scholarly journals Shape Processing Area LO and Illusory Contours

Perception ◽  
10.1068/p6388 ◽  
2009 ◽  
Vol 38 (8) ◽  
pp. 1260-1263 ◽  
Author(s):  
Lee H de-Wit ◽  
Robert W Kentridge ◽  
A David Milner
Keyword(s):  
Visual Cortex ◽  
Functional Mri ◽  
Primary Visual Cortex ◽  
Visual Illusions ◽  
Visual Area ◽  
Illusory Contours ◽  
Feedback Effects ◽  
Shape Representations ◽  
Shape Processing

Recent functional MRI has demonstrated that illusory contours can activate the primary visual cortex. Our investigation sought to demonstrate whether this correlation reflects computations performed in the primary visual cortex or feedback effects from shape processing area LO. We explored this in a patient who has a bilateral lesion to LO, but a functionally spared V1. Our data indicate that illusory contours are unable to influence behaviour without visual area LO. Whilst we would not claim that our data provide evidence for the ‘cognitive’ nature of illusory contours, they certainly suggest that illusory contours are dependent upon the computations involved in extracting shape representations in LO. Our data highlight the importance of neuropsychological research in interpreting the role of feedforward and feedback effects in the generation of visual illusions.

A Ghost in the Machine

2020 ◽  
pp. 14-22
Author(s):  
Thomas Boraud
Keyword(s):  
Decision Making ◽  
Functional Mri ◽  
Motor Function ◽  
Cognitive Processes ◽  
Visual Discrimination ◽  
Visual Area ◽  
Temporal Area ◽  
Normative Approach ◽  
Electrophysiological Activity

This chapter describes the neurobiological approach of decision-making. Until the late 1980s, ignoring the work of experimental economists and behaviourists, electrophysiologists restricted themselves to the study of sensory and motor function, believing it to be impossible for them to access cognitive processes. In 1989, William Newsome and Anthony Movshon broke the dogma while studying the role of neurons in the medio-temporal area of the cortex (an associative visual area) in the visual discrimination of macaques. They became the first researchers who were able to correlate decision-making with a pattern of electrophysiological activity in neurons. This correlation, which they called psychometric–neurometric pairing, became the backbone of all subsequent studies into the neurobiology of decision-making. The chapter then looks at the development of functional MRI, and presents a normative approach to decision-making and learning.

Functional postnatal development of the rat primary visual cortex and the role of visual experience: Dark rearing and monocular deprivation

1994 ◽  
Vol 34 (6) ◽  
pp. 709-720 ◽  
Author(s):  
Michela Fagiolini ◽  
Tommaso Pizzorusso ◽  
Nicoletta Berardi ◽  
Luciano Domenici ◽  
Lamberto Maffei
Keyword(s):  
Visual Cortex ◽  
Postnatal Development ◽  
Primary Visual Cortex ◽  
Visual Experience ◽  
Monocular Deprivation ◽  
Dark Rearing

A Potential Role of Auditory Induced Modulations in Primary Visual Cortex

2015 ◽  
Vol 28 (3-4) ◽  
pp. 331-349 ◽  
Author(s):  
Frederico A. C. Azevedo ◽  
Frederico A. C. Azevedo ◽  
Michael Ortiz-Rios ◽  
Frederico A. C. Azevedo ◽  
Michael Ortiz-Rios ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Sensory Information ◽  
Orienting Response ◽  
Auditory Signal ◽  
Sensory Sensitivity ◽  
Biologically Relevant ◽  
Additional Information ◽  
Functional Modulation

A biologically relevant event is normally the source of multiple, typically correlated, sensory inputs. To optimize perception of the outer world, our brain combines the independent sensory measurements into a coherent estimate. However, if sensory information is not readily available for every pertinent sense, the brain tries to acquire additional information via covert/overt orienting behaviors or uses internal knowledge to modulate sensory sensitivity based on prior expectations. Cross-modal functional modulation of low-level auditory areas due to visual input has been often described; however, less is known about auditory modulations of primary visual cortex. Here, based on some recent evidence, we propose that an unexpected auditory signal could trigger a reflexive overt orienting response towards its source and concomitantly increase the primary visual cortex sensitivity at the locations where the object is expected to enter the visual field. To this end, we propose that three major functionally specific pathways are employed in parallel. A stream orchestrated by the superior colliculus is responsible for the overt orienting behavior, while direct and indirect (via higher-level areas) projections from A1 to V1 respectively enhance spatiotemporal sensitivity and facilitate object detectability.

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