scholarly journals Space-Specific Deficits in Visual Orientation Discrimination Caused by Lesions in the Midbrain Stimulus Selection Network

2017 ◽  
Vol 27 (14) ◽  
pp. 2053-2064.e5 ◽  
Author(s):  
Eric I. Knudsen ◽  
Jason S. Schwarz ◽  
Phyllis F. Knudsen ◽  
Devarajan Sridharan
Keyword(s):  
Orientation Discrimination ◽  
Visual Orientation ◽  
Stimulus Selection

scholarly journals Investigating the Effects of tDCS on Visual Orientation Discrimination Task Performance: “the Possible Influence of Placebo”

2019 ◽  
Vol 4 (3) ◽  
pp. 235-249
Author(s):  
A. Bin Dawood ◽  
A. Dickinson ◽  
A. Aytemur ◽  
C. Howarth ◽  
E. Milne ◽  
...  
Keyword(s):  
Placebo Effect ◽  
Discrimination Task ◽  
Low Cost ◽  
Cortical Inhibition ◽  
Orientation Discrimination ◽  
Visual Orientation ◽  
Non Invasive ◽  
Clear Link ◽  
Cortical Modulation ◽  
Improved Performance

Abstract The non-invasive neuromodulation technique tDCS offers the promise of a low-cost tool for both research and clinical applications in psychology, psychiatry, and neuroscience. However, findings regarding its efficacy are often equivocal. A key issue is that the clinical and cognitive applications studied are often complex and thus effects of tDCS are difficult to predict given its known effects on the basic underlying neurophysiology, namely alterations in cortical inhibition-excitation balance. As such, it may be beneficial to assess the effects of tDCS in tasks whose performance has a clear link to cortical inhibition-excitation balance such as the visual orientation discrimination task (ODT). In prior studies in our laboratory, no practice effects were found during 2 consecutive runs of the ODT, thus in the current investigation, to examine the effects of tDCS, subjects received 10 min of 2 mA occipital tDCS (sham, anode, cathode) between a first and second run of ODT. Surprisingly, subjects’ performance significantly improved in the second run of ODT compared to the first one regardless of the tDCS stimulation type they received (anodal, cathodal, or sham-tDCS). Possible causes for such an improvement could have been due to either a generic “placebo” effect of tDCS (as all subjects received some form of tDCS) or an increased delay period between the two runs of ODT of the current study compared to our previous work (10-min duration required to administer tDCS as opposed to ~ 2 min in previous studies as a “break”). As such, we tested these two possibilities with a subsequent experiment in which subjects received 2-min or 10-min delay between the 2 runs (with no tDCS) or 10 min of sham-tDCS. Only sham-tDCS resulted in improved performance thus these data add to a growing literature suggesting that tDCS has powerful placebo effect that may occur even in the absence of active cortical modulation.

scholarly journals Choice-Related Activity during Visual Slant Discrimination in Macaque CIP but Not V3A

2018 ◽  
Author(s):  
L. Caitlin Elmore ◽  
Ari Rosenberg ◽  
Gregory C. DeAngelis ◽  
Dora E. Angelaki
Keyword(s):  
Visual Processing ◽  
Discrimination Task ◽  
Three Dimensional ◽  
Surface Orientation ◽  
Orientation Discrimination ◽  
Visual Orientation ◽  
Planar Surface ◽  
Related Activity ◽  
Planar Surfaces ◽  
3D Surface

AbstractCreating three-dimensional (3D) representations of the world from two-dimensional retinal images is fundamental to many visual guided behaviors including reaching and grasping. A critical component of this process is determining the 3D orientation of objects. Previous studies have shown that neurons in the caudal intraparietal area (CIP) of the macaque monkey represent 3D planar surface orientation (i.e., slant and tilt). Here we compare the responses of neurons in areas V3A (which is implicated in 3D visual processing and which precedes CIP in the visual hierarchy) and CIP to 3D oriented planar surfaces. We then examine whether activity in these areas correlates with perception during a fine slant discrimination task in which monkeys report if the top of a surface is slanted towards or away from them. Although we find that V3A and CIP neurons show similar sensitivity to planar surface orientation, significant choice-related activity during the slant discrimination task is rare in V3A but prominent in CIP. These results implicate both V3A and CIP in the representation of 3D surface orientation, and suggest a functional dissociation between the areas based on slant-related decision signals.Significance StatementSurface orientation perception is fundamental to visually guided behaviors such as reaching, grasping, and navigation. Previous studies implicate the caudal intraparietal area (CIP) in the representation of 3D surface orientation. Here we show that responses to 3D oriented planar surfaces are similar in CIP and V3A, which precedes CIP in the cortical hierarchy. However, we also find a qualitative distinction between the two areas: only CIP neurons show robust choice-related activity during a fine visual orientation discrimination task.

scholarly journals Targeted comodulation supports flexible and accurate decoding in V1

2021 ◽  
Author(s):  
Caroline Haimerl ◽  
Douglas A. Ruff ◽  
Marlene R. Cohen ◽  
Cristina Savin ◽  
Eero P. Simoncelli
Keyword(s):  
Orientation Discrimination ◽  
Physiological Data ◽  
Visual Orientation ◽  
Strongly Correlated ◽  
Neural Responses ◽  
Stimulus Information ◽  
Behavioral Task ◽  
V1 Neurons ◽  
Stochastic Modulation ◽  
And Task

AbstractSensory-guided behavior requires reliable encoding of stimulus information in neural responses, and task-specific decoding through selective combination of these responses. The former has been the topic of intensive study, but the latter remains largely a mystery. We propose a framework in which shared stochastic modulation of task-informative neurons serves as a label to facilitate downstream decoding. Theoretical analysis and computational simulations demonstrate that a decoder that exploits such a signal can achieve flexible and accurate readout. Using this theoretical framework, we analyze behavioral and physiological data obtained from monkeys performing a visual orientation discrimination task. The responses of recorded V1 neurons exhibit strongly correlated modulation. This modulation is stronger in those neurons that are most informative for the behavioral task and it is substantially reduced in a control condition where recorded neurons are uninformative. We demonstrate that this modulator label can be used to improve downstream decoding within a small number of training trials, consistent with observed behavior. Finally, we find that the trial-by-trial modulatory signal estimated from V1 populations is also present in the activity of simultaneously recorded MT units, and preferentially so if they are task-informative, supporting the hypothesis that it serves as a label for the selection and decoding of relevant downstream neurons.

scholarly journals Stimulus blanking reveals contrast-dependent transsaccadic feature transfer

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Lukasz Grzeczkowski ◽  
Heiner Deubel ◽  
Martin Szinte
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Eye Movement ◽  
Real Life ◽  
Saccadic Eye Movements ◽  
Orientation Discrimination ◽  
Visual Orientation ◽  
Visual Feature ◽  
Orientation Task ◽  
Static Images

Abstract Across saccadic eye movements, the visual system receives two successive static images corresponding to the pre- and the postsaccadic projections of the visual field on the retina. The existence of a mechanism integrating the content of these images is today still a matter of debate. Here, we studied the transfer of a visual feature across saccades using a blanking paradigm. Participants moved their eyes to a peripheral grating and discriminated a change in its orientation occurring during the eye movement. The grating was either constantly on the screen or briefly blanked during and after the saccade. Moreover, it either was of the same luminance as the background (i.e., isoluminant) or anisoluminant with respect to it. We found that for anisoluminant gratings, the orientation discrimination across saccades was improved when a blank followed the onset of the eye movement. Such effect was however abolished with isoluminant gratings. Additionally, performance was also improved when an anisoluminant grating presented before the saccade was followed by an isoluminant one. These results demonstrate that a detailed representation of the presaccadic image was transferred across saccades allowing participants to perform better on the transsaccadic orientation task. While such a transfer of visual orientation across saccade is masked in real-life anisoluminant conditions, the use of a blank and of an isoluminant postsaccadic grating allowed to reveal its existence.

P199 tES effects on a visual orientation discrimination task: Noise induction in a non-linear system

2017 ◽  
Vol 128 (3) ◽  
pp. e111-e112
Author(s):  
A. Zazio ◽  
M. Bortoletto ◽  
A. Fertonani ◽  
C. Pirulli ◽  
C. Miniussi
Keyword(s):  
Linear System ◽  
Discrimination Task ◽  
Orientation Discrimination ◽  
Visual Orientation ◽  
Non Linear ◽  
Non Linear System

scholarly journals Stimulus blanking reveals transsaccadic feature transfer

2019 ◽  
Author(s):  
Lukasz Grzeczkowski ◽  
Heiner Deubel ◽  
Martin Szinte
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Real Life ◽  
Saccadic Eye Movements ◽  
Orientation Discrimination ◽  
Visual Features ◽  
Visual Orientation ◽  
Orientation Task ◽  
Visual Projection ◽  
Static Images

AbstractAcross saccadic eye movements, the visual system receives two successive static images corresponding to the pre- and the postsaccadic projections of the visual field on the retina. The existence of a mechanism integrating the content of these images is today still a matter of debate. Here, we studied the transfer of a visual feature across saccades using a blanking paradigm. Participants moved their eyes to a peripheral grating and discriminated a change in its orientation occurring during the eye movement. The grating was either constantly on the screen or briefly blanked during and after the saccade. Moreover, it either was of the same luminance as the background (i.e., isoluminant) or anisoluminant with respect to it. We found that for anisoluminant grating, the orientation discrimination across saccade was improved when a blank followed the onset of the eye movement. Such effect was however abolished with isoluminant grating. Additionally, performance was also improved when an anisoluminant grating presented before the saccade was followed by an isoluminant one. These results demonstrate that a detailed representation of the presaccadic image was transferred across saccades allowing participants to perform better on the trans-saccadic orientation task. While such a transfer of visual orientation across saccade is masked in real-life anisoluminant conditions, the use of a blank and of isoluminant postsaccadic grating allowed here to reveal its existence.Significance statementStatic objects are perceived as not moving across eye movements despite their visual projection shifts on our retina. To compensate for such shifts and create a continuous perception of space, our brain may keep track of objects’ visual features across our movements. We found that shortly blanking a contrast-defined object during and after saccades allows to recover a detailed representation of its orientation. We propose that the transfer of visual content across saccades revealed with the use of a simple blank plays an important role in ensuring our continuous and stable perception of the world.

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