Origins of Functional Organization in the Visual Cortex
How are the complex maps for orientation selectivity (OS) created in the primary visual cortex (V1)? Rodents and rabbits have a random distribution of OS preferences across V1 while in cats, ferrets, and all primates cells with similar OS preferences cluster together into relatively wide cortical co...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2020-03-01
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| Series: | Frontiers in Systems Neuroscience |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fnsys.2020.00010/full |
| _version_ | 1828875547837464576 |
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| author | Michael Ibbotson Michael Ibbotson Young Jun Jung Young Jun Jung |
| author_facet | Michael Ibbotson Michael Ibbotson Young Jun Jung Young Jun Jung |
| author_sort | Michael Ibbotson |
| collection | DOAJ |
| description | How are the complex maps for orientation selectivity (OS) created in the primary visual cortex (V1)? Rodents and rabbits have a random distribution of OS preferences across V1 while in cats, ferrets, and all primates cells with similar OS preferences cluster together into relatively wide cortical columns. Given other clear similarities in the organization of the visual pathways, why is it that maps coding OS preferences are so radically different? Prominent models have been created of cortical OS mapping that incorporate Hebbian plasticity, intracortical interactions, and the properties of growing axons. However, these models suggest that the maps arise primarily through intracortical interactions. Here we focus on several other features of the visual system and brain that may influence V1 structure. These are: eye divergence, the total number of cells in V1, the thalamocortical networks, the topography of the retina and phylogeny. We outline the evidence for and against these factors contributing to map formation. One promising theory is that the central-to-peripheral ratio (CP ratio) of retinal cell density can be used to predict whether or not a species has pinwheel maps. Animals with high CP ratios (>7) have orientation columns while those with low CP ratios (<4) have random OS maps. The CP ratio is related to the total number of cells in cortex, which also appears to be a reasonable contributing factor. However, while these factors correlate with map structure to some extent, there is a gray area where certain species do not fit elegantly into the theory. A problem with the existing literature is that OS maps have been investigated in only a small number of mammals, from a small fraction of the mammalian phylogenetic tree. We suggest four species (agouti, fruit bat, sheep, and wallaby) that have a range of interesting characteristics, which sit at intermediate locations between primates and rodents, that make them good targets for filling in the missing gaps in the literature. We make predictions about the map structures of these species based on the organization of their brains and visual systems and, in doing so, set possible paths for future research. |
| first_indexed | 2024-12-13T08:01:15Z |
| format | Article |
| id | doaj.art-304b85a63a29498393809aaabd33fd41 |
| institution | Directory Open Access Journal |
| issn | 1662-5137 |
| language | English |
| last_indexed | 2024-12-13T08:01:15Z |
| publishDate | 2020-03-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Systems Neuroscience |
| spelling | doaj.art-304b85a63a29498393809aaabd33fd412022-12-21T23:54:26ZengFrontiers Media S.A.Frontiers in Systems Neuroscience1662-51372020-03-011410.3389/fnsys.2020.00010503882Origins of Functional Organization in the Visual CortexMichael Ibbotson0Michael Ibbotson1Young Jun Jung2Young Jun Jung3Australian College of Optometry, National Vision Research Institute, Carlton, VIC, AustraliaDepartment of Optometry and Vision Science, The University of Melbourne, Parkville, VIC, AustraliaAustralian College of Optometry, National Vision Research Institute, Carlton, VIC, AustraliaDepartment of Optometry and Vision Science, The University of Melbourne, Parkville, VIC, AustraliaHow are the complex maps for orientation selectivity (OS) created in the primary visual cortex (V1)? Rodents and rabbits have a random distribution of OS preferences across V1 while in cats, ferrets, and all primates cells with similar OS preferences cluster together into relatively wide cortical columns. Given other clear similarities in the organization of the visual pathways, why is it that maps coding OS preferences are so radically different? Prominent models have been created of cortical OS mapping that incorporate Hebbian plasticity, intracortical interactions, and the properties of growing axons. However, these models suggest that the maps arise primarily through intracortical interactions. Here we focus on several other features of the visual system and brain that may influence V1 structure. These are: eye divergence, the total number of cells in V1, the thalamocortical networks, the topography of the retina and phylogeny. We outline the evidence for and against these factors contributing to map formation. One promising theory is that the central-to-peripheral ratio (CP ratio) of retinal cell density can be used to predict whether or not a species has pinwheel maps. Animals with high CP ratios (>7) have orientation columns while those with low CP ratios (<4) have random OS maps. The CP ratio is related to the total number of cells in cortex, which also appears to be a reasonable contributing factor. However, while these factors correlate with map structure to some extent, there is a gray area where certain species do not fit elegantly into the theory. A problem with the existing literature is that OS maps have been investigated in only a small number of mammals, from a small fraction of the mammalian phylogenetic tree. We suggest four species (agouti, fruit bat, sheep, and wallaby) that have a range of interesting characteristics, which sit at intermediate locations between primates and rodents, that make them good targets for filling in the missing gaps in the literature. We make predictions about the map structures of these species based on the organization of their brains and visual systems and, in doing so, set possible paths for future research.https://www.frontiersin.org/article/10.3389/fnsys.2020.00010/fullprimary visual cortex (V1)orientation selectivitycortical mapsretinotopyphylogenyvisual system |
| spellingShingle | Michael Ibbotson Michael Ibbotson Young Jun Jung Young Jun Jung Origins of Functional Organization in the Visual Cortex Frontiers in Systems Neuroscience primary visual cortex (V1) orientation selectivity cortical maps retinotopy phylogeny visual system |
| title | Origins of Functional Organization in the Visual Cortex |
| title_full | Origins of Functional Organization in the Visual Cortex |
| title_fullStr | Origins of Functional Organization in the Visual Cortex |
| title_full_unstemmed | Origins of Functional Organization in the Visual Cortex |
| title_short | Origins of Functional Organization in the Visual Cortex |
| title_sort | origins of functional organization in the visual cortex |
| topic | primary visual cortex (V1) orientation selectivity cortical maps retinotopy phylogeny visual system |
| url | https://www.frontiersin.org/article/10.3389/fnsys.2020.00010/full |
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