• Science of Emotion and Sensibility
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• v.24 no.2
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• pp.57-64
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• 2021

It has long been speculated that the visual system should use a coding strategy that takes advantage of statistical redundancies in images. But how such a coding strategy should manifest in neural responses has been less clear. Low-level image structure related to the power spectrum of natural images appears to be captured by a hard-wired efficient code in the retina of the fly and precortical structures like the LGN of cats that maximizes information content through the limited capacity channel of the optic nerve. But visual images are typically filled with higher-order structure beyond that captured by the power spectrum and visual cortex is not constrained by the same capacity limits as the optic nerve. Whether and how visual cortex can flexibly code for higher order redundancies is unknown. Here we show using psychophysical techniques that the neural response in early human visual cortex may be modulated by orientation redundancies in images such that a visual feature that is contained within a predictive pattern results in slower reaction times than a feature that deviates from a pattern, suggesting lower neural responses to predictable stimuli in the visual cortex. Our results point to a neural response in early visual cortex that is sensitive to global patterns and redundancies in visual images and is in marked contrast to standard models of cortical visual processing.

• Applied Microscopy
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• v.27 no.4
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• pp.347-355
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• 1997

These studies were performed to observe the morphological changes of synapses in the visual cortex of rat during early postnatal development. Specimens of the visual cortex were taken from rats (Sprague Dawley) at 1, 3, 7, 14 and 21 days of age, and prepared for silver impregnation and electron microscopy. The number of synapse and the length of postsynaptic thickening were increased progressively with age, especially 14 and 21 days. The number of dendritic spine was increased conspicuously on postnatal days 14-21. And asymmetic, curved and axo-spinous synapses were increased markedly at the same ages. The present findings suggest that spurt of synaptogenesis in the rat visual cortex occurs during early postnatal development, especially in second to 3rd week period and asymmetric and/or curved axo-spinous synapse is a matured form of synapse with advanced age.

• Journal of Pharmacopuncture
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• v.4 no.1
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• pp.125-139
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• 2001

In order to study the effects of bee venom herbal acupuncture on the neurotransmitters of the rat brain cortex, herbal acupuncture with the bee venom group and normal saline group was performed bilaterally on the point corresponding to LI 4 of the rat. The average optical density of the neurotransmitters from the cerebral cortex was analyzed 30 minutes after the herbal acupuncture with immunohistochemical methods. The results were as follows: 1. The density of NADPH-diaphorase in the bee venom group was increased significantly at the motor cortex, visual cortex, auditory cortex, cingulate cortex, retrosplenial cortex, and perirhinal cortex, compared to the normal saline group. 2. The average optical density of vasoactive intestinal peptide in the bee venom group had significant changes at the insular cortex, retrosplenial cortex, and perirhinal cortex, compared to the normal saline group. 3. The average optical density of neuropeptide-Y in the bee venom group increased significantly at the visual cortex and cingulate cortex, compared to the normal saline group.

• Molecules and Cells
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• v.19 no.3
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• pp.408-417
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• 2005

Nitric oxide (NO) occurs in various types of cells in the central nervous system. We studied the distribution and morphology of neuronal nitric oxide synthase (NOS)-containing neurons in the visual cortex of mouse and rabbit with antibody immunocytochemistry. We also compared this labeling to that of calbindin D28K, calretinin, and parvalbumin. Staining for NOS was seen both in the specific layers and in selective cell types. The densest concentration of intense anti-NOS immunoreactive (IR) neurons was found in layer VI, while the weak anti-NOS-IR neurons were found in layer II/III in both animals. The NOS-IR neurons varied in morphology. The large majority of NOS-IR neurons were round or oval cells with many dendrites coursing in all directions. Two-color immunofluorescence revealed that only 16.7% of the NOS-IR cells were double-labeled with calbindin D28K in the mouse visual cortex, while more than half (51.7%) of the NOS-IR cells were double-labeled with calretinin and 25.0% of the NOS-IR cells were double-labeled with parvalbumin in mouse. By contrast, 92.4% of the NOS-IR neurons expressed calbindin D28K while only 2.5% of the NOS-IR neurons expressed calretinin in the rabbit visual cortex. In contrast with the mouse, none of the NOS-IR cells in the rabbit visual cortex were double-labeled with parvalbumin. The results indicate that neurons in the visual cortex of both animals express NOS in specific layers and cell types, which do not correlate with the expression of calbindin D28K, calretinin or parvalbumin between the two animals.

• Journal of Life Science
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• v.23 no.6
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• pp.804-811
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• 2013

Melanopsin is an opsin-like photopigment found in the small proportion of photosensitive ganglion cells of the retina. It is involved in the regulation of the synchronization of the circadian cycle as well as in the control of pupillary light reflex. The purpose of the present study is to investigate whether melanopsin is also expressed in the other areas of the central visual system outside the retina. We have studied the distribution and morphology of neurons containing melanopsin in the mouse visual cortex with antibody immunocytochemistry. Melanopsin immunoreactivity was mostly present in neuronal soma, but not in nuclei. We found that melanopsin was present in a large subset of neurons within the adult mouse visual cortex with the highest density in layer II/III. In layer I of the visual cortex, melanopsin-immunoreactive (IR) neurons were rarely encountered. In the mouse visual cortex, the majority of the melanopsin-IR neurons consisted of round/oval cells, but was varied in morphology. Vertical fusiform and pyramidal cells were also rarely labeled with the anti-melanopsin antibody. The labeled cells did not show any distinctive distributional pattern. Some melanopsin-IR neurons in mouse visual cortex co-localized with nitricoxide synthase, calbindin and parvalbumin. Our data indicate that melanopsin is located in specific neurons and surprisingly widespread in visual cortex. This finding raises the need of the functional study of melanopsin in central visual areas outside the retina.

• Journal of Acupuncture Research
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• v.21 no.2
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• pp.205-222
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• 2004

Objective: To investigate the effects of acupointed Choksamni(ST36), Kokchi(LI11) and Arbitrary acupoint on NADPH-diaphorase, neuronal nitric oxide synthase(nNOS), neuropeptide Y(NPY) and vasoactive intestinal peptide(VIP) in the cerebral cortex of spontaneously hypertensive rats. Methods: The experimental groups were divided into four groups: Normal, Choksamni(ST36), Kokchi(LI11), arbitrary group. Needles were inserted into acupoints at the depth of 0.5 cm with basic insertion method. Such stimulation was applied continuously for 10 minutes, every other day, for 10 sessions of treatments. Thereafter we evaluated changes in NADPH-d-positive neurons histochemically and changes in nNOS, NPY and VIP-positive neurons immunohistochemically. Results : The optical densities of NADPH-d-positive neurons of all the Choksamni & Kokchi groups were significantly different in all areas of cerebral cortex as compared to arbitrary group. In motor1, sensory2, cingulate2, insular, peripheral, visual cortex there was a significant difference between Choksamni & Kokchi group. The optical densities of nNOS-positive neurons of Choksamni group were significantly different in all areas except for auditory, visual and pisiform cortex and Kokchi group in all areas except for auditory and pisiform cortex as compared to arbitrary group. And there was a significant difference in cingulate1, cingulate2, ectohinal, visual cortex between Choksamni & Kokchi group. The optical densities of NPY neurons of Choksamni group were significantly different in cingulate2, insular, pisiform cortex and Kokchi group in motor1, motor2, sensory1, cingulate2, ectorhinal cortex as compared to arbitrary group. And there was no significant difference between Choksamni & Kokchi group. The optical densities of VIP neurons of Choksamni group were significantly different in all areas except for motor1, auditory cortex and Kokchi group in sensory1, insular, ectorhinal, perirhinal, visual, pisiform cortex as compared to arbitrary group. And there was a significant difference in cingulate1, cingulate2, retrosplenial, auditory corterx between Choksamni & Kokchi group. Conclusion : Our results demonstrated that acupuncture on Choksamni(ST36) & Kokchi(LI11) changes the control activities of the NO system in the cerebral cortex of SHR and according to areas there were significant difference between two groups. In all cerebral cortex areas there were distributed NPY & VIP and there were no significant difference among Choksamni(ST36), Kokchi(LI11) and arbitrary group.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.1
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• pp.51-55
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• 2002

This study was to investigate the effect of EEG wave type of visual cortex on conjugate movement of eyeball according to movement of visual target. Visual evoked potential(VEP) system used the Bio-Pag(production in USA) and recorded to 586 computer. The illumination of test room was 50lux and the visual target was red light dot of 3cm size. The results of dextroversion and levoversion as follows : The visual stimulation waves on the visual cortex have about 71% of delta wave, about 12% of beta wave, about 9% theta wave and about 6% of alpha wave respectively. The dextroversion and levoversion state was similar results on the histogram amplitude of EEG wave, frequency of EEG wave type, EEG wave style and phase diagram of amplitude. Expecially the histogram amplitude of EEG wave appeared almost the Gaussian shape and the phase analysis of amplitude of EEG wave was nearly linear shape. On the fast fourier transform of the amplitude and Hz, the frequency was almost low frequency under 20 Hz, and the dextroversion and levoversion shape was similar results.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.6
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• pp.399-405
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• 2010

Gamma-aminobutyric acid (GABA)-ergic inhibition is important in the function of the visual cortex. In a previous study, we reported a developmental increase in $GABA_A$ receptor-mediated inhibition in the rat visual cortex from 3 to 5 weeks of age. Because this developmental increase is crucial to the regulation of the induction of long-term synaptic plasticity, in the present study we investigated in detail the postnatal development of phasic and tonic inhibition. The amplitude of phasic inhibition evoked by electrical stimulation increased during development from 3 to 8 weeks of age, and the peak time and decay kinetics of inhibitory postsynaptic potential (IPSP) and current (IPSC) slowed progressively. Since the membrane time constant decreased during this period, passive membrane properties might not be involved in the kinetic changes of IPSP and IPSC. Tonic inhibition, another mode of $GABA_A$ receptor-mediated inhibition, also increased developmentally and reached a plateau at 5 weeks of age. These results indicate that the time course of the postnatal development of GABAergic inhibition matched well that of the functional maturation of the visual cortex. Thus, the present study provides significant insight into the roles of inhibitory development in the functional maturation of the visual cortical circuits.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2143-2149
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• 2007

Visual Cortex Stimulator is among artificial retina prosthesis for blind man, is the method that stimulate the brain cell directly without processing the information from retina to visual cortex. In this paper, we propose image construction and recognition model that is similar to human visual processing by recognizing the feature data with orientation information, that is, the characteristics of visual cortex. Back propagation algorithm based on Delta-bar delta is used to recognize after extracting image feature by Kirsh edge detector. Various numerical patterns are used to analyze the performance of proposed method. In experiment, the proposed recognition model to extract image characteristics with the orientation of information from retinal cells to visual cortex makes a little difference in a recognition rate but shows that it is not sensitive in a variety of learning rates similar to human vision system.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.05
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• pp.28-30
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• 1991

A visual prosthesis for the blind based upon electrical stimulation of the visual cortex requires the development of an array of electrodes. To establish design specifications for such an electrode array, we have conducted psychophysical experiments with normally sighted subjects wearing a portable 'phosphene' simulator. The simulator consists of a small video camera, a monitor masked by an opaque perforated film, and optical lenses. The visual angle subtended by the masked monitor is $1.7^{\circ}$ or less. We measured visual acuity and reading rate as a function of the number of pixels and their spacing. Our results indicate that a phosphene image produced by 600 electrodes implanted in a $1\;cm^2$, area near the foveal projection on the visual cortex should provide a limited but useful visual sense for the profoundly blind.