scholarly journals Adaptive Neuromorphic Circuit for Stereoscopic Disparity Using Ocular Dominance Map

2016 ◽  
Vol 2016 ◽  
pp. 1-16
Author(s):  
Sheena Sharma ◽  
Priti Gupta ◽  
C. M. Markan

Stereopsis or depth perception is a critical aspect of information processing in the brain and is computed from the positional shift or disparity between the images seen by the two eyes. Various algorithms and their hardware implementation that compute disparity in real time have been proposed; however, most of them compute disparity through complex mathematical calculations that are difficult to realize in hardware and are biologically unrealistic. The brain presumably uses simpler methods to extract depth information from the environment and hence newer methodologies that could perform stereopsis with brain like elegance need to be explored. This paper proposes an innovative aVLSI design that leverages the columnar organization of ocular dominance in the brain and uses time-staggered Winner Take All (ts-WTA) to adaptively create disparity tuned cells. Physiological findings support the presence of disparity cells in the visual cortex and show that these cells surface as a result of binocular stimulation received after birth. Therefore, creating in hardware cells that can learn different disparities with experience not only is novel but also is biologically more realistic. These disparity cells, when allowed to interact diffusively on a larger scale, can be used to adaptively create stable topological disparity maps in silicon.

2020 ◽  
Vol 117 (41) ◽  
pp. 25505-25516
Author(s):  
Birgit Kriener ◽  
Rishidev Chaudhuri ◽  
Ila R. Fiete

An elemental computation in the brain is to identify the best in a set of options and report its value. It is required for inference, decision-making, optimization, action selection, consensus, and foraging. Neural computing is considered powerful because of its parallelism; however, it is unclear whether neurons can perform this max-finding operation in a way that improves upon the prohibitively slow optimal serial max-finding computation (which takes∼N⁡log(N)time for N noisy candidate options) by a factor of N, the benchmark for parallel computation. Biologically plausible architectures for this task are winner-take-all (WTA) networks, where individual neurons inhibit each other so only those with the largest input remain active. We show that conventional WTA networks fail the parallelism benchmark and, worse, in the presence of noise, altogether fail to produce a winner when N is large. We introduce the nWTA network, in which neurons are equipped with a second nonlinearity that prevents weakly active neurons from contributing inhibition. Without parameter fine-tuning or rescaling as N varies, the nWTA network achieves the parallelism benchmark. The network reproduces experimentally observed phenomena like Hick’s law without needing an additional readout stage or adaptive N-dependent thresholds. Our work bridges scales by linking cellular nonlinearities to circuit-level decision-making, establishes that distributed computation saturating the parallelism benchmark is possible in networks of noisy, finite-memory neurons, and shows that Hick’s law may be a symptom of near-optimal parallel decision-making with noisy input.


2021 ◽  
Vol 15 ◽  
Author(s):  
Qiang Xu ◽  
Qirui Zhang ◽  
Gaoping Liu ◽  
Xi-jian Dai ◽  
Xinyu Xie ◽  
...  

Brain structural covariance network (SCN) can delineate the brain synchronized alterations in a long-range time period. It has been used in the research of cognition or neuropsychiatric disorders. Recently, causal analysis of structural covariance network (CaSCN), winner-take-all and cortex–subcortex covariance network (WTA-CSSCN), and modulation analysis of structural covariance network (MOD-SCN) have expended the technology breadth of SCN. However, the lack of user-friendly software limited the further application of SCN for the research. In this work, we developed the graphical user interface (GUI) toolkit of brain structural covariance connectivity based on MATLAB platform. The software contained the analysis of SCN, CaSCN, MOD-SCN, and WTA-CSSCN. Also, the group comparison and result-showing modules were included in the software. Furthermore, a simple showing of demo dataset was presented in the work. We hope that the toolkit could help the researchers, especially clinical researchers, to do the brain covariance connectivity analysis in further work more easily.


2020 ◽  
pp. 1-11
Author(s):  
Pavlo Tymoshchuk ◽  
s. Shatny

A hardware implementation design of parallelized fuzzy Adaptive Resonance Theory neural network is described and simulated. Parallel category choice and resonance are implemented in the network. Continuous-time and discrete-time winner-take-all neural circuits identifying the largest of M inputs are used as the winner-take-all units. The continuous-time circuit is described by a state equation with a discontinuous right-hand side. The discrete-time counterpart is governed by a difference equation. Corresponding functional block-diagrams of the circuits include M feed-forward hard- limiting neurons and one feedback neuron, which is used to compute the dynamic shift of inputs. The circuits combine arbitrary finite resolution of inputs, high convergence speed to the winner-take-all operation, low computational and hardware implementation complexity, and independence of initial conditions. The circuits are also used for finding elements of input vector with minimal/maximal values to normalize them in the range [0,1].


Author(s):  
Jeffrey M. Berry

The relationships between interest groups, political parties, and elections have always been dynamic, but in recent years change has accelerated in ways that have favored some interests over others. This chapter considers these developments as the result of a variety of factors, the most critical of which are the growth of polarization, a new legal landscape for campaign finance, and new organizational forms. The chapter goes on to suggest, that as bipartisanship has ebbed, elections have become winner-take-all affairs and interest groups are pushed to choose sides. The chapter further suggests that the rise of super PACs is especially notable as wealthy individuals have become increasingly important, single sources of campaign money, supplanting in part traditional interest groups, especially conventional PACs. It concludes that even as sums spent by super PACs and other interest groups have skyrocketed, the impact of their direct spending on persuading voters remains uncertain.


2011 ◽  
Vol 9 (3) ◽  
pp. 659-662 ◽  
Author(s):  
Brian Waddell

Jacob S. Hacker and Paul Pierson's Winner-Take-All Politics: How Washington Made the Rich Richer—And Turned Its Back on the Middle Class is both a work of political science and a contribution to broad public discussion of distributive politics. Its topic could not be more relevant to a US polity wracked by bitter partisan disagreements about taxes, social spending, financial regulation, social insecurity, and inequality. The political power of “the rich” is a theme of widespread public attention. The headline on the cover of the January–February 2011 issue of The American Interest—“Inequality and Democracy: Are Plutocrats Drowning Our Republic?”—is indicative. Francis Fukuyama's lead essay, entitled “Left Out,” clarifies that by “plutocracy,” the journal means “not just rule by the rich, but rule by and for the rich. We mean, in other words, a state of affairs in which the rich influence government in such a way as to protect and expand their own wealth and influence, often at the expense of others.” Fukuyama makes clear that he believes that this state of affairs obtains in the United States today.Readers of Perspectives on Politics will know that the topic has garnered increasing attention from political scientists in general and in our journal in particular. In March 2009, we featured a symposium on Larry Bartels's Unequal Democracy: The Political Economy of the New Gilded Age. And in December 2009, our lead article, by Jeffrey A. Winters and Benjamin I. Page, starkly posed the question “Oligarchy in the United States?” and answered it with an equally stark “yes.” Winner-Take-All Politics thus engages a broader scholarly discussion within US political science, at the same time that it both draws upon and echoes many “classic themes” of US political science from the work of Charles Beard and E. E. Schattschneider to Ted Lowi and Charles Lindblom.In this symposium, we have brought together a group of important scholars and commentators who offer a range of perspectives on the book and on the broader themes it engages. While most of our discussants are specialists on “American politics,” we have also sought out scholars beyond this subfield. Our charge to the discussants is to evaluate the book's central claims and evidence, with a focus on three related questions: 1) How compelling is its analysis of the “how” and “why” of recent US public policy and its “turn” in favor of “the rich” and against “the middle class”? 2) How compelling is its critique of the subfield of “American politics” for its focus on the voter–politician linkage and on “politics as spectacle” at the expense of an analysis of “politics as organized combat”? 3) And do you agree with its argument that recent changes in US politics necessitate a different, more comparative, and more political economy–centered approach to the study of US politics?—Jeffrey C. Isaac, Editor


Sign in / Sign up

Export Citation Format

Share Document