Geometrical Computations Explain Projection Patterns of Long-Range Horizontal Connections in Visual Cortex

2004 ◽  
Vol 16 (3) ◽  
pp. 445-476 ◽  
Author(s):  
Ohad Ben-Shahar ◽  
Steven Zucker
Keyword(s):  
Differential Geometry ◽  
Visual Cortex ◽  
Long Range ◽  
Contour Integration ◽  
Integration Process ◽  
Good Continuation ◽  
Significant Evidence ◽  
Horizontal Connections ◽  
Functional Explanations ◽  
First Time

Neurons in primary visual cortex respond selectively to oriented stimuli such as edges and lines. The long-range horizontal connections between them are thought to facilitate contour integration. While many physiological and psychophysical findings suggest that collinear or association field models of good continuation dictate particular projection patterns of horizontal connections to guide this integration process, significant evidence of interactions inconsistent with these hypotheses is accumulating. We first show that natural random variations around the collinear and association field models cannot account for these inconsistencies, a fact that motivates the search for more principled explanations. We then develop a model of long-range projection fields that formalizes good continuation based on differential geometry. The analysis implicates curvature(s) in a fundamental way, and the resulting model explains both consistent data and apparent outliers. It quantitatively predicts the (typically ignored) spread in projection distribution, its nonmonotonic variance, and the differences found among individual neurons. Surprisingly, and for the first time, this model also indicates that texture (and shading) continuation can serve as alternative and complementary functional explanations to contour integration. Because current anatomical data support both (curve and texture) integration models equally and because both are important computationally, new testable predictions are derived to allow their differentiation and identification.

scholarly journals Spontaneous retinal waves generate long-range horizontal connectivity in visual cortex

2020 ◽  
Author(s):  
Jinwoo Kim ◽  
Min Song ◽  
Se-Bum Paik
Keyword(s):  
Visual Cortex ◽  
Long Range ◽  
Primary Visual Cortex ◽  
Cortical Neurons ◽  
Activity Patterns ◽  
Developmental Model ◽  
List Type ◽  
Retinal Waves ◽  
Horizontal Connections ◽  
Eye Opening

AbstractIn the primary visual cortex (V1) of higher mammals, long-range horizontal connections (LHCs) are observed to develop, linking iso-orientation domains of cortical tuning. It is unknown how this feature-specific wiring of circuitry develops before eye opening. Here, we show that LHCs in V1 may originate from spatio-temporally structured feedforward activities generated from spontaneous retinal waves. Using model simulations based on the anatomy and observed activity patterns of the retina, we show that waves propagating in retinal mosaics can initialize the wiring of LHCs by co-activating neurons of similar tuning, whereas equivalent random activities cannot induce such organizations. Simulations showed that emerged LHCs can produce the patterned activities observed in V1, matching topography of the underlying orientation map. We also confirmed that the model can also reproduce orientation-specific microcircuits in salt-and-pepper organizations in rodents. Our results imply that early peripheral activities contribute significantly to cortical development of functional circuits.HighlightsDevelopmental model of long-range horizontal connections (LHCs) in V1 is simulatedSpontaneous retinal waves generate feature-specific wiring of LHCs in visual cortexEmerged LHCs induce orientation-matching patterns of spontaneous cortical activityRetinal waves induce orientation-specific microcircuits of visual cortex in rodentsSignificance statementLong-range horizontal connections (LHCs) in the primary visual cortex (V1) are observed to emerge before the onset of visual experience, selectively connecting iso-domains of orientation maps. However, it is unknown how such tuning-specific wirings develop before eye-opening. Here, we show that LHCs in V1 originate from the tuning-specific activation of cortical neurons by spontaneous retinal waves during early developmental stages. Our simulations of a visual cortex model show that feedforward activities from the retina initialize the spatial organization of activity patterns in V1, which induces visual feature-specific wirings of V1 neurons. Our model also explains the origin of cortical microcircuits observed in rodents, suggesting that the proposed developmental mechanism is applicable universally to circuits of various mammalian species.

scholarly journals Integration of Contours Defined by Second-Order Contrast-Modulation of Texture

2019 ◽  
Author(s):  
Alex S Baldwin ◽  
Madeleine Kenwood ◽  
Robert F Hess
Keyword(s):  
Internal Noise ◽  
Input Image ◽  
Contour Integration ◽  
Second Order ◽  
Integration Process ◽  
Good Continuation ◽  
Noise Condition ◽  
Noise Masking ◽  
First Order ◽  
Multiple Factors

ABSTRACTBoundaries in the visual world can be defined by changes in luminance and texture in the input image. A “contour integration” process joins together local changes into percepts of lines or edges. A previous study tested the integration of contours defined by second-order contrast-modulation. Their contours were placed in a background of random wavelets. Subjects performed near chance. We re-visited second-order contour integration with a different task. Subjects distinguished contours with “good continuation” from distractors. We measured thresholds in different amounts of external orientation or position noise. This gave two noise-masking functions. We also measured thresholds for contours with a baseline curvature to assess performance with more curvy targets. Our subjects were able to discriminate the good continuation of second-order contours. Thresholds were higher than for first-order contours. In our modelling, we found this was due to multiple factors. There was a doubling of equivalent internal noise between first- and second-order contour integration. There was also a reduction in efficiency. The efficiency difference was only significant in our orientation noise condition. For both first- and second-order stimuli, subjects were also able to perform our task with more curved contours. We conclude that humans can integrate second-order contours, even when they are curved. There is however reduced performance compared to first-order contours. We find both an impaired input to the integrating mechanism, and reduced efficiency seem responsible. Second-order contour integration may be more affected by the noise background used in the previous study. Difficulty segregating that background may explain their result.

scholarly journals Experience-expectant development of contour integration mechanisms in human visual cortex

10.1167/5.2.3 ◽  
2005 ◽  
Vol 5 (2) ◽  
pp. 3 ◽  
Author(s):  
Anthony M. Norcia ◽  
Vanitha Sampath ◽  
Hou Chuan ◽  
Mark W. Pettet
Keyword(s):  
Visual Cortex ◽  
Contour Integration ◽  
Human Visual Cortex ◽  
Integration Mechanisms

scholarly journals Corrigendum

2018 ◽  
Vol 14 (2) ◽  
pp. NP1-NP2
Keyword(s):  
Intellectual Property ◽  
Long Range ◽  
Labor Law ◽  
The Internet ◽  
Law Of War ◽  
Acoustic Device ◽  
The Law ◽  
Media Reports ◽  
First Time ◽  
Us University

James E.K. Parker, Towards an Acoustic Jurisprudence: Law and the Long Range Acoustic Device, Law, Culture and the Humanities (LCH). DOI: 10.1177/1743872115615502 The following corrections have been made to the article: Under heading III.1, another paragraph has been added. This paragraph begins ‘Whereas normal loudspeaker works…’ Under heading III.2, a paragraph has been edited: ‘In effect, what ATC did with the LRAD…’ Under heading III.2, the first sentence of the last paragraph has been expanded to clarify that the G-20 summit was held in Pittsburgh: The LRAD seems to have been used by police for the first time in Georgia in 2007, before receiving its first and most notorious outing on American soil in September 2009 at protests relating to the G-20 Summit being held in Pittsburgh.66 Under heading III.4, the sentence below in the second paragraph has been changed as follows: The law of property provides the conditions for the circulation and ownership of knowledge that enable developments in the science of acoustics at a US university in the 1950s to re-emerge as failed commercial prototypes in Japan in the 1980s only to be taken up again in 1996 by ACT before being patented, trademarked and marketed first as HSS® and then as the LRAD.82 Under heading III.4, the following has been added to the end of the paragraph ‘If the LRAD was originally imagined…’: Not that the presiding judge in the Toronto case would know however. In his discussion of a deposition by Professor David Wood, of Queen’s University, relating to ‘videos posted on the internet’ documenting the LRAD’s use at Pittsburgh, Justice Brown notes that, ‘unfortunately, Professor Wood did not attach any of those media reports or videos as exhibits to his affidavit. As a result, I cannot attach any weight to his statements.’93 Indeed, it’s not clear that any recordings of an LRAD in action were ever actually played in court. As far as I know, the LRAD has yet to feature in the ‘judicial soundscape’. In the conclusion the word ‘copyright’ has been replaced with ‘intellectual property’: The LRAD is the product of diverse institutions, jurisdictions and areas of doctrine, stretching from the law of intellectual property through the law of war to constitutional and labor law. The references and reference numbers have been updated accordingly. All the subsequent versions of the article will be corrected.

scholarly journals Local and Global Gestalt Laws: A Neurally Based Spectral Approach

2017 ◽  
Vol 29 (2) ◽  
pp. 394-422 ◽  
Author(s):  
Marta Favali ◽  
Giovanna Citti ◽  
Alessandro Sarti
Keyword(s):  
Mathematical Model ◽  
Spectral Analysis ◽  
Group Theory ◽  
Visual Cortex ◽  
Connectivity Matrix ◽  
Spectral Approach ◽  
Good Continuation ◽  
Functional Architecture ◽  
Lie Group Theory ◽  
Gestalt Laws

This letter presents a mathematical model of figure-ground articulation that takes into account both local and global gestalt laws and is compatible with the functional architecture of the primary visual cortex (V1). The local gestalt law of good continuation is described by means of suitable connectivity kernels that are derived from Lie group theory and quantitatively compared with long-range connectivity in V1. Global gestalt constraints are then introduced in terms of spectral analysis of a connectivity matrix derived from these kernels. This analysis performs grouping of local features and individuates perceptual units with the highest salience. Numerical simulations are performed, and results are obtained by applying the technique to a number of stimuli.

scholarly journals Current Challenges of European Integration - 12th Network Europe Conference, 9 – 10 November 2020

2021 ◽  
Author(s):  
André S. Berne ◽  
Jelena Ceranic Perisic ◽  
Viorel Cibotaru ◽  
Alex de Ruyter ◽  
Ivana Kunda ◽  
...  
Keyword(s):  
Member State ◽  
European Integration ◽  
European Commission ◽  
Majority Vote ◽  
Integration Process ◽  
Asylum Policy ◽  
Massive Influx ◽  
The Common ◽  
First Time ◽  
The Eu

Crises are not a new phenomenon in the context of European integration. Additional integration steps could often only be achieved under the pressure of crises.  At present, however, the EU is characterised by multiple crises, so that the integration process as a whole is sometimes being questioned. In 2015, the crisis in the eurozone had escalated to such an extent that for the first time a member state was threatened to leave the eurozone. Furthermore, the massive influx of refugees into the EU has revealed the shortcomings of the Schengen area and the common asylum policy. Finally, with the majority vote of the British in the referendum of 23 June 2016 in favour of the Brexit, the withdrawal of a member state became a reality for the first time. Even in the words of the European Commission, the EU has reached a crossroads. Against this background, the twelfth Network Europe conference included talks on the numerous challenges and future integration scenarios in Europe. 

Sign in / Sign up

Export Citation Format

Share Document