Two visual contrast processes: One new, one old.

2013 ◽  
pp. 13-27 ◽  
Author(s):  
Norma Graham ◽  
S. Sabina Wolfson
Keyword(s):  
Visual Contrast

Visual contrast modulates maturation of camouflage body patterning in cuttlefish (Sepia pharaonis).

2010 ◽  
Vol 124 (3) ◽  
pp. 261-270 ◽  
Author(s):  
Yi-Hsin Lee ◽  
Hong Young Yan ◽  
Chuan-Chin Chiao
Keyword(s):  
Sepia Pharaonis ◽  
Visual Contrast ◽  
Body Patterning

scholarly journals Visual Contrast Sensitivity in Early-Stage Parkinson's Disease

2016 ◽  
Vol 57 (13) ◽  
pp. 5696 ◽  
Author(s):  
Wendy Ming ◽  
Dimitrios J. Palidis ◽  
Miriam Spering ◽  
Martin J. McKeown
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Contrast Sensitivity ◽  
Early Stage ◽  
Visual Contrast ◽  
Visual Contrast Sensitivity

scholarly journals The role of boundary length and adjacent patch contrast in guppy mate choice

2020 ◽  
Author(s):  
Adélaïde Sibeaux ◽  
Thomas Camduras ◽  
John A Endler
Keyword(s):  
Mate Choice ◽  
Coefficient Of Variation ◽  
Color Pattern ◽  
Strength Analysis ◽  
Visual Contrast ◽  
Female Preferences ◽  
Signal Amplifier ◽  
Polymorphic Species ◽  
Adjacent Patch

Abstract The presence of various combinations of adjacent colors within polymorphic species’ color pattern could have a major impact on mate choice. We studied the role of pattern geometry in predicting mate choice in guppies using boundary strength analysis (BSA). BSA estimates the visual contrast intensity between two adjacent color patches (ΔS) weighted by the lengths of the boundaries between these adjacent color patches. We measured both the chromatic (hue and saturation) and achromatic (luminance) ΔS for each pair of adjacent patches. For each male’s color pattern, we measured BSA as both mean (mΔS) and coefficient of variation (cvΔS) of all ΔS weighted by their corresponding boundary lengths. We also determined if specific color patch boundaries had an impact on female preferences and whether these predicted overall male contrast (mΔS). We found that males with a higher mΔS were more attractive to females and that six boundaries containing either fuzzy black or black as one of the pair colors significantly affected female preferences, indicating that 1) females favored highly conspicuous males and 2) melanin-based patches could be used as a signal amplifier, not only for orange but for other colors.

Interrelation between Qai’lullah, Blue Light Exposure and Neurocognitive Performances: A Short Review

2021 ◽  
Vol 02 (02) ◽  
Author(s):  
Nur Farhana Fadzil ◽  
◽  
Siti Amira Othman ◽  
Keyword(s):  
Job Performance ◽  
Blue Light ◽  
Memory Consolidation ◽  
Light Exposure ◽  
Short Review ◽  
High Energy ◽  
Neurocognitive Performance ◽  
Night Sleep ◽  
Visual Contrast ◽  
The World

Qai’lullah or napping is a phenomenon that is widely practiced in the world. Islam advocates mid-day napping as it is primarily practiced by the Prophet Muhammad (pbuh). Scientists and scholars also acknowledge the benefits beyond this practice after various research and studies done. Hence, this article emphasizes topic of sleep in Islamic insight, their stages of sleeps according to Quran and the practiced of Qai’lullah or mid-day napping. The high-energy blue light exposure from the natural source, Sun and also digital screens reported reduce visual contrast and affect the sharpness and clarity by creating glares lead to mental and physical fatigue. Thus, a short nap in the mid-afternoon helps to boost memory, lift our mood, and improve job performance. The effect associated with qai’lullah are also being reviewed including improved the neurocognitive performance, alertness, recover the loss night sleep and enhanced the quality and increased memory consolidation in people.

Light therapy increases visual contrast sensitivity in seasonal affective disorder

2004 ◽  
Vol 126 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Zoltán Szabó ◽  
Andrea Antal ◽  
Zsolt Tokaji ◽  
János Kálmán ◽  
Szabolcs Kéri ◽  
...  
Keyword(s):  
Affective Disorder ◽  
Contrast Sensitivity ◽  
Seasonal Affective Disorder ◽  
Light Therapy ◽  
Visual Contrast ◽  
Visual Contrast Sensitivity

scholarly journals Passive sensorimotor stimulation triggers long lasting alpha-band fluctuations in visual perception

2018 ◽  
Vol 119 (2) ◽  
pp. 380-388 ◽  
Author(s):  
Alice Tomassini ◽  
Alessandro D’Ausilio
Keyword(s):  
Visual Perception ◽  
Median Nerve ◽  
Movement Planning ◽  
Sensorimotor System ◽  
Alpha Power ◽  
Alpha Band ◽  
Movement Initiation ◽  
Visual Contrast ◽  
Sensorimotor Processes ◽  
Stimulation Of

Movement planning and execution rely on the anticipation and online control of the incoming sensory input. Evidence suggests that sensorimotor processes may synchronize visual rhythmic activity in preparation of action performance. Indeed, we recently reported periodic fluctuations of visual contrast sensitivity that are time-locked to the onset of an intended movement of the arm. However, the origin of the observed visual modulations has so far remained unclear because of the endogenous (and thus temporally undetermined) activation of the sensorimotor system that is associated with voluntary movement initiation. In this study, we activated the sensorimotor circuitry involved in the hand control in an exogenous and controlled way by means of peripheral stimulation of the median nerve and characterized the spectrotemporal dynamics of the ensuing visual perception. The stimulation of the median nerve triggers robust and long-lasting (∼1 s) alpha-band oscillations in visual perception, whose strength is temporally modulated in a way that is consistent with the changes in alpha power described at the neurophysiological level after sensorimotor stimulation. These findings provide evidence in support of a causal role of the sensorimotor system in modulating oscillatory activity in visual areas with consequences for visual perception. NEW & NOTEWORTHY This study shows that the peripheral activation of the somatomotor hand system triggers long-lasting alpha periodicity in visual perception. This demonstrates that not only the endogenous sensorimotor processes involved in movement preparation but also the passive stimulation of the sensorimotor system can synchronize visual activity. The present work suggests that oscillation-based mechanisms may subserve core (task independent) sensorimotor integration functions.

scholarly journals Thalamic inputs determine functionally distinct gamma bands in mouse primary visual cortex

2020 ◽  
Author(s):  
Nicolò Meneghetti ◽  
Chiara Cerri ◽  
Elena Tantillo ◽  
Eleonora Vannini ◽  
Matteo Caleo ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Information ◽  
Narrow Band ◽  
Broad Band ◽  
Gamma Band ◽  
Neuron Network ◽  
Sensory Stimuli ◽  
Thalamic Input ◽  
Visual Contrast

AbstractGamma band is known to be involved in the encoding of visual features in the primary visual cortex (V1). Recent results in rodents V1 highlighted the presence, within a broad gamma band (BB) increasing with contrast, of a narrow gamma band (NB) peaking at ∼60 Hz suppressed by contrast and enhanced by luminance. However, the processing of visual information by the two channels still lacks a proper characterization. Here, by combining experimental analysis and modeling, we prove that the two bands are sensitive to specific thalamic inputs associated with complementary contrast ranges. We recorded local field potentials from V1 of awake mice during the presentation of gratings and observed that NB power progressively decreased from low to intermediate levels of contrast. Conversely, BB power was insensitive to low levels of contrast but it progressively increased going from intermediate to high levels of contrast. Moreover, BB response was stronger immediately after contrast reversal, while the opposite held for NB. All the aforementioned dynamics were accurately reproduced by a recurrent excitatory-inhibitory leaky integrate-and-fire network, mimicking layer IV of mouse V1, provided that the sustained and periodic component of the thalamic input were modulated over complementary contrast ranges. These results shed new light on the origin and function of the two V1 gamma bands. In addition, here we propose a simple and effective model of response to visual contrast that might help in reconstructing network dysfunction underlying pathological alterations of visual information processing.Significance StatementGamma band is a ubiquitous hallmark of cortical processing of sensory stimuli. Experimental evidence shows that in the mouse visual cortex two types of gamma activity are differentially modulated by contrast: a narrow band (NB), that seems to be rodent specific, and a standard broad band (BB), observed also in other animal models.We found that narrow band correlates and broad band anticorrelates with visual contrast in two complementary contrast ranges (low and high respectively). Moreover, BB displayed an earlier response than NB. A thalamocortical spiking neuron network model reproduced the aforementioned results, suggesting they might be due to the presence of two complementary but distinct components of the thalamic input into visual cortical circuitry.

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