This second installment of the series I am posting about the Anatomy of the Brain deals with the Occipital Lobe. The occipital lobe is the visual processing center of the mammalian brain.
The primary visual cortex is Brodmann area 17, located in the interior portion of the occipital lobe. Although located at the back of the brain, the Occipital Lobe is responsible for vision which enters the brain through the eyes at the front of the brain.
The Occipital Lobes are positioned at the back region of the cerebral cortex and are the main centers for visual processing. In addition to the occipital lobes, posterior portions of the parietal lobes and temporal lobes are also involved in visual perception. Located within the occipital lobes is the primary visual cortex. This region of the brain receives visual input from the retina. These visual signals are interpreted in the occipital lobes.
The occipital lobes are involved in several functions of the body including:
- Visual Perception
- Color Recognition
They are not particularly vulnerable to injury because of their location at the back of the brain, although any significant trauma to the brain could produce subtle changes to our visual-perceptual system. Disorders of the occipital lobe can cause visual hallucinations and illusions. Visual hallucinations (visual images with no external stimuli) can be caused by lesions to the occipital region or temporal lobe seizures. Visual illusions (distorted perceptions) can take the form of objects appearing larger or smaller than they actually are, objects lacking color or objects having abnormal coloring. Lesions in the parietal-temporal-occipital association area can cause word blindness with writing impairments (alexia and agraphia). (Kandel, E., Schwartz, J., & Jessell, T. Principles of Neural Science. 3rd edition. New York: NY. Elsevier, 1991.)