One hundred million years of interhemispheric communication: the history of the corpus callosum
Analysis of regional corpus callosum fiber composition reveals that callosal regions connecting primary and secondary sensory areas tend to have higher proportions of coarse-diameter, highly myelinated fibers than callosal regions connecting so-called higher-order areas. This suggests that in primar...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Associação Brasileira de Divulgação Científica
2003-04-01
|
| Series: | Brazilian Journal of Medical and Biological Research |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000400002 |
| _version_ | 1811331336202354688 |
|---|---|
| author | F. Aboitiz J. Montiel |
| author_facet | F. Aboitiz J. Montiel |
| author_sort | F. Aboitiz |
| collection | DOAJ |
| description | Analysis of regional corpus callosum fiber composition reveals that callosal regions connecting primary and secondary sensory areas tend to have higher proportions of coarse-diameter, highly myelinated fibers than callosal regions connecting so-called higher-order areas. This suggests that in primary/secondary sensory areas there are strong timing constraints for interhemispheric communication, which may be related to the process of midline fusion of the two sensory hemifields across the hemispheres. We postulate that the evolutionary origin of the corpus callosum in placental mammals is related to the mechanism of midline fusion in the sensory cortices, which only in mammals receive a topographically organized representation of the sensory surfaces. The early corpus callosum may have also served as a substrate for growth of fibers connecting higher-order areas, which possibly participated in the propagation of neuronal ensembles of synchronized activity between the hemispheres. However, as brains became much larger, the increasingly longer interhemispheric distance may have worked as a constraint for efficient callosal transmission. Callosal fiber composition tends to be quite uniform across species with different brain sizes, suggesting that the delay in callosal transmission is longer in bigger brains. There is only a small subset of large-diameter callosal fibers whose size increases with increasing interhemispheric distance. These limitations in interhemispheric connectivity may have favored the development of brain lateralization in some species like humans. "...if the currently received statements are correct, the appearance of the corpus callosum in the placental mammals is the greatest and most sudden modification exhibited by the brain in the whole series of vertebrated animals..." T.H. Huxley (1). |
| first_indexed | 2024-04-13T16:18:03Z |
| format | Article |
| id | doaj.art-4728ee6eca884dd48157ea61b2bd0782 |
| institution | Directory Open Access Journal |
| issn | 0100-879X 1414-431X |
| language | English |
| last_indexed | 2024-04-13T16:18:03Z |
| publishDate | 2003-04-01 |
| publisher | Associação Brasileira de Divulgação Científica |
| record_format | Article |
| series | Brazilian Journal of Medical and Biological Research |
| spelling | doaj.art-4728ee6eca884dd48157ea61b2bd07822022-12-22T02:40:00ZengAssociação Brasileira de Divulgação CientíficaBrazilian Journal of Medical and Biological Research0100-879X1414-431X2003-04-0136440942010.1590/S0100-879X2003000400002One hundred million years of interhemispheric communication: the history of the corpus callosumF. AboitizJ. MontielAnalysis of regional corpus callosum fiber composition reveals that callosal regions connecting primary and secondary sensory areas tend to have higher proportions of coarse-diameter, highly myelinated fibers than callosal regions connecting so-called higher-order areas. This suggests that in primary/secondary sensory areas there are strong timing constraints for interhemispheric communication, which may be related to the process of midline fusion of the two sensory hemifields across the hemispheres. We postulate that the evolutionary origin of the corpus callosum in placental mammals is related to the mechanism of midline fusion in the sensory cortices, which only in mammals receive a topographically organized representation of the sensory surfaces. The early corpus callosum may have also served as a substrate for growth of fibers connecting higher-order areas, which possibly participated in the propagation of neuronal ensembles of synchronized activity between the hemispheres. However, as brains became much larger, the increasingly longer interhemispheric distance may have worked as a constraint for efficient callosal transmission. Callosal fiber composition tends to be quite uniform across species with different brain sizes, suggesting that the delay in callosal transmission is longer in bigger brains. There is only a small subset of large-diameter callosal fibers whose size increases with increasing interhemispheric distance. These limitations in interhemispheric connectivity may have favored the development of brain lateralization in some species like humans. "...if the currently received statements are correct, the appearance of the corpus callosum in the placental mammals is the greatest and most sudden modification exhibited by the brain in the whole series of vertebrated animals..." T.H. Huxley (1).http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000400002CommissuresEvolutionInterhemispheric transferLateralizationSynchronization |
| spellingShingle | F. Aboitiz J. Montiel One hundred million years of interhemispheric communication: the history of the corpus callosum Brazilian Journal of Medical and Biological Research Commissures Evolution Interhemispheric transfer Lateralization Synchronization |
| title | One hundred million years of interhemispheric communication: the history of the corpus callosum |
| title_full | One hundred million years of interhemispheric communication: the history of the corpus callosum |
| title_fullStr | One hundred million years of interhemispheric communication: the history of the corpus callosum |
| title_full_unstemmed | One hundred million years of interhemispheric communication: the history of the corpus callosum |
| title_short | One hundred million years of interhemispheric communication: the history of the corpus callosum |
| title_sort | one hundred million years of interhemispheric communication the history of the corpus callosum |
| topic | Commissures Evolution Interhemispheric transfer Lateralization Synchronization |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000400002 |
| work_keys_str_mv | AT faboitiz onehundredmillionyearsofinterhemisphericcommunicationthehistoryofthecorpuscallosum AT jmontiel onehundredmillionyearsofinterhemisphericcommunicationthehistoryofthecorpuscallosum |