• 감성과학
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• 제24권2호
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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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• 제27권4호
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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.

• 대한약침학회지
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• 제4권1호
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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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• 제19권3호
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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.

• 생명과학회지
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• 제23권6호
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• pp.804-811
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• 2013

Melanopsin은 옵신과 비슷한 광색소로 망막 광민감성 신경절 세포에서 적은 비율로 발견 된다. Melanopsin은 일주기 리듬조절에 관여 하고 동공반사를 조절한다. 이번 연구의 목적은 melanopsin이 망막 이외의 중추 시각계 에서도 발견 되는지를 알아 보는 것이다. 우리는 생쥐 시각 피질에 존재하는 melanopsin을 가지는 신경세포를 면역조직화학법을 통해 염색하여 melanopsin의 분포와 형태를 분석하였다. Melanopsin 면역반응은 핵을 제외한 신경세포의 세포체에서 일어났다. 우리는 melanopsin이 성체 생쥐의 시각 피질의 2,3층에서 높은 밀도로 모여서 존재하는 것을 확인했다. 시각 피질 1층에서 melanopsin 면역반응을 보인 신경세포는 드물게 발견 되었다. 생쥐 시각 피질에서 발견된 melanopsin의 세포종류는 주로 round/oval 세포였으나, vertical fusiform 그리고 pyramidal 세포 등도 드물게 발견 되었다. 염색된 세포들의 분포는 특이적이지 않았다. 우리의 실험 데이터로 melanopsin이 시각피질에도 분포한다는 것을 알 수 있었다. 또한, melanopsin을 가지는 신경세포는 nitric oxide synthase, calbindin and parvalbumin과도 같이 발현 되는 것을 관찰했다. 이러한 실험결과는 망막 이외의 부분에서 발견되는 melanopsin의 기능에 대한 연구가 필요함을 야기한다.

• Journal of Acupuncture Research
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• 제21권2호
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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.

• 한국안광학회지
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• 제7권1호
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• pp.51-55
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• 2002

본 연구는 정상 시력을 가진 피검자의 안구가 동향운동을 하도록 주시점의 위치를 변경하며, 동향운동이 대뇌 시 피질 cerebral visual cortex의 뇌파에 미치는 영향을 분석하였다. 시 유발전위 장치(visual evoked potential system)는 Bio-Pag(production in USA)을 이용하였으며, 검사결과는 컴퓨터에 입력하여 분석하였다. 검사실의 조도는 50lux이며, 사용한 시표의 직경은 3 cm의 붉은 광점이며, 우전 dextroversion과 좌전 levoversion에 따른 결과는 다음과 같다. 1. 시자극에 관계하는 시 피질의 뇌파 출현의 높은 빈도는 delta wave, beta wave, theta wave 그리고 alpha wave의 순으로 나타났다. 2. 우전과 좌전에 대한 뇌파의 종류와 진폭은 거의 비슷하다. 3. 진폭에 대한 히스토그램은 우전과 좌전 모두 가우시안 Gausian 분포로 나타났다. 4. 뇌파의 진폭에 대한 위상 분석의 결과는 거의 비슷하다. 5. 뇌파 진폭과 주파수에 대한 fast fourier transform 분석에서 대개 20 Hz 이하의 저주파 low frequency로 나타났으며, 우전과 좌전의 결과는 비슷하다.

• The Korean Journal of Physiology and Pharmacology
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• 제14권6호
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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.

• 한국정보통신학회논문지
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• 제11권11호
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• pp.2143-2149
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• 2007

최근 시각 장애인을 위한 인공망막 모델 구현에 관한 연구 중 시피질 자극기 기술은 시각 자극 전달의 중간 단계를 생략하고 직접 뇌세포를 자극하는 것이다. 본 논문에서는 망막에서 시각 피질로 시각정보를 전달할 때 발생하는 시각 피질의 특성, 즉 방향성에 대한 반응 특성을 특징 데이터로 구성하여 인식함으로써 인간 시각 정보 처리와 유사한 영상 추출 및 인식 모델을 제안한다. 제안된 방법은 영상의 특징을 추출 한 후 Delta-bar-delta 기반 오류 역전파 알고리즘을 적용하여 영상의 특징들을 인식한다. 제시된 방법의 성능을 분석하기 위하여 다양한 숫자 패턴들을 대상으로 실험한 결과, 제안된 망막 세포로부터 전달된 정보를 방향성에 대한 민감성을 고려하여 영상의 특성을 추출하여 인식하는 모델이 기존의 영상 추출 및 인식 모델보다 인식률에 있어서는 별 차이가 없지만 다양한 실험에서 확인할 수 있듯이 인간 시각과 같이 인식 성능이 민감하지 않는 것을 알 수 있었다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1991년도 춘계학술대회
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• pp.28-30
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• 1991

뇌의 시세포를 전기적으로 자극할때 작고 환한 섬광을 보게된다. 이 원리를 이용하여 전기 핀 배열판으로 축구 경기장의 전광판 같은 이미지를 만들어 맹인을 위한 기능적 시각, 걷기 혹은 글 읽기를 가능케 할 수 있다. 유타대학 생체공학과는 인공시각 연구에서 최고의 역사를 가지고 있다. 최근에 개발된 실리콘 전극 배열판은 가까운 장래의 인체 실험을 남겨놓고 있다.