Occipital lobe
472212
226177181
2008-07-17T04:39:22Z
Landon1980
6681090
Reverted edits by [[Special:Contributions/60.241.82.45|60.241.82.45]] ([[User talk:60.241.82.45|talk]]) to last version by Nx01rules
{{Infobox Brain|
Name = {{PAGENAME}} |
Latin = lobus occipitalis |
GraySubject = 189 |
GrayPage = 823 |
Map = Cerebrum map|
MapPos = |
MapCaption = Lobes of the human brain (the occipital lobe is shown in red)|
Image2 = Gray727.svg |
Caption2 = Medial surface of left cerebral hemisphere. ([[cuneus]] and [[lingual gyrus]] are at left.) |
IsPartOf = |
Components = |
Artery = |
Vein = |
BrainInfoType = hier |
BrainInfoNumber = 122 |
MeshName = Occipital+Lobe |
MeshNumber = A08.186.211.730.885.213.571 |
}}
The '''occipital lobe''' is the [[Visual perception|visual processing center]] of the [[mammal]]ian [[brain]] containing most of the anatomical region of the [[visual cortex]].<ref name="titleSparkNotes: Brain Anatomy: Parietal and Occipital Lobes">{{cite web |url=http://www.sparknotes.com/psychology/neuro/brainanatomy/section5.rhtml |title=SparkNotes: Brain Anatomy: Parietal and Occipital Lobes |accessdate=2008-02-27 |format= |work=}}</ref> The [[primary visual cortex]] is [[Brodmann area|Brodmann area 17]], commonly called V1 (visual one). Human V1 is located on the [[Medial (disambiguation)|medial]] side of the occipital lobe within the [[calcarine sulcus]]; the full extent of V1 often continues onto the posterior pole of the occipital lobe. V1 is often also called striate cortex because it can be identified by a large stripe of myelin, the [[Stria of Gennari| Stria of Gennari]]. Visually driven regions outside V1 are called [[Extrastriate| extrastriate cortex]]. There are many extrastriate regions, and these are specialized for different visual tasks, such as visuospatial processing, color discrimination and motion perception.
==Anatomy==
The occipital lobes are the smallest of four true lobes in the human brain. Located in the rearmost portion of the skull, the occipital lobes are part of the [[Cerebral hemisphere|forebrain structure]].
The lobes rest on the tentorium cerebelli, a process of dura mater that separates the cerebrum from the [[cerebellum]]. They are structurally isolated in their respective cerebral hemispheres by the separation of the [[cerebral fissure]]. The front edge of the occipitalseveral lateral occipital gyri, which are separated by lateral occipital sulcus.
The occipital aspects along the inside face of each hemisphere are divided by the [[calcarine sulcus]]. Above the medial, Y-shaped sulcus lies the [[cuneus]], and the area below the sulcus is the [[lingual gyrus]].
==Function==
[[retina|Retinal]] [[photoreceptor cell|sensors]] convey stimuli through the optic tracts to the [[lateral geniculate body|lateral geniculate bodies]], where optic radiations continue to the visual cortex. Each visual cortex receives raw sensory information from the outside half of the retina on the same side of the head and from the inside half of the retina on the other side of the head.
The cuneus (Brodman's area 17) receives visual information from the contralateral superior retina representing the inferior visual field. The lingula receives information from the contralateral inferior retina representing the superior visual field.
Cells on the posterior aspect of the occipital lobes' [[gray matter]] are arranged as a spatial map of the retinal field. [[Functional neuroimaging]] reveals similar patterns of response in cortical tissue of the lobes when the retinal fields are exposed to a strong pattern.
If one occipital lobe is damaged, the result can be [[homonymous hemianopsia|homonomous]] [[vision loss]] from similarly positioned "field cuts" in each eye. Occipital [[lesion]]s can cause visual [[hallucination]]s. Lesions in the parietal-temporal-occipital [[association area]] are associated with [[color agnosia]], [[movement agnosia]], and [[agraphia]].
The function of the occipital lobe is to control vision and color recognition.
It has also been shown to help in [[hearing]].
==Functional anatomy==
The occipital lobe is divided into several functional visual areas. Each visual area contains a full map of the visual world. Although there are no anatomical markers distinguishing these areas (except for the prominent striations in the [[striate cortex]]), physiologists have used electrode recordings to divide the cortex into different functional regions.
The first functional area is the [[primary visual cortex]]. It contains a low-level description of the local orientation, spatial-frequency and color properties within small [[receptive fields]]. [[Primary visual cortex]] projects to the occipital areas of the [[ventral stream]] ([[visual area V2]] and [[visual area V4]]), and the occipital areas of the [[dorsal stream]] - [[visual area V3]], [[visual area MT]] (V5), and [[visual area DP]].
==Additional images==
<gallery>
Image:Gray724.png|Base of brain.
Image:Gray1197.png|Drawing to illustrate the relations of the brain to the skull.
Image:Brain animated color nevit.gif|Occipital lobe in blue
</gallery>
==See also==
*[[Lobes of the brain]]
*[[list of regions in the human brain|Regions of the human brain]]
*[[Sulcus Lunatus]]
*[[Visual evoked potential]]
==References==
{{reflist}}
{{Prosencephalon}}
[[Category:Cerebrum]]
[[de:Occipitallappen]]
[[el:Ινιακός λοβός]]
[[es:Lóbulo occipital]]
[[fa:لوب پسسری]]
[[fr:Lobe occipital]]
[[nl:Occipitale kwab]]
[[ja:後頭葉]]
[[no:Bakhodelapp]]
[[pl:Płat potyliczny]]
[[pt:Lóbulo occipital]]
[[sv:Occipitallob]]
[[zh:枕叶]]