scholarly journals Interaction between Bottom-up Saliency and Top-down Control: How Saliency Maps Are Created in the Human Brain

2012 ◽  
Vol 22 (12) ◽  
pp. 2943-2952 ◽  
Author(s):  
Lucia Melloni ◽  
Sara van Leeuwen ◽  
Arjen Alink ◽  
Notger G. Müller
Keyword(s):  
Human Brain ◽  
Top Down ◽  
Bottom Up ◽  
Saliency Maps

scholarly journals Ramsey’s Theory Meets The Human Brain Connectome

2021 ◽  
Author(s):  
Arturo Tozzi
Keyword(s):  
Neural Networks ◽  
Human Brain ◽  
Network Theory ◽  
Neuronal Networks ◽  
Top Down ◽  
Bottom Up ◽  
Functional Interactions ◽  
Brain Connectome

Ramsey’s theory (RAM) from combinatorics and network theory goes looking for regularities and repeated patterns inside structures equipped with nodes and edges. RAM represents the outcome of a dual methodological commitment: by one side a top-down approach evaluates the possible arrangement of specific subgraphs when the number of graph’s vertices is already known, by another side a bottom-up approach calculates the possible number of graph’s vertices when the arrangement of specific subgraphs is already known. Since natural neural networks are often represented in terms of graphs, we suggest to utilize RAM for the analytical and computational assessment of a peculiar structure supplied with neuronal vertices and axonal edges, i.e., the human brain connectome. We discuss how a RAM approach in neuroscientific issues might be able to locate and trace unexplored motifs shared between different cortical and subcortical subareas. Furthermore, we will describe how notable RAM outcomes, such as the Ramsey’s theorem and the Ramsey’s number, could contribute to uncover still unknown anatomical connexions endowed in neuronal networks and unexpected functional interactions among grey zones of the human brain.

scholarly journals Top-down and bottom-up mechanisms in biasing competition in the human brain

2009 ◽  
Vol 49 (10) ◽  
pp. 1154-1165 ◽  
Author(s):  
Diane M. Beck ◽  
Sabine Kastner
Keyword(s):  
Human Brain ◽  
Top Down ◽  
Bottom Up

scholarly journals Sharpening of hierarchical visual feature representations of blurred images

2017 ◽  
Author(s):  
Mohamed Abdelhack ◽  
Yukiyasu Kamitani
Keyword(s):  
Neural Network ◽  
Visual System ◽  
Human Brain ◽  
Deep Neural Network ◽  
Prior Information ◽  
Visual Input ◽  
Top Down ◽  
Bottom Up ◽  
Reference Space ◽  
Blurred Images

AbstractThe robustness of the visual system lies in its ability to perceive degraded images. This is achieved through interacting bottom-up, recurrent, and top-down pathways that process the visual input in concordance with stored prior information. The interaction mechanism by which they integrate visual input and prior information is still enigmatic. We present a new approach using deep neural network (DNN) representation to reveal the effects of such integration on degraded visual inputs. We transformed measured human brain activity resulting from viewing blurred images to the hierarchical representation space derived from a feedforward DNN. Transformed representations were found to veer towards the original non-blurred image and away from the blurred stimulus image. This indicated deblurring or sharpening in the neural representation, and possibly in our perception. We anticipate these results will help unravel the interplay mechanism between bottom-up, recurrent, and top-down pathways, leading to more comprehensive models of vision.Significance statementOne powerful characteristic of the visual system is its ability to complement visual information for incomplete visual images. It operates by projecting information from higher visual and semantic areas of the brain into the lower and mid-level representations of the visual stimulus. We investigate the mechanism by which the human brain represents blurred visual stimuli. By decoding fMRI activity into a feedforward-only deep neural network reference space, we found that neural representations of blurred images are biased towards their corresponding deblurred images. This indicates a sharpening mechanism occurring in the visual cortex.

Psychology and Culture: Top Down Versus Bottom Up?

PsycCRITIQUES ◽  
2005 ◽  
Vol 50 (19) ◽  
Author(s):  
Michael Cole
Keyword(s):  
Top Down ◽  
Bottom Up
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