scholarly journals Effects of visuomotor delays on the control of movement and on perceptual localization in the presence and absence of visual targets

2019 ◽  
Vol 122 (6) ◽  
pp. 2259-2271
Author(s):  
Guy Avraham ◽  
Erez Sulimani ◽  
Ferdinando A. Mussa-Ivaldi ◽  
Ilana Nisky
Keyword(s):  
Visual Target ◽  
Sensory System ◽  
Delayed Feedback ◽  
Perceptual Bias ◽  
Hand Position ◽  
State Information ◽  
Reaching Movement ◽  
Current State ◽  
Visual Targets ◽  
The Invisible

The sensory system constantly deals with delayed feedback. Recent studies showed that playing a virtual game of pong with delayed feedback caused hypermetric reaching movements. We investigated whether this effect is associated with a perceptual bias. In addition, we examined the importance of the target in causing hypermetric movements. In a first experiment, participants played a delayed pong game and blindly reached to presented targets. Following each reaching movement, they assessed the position of the invisible cursor. We found that participants performed hypermetric movements but reported that the invisible cursor reached the target, suggesting that they were unaware of the hypermetria and that their perception was biased toward the target rather than toward their hand position. In a second experiment, we removed the visual target, and strikingly, the hypermetria vanished. Moreover, participants reported that the invisible cursor was located with their hand. Taking these results together, we conclude that the adaptation to the visuomotor delay during the pong game selectively affected the execution of goal directed movements, resulting in hypermetria and perceptual bias when movements are directed toward visual targets but not when such targets are absent. NEW & NOTEWORTHY Recent studies showed that adaptation to visuomotor delays causes hypermetric movements in the absence of visual feedback, suggesting that visuomotor delay is represented using current state information. We report that this adaptation also affects perception. Importantly, both the motor and perceptual effects are selective to the representations that are used in the execution of goal-directed movements toward visual targets.

“Motor Oblique Effect”: Perceptual Direction Discrimination and Pointing to Memorized Visual Targets Share the Same Preference for Cardinal Orientations

2007 ◽  
Vol 97 (2) ◽  
pp. 1068-1077 ◽  
Author(s):  
Nikolaos Smyrnis ◽  
Asimakis Mantas ◽  
Ioannis Evdokimidis
Keyword(s):  
Visual Target ◽  
Motor Task ◽  
Oblique Effect ◽  
Quadratic Function ◽  
Initial Direction ◽  
Direction Discrimination ◽  
Pointing Movements ◽  
Equivalent Measure ◽  
Visual Targets ◽  
Target Locations

In previous studies we observed a pattern of systematic directional errors when humans pointed to memorized visual target locations in two-dimensional (2-D) space. This directional error was also observed in the initial direction of slow movements toward visual targets or movements to kinesthetically defined targets in 2-D space. In this study we used a perceptual experiment where subjects decide whether an arrow points in the direction of a visual target in 2-D space and observed a systematic distortion in direction discrimination known as the “oblique effect.” More specifically, direction discrimination was better for cardinal directions than for oblique. We then used an equivalent measure of direction discrimination in a task where subjects pointed to memorized visual target locations and showed the presence of a motor oblique effect. We finally modeled the oblique effect in the perceptual and motor task using a quadratic function. The model successfully predicted the observed direction discrimination differences in both tasks and, furthermore, the parameter of the model that was related to the shape of the function was not different between the motor and the perceptual tasks. We conclude that a similarly distorted representation of target direction is present for memorized pointing movements and perceptual direction discrimination.

scholarly journals Learned rather than online relative weighting of visual-proprioceptive sensory cues

2018 ◽  
Vol 119 (5) ◽  
pp. 1981-1992 ◽  
Author(s):  
Laura Mikula ◽  
Valérie Gaveau ◽  
Laure Pisella ◽  
Aarlenne Z. Khan ◽  
Gunnar Blohm
Keyword(s):  
Multisensory Integration ◽  
Visual Information ◽  
Target Location ◽  
Hand Position ◽  
Proprioceptive Information ◽  
Sensory Cues ◽  
Reaching Movement ◽  
Left And Right ◽  
Neuronal Representation ◽  
Relative Weighting

When reaching to an object, information about the target location as well as the initial hand position is required to program the motor plan for the arm. The initial hand position can be determined by proprioceptive information as well as visual information, if available. Bayes-optimal integration posits that we utilize all information available, with greater weighting on the sense that is more reliable, thus generally weighting visual information more than the usually less reliable proprioceptive information. The criterion by which information is weighted has not been explicitly investigated; it has been assumed that the weights are based on task- and effector-dependent sensory reliability requiring an explicit neuronal representation of variability. However, the weights could also be determined implicitly through learned modality-specific integration weights and not on effector-dependent reliability. While the former hypothesis predicts different proprioceptive weights for left and right hands, e.g., due to different reliabilities of dominant vs. nondominant hand proprioception, we would expect the same integration weights if the latter hypothesis was true. We found that the proprioceptive weights for the left and right hands were extremely consistent regardless of differences in sensory variability for the two hands as measured in two separate complementary tasks. Thus we propose that proprioceptive weights during reaching are learned across both hands, with high interindividual range but independent of each hand’s specific proprioceptive variability. NEW & NOTEWORTHY How visual and proprioceptive information about the hand are integrated to plan a reaching movement is still debated. The goal of this study was to clarify how the weights assigned to vision and proprioception during multisensory integration are determined. We found evidence that the integration weights are modality specific rather than based on the sensory reliabilities of the effectors.

scholarly journals A bimodal extension of the Eriksen flanker task

2020 ◽  
Author(s):  
Rolf Ulrich ◽  
Laura Prislan ◽  
Jeff Miller
Keyword(s):  
Visual Target ◽  
Target Item ◽  
Flanker Task ◽  
Response Competition ◽  
Relevant Information ◽  
Irrelevant Information ◽  
Flanker Effect ◽  
Starting Point ◽  
Visual Targets ◽  
Task Irrelevant

Abstract The Eriksen flanker task is a traditional conflict paradigm for studying the influence of task-irrelevant information on the processing of task-relevant information. In this task, participants are asked to respond to a visual target item (e.g., a letter) that is flanked by task-irrelevant items (e.g., also letters). Responses are typically faster and more accurate when the task-irrelevant information is response-congruent with the visual target than when it is incongruent. Several researchers have attributed the starting point of this flanker effect to poor selective filtering at a perceptual level (e.g., spotlight models), which subsequently produces response competition at post-perceptual stages. The present study examined whether a flanker-like effect could also be established within a bimodal analog of the flanker task with auditory irrelevant letters and visual target letters, which must be processed along different processing routes. The results of two experiments revealed that a flanker-like effect is also present with bimodal stimuli. In contrast to the unimodal flanker task, however, the effect only emerged when flankers and targets shared the same letter name, but not when they were different letters mapped onto the same response. We conclude that the auditory flankers can influence the time needed to recognize visual targets but do not directly activate their associated responses.

Dependence of Saccade-Related Activity in the Primate Superior Colliculus on Visual Target Presence

2001 ◽  
Vol 86 (2) ◽  
pp. 676-691 ◽  
Author(s):  
Jay A. Edelman ◽  
Michael E. Goldberg
Keyword(s):  
Superior Colliculus ◽  
Visual Target ◽  
Visual Response ◽  
Target Presence ◽  
Related Activity ◽  
Intermediate Layers ◽  
Saccade Velocity ◽  
Trial Basis ◽  
Visual Targets ◽  
Extracellular Activity

Neurons in the intermediate layers of the superior colliculus respond to visual targets and/or discharge immediately before and during saccades. These visual and motor responses have generally been considered independent, with the visual response dependent on the nature of the stimulus, and the saccade-related activity related to the attributes of the saccade, but not to how the saccade was elicited. In these experiments we asked whether saccade-related discharge in the superior colliculus depended on whether the saccade was directed to a visual target. We recorded extracellular activity of neurons in the intermediate layers of the superior colliculus of three rhesus monkeys during saccades in tasks in which we varied the presence or absence of a visual target and the temporal delays between the appearance and disappearance of a target and saccade initiation. Across our sample of neurons ( n = 64), discharge was highest when a saccade was made to a still-present visual target, regardless of whether the target had recently appeared or had been present for several hundred milliseconds. Discharge was intermediate when the target had recently disappeared and lowest when the target had never appeared during that trial. These results are consistent with the hypothesis that saccade-related discharge decreases as the time between the target disappearance and saccade initiation increases. Saccade velocity was also higher for saccades to visual targets, and correlated on a trial-by-trial basis with perisaccadic discharge for many neurons. However, discharge of many neurons was dependent on task but independent of saccade velocity, and across our sample of neurons, saccade velocity was higher for saccades made immediately after target appearance than would be predicted by discharge level. A tighter relationship was found between saccade precision and perisaccadic discharge. These findings suggest that just as the purpose of the saccadic system in primates is to drive the fovea to a visual target, presaccadic motor activity in the superior colliculus is most intense when such a target is actually present. This enhanced activity may, itself, contribute to the enhanced performance of the saccade system when the saccade is made to a real visual target.

Interactions between Voluntary and Stimulus-driven Spatial Attention Mechanisms across Sensory Modalities

2009 ◽  
Vol 21 (12) ◽  
pp. 2384-2397 ◽  
Author(s):  
Valerio Santangelo ◽  
Marta Olivetti Belardinelli ◽  
Charles Spence ◽  
Emiliano Macaluso
Keyword(s):  
Spatial Attention ◽  
Auditory Stimulus ◽  
Attentional Control ◽  
Spatial Information ◽  
Visual Target ◽  
Exogenous Attention ◽  
Physiological Basis ◽  
Sensory Modalities ◽  
Visual Targets ◽  
Task Irrelevant

In everyday life, the allocation of spatial attention typically entails the interplay between voluntary (endogenous) and stimulus-driven (exogenous) attention. Furthermore, stimuli in different sensory modalities can jointly influence the direction of spatial attention, due to the existence of cross-sensory links in attentional control. Using fMRI, we examined the physiological basis of these interactions. We induced exogenous shifts of auditory spatial attention while participants engaged in an endogenous visuospatial cueing task. Participants discriminated visual targets in the left or right hemifield. A central visual cue preceded the visual targets, predicting the target location on 75% of the trials (endogenous visual attention). In the interval between the endogenous cue and the visual target, task-irrelevant nonpredictive auditory stimuli were briefly presented either in the left or right hemifield (exogenous auditory attention). Consistent with previous unisensory visual studies, activation of the ventral fronto-parietal attentional network was observed when the visual targets were presented at the uncued side (endogenous invalid trials, requiring visuospatial reorienting), as compared with validly cued targets. Critically, we found that the side of the task-irrelevant auditory stimulus modulated these activations, reducing spatial reorienting effects when the auditory stimulus was presented on the same side as the upcoming (invalid) visual target. These results demonstrate that multisensory mechanisms of attentional control can integrate endogenous and exogenous spatial information, jointly determining attentional orienting toward the most relevant spatial location.

Perceptual bias following visual target selection

NeuroImage ◽  
2005 ◽  
Vol 25 (4) ◽  
pp. 1168-1174 ◽  
Author(s):  
Matthijs Vink ◽  
René S. Kahn ◽  
Mathijs Raemaekers ◽  
Nick F. Ramsey
Keyword(s):  
Visual Target ◽  
Target Selection ◽  
Perceptual Bias

scholarly journals Experience-dependent increases in sharp-wave ripples near visual targets

2016 ◽  
Author(s):  
Timothy K. Leonard ◽  
Kari L. Hoffman
Keyword(s):  
Visual Target ◽  
Visual Exploration ◽  
Goal Location ◽  
Sharp Wave ◽  
Temporal Properties ◽  
Visual Targets ◽  
Past Experiences

We measured hippocampal sharp-wave ripples during goal-directed visual exploration in macaques. Exploratory sharp-wave ripples were more frequent on familiar trials, in the second half of search, and near the visual target (i.e., the goal location). These spatial and temporal properties may help SWRs coordinate hippocampal and extra-hippocampal firing sequences that guide actions based on past experiences.

scholarly journals International Documents and National Legislation of Ukrainian Regulation of the Right for Journalists Freedom of Speech

2018 ◽  
pp. 34-45
Author(s):  
Tetiana Prystupenko
Keyword(s):  
International Organizations ◽  
Freedom Of Speech ◽  
Information Policy ◽  
International Standards ◽  
Practical Implementation ◽  
National Strategy ◽  
State Information ◽  
National Legislation ◽  
Current State ◽  
The Right

The relevence of the study of the issue related to the right to freedom of speech of domestic journalists in the context of international documents and national legislation of Ukraine in this area is caused by the necessity of applying international standards in the real activities of media representatives and development of effective state information policy in this direction. The objective of the research is to ascertain the current state as to protection of the right to freedom of speech of Ukrainian journalists, its interrelation with the program activities in this direction of influential international organizations, national legislation in the conditions of European choice of Ukraine. The study is based on the Concept of national strategy on human rights, the domestic legislative experience in protecting the right to freedom of speech of media representatives and its practical implementation, the global information activities of UN / UNESCO in this context. The situation concerning restriction of freedom of speech in Ukraine, the rights and freedoms of journalists and other democratic values takes place contrary to the norms and provisions of the Constitution of Ukraine, other legislative acts of the state as well as international documents ratified by Verkhovna Rada of Ukraine.

Effect of visuomotor-map uncertainty on visuomotor adaptation

2012 ◽  
Vol 107 (6) ◽  
pp. 1576-1585 ◽  
Author(s):  
Naoki Saijo ◽  
Hiroaki Gomi
Keyword(s):  
Feedback Control ◽  
Probe Trial ◽  
Visual Target ◽  
Hand Movement ◽  
Visuomotor Adaptation ◽  
Proprioceptive Feedback ◽  
Visuomotor Rotation ◽  
Feedback Controls ◽  
Reaching Movement ◽  
End Point

Vision and proprioception contribute to generating hand movement. If a conflict between the visual and proprioceptive feedback of hand position is given, reaching movement is disturbed initially but recovers after training. Although previous studies have predominantly investigated the adaptive change in the motor output, it is unclear whether the contributions of visual and proprioceptive feedback controls to the reaching movement are modified by visuomotor adaptation. To investigate this, we focused on the change in proprioceptive feedback control associated with visuomotor adaptation. After the adaptation to gradually introduce visuomotor rotation, the hand reached the shifted position of the visual target to move the cursor to the visual target correctly. When the cursor feedback was occasionally eliminated (probe trial), the end point of the hand movement was biased in the visual-target direction, while the movement was initiated in the adapted direction, suggesting the incomplete adaptation of proprioceptive feedback control. Moreover, after the learning of uncertain visuomotor rotation, in which the rotation angle was randomly fluctuated on a trial-by-trial basis, the end-point bias in the probe trial increased, but the initial movement direction was not affected, suggesting a reduction in the adaptation level of proprioceptive feedback control. These results suggest that the change in the relative contribution of visual and proprioceptive feedback controls to the reaching movement in response to the visuomotor-map uncertainty is involved in visuomotor adaptation, whereas feedforward control might adapt in a manner different from that of the feedback control.

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