Priming Hand Grip in the Dorsal Visual Processing Stream

2011 ◽  
Author(s):  
Todd A. Kahan ◽  
Simone H. Schriger
Keyword(s):  
Visual Processing ◽  
Hand Grip ◽  
Processing Stream

Context-Dependent Modulation of Early Visual Cortical Responses to Numerical and Nonnumerical Magnitudes

2021 ◽  
pp. 1-12
Author(s):  
Joonkoo Park ◽  
Sonia Godbole ◽  
Marty G. Woldorff ◽  
Elizabeth M. Brannon
Keyword(s):  
Visual Processing ◽  
Context Dependency ◽  
Numerical Magnitude ◽  
Continuous Variables ◽  
Processing Stream ◽  
Cortical Responses ◽  
Early Visual Cortex ◽  
Context Dependent ◽  
Visual Cortical ◽  
The Brain

Abstract Whether and how the brain encodes discrete numerical magnitude differently from continuous nonnumerical magnitude is hotly debated. In a previous set of studies, we orthogonally varied numerical (numerosity) and nonnumerical (size and spacing) dimensions of dot arrays and demonstrated a strong modulation of early visual evoked potentials (VEPs) by numerosity and not by nonnumerical dimensions. Although very little is known about the brain's response to systematic changes in continuous dimensions of a dot array, some authors intuit that the visual processing stream must be more sensitive to continuous magnitude information than to numerosity. To address this possibility, we measured VEPs of participants viewing dot arrays that changed exclusively in one nonnumerical magnitude dimension at a time (size or spacing) while holding numerosity constant and compared this to a condition where numerosity was changed while holding size and spacing constant. We found reliable but small neural sensitivity to exclusive changes in size and spacing; however, changing numerosity elicited a much more robust modulation of the VEPs. Together with previous work, these findings suggest that sensitivity to magnitude dimensions in early visual cortex is context dependent: The brain is moderately sensitive to changes in size and spacing when numerosity is held constant, but sensitivity to these continuous variables diminishes to a negligible level when numerosity is allowed to vary at the same time. Neurophysiological explanations for the encoding and context dependency of numerical and nonnumerical magnitudes are proposed within the framework of neuronal normalization.

scholarly journals Defining the Units of Competition: Influences of Perceptual Organization on Competitive Interactions in Human Visual Cortex

2010 ◽  
Vol 22 (11) ◽  
pp. 2417-2426 ◽  
Author(s):  
Stephanie A. McMains ◽  
Sabine Kastner
Keyword(s):  
Visual Cortex ◽  
Perceptual Organization ◽  
Visual Processing ◽  
Perceptual Grouping ◽  
Neural Representation ◽  
Competitive Interactions ◽  
Illusory Figure ◽  
Processing Stream ◽  
Neural Processes ◽  
Early Visual Cortex

Multiple stimuli that are present simultaneously in the visual field compete for neural representation. At the same time, however, multiple stimuli in cluttered scenes also undergo perceptual organization according to certain rules originally defined by the Gestalt psychologists such as similarity or proximity, thereby segmenting scenes into candidate objects. How can these two seemingly orthogonal neural processes that occur early in the visual processing stream be reconciled? One possibility is that competition occurs among perceptual groups rather than at the level of elements within a group. We probed this idea using fMRI by assessing competitive interactions across visual cortex in displays containing varying degrees of perceptual organization or perceptual grouping (Grp). In strong Grp displays, elements were arranged such that either an illusory figure or a group of collinear elements were present, whereas in weak Grp displays the same elements were arranged randomly. Competitive interactions among stimuli were overcome throughout early visual cortex and V4, when elements were grouped regardless of Grp type. Our findings suggest that context-dependent grouping mechanisms and competitive interactions are linked to provide a bottom–up bias toward candidate objects in cluttered scenes.

Short- and Long-range Neural Synchrony in Grapheme–Color Synesthesia

2013 ◽  
Vol 25 (7) ◽  
pp. 1148-1162 ◽  
Author(s):  
Gregor Volberg ◽  
Anna Karmann ◽  
Stefanie Birkner ◽  
Mark W. Greenlee
Keyword(s):  
Long Range ◽  
Visual Processing ◽  
Short Range ◽  
Phase Locking ◽  
Brain Structures ◽  
Neural Synchrony ◽  
Beta Band ◽  
Color Processing ◽  
Processing Stream ◽  
Theta Frequency

Grapheme–color synesthesia is a perceptual phenomenon where single graphemes (e.g., the letter “E”) induce simultaneous sensations of colors (e.g., the color green) that were not objectively shown. Current models disagree as to whether the color sensations arise from increased short-range connectivity between anatomically adjacent grapheme- and color-processing brain structures or from decreased effectiveness of inhibitory long-range connections feeding back into visual cortex. We addressed this issue by examining neural synchrony obtained from EEG activity, in a sample of grapheme–color synesthetes that were presented with color-inducing versus non-color-inducing graphemes. For color-inducing graphemes, the results showed a decrease in the number of long-range couplings in the theta frequency band (4–7 Hz, 280–540 msec) and a concurrent increase of short-range phase-locking within lower beta band (13–20 Hz, 380–420 msec at occipital electrodes). Because the effects were both found in long-range synchrony and later within the visual processing stream, the results support the idea that reduced inhibition is an important factor for the emergence of synesthetic colors.

Neural Activation in the Dorsal Visual Processing Stream is Context-Dependent in Williams Syndrome

2021 ◽  
Vol 89 (9) ◽  
pp. S267
Author(s):  
Katherine M. Soderberg ◽  
Tiffany A. Nash ◽  
Philip D. Kohn ◽  
J. Shane Kippenhan ◽  
Madeline R. Hamborg ◽  
...  
Keyword(s):  
Williams Syndrome ◽  
Visual Processing ◽  
Neural Activation ◽  
Processing Stream ◽  
Context Dependent

scholarly journals The Role of the Dorsal Visual Processing Stream in Tool Identification

2010 ◽  
Vol 21 (6) ◽  
pp. 772-778 ◽  
Author(s):  
Jorge Almeida ◽  
Bradford Z. Mahon ◽  
Alfonso Caramazza
Keyword(s):  
Visual Processing ◽  
Processing Stream

scholarly journals Not All Emotions Are Equal: Fear Chemosignals Lower Awareness Thresholds Only for Fearful Faces

2020 ◽  
Vol 45 (7) ◽  
pp. 601-608
Author(s):  
Fábio Silva ◽  
Nuno Gomes ◽  
Sebastian Korb ◽  
Gün R Semin
Keyword(s):  
Facial Expressions ◽  
Visual Processing ◽  
Visual Awareness ◽  
Emotional States ◽  
Body Odor ◽  
Emotional Facial Expressions ◽  
Continuous Flash Suppression ◽  
Fearful Faces ◽  
Processing Stream ◽  
Body Odors

Abstract Exposure to body odors (chemosignals) collected under different emotional states (i.e., emotional chemosignals) can modulate our visual system, biasing visual perception. Recent research has suggested that exposure to fear body odors, results in a generalized faster access to visual awareness of different emotional facial expressions (i.e., fear, happy, and neutral). In the present study, we aimed at replicating and extending these findings by exploring if these effects are limited to fear odor, by introducing a second negative body odor—that is, disgust. We compared the time that 3 different emotional facial expressions (i.e., fear, disgust, and neutral) took to reach visual awareness, during a breaking continuous flash suppression paradigm, across 3 body odor conditions (i.e., fear, disgust, and neutral). We found that fear body odors do not trigger an overall faster access to visual awareness, but instead sped-up access to awareness specifically for facial expressions of fear. Disgust odor, on the other hand, had no effects on awareness thresholds of facial expressions. These findings contrast with prior results, suggesting that the potential of fear body odors to induce visual processing adjustments is specific to fear cues. Furthermore, our results support a unique ability of fear body odors in inducing such visual processing changes, compared with other negative emotional chemosignals (i.e., disgust). These conclusions raise interesting questions as to how fear odor might interact with the visual processing stream, whilst simultaneously giving rise to future avenues of research.

Three-dimensional structure-from-motion activates shape-specific areas in the ventral visual processing stream

NeuroImage ◽  
2000 ◽  
Vol 11 (5) ◽  
pp. S691
Author(s):  
Marcus Naumer ◽  
Milene Bonte ◽  
Marcel Grether ◽  
Lars Muckli ◽  
Andreas Engel ◽  
...  
Keyword(s):  
Structure From Motion ◽  
Visual Processing ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Processing Stream

Interactions of reading and semantics along the ventral visual processing stream

2019 ◽  
Vol 27 (1) ◽  
pp. 21-37
Author(s):  
Josh Neudorf ◽  
Chelsea Ekstrand ◽  
Shaylyn Kress ◽  
Alexandra Neufeldt ◽  
Ron Borowsky
Keyword(s):  
Visual Processing ◽  
Processing Stream

scholarly journals Superior colliculus encodes visual saliency before the primary visual cortex

2017 ◽  
Vol 114 (35) ◽  
pp. 9451-9456 ◽  
Author(s):  
Brian J. White ◽  
Janis Y. Kan ◽  
Ron Levy ◽  
Laurent Itti ◽  
Douglas P. Munoz
Keyword(s):  
Visual Cortex ◽  
Superior Colliculus ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Visual Saliency ◽  
Saliency Map ◽  
Stimulus Onset ◽  
Brain Areas ◽  
V1 Neurons ◽  
Processing Stream

Models of visual attention postulate the existence of a bottom-up saliency map that is formed early in the visual processing stream. Although studies have reported evidence of a saliency map in various cortical brain areas, determining the contribution of phylogenetically older pathways is crucial to understanding its origin. Here, we compared saliency coding from neurons in two early gateways into the visual system: the primary visual cortex (V1) and the evolutionarily older superior colliculus (SC). We found that, while the response latency to visual stimulus onset was earlier for V1 neurons than superior colliculus superficial visual-layer neurons (SCs), the saliency representation emerged earlier in SCs than in V1. Because the dominant input to the SCs arises from V1, these relative timings are consistent with the hypothesis that SCs neurons pool the inputs from multiple V1 neurons to form a feature-agnostic saliency map, which may then be relayed to other brain areas.

Perceptual Continuity and the Emergence of Perceptual Persistence in the Ventral Visual Pathway

2005 ◽  
Vol 93 (6) ◽  
pp. 3453-3462 ◽  
Author(s):  
Mary-Ellen Large ◽  
Adrian Aldcroft ◽  
Tutis Vilis
Keyword(s):  
Visual Processing ◽  
Gradual Increase ◽  
Brain Activity ◽  
Occipital Area ◽  
Line Drawings ◽  
Visual Elements ◽  
Processing Stream ◽  
Visual Areas ◽  
Ventral Visual Pathway ◽  
Perceptual Continuity

Perceptual continuity is an important aspect of our experience of the visual world. In this study, we focus on an example of perceptual continuity involving the maintenance of figure—ground segregation despite the removal of binding cues that initiated the segregation. Fragmented line drawings of objects were superimposed on a background of randomly oriented lines. Global forms could be discriminated from the background based on differences in motion or differences in color/brightness. Furthermore, perception of a global form persisted after the binding cue had been removed. A comparison between the persistence of forms constructed from motion or color demonstrated that both forms produced persistence after the object defining cues were removed. Functional imaging showed a gradual increase in the persistence of brain activity in the lower visual areas (V1, V2, VP), which reached significance in V4v and peaked in the lateral occipital area. There was no difference in the location of persistence for color- or motion-defined forms. These results suggest that the retention of a global percept is an emerging property of the ventral visual processing stream and the maintenance of grouped visual elements is independent of cue type. We postulated that perceptual persistence depends on a system of perceptual memory reflecting the state of perceptual organization.

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