scholarly journals The human visual cortex response to melanopsin-directed stimulation is accompanied by a distinct perceptual experience

2017 ◽  
Author(s):  
Manuel Spitschan ◽  
Andrew S. Bock ◽  
Jack Ryan ◽  
Giulia Frazzetta ◽  
David H. Brainard ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Functional Mri ◽  
Perceptual Experience ◽  
Visual Pathway ◽  
Visual Functions ◽  
Human Visual Cortex ◽  
Pupil Constriction ◽  
Stimulation Of

AbstractThe photopigment melanopsin supports reflexive visual functions in people, such as pupil constriction and circadian photoentrainment. What contribution melanopsin makes to conscious visual perception is less studied. We devised a stimulus that targeted melanopsin separately from the cones using pulsed (3 s) spectral modulations around a photopic background. Pupil-lometry confirmed that the melanopsin stimulus drives a retinal mechanism distinct from luminance. In each of four subjects, a functional MRI response in area V1 was found. This response scaled with melanopic contrast and was not easily explained by imprecision in the silencing of the cones. Twenty additional subjects then observed melanopsin pulses and provided a structured rating of the perceptual experience. Melanopsin stimulation was described as an unpleasant, blurry, minimal brightening that quickly faded. We conclude that isolated stimulation of melanopsin is likely associated with a response within the cortical visual pathway and with an evoked conscious percept.

scholarly journals The human visual cortex response to melanopsin-directed stimulation is accompanied by a distinct perceptual experience

2017 ◽  
Vol 114 (46) ◽  
pp. 12291-12296 ◽  
Author(s):  
Manuel Spitschan ◽  
Andrew S. Bock ◽  
Jack Ryan ◽  
Giulia Frazzetta ◽  
David H. Brainard ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Functional Mri ◽  
Perceptual Experience ◽  
Visual Pathway ◽  
Visual Functions ◽  
Human Visual Cortex ◽  
Pupil Constriction ◽  
Stimulation Of

The photopigment melanopsin supports reflexive visual functions in people, such as pupil constriction and circadian photoentrainment. What contribution melanopsin makes to conscious visual perception is less studied. We devised a stimulus that targeted melanopsin separately from the cones using pulsed (3-s) spectral modulations around a photopic background. Pupillometry confirmed that the melanopsin stimulus evokes a response different from that produced by cone stimulation. In each of four subjects, a functional MRI response in area V1 was found. This response scaled with melanopic contrast and was not easily explained by imprecision in the silencing of the cones. Twenty additional subjects then observed melanopsin pulses and provided a structured rating of the perceptual experience. Melanopsin stimulation was described as an unpleasant, blurry, minimal brightening that quickly faded. We conclude that isolated stimulation of melanopsin is likely associated with a response within the cortical visual pathway and with an evoked conscious percept.

scholarly journals Electrical Stimulation of the Human Visual Cortex Preliminary Report

1974 ◽  
Vol 1 (4) ◽  
pp. 236-238 ◽  
Author(s):  
Andrew Talalla ◽  
Leo Bullara ◽  
Robert Pudenz
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Feasibility Study ◽  
Preliminary Report ◽  
Visual Prosthesis ◽  
Human Visual Cortex ◽  
Stimulation Of

SUMMARY:A feasibility study for the development of a human visual prosthesis has led several workers to observe the effects of electrical stimulation of the human visual cortex. Experience with such stimulations of three normal-sighted patients is reported. The results confirm some of the findings of other workers, but do not show that multiple phosphenes were experienced by our patients, using strictly limited parameters of stimulation.

Fuzzy clustering of gradient-echo functional MRI in the human visual cortex. Part I: Reproducibility

1997 ◽  
Vol 7 (6) ◽  
pp. 1094-1101 ◽  
Author(s):  
Richard Baumgartner ◽  
Gordon Scarth ◽  
Claudia Teichtmeister ◽  
Ray Somorjai ◽  
Ewald Moser
Keyword(s):  
Visual Cortex ◽  
Functional Mri ◽  
Fuzzy Clustering ◽  
Gradient Echo ◽  
Human Visual Cortex

scholarly journals Right hemispheric dominance of visual phenomena evoked by intracerebral stimulation of the human visual cortex

2013 ◽  
Vol 35 (7) ◽  
pp. 3360-3371 ◽  
Author(s):  
Jacques Jonas ◽  
Solène Frismand ◽  
Jean-Pierre Vignal ◽  
Sophie Colnat-Coulbois ◽  
Laurent Koessler ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Hemispheric Dominance ◽  
Human Visual Cortex ◽  
Visual Phenomena ◽  
Stimulation Of

Asymmetrical Activation of Human Visual Cortex Demonstrated by Functional MRI with Monocular Stimulation

NeuroImage ◽  
2001 ◽  
Vol 14 (3) ◽  
pp. 632-641 ◽  
Author(s):  
A.T. Toosy ◽  
D.J. Werring ◽  
G.T. Plant ◽  
E.T. Bullmore ◽  
D.H. Miller ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Functional Mri ◽  
Human Visual Cortex ◽  
Monocular Stimulation

Texture Segregation in the Human Visual Cortex: A Functional MRI Study

2000 ◽  
Vol 83 (4) ◽  
pp. 2453-2457 ◽  
Author(s):  
Sabine Kastner ◽  
Peter De Weerd ◽  
Leslie G. Ungerleider
Keyword(s):  
Visual Cortex ◽  
Functional Mri ◽  
Receptive Fields ◽  
Higher Order ◽  
Checkerboard Pattern ◽  
Texture Segregation ◽  
Human Visual Cortex ◽  
Cell Recording ◽  
Visual Scenes ◽  
Mri Study

The segregation of visual scenes based on contour information is a fundamental process of early vision. Contours can be defined by simple cues, such as luminance, as well as by more complex cues, such as texture. Single-cell recording studies in monkeys suggest that the neural processing of complex contours starts as early as primary visual cortex. Additionally, lesion studies in monkeys indicate an important contribution of higher order areas to these processes. Using functional MRI, we have investigated the level at which neural correlates of texture segregation can be found in the human visual cortex. Activity evoked by line textures, with and without texture-defined boundaries, was compared in five healthy subjects. Areas V1, V2/VP, V4, TEO, and V3A were activated by both kinds of line textures as compared with blank presentations. Textures with boundaries forming a checkerboard pattern, relative to uniform textures, evoked significantly more activity in areas V4, TEO, less reliably in V3A, but not in V1 or V2/VP. These results provide evidence that higher order areas with large receptive fields play an important role in the segregation of visual scenes based on texture-defined boundaries.

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