Pub Date : 2024-05-10DOI: 10.1017/S0952523824000014
Hannah M Follett, Emma Warr, Jenna Grieshop, Ching Tzu Yu, Mina Gaffney, Owen R Bowie, Jong Won Lee, Sergey Tarima, Dana K Merriman, Joseph Carroll
Animal models of retinal degeneration are critical for understanding disease and testing potential therapies. Inducing degeneration commonly involves the administration of chemicals that kill photoreceptors by disrupting metabolic pathways, signaling pathways, or protein synthesis. While chemically induced degeneration has been demonstrated in a variety of animals (mice, rats, rabbits, felines, 13-lined ground squirrels (13-LGS), pigs, chicks), few studies have used noninvasive high-resolution retinal imaging to monitor the in vivo cellular effects. Here, we used longitudinal scanning light ophthalmoscopy (SLO), optical coherence tomography, and adaptive optics SLO imaging in the euthermic, cone-dominant 13-LGS (46 animals, 52 eyes) to examine retinal structure following intravitreal injections of chemicals, which were previously shown to induce photoreceptor degeneration, throughout the active season of 2019 and 2020. We found that iodoacetic acid induced severe pan-retinal damage in all but one eye, which received the lowest concentration. While sodium nitroprusside successfully induced degeneration of the outer retinal layers, the results were variable, and damage was also observed in 50% of contralateral control eyes. Adenosine triphosphate and tunicamycin induced outer retinal specific damage with varying results, while eyes injected with thapsigargin did not show signs of degeneration. Given the variability of damage we observed, follow-up studies examining the possible physiological origins of this variability are critical. These additional studies should further advance the utility of chemically induced photoreceptor degeneration models in the cone-dominant 13-LGS.
{"title":"Chemically induced cone degeneration in the 13-lined ground squirrel.","authors":"Hannah M Follett, Emma Warr, Jenna Grieshop, Ching Tzu Yu, Mina Gaffney, Owen R Bowie, Jong Won Lee, Sergey Tarima, Dana K Merriman, Joseph Carroll","doi":"10.1017/S0952523824000014","DOIUrl":"10.1017/S0952523824000014","url":null,"abstract":"<p><p>Animal models of retinal degeneration are critical for understanding disease and testing potential therapies. Inducing degeneration commonly involves the administration of chemicals that kill photoreceptors by disrupting metabolic pathways, signaling pathways, or protein synthesis. While chemically induced degeneration has been demonstrated in a variety of animals (mice, rats, rabbits, felines, 13-lined ground squirrels (13-LGS), pigs, chicks), few studies have used noninvasive high-resolution retinal imaging to monitor the <i>in vivo</i> cellular effects. Here, we used longitudinal scanning light ophthalmoscopy (SLO), optical coherence tomography, and adaptive optics SLO imaging in the euthermic, cone-dominant 13-LGS (46 animals, 52 eyes) to examine retinal structure following intravitreal injections of chemicals, which were previously shown to induce photoreceptor degeneration, throughout the active season of 2019 and 2020. We found that iodoacetic acid induced severe pan-retinal damage in all but one eye, which received the lowest concentration. While sodium nitroprusside successfully induced degeneration of the outer retinal layers, the results were variable, and damage was also observed in 50% of contralateral control eyes. Adenosine triphosphate and tunicamycin induced outer retinal specific damage with varying results, while eyes injected with thapsigargin did not show signs of degeneration. Given the variability of damage we observed, follow-up studies examining the possible physiological origins of this variability are critical. These additional studies should further advance the utility of chemically induced photoreceptor degeneration models in the cone-dominant 13-LGS.</p>","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11106521/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140897332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-05DOI: 10.1017/S0952523823000044
Katherine Tsay, Sara Safari, Abdullah Abou-Samra, Jan Kremers, Radouil Tzekov
{"title":"Pre-stimulus bioelectrical activity in lightadapted ERG under blue versus white background - CORRIGENDUM.","authors":"Katherine Tsay, Sara Safari, Abdullah Abou-Samra, Jan Kremers, Radouil Tzekov","doi":"10.1017/S0952523823000044","DOIUrl":"10.1017/S0952523823000044","url":null,"abstract":"","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10808881/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139098722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-20DOI: 10.1017/S0952523823000020
Michael H Hofmann, Isabelle C Gebhardt
The vertebrate eye allows to capture an enormous amount of detail about the surrounding world which can only be exploited with sophisticated central information processing. Furthermore, vision is an active process due to head and eye movements that enables the animal to change the gaze and actively select objects to investigate in detail. The entire system requires a coordinated coevolution of its parts to work properly. Ray-finned fishes offer a unique opportunity to study the evolution of the visual system due to the high diversity in all of its parts. Here, we are bringing together information on retinal specializations (fovea), central visual centers (brain morphology studies), and eye movements in a large number of ray-finned fishes in a cladistic framework. The nucleus glomerulosus-inferior lobe system is well developed only in Acanthopterygii. A fovea, independent eye movements, and an enlargement of the nucleus glomerulosus-inferior lobe system coevolved at least five times independently within Acanthopterygii. This suggests that the nucleus glomerulosus-inferior lobe system is involved in advanced object recognition which is especially well developed in association with a fovea and independent eye movements. None of the non-Acanthopterygii have a fovea (except for some deep sea fish) or independent eye movements and they also lack important parts of the glomerulosus-inferior lobe system. This suggests that structures for advanced visual object recognition evolved within ray-finned fishes independent of the ones in tetrapods and non-ray-finned fishes as a result of a coevolution of retinal, central, and oculomotor structures.
{"title":"Evolution of the visual system in ray-finned fishes.","authors":"Michael H Hofmann, Isabelle C Gebhardt","doi":"10.1017/S0952523823000020","DOIUrl":"10.1017/S0952523823000020","url":null,"abstract":"<p><p>The vertebrate eye allows to capture an enormous amount of detail about the surrounding world which can only be exploited with sophisticated central information processing. Furthermore, vision is an active process due to head and eye movements that enables the animal to change the gaze and actively select objects to investigate in detail. The entire system requires a coordinated coevolution of its parts to work properly. Ray-finned fishes offer a unique opportunity to study the evolution of the visual system due to the high diversity in all of its parts. Here, we are bringing together information on retinal specializations (fovea), central visual centers (brain morphology studies), and eye movements in a large number of ray-finned fishes in a cladistic framework. The nucleus glomerulosus-inferior lobe system is well developed only in Acanthopterygii. A fovea, independent eye movements, and an enlargement of the nucleus glomerulosus-inferior lobe system coevolved at least five times independently within Acanthopterygii. This suggests that the nucleus glomerulosus-inferior lobe system is involved in advanced object recognition which is especially well developed in association with a fovea and independent eye movements. None of the non-Acanthopterygii have a fovea (except for some deep sea fish) or independent eye movements and they also lack important parts of the glomerulosus-inferior lobe system. This suggests that structures for advanced visual object recognition evolved within ray-finned fishes independent of the ones in tetrapods and non-ray-finned fishes as a result of a coevolution of retinal, central, and oculomotor structures.</p>","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11016354/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138809975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-13DOI: 10.1017/s0952523823000032
Katherine Tsay, Sara Safari, Abdullah Abu-Samra, Jan Kremers, Radouil Tzekov
To compare the baseline signal between two conditions used to generate the photopic negative response (PhNR) of the full-field electroretinogram (ERG): red flash on a blue background (RoB) and white flash on a white background (LA3). The secondary purpose is to identify how the level of pre-stimulus signal affects obtaining an unambiguous PhNR component. A retrospective chart review was conducted on four cohorts of patients undergoing routine ERG testing. In each group, LA3 was recorded the same way while RoB was generated differently using various luminances of red and blue light. The background bioelectrical activity 30 ms before the flash was extracted, and the root mean square (RMS) of the signal was calculated and compared between RoB and LA3 using Wilcoxon test. Pre-stimulus noise was significantly higher under RoB stimulation versus LA3 in all four conditions for both right and left eyes (ratio RoB/LA3 RMS 1.70 and 1.57 respectively, p < 0.033). There was also no significant difference between the RMS of either LA3 or RoB across protocols, indicating that the baseline noise across cohorts were comparable. Additionally, pre-stimulus noise was higher in signals where PhNR was not clearly identifiable as an ERG component versus signals with the presence of unambiguous PhNR component under RoB in all four groups for both eyes (p < 0.05), whereas the difference under LA3 was less pronounced. Our study suggests that LA3 produces less background bioelectrical activity, likely due to decreased facial muscle activity. As it seems that the pre-stimulus signal level affects PhNR recordability, LA3 may also produce a better-quality signal compared to RoB. Therefore, until conditions for a comparable bioelectrical activity under RoB are established, we believe that LA3 should be considered at least as a supplementary method to evaluate retinal ganglion cell function by ERG.
{"title":"Pre-stimulus bioelectrical activity in light-adapted ERG under blue versus white background","authors":"Katherine Tsay, Sara Safari, Abdullah Abu-Samra, Jan Kremers, Radouil Tzekov","doi":"10.1017/s0952523823000032","DOIUrl":"https://doi.org/10.1017/s0952523823000032","url":null,"abstract":"<p>To compare the baseline signal between two conditions used to generate the photopic negative response (PhNR) of the full-field electroretinogram (ERG): red flash on a blue background (RoB) and white flash on a white background (LA3). The secondary purpose is to identify how the level of pre-stimulus signal affects obtaining an unambiguous PhNR component. A retrospective chart review was conducted on four cohorts of patients undergoing routine ERG testing. In each group, LA3 was recorded the same way while RoB was generated differently using various luminances of red and blue light. The background bioelectrical activity 30 ms before the flash was extracted, and the root mean square (RMS) of the signal was calculated and compared between RoB and LA3 using Wilcoxon test. Pre-stimulus noise was significantly higher under RoB stimulation versus LA3 in all four conditions for both right and left eyes (ratio RoB/LA3 RMS 1.70 and 1.57 respectively, <span>p</span> < 0.033). There was also no significant difference between the RMS of either LA3 or RoB across protocols, indicating that the baseline noise across cohorts were comparable. Additionally, pre-stimulus noise was higher in signals where PhNR was not clearly identifiable as an ERG component versus signals with the presence of unambiguous PhNR component under RoB in all four groups for both eyes (<span>p</span> < 0.05), whereas the difference under LA3 was less pronounced. Our study suggests that LA3 produces less background bioelectrical activity, likely due to decreased facial muscle activity. As it seems that the pre-stimulus signal level affects PhNR recordability, LA3 may also produce a better-quality signal compared to RoB. Therefore, until conditions for a comparable bioelectrical activity under RoB are established, we believe that LA3 should be considered at least as a supplementary method to evaluate retinal ganglion cell function by ERG.</p>","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138632608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-23DOI: 10.1017/S0952523823000019
Jiajia Wu, Yeon Jin Kim, Dennis M Dacey, John B Troy, Robert G Smith
In a recent study, visual signals were recorded for the first time in starburst amacrine cells of the macaque retina, and, as for mouse and rabbit, a directional bias observed in calcium signals was recorded from near the dendritic tips. Stimulus motion from the soma toward the tip generated a larger calcium signal than motion from the tip toward the soma. Two mechanisms affecting the spatiotemporal summation of excitatory postsynaptic currents have been proposed to contribute to directional signaling at the dendritic tips of starbursts: (1) a "morphological" mechanism in which electrotonic propagation of excitatory synaptic currents along a dendrite sums bipolar cell inputs at the dendritic tip preferentially for stimulus motion in the centrifugal direction; (2) a "space-time" mechanism that relies on differences in the time-courses of proximal and distal bipolar cell inputs to favor centrifugal stimulus motion. To explore the contributions of these two mechanisms in the primate, we developed a realistic computational model based on connectomic reconstruction of a macaque starburst cell and the distribution of its synaptic inputs from sustained and transient bipolar cell types. Our model suggests that both mechanisms can initiate direction selectivity in starburst dendrites, but their contributions differ depending on the spatiotemporal properties of the stimulus. Specifically, the morphological mechanism dominates when small visual objects are moving at high velocities, and the space-time mechanism contributes most for large visual objects moving at low velocities.
{"title":"Two mechanisms for direction selectivity in a model of the primate starburst amacrine cell.","authors":"Jiajia Wu, Yeon Jin Kim, Dennis M Dacey, John B Troy, Robert G Smith","doi":"10.1017/S0952523823000019","DOIUrl":"10.1017/S0952523823000019","url":null,"abstract":"<p><p>In a recent study, visual signals were recorded for the first time in starburst amacrine cells of the macaque retina, and, as for mouse and rabbit, a directional bias observed in calcium signals was recorded from near the dendritic tips. Stimulus motion from the soma toward the tip generated a larger calcium signal than motion from the tip toward the soma. Two mechanisms affecting the spatiotemporal summation of excitatory postsynaptic currents have been proposed to contribute to directional signaling at the dendritic tips of starbursts: (1) a \"morphological\" mechanism in which electrotonic propagation of excitatory synaptic currents along a dendrite sums bipolar cell inputs at the dendritic tip preferentially for stimulus motion in the centrifugal direction; (2) a \"space-time\" mechanism that relies on differences in the time-courses of proximal and distal bipolar cell inputs to favor centrifugal stimulus motion. To explore the contributions of these two mechanisms in the primate, we developed a realistic computational model based on connectomic reconstruction of a macaque starburst cell and the distribution of its synaptic inputs from sustained and transient bipolar cell types. Our model suggests that both mechanisms can initiate direction selectivity in starburst dendrites, but their contributions differ depending on the spatiotemporal properties of the stimulus. Specifically, the morphological mechanism dominates when small visual objects are moving at high velocities, and the space-time mechanism contributes most for large visual objects moving at low velocities.</p>","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10207453/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9685400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-09DOI: 10.1017/S0952523822000074
L. Spillmann
Colin Blakemore, who died in Oxford on June 27 last year at the age of 78, was a world-renowned British neuroscientist and a highly influential andmuch-admiredmember of the vision community. As a medical student at Cambridge, Blakemore was influenced by Richard Gregory, and he subsequently maintained a keen interest in all aspects of visual science. He is best remembered for his studies on the development of the visual brain in kittens and the demonstration of neural plasticity. His findings were crucial for a better understanding of how brain cells organize themselves in response to the visual environment after birth. After graduating with a First at Cambridge, Blakemore went to the University of California at Berkeley in 1965 for his Ph.D. There he worked with Horace Barlow and Jack Pettigrew on binocular depth discrimination in the cat. He found that the response of binocular units in area V1 depended crucially on the alignment of the binocular stimulus in the two eyes. When the stimulus in one eye was off target, the response was vetoed. Blakemore returned to Cambridge in 1968 to take up a lectureship in physiology and, 3 years later, to become a Fellow at Downing College. It was during that time that he left the study of perception behind in favor of combining behavioral methods and neurophysiological techniques for the study of the visual system. In a ground-breaking experiment with Grahame Cooper, in 1970, he demonstrated that a kitten, which was reared in complete darkness since birth and then exposed to a vertically striped cylinder for 5 hours every day, was severely visually impaired when tested half a year later. In addition to showing no placement response and being seemingly oblivious toward an approaching object, the kitten behaved as if it was blind to a moving horizontal line. Conversely, a kitten that had been exposed to a horizontally striped cylinder, was blind to a moving vertical line. These results showed that the striate cortex could bemodified by selective experience early in life and that normal visual experience is crucial for normal maturation. When the authors recorded from cortical cells, the typical orientation tuning was gravely disturbed and only those cells tuned to near-vertical (or horizontal) responded, consistent with the behavioral deficit. This experiment triggered the great Nature–Nurture debate in the seventies and eighties. Numerous studies were performed in Cambridge and by other vision scientists, to further elucidate the early development of vision and visual perception. In the early 1970s, for example, Blakemore and Richard Van Sluyters embarked on a series of deprivation studies in kittens, in which they surgically closed the lids of one eye and showed that the normal binocular dominance of cortical cells shifted entirely to the other eye. Conversely, when the previously open eye was closed and the initially closed eye reopened, the ocular dominance was reversed, so that now every cell was dominated
科林·布莱克莫尔于去年6月27日在牛津逝世,享年78岁。他是一位享誉世界的英国神经科学家,也是视觉界一位极具影响力且备受尊敬的成员。作为剑桥大学医学院的学生,布莱克莫尔受到理查德·格雷戈里的影响,他随后对视觉科学的各个方面都保持着浓厚的兴趣。他最著名的研究是小猫视觉大脑的发育和神经可塑性的证明。他的发现对于更好地理解出生后大脑细胞如何组织自身以应对视觉环境至关重要。在剑桥大学以一等成绩毕业后,布莱克莫尔于1965年前往加州大学伯克利分校攻读博士学位。在那里,他与霍勒斯·巴洛和杰克·佩蒂格鲁一起研究猫的双目深度识别。他发现V1区的双眼单元的反应关键取决于双眼刺激在两只眼睛中的排列。当一只眼睛的刺激偏离目标时,反应被否决。1968年,布莱克莫尔回到剑桥,开始担任生理学讲师,三年后,他成为唐宁学院的研究员。正是在那段时间里,他放弃了对感知的研究,转而将行为方法和神经生理学技术结合起来研究视觉系统。1970年,他与格雷厄姆·库珀(graham Cooper)进行了一项开创性的实验,证明了一只小猫从出生起就在完全黑暗的环境中长大,然后每天在一个垂直条纹的圆柱体中暴露5小时,在半年后的测试中,它的视力严重受损。除了没有表现出对位置的反应,似乎对接近的物体视而不见之外,小猫表现得好像对移动的水平线视而不见。相反,一只小猫被暴露在一个水平条纹的圆柱体中,对移动的垂直线视而不见。这些结果表明,纹状皮层可以通过生命早期的选择性经验进行修饰,正常的视觉经验对正常的成熟至关重要。当作者从皮质细胞中记录时,典型的定向调谐受到严重干扰,只有那些调谐到接近垂直(或水平)的细胞有反应,这与行为缺陷相一致。这个实验引发了七、八十年代关于先天与后天的大争论。剑桥大学和其他视觉科学家进行了大量的研究,以进一步阐明视觉和视觉感知的早期发展。例如,在20世纪70年代早期,布莱克莫尔和理查德·范·斯鲁特对小猫进行了一系列剥夺性研究,他们通过手术关闭一只眼睛的眼睑,结果发现正常双眼的皮质细胞完全转移到了另一只眼睛。相反,当先前打开的眼睛闭上,而最初关闭的眼睛重新打开时,眼睛的优势被逆转,因此现在每个细胞都被最初被剥夺的眼睛的输入所主导。重要的是,这只在长达3个月的关键时期内起作用,高峰约为30天。布莱克莫尔、安东尼·莫夫森和范·斯卢特斯更进了一步,他们把小猫暴露在特定空间频率的光栅中,发现它们可以使皮质细胞偏向于那个频率。因此,神经元的反应可以通过选择性地暴露于光栅条纹的间距来改变。这些结果的重要性,以及哈佛医学院的托斯滕·维塞尔(TorstenWiesel)的研究结果,立即被临床眼科医生如冈特·冯·诺登(Gunter von Noorden)认识到。维塞尔对猫咪和猴子进行了手术诱导斜视的研究。长期以来,他们一直试图了解斜视儿童弱视的发展,这种情况下,一只眼睛的视觉分辨率和对比敏感度由于两只眼睛的不对准而不可逆转地受损。基于这些结果,世界各地的眼科医生现在对4岁之前的斜视儿童进行矫正手术,也就是在人类视力的关键时期。布莱克莫尔还指出,当小猫在它们的眼睛前面放一个扩散器,从而模糊了视网膜图像时,皮质细胞变得没有反应。这就解释了为什么患有先天性白内障(即晶状体混浊)的儿童在生命早期由于缺乏模式视力而变得弱视或失明。布莱克莫尔是一位天赋异禀的演说家,他以优雅、才华和魅力来传达他的成果和观察。因此,32岁的他成为最年轻的在BBC广播上发表著名的里斯讲座的人也就不足为奇了。我选的题目是“心智的机制”。12年后,他还主持了一部13集的BBC电视连续剧《思维机器》。 那个时候,视觉研究正处于鼎盛时期,每隔一个月就会有新的令人兴奋的东西出现,而且有像布莱克莫尔这样的英雄可以崇拜。几本书也在印刷中证明了他独特的风格。视觉神经科学
{"title":"Colin Blakemore (1944–2022)","authors":"L. Spillmann","doi":"10.1017/S0952523822000074","DOIUrl":"https://doi.org/10.1017/S0952523822000074","url":null,"abstract":"Colin Blakemore, who died in Oxford on June 27 last year at the age of 78, was a world-renowned British neuroscientist and a highly influential andmuch-admiredmember of the vision community. As a medical student at Cambridge, Blakemore was influenced by Richard Gregory, and he subsequently maintained a keen interest in all aspects of visual science. He is best remembered for his studies on the development of the visual brain in kittens and the demonstration of neural plasticity. His findings were crucial for a better understanding of how brain cells organize themselves in response to the visual environment after birth. After graduating with a First at Cambridge, Blakemore went to the University of California at Berkeley in 1965 for his Ph.D. There he worked with Horace Barlow and Jack Pettigrew on binocular depth discrimination in the cat. He found that the response of binocular units in area V1 depended crucially on the alignment of the binocular stimulus in the two eyes. When the stimulus in one eye was off target, the response was vetoed. Blakemore returned to Cambridge in 1968 to take up a lectureship in physiology and, 3 years later, to become a Fellow at Downing College. It was during that time that he left the study of perception behind in favor of combining behavioral methods and neurophysiological techniques for the study of the visual system. In a ground-breaking experiment with Grahame Cooper, in 1970, he demonstrated that a kitten, which was reared in complete darkness since birth and then exposed to a vertically striped cylinder for 5 hours every day, was severely visually impaired when tested half a year later. In addition to showing no placement response and being seemingly oblivious toward an approaching object, the kitten behaved as if it was blind to a moving horizontal line. Conversely, a kitten that had been exposed to a horizontally striped cylinder, was blind to a moving vertical line. These results showed that the striate cortex could bemodified by selective experience early in life and that normal visual experience is crucial for normal maturation. When the authors recorded from cortical cells, the typical orientation tuning was gravely disturbed and only those cells tuned to near-vertical (or horizontal) responded, consistent with the behavioral deficit. This experiment triggered the great Nature–Nurture debate in the seventies and eighties. Numerous studies were performed in Cambridge and by other vision scientists, to further elucidate the early development of vision and visual perception. In the early 1970s, for example, Blakemore and Richard Van Sluyters embarked on a series of deprivation studies in kittens, in which they surgically closed the lids of one eye and showed that the normal binocular dominance of cortical cells shifted entirely to the other eye. Conversely, when the previously open eye was closed and the initially closed eye reopened, the ocular dominance was reversed, so that now every cell was dominated","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44326981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Glaucoma is an eye disease characterized by a progressive vision loss usually starting in peripheral vision. However, a deficit for scene categorization is observed even in the preserved central vision of patients with glaucoma. We assessed the processing and integration of spatial frequencies in the central vision of patients with glaucoma during scene categorization, considering the severity of the disease, in comparison to age-matched controls. In the first session, participants had to categorize scenes filtered in low-spatial frequencies (LSFs) and high-spatial frequencies (HSFs) as a natural or an artificial scene. Results showed that the processing of spatial frequencies was impaired only for patients with severe glaucoma, in particular for HFS scenes. In the light of proactive models of visual perception, we investigated how LSF could guide the processing of HSF in a second session. We presented hybrid scenes (combining LSF and HSF from two scenes belonging to the same or different semantic category). Participants had to categorize the scene filtered in HSF while ignoring the scene filtered in LSF. Surprisingly, results showed that the semantic influence of LSF on HSF was greater for patients with early glaucoma than controls, and then disappeared for the severe cases. This study shows that a progressive destruction of retinal ganglion cells affects the spatial frequency processing in central vision. This deficit may, however, be compensated by increased reliance on predictive mechanisms at early stages of the disease which would however decline in more severe cases.
{"title":"Impact of glaucoma on the spatial frequency processing of scenes in central vision.","authors":"Audrey Trouilloud, Elvia Ferry, Muriel Boucart, Louise Kauffmann, Aude Warniez, Jean-François Rouland, Carole Peyrin","doi":"10.1017/S0952523822000086","DOIUrl":"https://doi.org/10.1017/S0952523822000086","url":null,"abstract":"<p><p>Glaucoma is an eye disease characterized by a progressive vision loss usually starting in peripheral vision. However, a deficit for scene categorization is observed even in the preserved central vision of patients with glaucoma. We assessed the processing and integration of spatial frequencies in the central vision of patients with glaucoma during scene categorization, considering the severity of the disease, in comparison to age-matched controls. In the first session, participants had to categorize scenes filtered in low-spatial frequencies (LSFs) and high-spatial frequencies (HSFs) as a natural or an artificial scene. Results showed that the processing of spatial frequencies was impaired only for patients with severe glaucoma, in particular for HFS scenes. In the light of proactive models of visual perception, we investigated how LSF could guide the processing of HSF in a second session. We presented hybrid scenes (combining LSF and HSF from two scenes belonging to the same or different semantic category). Participants had to categorize the scene filtered in HSF while ignoring the scene filtered in LSF. Surprisingly, results showed that the semantic influence of LSF on HSF was greater for patients with early glaucoma than controls, and then disappeared for the severe cases. This study shows that a progressive destruction of retinal ganglion cells affects the spatial frequency processing in central vision. This deficit may, however, be compensated by increased reliance on predictive mechanisms at early stages of the disease which would however decline in more severe cases.</p>","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9970733/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10796492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-02DOI: 10.1017/S0952523822000062
Jaime F Olavarria, Huixin Qi, Toru Takahata, Jon H Kaas
Studies in the greater galago have not provided a comprehensive description of the organization of eye-specific retino-geniculate-cortical projections to the recipient layers in V1. Here we demonstrate the overall patterns of ocular dominance domains in layers III, IV, and VI revealed following a monocular injection of the transneuronal tracer wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP). We also correlate these patterns with the array of cytochrome oxidase (CO) blobs in tangential sections through the unfolded and flattened cortex. In layer IV, we observed for the first time that eye-specific domains form an interconnected pattern of bands 200-250 μm wide arranged such that they do not show orientation bias and do not meet the V1 border at right angles, as is the case in macaques. We also observed distinct WGA-HRP labeled patches in layers III and VI. The patches in layer III, likely corresponding to patches of K lateral geniculate nucleus (LGN) input, align with layer IV ocular dominance columns (ODCs) of the same eye dominance and overlap partially with virtually all CO blobs in both hemispheres, implying that CO blobs receive K LGN input from both eyes. We further found that CO blobs straddle the border between layer IV ODCs, such that the distribution of CO staining is approximately equal over ipsilateral and contralateral ODCs. These results, together with studies showing that a high percentage of cells in CO blobs are monocular, suggest that CO blobs consist of ipsilateral and contralateral subregions that are in register with underlying layer IV ODCs of the same eye dominance. In macaques and humans, CO blobs are centered on ODCs in layer IV. Our finding that CO blobs in galago straddle the border of neighboring layer IV ODCs suggests that this novel feature may represent an alternative way by which visual information is processed by eye-specific modular architecture in mammalian V1.
{"title":"Overall patterns of eye-specific retino-geniculo-cortical projections to layers III, IV, and VI in primary visual cortex of the greater galago (<i>Otolemur crassicudatus</i>), and correlation with cytochrome oxidase blobs.","authors":"Jaime F Olavarria, Huixin Qi, Toru Takahata, Jon H Kaas","doi":"10.1017/S0952523822000062","DOIUrl":"https://doi.org/10.1017/S0952523822000062","url":null,"abstract":"<p><p>Studies in the greater galago have not provided a comprehensive description of the organization of eye-specific retino-geniculate-cortical projections to the recipient layers in V1. Here we demonstrate the overall patterns of ocular dominance domains in layers III, IV, and VI revealed following a monocular injection of the transneuronal tracer wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP). We also correlate these patterns with the array of cytochrome oxidase (CO) blobs in tangential sections through the unfolded and flattened cortex. In layer IV, we observed for the first time that eye-specific domains form an interconnected pattern of bands 200-250 μm wide arranged such that they do not show orientation bias and do not meet the V1 border at right angles, as is the case in macaques. We also observed distinct WGA-HRP labeled patches in layers III and VI. The patches in layer III, likely corresponding to patches of K lateral geniculate nucleus (LGN) input, align with layer IV ocular dominance columns (ODCs) of the same eye dominance and overlap partially with virtually all CO blobs in both hemispheres, implying that CO blobs receive K LGN input from both eyes. We further found that CO blobs straddle the border between layer IV ODCs, such that the distribution of CO staining is approximately equal over ipsilateral and contralateral ODCs. These results, together with studies showing that a high percentage of cells in CO blobs are monocular, suggest that CO blobs consist of ipsilateral and contralateral subregions that are in register with underlying layer IV ODCs of the same eye dominance. In macaques and humans, CO blobs are centered on ODCs in layer IV. Our finding that CO blobs in galago straddle the border of neighboring layer IV ODCs suggests that this novel feature may represent an alternative way by which visual information is processed by eye-specific modular architecture in mammalian V1.</p>","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2022-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9634673/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9242523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-13DOI: 10.1017/S0952523822000050
Rosa Maria Guimarães Brito, Bruna Rafaela Silva Sousa, Letícia Miquilini, Paulo Roney Kilpp Goulart, Marcelo Fernandes Costa, Dora Fix Ventura, Maria Izabel Tentes Cortes, Givago Silva Souza
Aging causes impairment of contrast sensitivity and chromatic discrimination, leading to changes in the perceptual interactions between color and luminance information. We aimed to investigate the influence of chromatic noise on luminance contrast thresholds in young and older adults. Forty participants were divided equally into Young (29.6 ± 6.3-year-old) and Elderly Groups (57.8 ± 6.6-year-old). They performed a luminance contrast discrimination task in the presence of chromatic noise maskers using a mosaic stimulus in a mosaic background. Four chromatic noise masking protocols were applied (protan, deutan, tritan, and no-noise protocols). We found that luminance contrast thresholds were significantly elevated by the addition of chromatic noise in both age groups (P < 0.05). In the Elderly group, but not the younger group, thresholds obtained in the tritan protocol were lower than those obtained from protan and deutan protocols (P < 0.05). For all protocols, the luminance contrast thresholds of elderly participants were higher than in young people (P < 0.01). Tritan chromatic noise was less effective in inhibiting luminance discrimination in elderly participants.
老化会导致对比敏感度和色彩辨别能力受损,从而导致颜色和亮度信息之间的感知交互作用发生变化。我们的目的是研究彩色噪声对年轻人和老年人亮度对比阈值的影响。40名参与者平均分为青年组(29.6±6.3岁)和老年组(57.8±6.6岁)。他们在彩色噪声掩蔽物存在的情况下,在马赛克背景下使用马赛克刺激进行亮度对比辨别任务。采用四种彩色噪声掩蔽方案(protan, deutan, tritan和无噪声方案)。我们发现,两个年龄组的亮度对比阈值通过添加色度噪声而显著提高(P P P
{"title":"Differences in chromatic noise suppression of luminance contrast discrimination in young and elderly people.","authors":"Rosa Maria Guimarães Brito, Bruna Rafaela Silva Sousa, Letícia Miquilini, Paulo Roney Kilpp Goulart, Marcelo Fernandes Costa, Dora Fix Ventura, Maria Izabel Tentes Cortes, Givago Silva Souza","doi":"10.1017/S0952523822000050","DOIUrl":"https://doi.org/10.1017/S0952523822000050","url":null,"abstract":"<p><p>Aging causes impairment of contrast sensitivity and chromatic discrimination, leading to changes in the perceptual interactions between color and luminance information. We aimed to investigate the influence of chromatic noise on luminance contrast thresholds in young and older adults. Forty participants were divided equally into Young (29.6 ± 6.3-year-old) and Elderly Groups (57.8 ± 6.6-year-old). They performed a luminance contrast discrimination task in the presence of chromatic noise maskers using a mosaic stimulus in a mosaic background. Four chromatic noise masking protocols were applied (protan, deutan, tritan, and no-noise protocols). We found that luminance contrast thresholds were significantly elevated by the addition of chromatic noise in both age groups (<i>P</i> < 0.05). In the Elderly group, but not the younger group, thresholds obtained in the tritan protocol were lower than those obtained from protan and deutan protocols (<i>P</i> < 0.05). For all protocols, the luminance contrast thresholds of elderly participants were higher than in young people (<i>P</i> < 0.01). Tritan chromatic noise was less effective in inhibiting luminance discrimination in elderly participants.</p>","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2022-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33502861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-27DOI: 10.1017/S0952523822000049
Manuel G Bruera, María M Benedetto, Mario E Guido, Alicia L Degano, María A Contin
To study the macroglia and microglia and the immune role in long-time light exposure in rat eyes, we performed glial cell characterization along the time-course of retinal degeneration induced by chronic exposure to low-intensity light. Animals were exposed to light for periods of 2, 4, 6, or 8 days, and the retinal glial response was evaluated by immunohistochemistry, western blot and real-time reverse transcription polymerase chain reaction. Retinal cells presented an increased expression of the macroglia marker GFAP, as well as increased mRNA levels of microglia markers Iba1 and CD68 after 6 days. Also, at this time-point, we found a higher number of Iba1-positive cells in the outer nuclear layer area; moreover, these cells showed the characteristic activated-microglia morphology. The expression levels of immune mediators TNF, IL-6, and chemokines CX3CR1 and CCL2 were also significantly increased after 6 days. All the events of glial activation occurred after 5-6 days of constant light exposure, when the number of photoreceptor cells has already decreased significantly. Herein, we demonstrated that glial and immune activation are secondary to neurodegeneration; in this scenario, our results suggest that photoreceptor death is an early event that occurs independently of glial-derived immune responses.
{"title":"Glial cell response to constant low light exposure in rat retina.","authors":"Manuel G Bruera, María M Benedetto, Mario E Guido, Alicia L Degano, María A Contin","doi":"10.1017/S0952523822000049","DOIUrl":"https://doi.org/10.1017/S0952523822000049","url":null,"abstract":"<p><p>To study the macroglia and microglia and the immune role in long-time light exposure in rat eyes, we performed glial cell characterization along the time-course of retinal degeneration induced by chronic exposure to low-intensity light. Animals were exposed to light for periods of 2, 4, 6, or 8 days, and the retinal glial response was evaluated by immunohistochemistry, western blot and real-time reverse transcription polymerase chain reaction. Retinal cells presented an increased expression of the macroglia marker GFAP, as well as increased mRNA levels of microglia markers Iba1 and CD68 after 6 days. Also, at this time-point, we found a higher number of Iba1-positive cells in the outer nuclear layer area; moreover, these cells showed the characteristic activated-microglia morphology. The expression levels of immune mediators TNF, IL-6, and chemokines CX3CR1 and CCL2 were also significantly increased after 6 days. All the events of glial activation occurred after 5-6 days of constant light exposure, when the number of photoreceptor cells has already decreased significantly. Herein, we demonstrated that glial and immune activation are secondary to neurodegeneration; in this scenario, our results suggest that photoreceptor death is an early event that occurs independently of glial-derived immune responses.</p>","PeriodicalId":23556,"journal":{"name":"Visual Neuroscience","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2022-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40377931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}