Perception Case

Perception is a unique and complicated task performed by various parts of the brain that help us to see and understand the world around us. While the idea of simply seeing something and understanding its being seems simple enough, the actual process is a compartmentalized one that takes place within the visual association cortex. The primary visual cortex receives information from an area of the thalamus responsible for visual information and then sends this information to the visual association cortex. It is here that individual modules combine in order to make sense of objects and entire visual scenes. As neurons send axons to the region that surrounds the striate cortex, the visual association cortex divides into two pathways within the occipital lobe: the ventral stream and dorsal stream. While both analyze information in order to understand a particular image, the ventral stream focuses on the shape, color, and orientation of an object (known as the "what" system) and the dorsal stream focuses on the movement and spatial frequency of an object (known as the "where" system). It is necessary to understand the unique functions of each stream and how they each attribute to the overall goal of processing visual information in order to understand the composition of the visual association cortex.

These two streams of analysis both are working towards the same goal of breaking down and understanding an object that has been perceived as visual information. Both receive their information from the primary visual cortex and are just separate regions of the visual association cortex within the occipital lobe that are being used in order to make sense of separate kinds of information. Once the ventral stream has processed and understood what the object is in terms of shape, color, and orientation, it then moves the information onto the next level of visual association. Similarly, once the dorsal stream has processed and understood what the object is in terms of movement and spatial frequency, it then moves the information onto the next level of visual association. Information comes from and is passed on to the same two regions for both streams. Damage to either of these streams in their respective areas will cause various forms of visual processing disorders that will vary based on the area affected, but ultimately both affect an individual's ability to gather information visually. In conclusion, both streams receive and distribute their information to the same areas, if either is damaged can result in some form of a visual processing disorder, and both work in order for an individual to understand information about an object that has been perceived visually.

While both streams are similar, the ventral stream forms very different information from the dorsal stream. The ventral stream is concerned with the "what" of the object and therefore focuses on the perception of form and color. This analysis takes place in the inferior temporal cortex at the end of the ventral stream where perceptions of three-dimensional objects