Linking contrast sensitivity to cortical magnification in human primary visual cortex

2021 ◽  
Author(s):  
Marc M. Himmelberg ◽  
Jonathan Winawer ◽  
Marisa Carrasco
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Contrast Sensitivity ◽  
Surface Area ◽  
Primary Visual Cortex ◽  
Fundamental Property ◽  
Polar Angle ◽  
Strongly Correlated ◽  
V1 Neurons ◽  
Cortical Magnification

ABSTRACTThe size and organization of primary visual cortex (V1) varies across individuals. Across neurotypical adults, V1 size varies more than twofold. Within individuals, surface area per unit of visual field – cortical magnification – varies with eccentricity and polar angle. Contrast sensitivity and cortical magnification covary with eccentricity, therefore it has been hypothesized that cortical magnification, specifically the number of activated V1 neurons, limits contrast sensitivity. Here, we quantify the relation between contrast sensitivity and V1 cortical magnification across observers and polar angle. We measured contrast sensitivity at four cardinal meridians in 29 observers. We then used fMRI to measure the size of V1 in the same observers, and the amount of surface area representing each of the four meridians (wedge-ROIs within 15° polar angle of the meridians, 1 to 8° eccentricity). We found that: First, an observer’s contrast sensitivity (averaged across polar angles) was predicted by the size of V1. Second, contrast sensitivity at each cardinal meridian was correlated with the surface area of the wedge-ROIs centered at the corresponding meridian. Third, increases in contrast sensitivity and cortical magnification at the horizontal compared to vertical meridian (horizontal-vertical anisotropy, ‘HVA’) were strongly correlated: a larger HVA in contrast sensitivity corresponded to a larger HVA in cortical magnification. These results reveal that contrast sensitivity and cortical magnification co-vary across observers and demonstrate a link between perceptual polar angle asymmetries and cortical anatomy. Broadly, the results show a link between visual perception and the idiosyncratic cortical organization of V1 in neurotypical observers.SIGNIFICANCE STATEMENTContrast sensitivity is a fundamental property of the human visual system, which indexes the limits of what one can detect or discriminate – the window of visibility. Contrast sensitivity varies with stimulus location on the retina and across observers. These variations are not well understood. Using psychophysics and magnetic resonance imaging, we tested the hypothesis that contrast sensitivity depends on the amount of responsive tissue in primary visual cortex (V1). Individuals with greater contrast sensitivity had a larger V1. Further, within observers, variation in contrast sensitivity across polar angle locations matched the variation in V1 surface area representing those locations. These findings demonstrate a tight link between visual perception and cortical anatomy, both within and among people.

scholarly journals Learning enhances sensory processing in mouse V1 before improving behavior

2016 ◽  
Author(s):  
Ovidiu Jurjut ◽  
Petya Georgieva ◽  
Laura Busse ◽  
Steffen Katzner
Keyword(s):  
Visual Cortex ◽  
Classical Conditioning ◽  
Contrast Sensitivity ◽  
Primary Visual Cortex ◽  
Sensory Processing ◽  
Sensory Information ◽  
Fundamental Property ◽  
Orientation Discrimination ◽  
Orientation Tuning ◽  
V1 Neurons

AbstractA fundamental property of visual cortex is to enhance the representation of those stimuli that are relevant for behavior, but it remains poorly understood how such enhanced representations arise during learning. Using classical conditioning in mice, we show that orientation discrimination is learned in a sequence of distinct behavioral stages, in which animals first rely on stimulus appearance before exploiting its orientation to guide behavior. After confirming that orientation discrimination under classical conditioning requires primary visual cortex (V1), we measured, during learning, response properties of V1 neurons. Learning improved neural discriminability, sharpened orientation tuning and led to higher contrast sensitivity. Remarkably, these learning-related improvements in the V1 representation were fully expressed before successful orientation discrimination was evident in the animals’ behavior. We propose that V1 plays a key role early in discrimination learning to enhance behaviorally relevant sensory information.

scholarly journals Linking individual differences in human V1 to perception around the visual field

2021 ◽  
Author(s):  
Marc Himmelberg ◽  
Jonathan Winawer ◽  
Marisa Carrasco
Keyword(s):  
Individual Differences ◽  
Visual Field ◽  
Contrast Sensitivity ◽  
Polar Angle ◽  
Strongly Correlated ◽  
Ideal Model ◽  
Vertical Meridian ◽  
Perceptual Contrast ◽  
Cortical Magnification ◽  
Ideal Model System

Abstract A central question in neuroscience is how the organization of cortical maps relates to perception, for which human primary visual cortex (V1) is an ideal model system. V1 nonuniformly samples the retinal image, with greater cortical magnification (surface area per degree of visual field) at the fovea than periphery, and at the horizontal than vertical meridian. Moreover, the size and organization of V1 differs greatly across individuals. Here, we used fMRI and psychophysics in the same individuals to quantify individual differences in V1 cortical magnification and perceptual contrast sensitivity at the four polar angle meridians. Across individuals, the overall size of V1 and localized cortical magnification both positively correlated with contrast sensitivity. Moreover, increases in cortical magnification and contrast sensitivity at the horizontal compared to the vertical meridian were strongly correlated. These data reveal a tight link between cortical anatomy and visual perception at the level of individual observer and stimulus location.

scholarly journals Causal role for sleep-dependent reactivation of learning-activated sensory ensembles for fear memory consolidation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Brittany C. Clawson ◽  
Emily J. Pickup ◽  
Amy Ensing ◽  
Laura Geneseo ◽  
James Shaver ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Memory Consolidation ◽  
Critical Role ◽  
Visual Presentation ◽  
Fear Memory ◽  
Memory Recall ◽  
Visual Cue ◽  
V1 Neurons ◽  
Targeted Recombination

AbstractLearning-activated engram neurons play a critical role in memory recall. An untested hypothesis is that these same neurons play an instructive role in offline memory consolidation. Here we show that a visually-cued fear memory is consolidated during post-conditioning sleep in mice. We then use TRAP (targeted recombination in active populations) to genetically label or optogenetically manipulate primary visual cortex (V1) neurons responsive to the visual cue. Following fear conditioning, mice respond to activation of this visual engram population in a manner similar to visual presentation of fear cues. Cue-responsive neurons are selectively reactivated in V1 during post-conditioning sleep. Mimicking visual engram reactivation optogenetically leads to increased representation of the visual cue in V1. Optogenetic inhibition of the engram population during post-conditioning sleep disrupts consolidation of fear memory. We conclude that selective sleep-associated reactivation of learning-activated sensory populations serves as a necessary instructive mechanism for memory consolidation.

scholarly journals A direct interareal feedback-to-feedforward circuit in primate visual cortex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Caitlin Siu ◽  
Justin Balsor ◽  
Sam Merlin ◽  
Frederick Federer ◽  
Alessandra Angelucci
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Projection Neurons ◽  
V1 Neurons ◽  
Cortical Areas ◽  
Area V2 ◽  
Computational Work ◽  
Primate Visual Cortex ◽  
Similar Area ◽  
Hierarchical Computation

AbstractThe mammalian sensory neocortex consists of hierarchically organized areas reciprocally connected via feedforward (FF) and feedback (FB) circuits. Several theories of hierarchical computation ascribe the bulk of the computational work of the cortex to looped FF-FB circuits between pairs of cortical areas. However, whether such corticocortical loops exist remains unclear. In higher mammals, individual FF-projection neurons send afferents almost exclusively to a single higher-level area. However, it is unclear whether FB-projection neurons show similar area-specificity, and whether they influence FF-projection neurons directly or indirectly. Using viral-mediated monosynaptic circuit tracing in macaque primary visual cortex (V1), we show that V1 neurons sending FF projections to area V2 receive monosynaptic FB inputs from V2, but not other V1-projecting areas. We also find monosynaptic FB-to-FB neuron contacts as a second motif of FB connectivity. Our results support the existence of FF-FB loops in primate cortex, and suggest that FB can rapidly and selectively influence the activity of incoming FF signals.

Differential contributions of magnocellular and parvocellular pathways to the contrast response of neurons in bush baby primary visual cortex (V1)

2000 ◽  
Vol 17 (1) ◽  
pp. 71-76 ◽  
Author(s):  
JOHN D. ALLISON ◽  
PETER MELZER ◽  
YUCHUAN DING ◽  
A.B. BONDS ◽  
VIVIEN A. CASAGRANDE
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Response Amplitude ◽  
Contrast Threshold ◽  
Peak Response ◽  
V1 Neurons ◽  
Bush Baby ◽  
High Stimulus ◽  
Average Contrast ◽  
Contrast Response

How neurons in the primary visual cortex (V1) of primates process parallel inputs from the magnocellular (M) and parvocellular (P) layers of the lateral geniculate nucleus (LGN) is not completely understood. To investigate whether signals from the two pathways are integrated in the cortex, we recorded contrast-response functions (CRFs) from 20 bush baby V1 neurons before, during, and after pharmacologically inactivating neural activity in either the contralateral LGN M or P layers. Inactivating the M layer reduced the responses of V1 neurons (n = 10) to all stimulus contrasts and significantly elevated (t = 8.15, P < 0.01) their average contrast threshold from 8.04 (± 4.1)% contrast to 22.46 (± 6.28)% contrast. M layer inactivation also significantly reduced (t = 4.06, P < 0.01) the average peak response amplitude. Inactivating the P layer did not elevate the average contrast threshold of V1 neurons (n = 10), but significantly reduced (t = 4.34, P < 0.01) their average peak response amplitude. These data demonstrate that input from the M pathway can account for the responses of V1 neurons to low stimulus contrasts and also contributes to responses to high stimulus contrasts. The P pathway appears to influence mainly the responses of V1 neurons to high stimulus contrasts. None of the cells in our sample, which included cells in all output layers of V1, appeared to receive input from only one pathway. These findings support the view that many V1 neurons integrate information about stimulus contrast carried by the LGN M and P pathways.

scholarly journals Traumatic brain injury to primary visual cortex produces long-lasting circuit dysfunction

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Jan C. Frankowski ◽  
Andrzej T. Foik ◽  
Alexa Tierno ◽  
Jiana R. Machhor ◽  
David C. Lyon ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Visual Cortex ◽  
Brain Injury ◽  
Primary Visual Cortex ◽  
Visual Stimuli ◽  
Orientation Tuning ◽  
V1 Neurons ◽  
Adult Mice ◽  
Electrophysiological Recordings

AbstractPrimary sensory areas of the mammalian neocortex have a remarkable degree of plasticity, allowing neural circuits to adapt to dynamic environments. However, little is known about the effects of traumatic brain injury on visual circuit function. Here we used anatomy and in vivo electrophysiological recordings in adult mice to quantify neuron responses to visual stimuli two weeks and three months after mild controlled cortical impact injury to primary visual cortex (V1). We found that, although V1 remained largely intact in brain-injured mice, there was ~35% reduction in the number of neurons that affected inhibitory cells more broadly than excitatory neurons. V1 neurons showed dramatically reduced activity, impaired responses to visual stimuli and weaker size selectivity and orientation tuning in vivo. Our results show a single, mild contusion injury produces profound and long-lasting impairments in the way V1 neurons encode visual input. These findings provide initial insight into cortical circuit dysfunction following central visual system neurotrauma.

Parallel Advantage: Further Evidence for Bottom-up Saliency Computation by Human Primary Visual Cortex

Perception ◽  
2022 ◽  
Vol 51 (1) ◽  
pp. 60-69
Author(s):  
Li Zhaoping
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Surround Suppression ◽  
Bottom Up ◽  
Black Disk ◽  
V1 Neurons ◽  
Behavioral Observations ◽  
White Disk ◽  
Special Case

Finding a target among uniformly oriented non-targets is typically faster when this target is perpendicular, rather than parallel, to the non-targets. The V1 Saliency Hypothesis (V1SH), that neurons in the primary visual cortex (V1) signal saliency for exogenous attentional attraction, predicts exactly the opposite in a special case: each target or non-target comprises two equally sized disks displaced from each other by 1.2 disk diameters center-to-center along a line defining its orientation. A target has two white or two black disks. Each non-target has one white disk and one black disk, and thus, unlike the target, activates V1 neurons less when its orientation is parallel rather than perpendicular to the neurons’ preferred orientations. When the target is parallel, rather than perpendicular, to the uniformly oriented non-targets, the target’s evoked V1 response escapes V1’s iso-orientation surround suppression, making the target more salient. I present behavioral observations confirming this prediction.

scholarly journals Pure tones modulate the representation of orientation and direction in the primary visual cortex

2019 ◽  
Vol 121 (6) ◽  
pp. 2202-2214 ◽  
Author(s):  
John P. McClure ◽  
Pierre-Olivier Polack
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Stimulus ◽  
Visual Stimuli ◽  
Direction Selectivity ◽  
Multimodal Integration ◽  
Visual Responses ◽  
V1 Neurons ◽  
Pure Tones ◽  
The Impact

Multimodal sensory integration facilitates the generation of a unified and coherent perception of the environment. It is now well established that unimodal sensory perceptions, such as vision, are improved in multisensory contexts. Whereas multimodal integration is primarily performed by dedicated multisensory brain regions such as the association cortices or the superior colliculus, recent studies have shown that multisensory interactions also occur in primary sensory cortices. In particular, sounds were shown to modulate the responses of neurons located in layers 2/3 (L2/3) of the mouse primary visual cortex (V1). Yet, the net effect of sound modulation at the V1 population level remained unclear. In the present study, we performed two-photon calcium imaging in awake mice to compare the representation of the orientation and the direction of drifting gratings by V1 L2/3 neurons in unimodal (visual only) or multimodal (audiovisual) conditions. We found that sound modulation depended on the tuning properties (orientation and direction selectivity) and response amplitudes of V1 L2/3 neurons. Sounds potentiated the responses of neurons that were highly tuned to the cue’s orientation and direction but weakly active in the unimodal context, following the principle of inverse effectiveness of multimodal integration. Moreover, sound suppressed the responses of neurons untuned for the orientation and/or the direction of the visual cue. Altogether, sound modulation improved the representation of the orientation and direction of the visual stimulus in V1 L2/3. Namely, visual stimuli presented with auditory stimuli recruited a neuronal population better tuned to the visual stimulus orientation and direction than when presented alone. NEW & NOTEWORTHY The primary visual cortex (V1) receives direct inputs from the primary auditory cortex. Yet, the impact of sounds on visual processing in V1 remains controverted. We show that the modulation by pure tones of V1 visual responses depends on the orientation selectivity, direction selectivity, and response amplitudes of V1 neurons. Hence, audiovisual stimuli recruit a population of V1 neurons better tuned to the orientation and direction of the visual stimulus than unimodal visual stimuli.

scholarly journals Disparity processing in primary visual cortex

2016 ◽  
Vol 371 (1697) ◽  
pp. 20150255 ◽  
Author(s):  
Sid Henriksen ◽  
Seiji Tanabe ◽  
Bruce Cumming
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Striate Cortex ◽  
Three Dimensional ◽  
Empirical Support ◽  
Energy Model ◽  
Correspondence Problem ◽  
Stereo Correspondence ◽  
V1 Neurons ◽  
The Right

The first step in binocular stereopsis is to match features on the left retina with the correct features on the right retina, discarding ‘false’ matches. The physiological processing of these signals starts in the primary visual cortex, where the binocular energy model has been a powerful framework for understanding the underlying computation. For this reason, it is often used when thinking about how binocular matching might be performed beyond striate cortex. But this step depends critically on the accuracy of the model, and real V1 neurons show several properties that suggest they may be less sensitive to false matches than the energy model predicts. Several recent studies provide empirical support for an extended version of the energy model, in which the same principles are used, but the responses of single neurons are described as the sum of several subunits, each of which follows the principles of the energy model. These studies have significantly improved our understanding of the role played by striate cortex in the stereo correspondence problem. This article is part of the themed issue ‘Vision in our three-dimensional world’.

scholarly journals Spatial Distribution of Contextual Interactions in Primary Visual Cortex and in Visual Perception

2000 ◽  
Vol 84 (4) ◽  
pp. 2048-2062 ◽  
Author(s):  
Mitesh K. Kapadia ◽  
Gerald Westheimer ◽  
Charles D. Gilbert
Keyword(s):  
Spatial Distribution ◽  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Cortical Neurons ◽  
Receptive Fields ◽  
Human Perception ◽  
Spatial Arrangement ◽  
Orthogonal Axis ◽  
V1 Neurons ◽  
Contextual Interactions

To examine the role of primary visual cortex in visuospatial integration, we studied the spatial arrangement of contextual interactions in the response properties of neurons in primary visual cortex of alert monkeys and in human perception. We found a spatial segregation of opposing contextual interactions. At the level of cortical neurons, excitatory interactions were located along the ends of receptive fields, while inhibitory interactions were strongest along the orthogonal axis. Parallel psychophysical studies in human observers showed opposing contextual interactions surrounding a target line with a similar spatial distribution. The results suggest that V1 neurons can participate in multiple perceptual processes via spatially segregated and functionally distinct components of their receptive fields.

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