Ocular dominance column
An ocular dominance column is a bundle of so-called "orientation columns" , each of which in turn traverses all six layers of the lateral geniculate body (CGL) as a compact network of neurons in a vertical direction . In the primary visual cortex , too , the neurons of the area striata ( Brodmann area 17, V1) as part of the visual cortex are histologically organized in ocular dominance columns arranged perpendicular to the surface.
Basically, the ocular dominance columns receive information about the orientation of a light stimulus that hits the retina . This stimulus identification is used for object recognition.
morphology
The corpus geniculatum laterale (CGL) and the primary visual cortex , like the entire neocortex, have six horizontal layers. These layers are designated there from ventral to dorsal with 1 to 6. In the fourth layer, the visual cortex receives most of its afferents from the corpus geniculatum laterale (CGL) of the thalamus .
The six-layer CGL contains the axons of the ipsilateral eye in layers 2, 3 and 5 , while layers 1, 4 and 6 contain the axons of the contralateral eye. An ocular dominance column runs through layers 1 to 6 of the corpus geniculatum laterale.
physiology
If the retina is now stimulated by a light stimulus, the transmission of visual information from the retina via the optic nerve to the optic chiasm and further via the optic tract to the CGL. The visual information is then passed on to the primary visual cortex, where the processing of the light stimulus is reflected.
The reaction of the cortical neurons to a light stimulus shows that neurons within a column have the same preference for the orientation of light bars that hit the retina. Bundles of such orientation columns, called ocular dominance columns , contain the information of a point in one eye. This means that there is an ocular dominance column for the left and right eye for each area of the visual field.
Delimitations
Blobs , on the other hand, are color-sensitive columns that do not receive any information about their orientation. The interblobs around the blobs, however, receive orientation afferents.
In summary, a hypercolumn is the functional module of the primary visual cortex ( primary visual cortex [V1]) and contains two ocular dominance columns and several blobs and interblobs.
Individual evidence
- ↑ N. Birbaumer, RF Schmidt: Biological Psychology , 6th edition, Springer 2006, ISBN 978-3-540-25460-7