Functional characteristics of visual cortical neurons during local photic stimulation of their receptive fields in cats

1983 ◽  
Vol 15 (1) ◽  
pp. 49-56
Author(s):  
N. A. Lazareva ◽  
R. V. Novikova ◽  
A. S. Tikhomirov ◽  
M. A. Kulikov
Keyword(s):  
Cortical Neurons ◽  
Receptive Fields ◽  
Photic Stimulation ◽  
Functional Characteristics ◽  
Visual Cortical ◽  
Stimulation Of

Receptive fields of visual cortical neurons during changes in parameters of photic stimulation in cats

1980 ◽  
Vol 12 (2) ◽  
pp. 77-84
Author(s):  
I. A. Shevelev ◽  
V. G. Marchenko ◽  
I. V. Maksimova
Keyword(s):  
Cortical Neurons ◽  
Receptive Fields ◽  
Photic Stimulation ◽  
Visual Cortical

Excitatory amino acid receptor-mediated transmission in geniculocortical and intracortical pathways within visual cortex

1991 ◽  
Vol 66 (1) ◽  
pp. 293-306 ◽  
Author(s):  
L. J. Larson-Prior ◽  
P. S. Ulinski ◽  
N. T. Slater
Keyword(s):  
Visual Cortex ◽  
Amino Acid ◽  
Cortical Neurons ◽  
Excitatory Amino Acid ◽  
Nmda Antagonist ◽  
Receptor Subtypes ◽  
Excitatory Amino Acid Receptor ◽  
Visual Cortical ◽  
Stimulation Of

1. A preparation of turtle (Chrysemys picta and Pseudemys scripta) brain in which the integrity of the intracortical and geniculocortical pathways in visual cortex are maintained in vitro has been used to differentiate the excitatory amino acid (EAA) receptor subtypes involved in geniculocortical and intracortical synapses. 2. Stimulation of the geniculocortical fibers at subcortical loci produces monosynaptic excitatory postsynaptic potentials (EPSPs) in visual cortical neurons. These EPSPs are blocked by the broad-spectrum EAA receptor antagonist kynurenate (1-2 mM) and the non-N-methyl-D-aspartate (NMDA) antagonist 6, 7-dinitroquinoxaline-2,3-dione (DNQX, 10 microM), but not by the NMDA antagonist D,L-2-amino-5-phosphonovalerate (D,L-AP-5, 100 microM). These results indicate that the geniculocortical EPSP is mediated by EAAs that access principally, if not exclusively, EAA receptors of the non-NMDA subtypes. 3. Stimulation of intracortical fibers evokes compound EPSPs that could be resolved into three components differing in latency to peak. The component with the shortest latency was not affected by any of the EAA-receptor antagonists tested. The second component, of intermediate latency, was blocked by kyurenate and DNQX but not by D,L-AP-5. The component of longest latency was blocked by kynurenate and D,L-AP-5, but not by DNQX. These results indicate that the compound intracortical EPSP is comprised of three pharmacologically distinct components that are mediated by an unknown receptor, by quisqualate/kainate, and by NMDA receptors, respectively. 4. Repetitive stimulation of intracortical pathways at 0.33 Hz produces a dramatic potentiation of the late, D,L-AP-5-sensitive component of the intracortical EPSP. 5. These experiments lead to a hypothesis about the subtypes of EAA receptors that are accessed by the geniculocortical and intracortical pathways within visual cortex.

The response dynamics of primate visual cortical neurons to simulated optical blur

2009 ◽  
Vol 26 (4) ◽  
pp. 411-420 ◽  
Author(s):  
MICHAEL L. RISNER ◽  
TIMOTHY J. GAWNE
Keyword(s):  
Cortical Neurons ◽  
Receptive Fields ◽  
Luminance Contrast ◽  
Form Perception ◽  
Response Dynamics ◽  
V1 Neurons ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Optical Blur ◽  
Visual Cortical

AbstractNeurons in visual cortical area V1 typically respond well to lines or edges of specific orientations. There have been many studies investigating how the responses of these neurons to an oriented edge are affected by changes in luminance contrast. However, in natural images, edges vary not only in contrast but also in the degree of blur, both because of changes in focus and also because shadows are not sharp. The effect of blur on the response dynamics of visual cortical neurons has not been explored. We presented luminance-defined single edges in the receptive fields of parafoveal (1–6 deg eccentric) V1 neurons of two macaque monkeys trained to fixate a spot of light. We varied the width of the blurred region of the edge stimuli up to 0.36 deg of visual angle. Even though the neurons responded robustly to stimuli that only contained high spatial frequencies and 0.36 deg is much larger than the limits of acuity at this eccentricity, changing the degree of blur had minimal effect on the responses of these neurons to the edge. Primates need to measure blur at the fovea to evaluate image quality and control accommodation, but this might only involve a specialist subpopulation of neurons. If visual cortical neurons in general responded differently to sharp and blurred stimuli, then this could provide a cue for form perception, for example, by helping to disambiguate the luminance edges created by real objects from those created by shadows. On the other hand, it might be important to avoid the distraction of changing blur as objects move in and out of the plane of fixation. Our results support the latter hypothesis: the responses of parafoveal V1 neurons are largely unaffected by changes in blur over a wide range.

scholarly journals Development of cortical orientation selectivity in the absence of visual experience with contour

2011 ◽  
Vol 106 (4) ◽  
pp. 1923-1932 ◽  
Author(s):  
Tomokazu Ohshiro ◽  
Shaista Hussain ◽  
Michael Weliky
Keyword(s):  
Cortical Neurons ◽  
Computational Models ◽  
Visual Experience ◽  
Receptive Fields ◽  
Orientation Selectivity ◽  
Experimental Result ◽  
Full Development ◽  
Visual Inputs ◽  
Eye Opening ◽  
Visual Cortical

Visual cortical neurons are selective for the orientation of lines, and the full development of this selectivity requires natural visual experience after eye opening. Here we examined whether this selectivity develops without seeing lines and contours. Juvenile ferrets were reared in a dark room and visually trained by being shown a movie of flickering, sparse spots. We found that despite the lack of contour visual experience, the cortical neurons of these ferrets developed strong orientation selectivity and exhibited simple-cell receptive fields. This finding suggests that overt contour visual experience is unnecessary for the maturation of orientation selectivity and is inconsistent with the computational models that crucially require the visual inputs of lines and contours for the development of orientation selectivity. We propose that a correlation-based model supplemented with a constraint on synaptic strength dynamics is able to account for our experimental result.

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