Selection ◽  
Mind Wandering ◽  
Attentional Selection ◽  
Self Report ◽  
Cortical Processing ◽  
High Frequency Activity ◽  
External Stimuli ◽  
Local Sleep

Abstract Mind-wandering (MW) is a subjective, cognitive phenomenon, in which thoughts move away from the task toward an internal train of thoughts, possibly during phases of neuronal sleep-like activity (local sleep, LS). MW decreases cortical processing of external stimuli and is assumed to decouple attention from the external world. Here, we directly tested how indicators of LS, cortical processing, and attentional selection change in a pop-out visual search task during phases of MW. Participants’ brain activity was recorded using magnetoencephalography, MW was assessed via self-report using randomly interspersed probes. As expected, the performance decreased under MW. Consistent with the occurrence of LS, MW was accompanied by a decrease in high-frequency activity (HFA, 80–150 Hz) and an increase in slow wave activity (SWA, 1–6 Hz). In contrast, visual attentional selection as indexed by the N2pc component was enhanced during MW with the N2pc amplitude being directly linked to participants’ performance. This observation clearly contradicts accounts of attentional decoupling that would predict a decrease in attention-related responses to external stimuli during MW. Together, our results suggest that MW occurs during phases of LS with processes of attentional target selection being upregulated, potentially to compensate for the mental distraction during MW.

scholarly journals Tri-axial accelerometry shows differences in energy expenditure and parental effort throughout the breeding season in long-lived raptors

2021 ◽  
Author(s):  
Pascual LÓPEZ-LÓPEZ ◽  
Arturo M PERONA ◽  
Olga EGEA-CASAS ◽  
Jon ETXEBARRIA MORANT ◽  
Vicente URIOS
Keyword(s):  
Energy Expenditure ◽  
Parental Care ◽  
Breeding Season ◽  
Video Recording ◽  
Experimental Manipulation ◽  
Biparental Care ◽  
Breeding Ecology ◽  
Parental Effort ◽  
Ecological Data ◽  
Movement Trajectories

Abstract Cutting-edge technologies are extremely useful to develop new workflows in studying ecological data, particularly to understand animal behaviour and movement trajectories at the individual level. Although parental care is a well-studied phenomenon, most studies have been focused on direct observational or video recording data, as well as experimental manipulation. Therefore, what happens out of our sight still remains unknown. Using high-frequency GPS/GSM dataloggers and tri-axial accelerometers we monitored 25 Bonelli’s eagles (Aquila fasciata) during the breeding season to understand parental activities from a broader perspective. We used recursive data, measured as number of visits and residence time, to reveal nest attendance patterns of biparental care with role specialization between sexes. Accelerometry data interpreted as the Overall Dynamic Body Acceleration, a proxy of energy expenditure, showed strong differences in parental effort throughout the breeding season and between sexes. Thereby, males increased substantially their energetic requirements, due to the increased workload, while females spent most of the time on the nest. Furthermore, during critical phases of the breeding season, a low percentage of suitable hunting spots in eagles’ territories led them to increase their ranging behaviour in order to find food, with important consequences in energy consumption and mortality risk. Our results highlight the crucial role of males in raptor species exhibiting biparental care. Finally, we exemplify how biologging technologies are an adequate and objective method to study parental care in raptors as well as to get deeper insight into breeding ecology of birds in general.

scholarly journals Shape Selectivity in Primate Frontal Eye Field

2008 ◽  
Vol 100 (2) ◽  
pp. 796-814 ◽  
Author(s):  
Xinmiao Peng ◽  
Margaret E. Sereno ◽  
Amanda K. Silva ◽  
Sidney R. Lehky ◽  
Anne B. Sereno
Keyword(s):  
Functional Organization ◽  
Target Selection ◽  
Visual Stimuli ◽  
Shape Selectivity ◽  
Saccade Target ◽  
Frontal Eye Field ◽  
Gaze Shift ◽  
Match To Sample ◽  
Neurophysiological Studies ◽  
Eye Field

Previous neurophysiological studies of the frontal eye field (FEF) in monkeys have focused on its role in saccade target selection and gaze shift control. It has been argued that FEF neurons indicate the locations of behaviorally significant visual stimuli and are not inherently sensitive to specific features of the visual stimuli per se. Here, for the first time, we directly examined single cell responses to simple, two-dimensional shapes and found that shape selectivity exists in a substantial number of FEF cells during a passive fixation task or during the sample, delay (memory), and eye movement periods in a delayed match to sample (DMTS) task. Our data demonstrate that FEF neurons show sensory and mnemonic selectivity for stimulus shape features whether or not they are behaviorally significant for the task at hand. We also investigated the extent and localization of activation in the FEF using a variety of shape stimuli defined by static or dynamic cues employing functional magentic resonance imaging (fMRI) in anesthetized and paralyzed monkeys. Our fMRI results support the electrophysiological findings by showing significant FEF activation for a variety of shape stimuli and cues in the absence of attentional and motor processing. This shape selectivity in FEF is comparable to previous reports in the ventral pathway, inviting a reconsideration of the functional organization of the visual system.

The effects of audiovisual task-set in visual search

2012 ◽  
Vol 25 (0) ◽  
pp. 158
Author(s):  
Pawel J. Matusz ◽  
Martin Eimer
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Target Selection ◽  
Top Down ◽  
Search Tasks ◽  
Attentional Control Settings ◽  
Sensory Modalities ◽  
Attentional Selectivity ◽  
Auditory Features ◽  
Target Matching

We investigated whether top-down attentional control settings can specify task-relevant features in different sensory modalities (vision and audition). Two audiovisual search tasks were used where a spatially uninformative visual singleton cue preceded a target search array. In different blocks, participants searched for a visual target (defined by colour or shape in Experiments 1 and 2, respectively), or target defined by a combination of visual and auditory features (e.g., red target accompanied by a high-pitch tone). Spatial cueing effects indicative of attentional capture by target-matching visual singleton cues in the unimodal visual search task were reduced or completely eliminated when targets were audiovisually defined. The N2pc component (i.e. index attentional target selection in vision) triggered by these cues was reduced and delayed during search for audiovisual as compared to unimodal visual targets. These results provide novel evidence that the top-down control settings which guide attentional selectivity can include perceptual features from different sensory modalities.

scholarly journals Stability Assessment as a Criterion of Stabilization of the Movement Trajectory of Mobile Crane Working Elements

2018 ◽  
Vol 23 (1) ◽  
pp. 65-77 ◽  
Author(s):  
W. Kacalak ◽  
Z. Budniak ◽  
M. Majewski
Keyword(s):  
Trajectory Optimization ◽  
Assessment Method ◽  
Optimization Criterion ◽  
Movement Trajectory ◽  
Stability Assessment ◽  
Indicator Values ◽  
Movement Trajectories ◽  
Safety Indicator ◽  
Mobile Crane ◽  
The Mathematical Model

AbstractThe article presents a stability assessment method of the mobile crane handling system based on the safety indicator values that were accepted as the trajectory optimization criterion. With the use of the mathematical model built and the model built in the integrated CAD/CAE environment, analyses were conducted of the displacements of the mass centre of the crane system, reactions of the outrigger system, stabilizing and overturning torques that act on the crane as well as the safety indicator values for the given movement trajectories of the crane working elements.

Familiarity with images affects how dogs (Canis familiaris) process life-size video projections of humans

2018 ◽  
Vol 71 (6) ◽  
pp. 1457-1468
Author(s):  
Péter Pongrácz ◽  
András Péter ◽  
Ádám Miklósi
Keyword(s):  
Search Task ◽  
Visual Stimuli ◽  
Target Object ◽  
Important Conclusion ◽  
Motion Cues ◽  
Visual Elements ◽  
Video Images ◽  
Object Search ◽  
Actual Content ◽  
Video Presentations

A central problem of behavioural studies providing artificial visual stimuli for non-human animals is to determine how subjects perceive and process these stimuli. Especially in the case of videos, it is important to ascertain that animals perceive the actual content of the images and are not just reacting to the motion cues in the presentation. In this study, we set out to investigate how dogs process life-sized videos. We aimed to find out whether dogs perceive the actual content of video images or whether they only react to the videos as a set of dynamic visual elements. For this purpose, dogs were presented with an object search task where a life-sized projected human was hiding a target object. The videos were either normally oriented or displayed upside down, and we analysed dogs’ reactions towards the projector screen after the video presentations, and their performance in the search task. Results indicated that in the case of the normally oriented videos, dogs spontaneously perceived the actual content of the images. However, the ‘Inverted’ videos were first processed as a set of unrelated visual elements, and only after some exposure to these videos did the dogs show signs of perceiving the unusual configuration of the depicted scene. Our most important conclusion was that dogs process the same type of artificial visual stimuli in different ways, depending on the familiarity of the depicted scene, and that the processing mode can change with exposure to unfamiliar stimuli.

Calculation of Optimized Movement Trajectories for the Human Forearm

2013 ◽  
Vol 401-403 ◽  
pp. 1347-1352
Author(s):  
Li Li Yang
Keyword(s):  
Discrete Time ◽  
Linear Quadratic Regulator ◽  
Minimum Variance ◽  
Movement Trajectory ◽  
Linear Quadratic ◽  
Variance Model ◽  
Movement Trajectories ◽  
Human Forearm ◽  
Optimal Movement ◽  
Time Linear

Using the minimum variance model, optimal human forearm trajectories formation was investigated using a discrete time linear quadratic regulator. First, the continuous dynamics of the human forearm were established on the basis of the relation between muscle torque and neural control signal, and then we transferred the continuous system dynamics to discrete time notation. Finally we expressed the objective function of minimum variance model using a discrete time linear quadratic regulator and employed Riccati recursion to obtain the optimal movement trajectories of the human forearm. The results of example simulation show that the optimal movement trajectory of the forearm follows a smooth curve, and the speed curve of the hand is single peaked and bell shaped. These are in good agreement with the inherent kinematic properties of optimal movement, and therefore the method is effective for calculating the optimal movement trajectory of the human forearm.

Saccadic responses to consecutive visual stimuli in healthy people and patients with schizophrenia

2015 ◽  
Vol 41 (4) ◽  
pp. 372-377
Author(s):  
V. V. Shulgovskiy ◽  
M. V. Slavutskaya ◽  
I. S. Lebedeva ◽  
S. A. Karelin ◽  
V. V. Moiseeva ◽  
...  
Keyword(s):  
Visual Stimuli ◽  
Healthy People ◽  
Saccadic Responses

scholarly journals Parameter Measurements of Moving Gas Bubbles Using Image Tomography Title

2016 ◽  
Vol 21 (3) ◽  
pp. 5-14
Author(s):  
Mariusz Roland Rząsa
Keyword(s):  
Center Of Mass ◽  
Mass Movement ◽  
Measuring Method ◽  
Movement Trajectory ◽  
Bubble Shape ◽  
Test Results ◽  
Empirical Correlations ◽  
Movement Trajectories ◽  
Geometric Figures

Abstract The paper presents an idea of a new measuring method based on image tomography. This method focuses on registration of images of bubbles moving in two perpendicular directions. Two images are used for determination of the center of mass, movement trajectory and local velocities. Volume and area of bubbles are defined by using approximation of the bubble shape with the known geometric figures. The paper also presents the algorithm of reconstruction of the bubble shapes and movement trajectories, as well as exemplary test results. The obtained results were compared with empirical correlations in the published literature.

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