Area 21a in the cat and the detection of binocular orientation disparity

1992 ◽  
Vol 12 (1) ◽  
pp. 99-100
Author(s):  
E Wieniawa-Narkiewicz
Keyword(s):  
Area 21A ◽  
Orientation Disparity

Area 21a in the cat and the detection of binocular orientation disparity

2007 ◽  
Vol 12 (2) ◽  
pp. 269-272 ◽  
Author(s):  
E. Wieniawa-Narkiewicz ◽  
B. M. Wimborne ◽  
A. Michalski ◽  
G. H. Henry
Keyword(s):  
Area 21A ◽  
Orientation Disparity

Processing of form and motion in area 21a of cat visual cortex

1993 ◽  
Vol 10 (1) ◽  
pp. 93-115 ◽  
Author(s):  
B. Dreher ◽  
A. Michalski ◽  
R. H. T. Ho ◽  
C. W. F. Lee ◽  
W. Burke
Keyword(s):  
Spatial Organization ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Orientation Tuning ◽  
Area 17 ◽  
Horizontal Strip ◽  
Tuning Curves ◽  
Mean Width ◽  
Area 21A ◽  
The Mean

AbstractExtracellular recordings from single neurons have been made from presumed area 21a of the cerebral cortex of the cat, anesthetized with N2O/O2/sodium pentobarbitone mixture. Area 21a contains mainly a representation of a central horizontal strip of contralateral visual field about 5 deg above and below the horizontal meridian.Excitatory discharge fields of area 21a neurons were substantially (or slightly but significantly) larger than those of neurons at corresponding eccentricities in areas 17, 19, or 18, respectively. About 95% of area 21a neurons could be activated through either eye and the input from the ipsilateral eye was commonly dominant. Over 90% and less than 10% of neurons had, respectively, C-type and S-type receptive-field organization. Virtually all neurons were orientation-selective and the mean width at half-height of the orientation tuning curves at 52.9 deg was not significantly different from that of neurons in areas 17 and 18. About 30% of area 21a neurons had preferred orientations within 15 deg of the vertical.The mean direction-selectivity index (32.8%) of area 21a neurons was substantially lower than the indices for neurons in areas 17 or 18. Only a few neurons exhibited moderately strong end-zone inhibition. Area 21a neurons responded poorly to fast-moving stimuli and the mean preferred velocity at about 12.5 deg/s was not significantly different from that for area 17 neurons.Selective pressure block of Y fibers in contralateral optic nerve resulted in a small but significant reduction in the preferred velocities of neurons activated via the Y-blocked eye. By contrast, removal of the Y input did not produce significant changes in the spatial organization of receptive fields (S or C type), the size of the discharge fields, the width of orientation tuning curves, or direction-selectivity indices.Our results are consistent with the idea that area 21a receives its principal excitatory input from area 17 and is involved mainly in form rather than motion analysis.

Prolonged dark rearing and development of interocular orientation disparity in visual cortex

1983 ◽  
Vol 49 (3) ◽  
pp. 717-729 ◽  
Author(s):  
P. G. Shinkman ◽  
M. R. Isley ◽  
D. C. Rogers
Keyword(s):  
Visual Cortex ◽  
Orientation Disparity ◽  
Dark Rearing

scholarly journals Untethered lives: Barriers to societal integration as predictors of the sexual orientation disparity in suicidality

2019 ◽  
Vol 29 (Supplement_4) ◽  
Author(s):  
R Bränström ◽  
A van der Star ◽  
J E Pachankis
Keyword(s):  
Risk Factors ◽  
Sexual Orientation ◽  
Sexual Minorities ◽  
Social Institutions ◽  
Cross Sectional ◽  
National Public Health ◽  
Public Health Survey ◽  
And Bisexual ◽  
Orientation Disparity

Abstract Background Despite increasing legal protections and supportive attitudes toward sexual minorities (e.g., those who identify as lesbian, gay, and bisexual [LGB]) in recent decades, suicidality remains more common among this population than among heterosexuals. While barriers to societal integration have been widely theorized as determinants of suicidality for the general population, they have not been comprehensively explored to explain the sexual orientation disparity in suicidality and/or compared to more established contributors. Methods Data come from the cross-sectional Swedish National Public Health Survey, which randomly collected data from individuals (16-84 years of age) annually from 2010 to 2015 (1,281 (2.2%) self-identified as LGB). Analyses examined sexual orientation differences in suicidality (i.e., past-12-month ideation and attempts), and explored the role of barriers to societal integration (i.e., not living with a partner or children, unemployment, and lack of societal trust) in explaining this disparity over-and-above more commonly explored psychological (e.g., depression, substance use) and interpersonal (e.g., discrimination, victimization, lack of social support) suicidality risk factors. Results Compared to heterosexuals, suicidal ideation and attempts were more common among both gay men/lesbians (AORideation: 2.51; AORattempts: 4.66), and bisexuals (AORideation: 3.76; AORattempts: 6.06). Barriers to societal integration mediated the association between sexual orientation and suicidality even in models adjusting for established risk factors for suicidality. Conclusions The disproportionate barriers to societal integration that LGB individuals experience seem important contributors to the elevated risk of suicidality among sexual minorities. Preventive interventions should consider innovative ways to foster societal integration within sexual minority populations and to adjust hetero-centric social institutions to better include sexual minorities.

Corticocortical connections between area 21a and primary visual cortex in the cat

Neuroreport ◽  
1997 ◽  
Vol 8 (5) ◽  
pp. 1263-1266 ◽  
Author(s):  
John W. Morley ◽  
Liqun Yuan ◽  
Richard M. Vickery
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Corticocortical Connections ◽  
Area 21A

Spatial and temporal frequency tuning and contrast sensitivity of single neurons in area 21a of the cat

1996 ◽  
Vol 716 (1-2) ◽  
pp. 219-223 ◽  
Author(s):  
Eric Tardif ◽  
André Bergeron ◽  
Franco Lepore ◽  
Jean-Paul Guillemot
Keyword(s):  
Contrast Sensitivity ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Single Neurons ◽  
Area 21A

Sensory and non-sensory visual disorders in man and monkey

1982 ◽  
Vol 298 (1089) ◽  
pp. 3-13 ◽  
Keyword(s):  
Cerebral Cortex ◽  
Sensory Analysis ◽  
Receptive Fields ◽  
Visual Feature ◽  
Cerebral Damage ◽  
Visual Agnosia ◽  
Sensory Impairments ◽  
Visual Areas ◽  
Visual Disorders ◽  
Orientation Disparity

The posterior third of the cerebral cortex in monkeys consists of a patchwork of visual areas in each of which there is a ‘map’ of the retina. The details of the ‘map’ vary considerably from one area to another and one notable variation concerns the optimal visual feature to which the cells respond. Orientation, disparity, colour and movement are emphasized in separate areas that appear to be concerned with sensory analysis. Their existence and the possibility that brain damage is occasionally restricted chiefly to one such area may explain the rare highly selective visual sensory impairments that can follow posterior cerebral damage in man. Other areas are notable for having little or no retinotopic representation. Here the cells may have huge receptive fields and complex trigger features. When such regions are removed, the animal’s visual sensory abilities are intact but its recognition of patterns and objects is not. This condition resembles human visual agnosia.

Receptive Field Infrastructure Restructuring of Visually Driven Neurons of Extrastriate Area 21a

2012 ◽  
Author(s):  
D.K. Khachvankyan ◽  
J.A. Kozak ◽  
A.B. Sharanbekyan ◽  
A.L. Ghazaryan ◽  
B.A. Harutiunian-Kozak
Keyword(s):  
Receptive Field ◽  
Area 21A
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