Eye and Light
The blind spot is the area on the retina without photoreceptors. Therefore, the part of an image that falls on this region will NOT be seen. It is in this region that the optic nerve exits the eye on its way to the brain. Humans may use different parts of their brain to discriminate objects from people. In particular, we may have specialized neurons for recognizing faces. To complete this discussion:
- Define the problem of the final integration of visual information.
- What kind of problem does this present regarding our understanding of how the brain works?
- Is it a problem that needs to be solved?
- Do any recent papers in the scientific literature address this issue?
The Problem of Final IntegrationWe have seen how the brain combines information about some aspects of an object, but many researchers wonder where all the information about the object is brought together; how the brain combines information from different areas into a unitary whole is known as the binding problem. Imagine watching a person walking across your field of view; the person is moving, shifting orientation, and changing appearance as the lighting increases and decreases under a canopy of trees. At the same time, you are walking toward the person, but your brain copes easily with the changing size of the person’s image and the apparent movement of environmental objects toward you. It seems logical that a single center at the end of the visual pathway would combine all the information about shape, color, texture, and movement, constantly updating your perception of this image as the same person. In other words, the result would be a complete and dynamic awareness. Presumably, damage to that area would produce symptoms that are similar to blindsight but that affect all stimuli.
It has been suggested that our ultimate understanding of an object occurs in a part of the superior temporal gyrus that receives input from both neural streams (Baizer, Ungerleider, & Desimone, 1991) or in the part of the parietal cortex where damage causes neglect (Driver & Mattingley, 1998). Other investigators suspect frontal areas where both streams converge. But these ideas are highly speculative, and there is no convincing evidence for a master area where all perceptual information comes together to produce awareness (Crick, 1994; Zeki, 1992). The variety of hypothesized awareness centers suggests another possibility, that visual awareness is distributed throughout the network of 32 areas of cortex concerned with vision and their 305 interconnecting pathways (Van Essen, Anderson, & Felleman, 1992). This thinking is exemplified on a small scale in the interaction between V5/MT and V1. After a stimulus occurs, activity continues back and forth between these areas for a few hundred milliseconds, and disrupting this interchange eliminates awareness of movement (reviewed in McKeefry, Gouws, Burton, & Morland, 2009).(Garrett 331-332)Garrett, Bob L.. Brain & Behavior: An Introduction to Biological Psychology, 4th Edition. SAGE Publications, Inc, 07/2014. VitalBook file.