Some topological considerations of the optic pathway.
The contralateral projection of the vertebrate retinotopic map has a component of a mirror or uniaxial inversion in it. Here, a simple hypothesis is proposed which explains how this can come about. The emphasis is on topological considerations, in a global sense, of the overall map. An important feature of the hypothesis is that the optic nerve fibres follow pathways such that they retain their nearest neighbour relationships till they terminate in the optic tectum, i.e. no criss-crossing of the fibres is envisaged. Anatomical evidence for this is already available in the case of the optic tract of frog. Some speculations are also suggested concerning the role of this uniaxial inversion in information processing. The observations of optic tracts of other amphibian and some lower vertebrate systems are also considered.
D000818:Animals; D001931:Brain Mapping; D008954:Models, Biological; D009900:Optic Nerve / Q000033:anatomy & histology; D011898:Ranidae / Q000033:anatomy & histology; D012160:Retina / Q000033:anatomy & histology; D013477:Superior Colliculi / Q000033:anatomy & histology; D014714:Vertebrates / Q000033:anatomy & histology; D014795:Visual Pathways / Q000033:anatomy & histology*