What is the structure of the Visual Cortex?

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The role of eyes in human life is amazing. Eyes make us percieve the world around us better and we get to see all the beautiful and important things necessary for our survival. They make our human life colorful. One of the major components of the human eyes is Visual cortex. Imagine seeing things upside down. Well, this is where the Visual cortex helps us out. It is responsible for sorting these images and making them appear in the right direction to our eyes. The Visual cortex is a component of the cerebral cortex that receives and processes the sensory nerve impulses from the eyes. The cerebral cortex is a layer of neural tissue that participates actively in the reminiscence, concentration, consciousness, thinking process and language processes. The cerebral cortex is about 2–4 mm wide in human beings. There is one Visual cortex in each hemisphere of the brain. The Visual cortex that is present in the left hemisphere of the brain gets signals from the right visual area and vice versa. Visual Cortex is found in the occipital lobe at the rear of the brain. The occipital lobe is the part of the brain that converts the nerve impulses that are received from the eyes into images.



What does Visual cortex encompass?

Generally, the Visual cortex encompasses the primary visual cortex  and extra-striate visual cortical areas (visual area V2, visual area V3, visual area V4 and visual area MT or V5). The extrastriate cortex is found in the occipital cortex section of the human brain that is found behind the primary visual cortex. The primary visual cortex structurally corresponds to Brodmann area 17 or BA17. Brodmann area is a division of the cerebral cortex that is classified based on the grouping of You do not have access to view this node. The extrastriate cortical areas are made up of Brodmann area 18 and Brodmann area 19. Both belong to the occipital cortex sections of the human brain. V1 has a unique diagram of the spatial data in the mental image. The visual area V5 is believed to perform a key function in the motion perception. The process of understanding the speed and pathway of the objects or entities is known as motion perception. V5 is also called ‘visual area MT’.



What is the task of Visual cortex?

In essence, the task of the Visual cortex is to illustrate a person about what he or she is viewing at that particular moment. Visual cortex receives the impulses that are conveyed to it from the eye. These impulses include what and how the image should appear. However, the image received by the Visual cortex will be upside-down. So, the job of Visual cortex is to flip it and make the image appear in the right direction. Generally, the Visual cortex is referred to as the mind's eye of a person, as it illustrates a person’s memories or his or her mind's eye.   



What is the importance of primary Visual cortex?

Primary Visual cortex is the major cortical visual region. The primary Visual cortex is found at the rear of the occipital lobe in the cerebral cortex. Even if one portion of the primary Visual cortex is damaged it can lead to cortical blindness. The obliteration of the Visual cortex in the right hemisphere may cause blindness in the left visual area. It is extremely focused in handling still and mobile objects and is exceptional in identifying the prototype. The V1 of each hemisphere gets the information easily from the 'ipsilateral lateral geniculate nucleus' which is the most important communicate hub for visual information it gets from the retina of the eye. Each V1 conveys the data to two major streams:

  • Dorsal stream: Dorsal stream starts from V1 traverse the Visual region V2 and dorso medial area (also known as DM or V6 and Visual region V5) and finally reaches the posterior parietal cortex that plays a vital role in generating the movements that are expected. The dorsal stream is also called "Where Pathway" or "How Pathway" and is related to the You do not have access to view this node, depiction of positions of objects and also responsible for managing the movements of eyes and arms.
  • Ventral stream: Ventral stream starts from V1, traverses the visual V2 area and visual V4 area and finally passes through the inferior temporal cortex. Inferior temporal cortex is one of the highest levels of the ventral stream of visual processing. It takes part in the depiction of intricate features of objects. It may also be concerned in face discernment. The ventral stream is also known as the "What Pathway" and plays a major role in the identification of shapes and depiction of an object. It is also involved in the storage of permanent memories in the brain.



How is the Visual cortex organized in primates?

Basically, the primate Visual cortex is organized into two isolated processing methods such as a ventral stream for entity vision and a dorsal stream for space vision. The facts from functional brain imaging in humans reveals that the object depictions are not restricted to the ventral pathway but can also be predicted in a number of regions in the dorsal corridor also.



How is Visual cortex organized in humans?

Measurement of retino topic organization within human cortex is explained by the 'functional magnetic resonance imaging (fMRI)' method. The technique relies mostly on a visual stimulus that produces a wandering wave of neural activity inside the retino topically organized visual regions. Scientists deliberated the fMRI signal produced by this stimulus in visual cortex and depicted the outcomes on the images. Scientists utilized different techniques to find out the visual regions and to calculate the spatial accuracy of fMRI. In particular, the scientists did the following: 

  • Determined the margins connecting a number of retinotopically organized visual regions in the back side of the occipital lobe.
  • Deliberated the function involving the position of cortical area to visual field idiosyncrasy inside the V1 region.
  • Restricted movement inside 1.1 mm of the Visual cortex.
  • Determined the spatial resolution of the fMRI signal and discovered that signal amplitude drops to 60% at a spatial incidence of one full rotation per 9 mm of Visual cortex. 
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