scholarly journals Functional and structural organization of the foveal visual representation of the primate superior colliculus

2017 ◽  
Vol 17 (10) ◽  
pp. 739
Author(s):  
Chih-Yang Chen ◽  
Claudia Distler ◽  
Klaus-Peter Hoffmann ◽  
Ziad Hafed
Keyword(s):  
Superior Colliculus ◽  
Structural Organization ◽  
Visual Representation

scholarly journals Can the Outputs of LGN Y-Cells Support Emotion Recognition? A Computational Study

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Andrea De Cesarei ◽  
Maurizio Codispoti
Keyword(s):  
Facial Expression ◽  
Superior Colliculus ◽  
Emotion Recognition ◽  
Emotional Response ◽  
Computational Study ◽  
Visual Representation ◽  
Computational Approach ◽  
Emotional Facial Expression ◽  
Y Cells ◽  
Subcortical Pathway

It has been suggested that emotional visual input is processed along both a slower cortical pathway and a faster subcortical pathway which comprises the lateral geniculate nucleus (LGN), the superior colliculus, the pulvinar, and finally the amygdala. However, anatomical as well as functional evidence concerning the subcortical route is lacking. Here, we adopt a computational approach in order to investigate whether the visual representation that is achieved in the LGN may support emotion recognition and emotional response along the subcortical route. In four experiments, we show that the outputs of LGN Y-cells support neither facial expression categorization nor the same/different expression matching by an artificial classificator. However, the same classificator is able to perform at an above chance level in a statistics-based categorization of scenes containing animals and scenes containing people and of light and dark patterns. It is concluded that the visual representation achieved in the LGN is insufficient to allow for the recognition of emotional facial expression.

scholarly journals The foveal visual representation of the primate superior colliculus

2019 ◽  
Author(s):  
Chih-Yang Chen ◽  
Klaus-Peter Hoffmann ◽  
Claudia Distler ◽  
Ziad M. Hafed
Keyword(s):  
Superior Colliculus ◽  
Visual Representation ◽  
Scene Analysis ◽  
Gaze Shifts ◽  
Retinal Input ◽  
Highly Sensitive ◽  
Specific Manner ◽  
Visual Tasks ◽  
High Acuity ◽  
Visual Cortices

AbstractProcessing of foveal retinal input is important not only for high quality visual scene analysis, but also for ensuring precise, albeit tiny, gaze shifts during high acuity visual tasks. The representations of foveal retinal input in primate lateral geniculate nucleus and early visual cortices have been characterized. However, how such representations translate into precise eye movements remains unclear. Here we document functional and structural properties of the foveal visual representation of midbrain superior colliculus. We show that superior colliculus, classically associated with extra-foveal spatial representations needed for gaze shifts, is highly sensitive to visual input impinging on the fovea. Superior colliculus also represents such input in an orderly and very specific manner, and it magnifies representation of foveal images in neural tissue as much as primary visual cortex does. Primate superior colliculus contains a high-fidelity visual representation, with large foveal magnification, perfectly suited for active visuomotor control and perception.

scholarly journals The Foveal Visual Representation of the Primate Superior Colliculus

2019 ◽  
Vol 29 (13) ◽  
pp. 2109-2119.e7 ◽  
Author(s):  
Chih-Yang Chen ◽  
Klaus-Peter Hoffmann ◽  
Claudia Distler ◽  
Ziad M. Hafed
Keyword(s):  
Superior Colliculus ◽  
Visual Representation

Topography and extent of visual-field representation in the superior colliculus of the megachiropteran Pteropus

1994 ◽  
Vol 11 (6) ◽  
pp. 1037-1057 ◽  
Author(s):  
Marcello G.P. Rosa ◽  
Leisa M. Schmid
Keyword(s):  
Receptive Field ◽  
Superior Colliculus ◽  
Visual Representation ◽  
Cortical Lesions ◽  
Cortical Projection ◽  
Flying Foxes ◽  
Field Representation ◽  
Complete Representation ◽  
Visual Areas ◽  
Contralateral Eye

AbstractIt has been proposed that flying foxes (genus Pteropus) have a primate-like pattern of representation in the superficial layers of the superior colliculus (SC), whereby the visual representation in this structure is limited by the same decussation line that limits the retino-geniculo-cortical projection (Pettigrew, 1986). To test this hypothesis, visual receptive fields were plotted based on single- and multi-unit recordings in the SC of ten flying foxes. A complete representation of the contralateral hemifield was observed in the SC. Although the binocular hemifield of vision in Pteropus is 54 deg wide, receptive-field centers invaded the ipsilateral hemifield by only 8 deg, and the receptive-field borders by 13 deg. This invasion is similar to that observed at the border between visual areas VI and V2 in the occipital cortex. The extent of the ipsilateral invasion was not affected by a lesion that completely ablated the occipital visual areas, thus suggesting that this invasion may be consequence of a zone of nasotemporal overlap in the retinal projections to the two colliculi. Neurones located in the superficial layers typically responded briskly to stimulation of both eyes, with a bias towards the contralateral eye. After cortical lesions the neuronal responses to the ipsilateral eye were depressed, and the ocular-dominance histograms shifted towards an even stronger dominance by the contralateral eye. However, cells located in the rostral pole of the SC remained responsive to the ipsilateral eye after cortical lesions. Responses in the stratum opticum and stratum griseum intermediate were more severely affected by cortical lesions than those in the stratum griseum superficiale. Our results demonstrate that the SC in flying foxes retain some generalized mammalian characteristics, such as the stronger direct projections of the contralateral eye and the location of the upper, lower, central, and peripheral representations in the SC. Nonetheless, the extent of visual representation in the SC demonstrates a specialized, primate-like pattern. These observations are consistent with the hypothesis that megachiropterans are members of a group that branched off early during the differentiation of primates from basal mammals.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

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