Motion areas

To me, having multiple areas for motion processing isn’t redundant when looked at compared to the rest of the visual system and brain. If there was no overlap, we could get away with just having V1. But to enhance our visual experience, we have specialized areas that have evolved over time. We have already talked about some of these specific visual areas such as the ‘face recognition area’ which is really for recognizing well-known objects. Also, there’s the ventral and dorsal streams that help us tell where something is and what it is. It only makes sense to have areas specific to motion. MT is responsible for the more basic components of motion. Also, it is involved in eye movements in response to motion. Beyond this is MST where we can distinguish complex movements like optic flow and STS where we can notice biological motion. As the neural signal continues, more information is discovered about the targeted object.

An interesting disorder that may come out of a deficit in MT is dyslexia. I’ve read a few papers about this developmental disorder lately and thought it tied in with motion discussion. One of the theories behind dyslexia is the ‘Visual Deficit Hypothesis’ that posits that problems in MT cause blurring and altered scanning during reading. In some individuals, it was found that MT had lower activation and also had smaller neuron size and larger disorganization (Eden, 1996). We already talked about some of the abnormal eye movements that may be causing blurring. One is the vergence eye movements where eyes move in opposite directions like when focusing on an incoming object. Another is the concept of spatial constancy where we know that an object is moving relative to our retina. In the papers, some of the quick fixes they thought of was larger print and closing one eye to reduce blurring.

Some of the disorders we talked about in class regarding motion were also pretty ‘moving.’ The one condition where the woman experienced snapshots of the world was one of the more amazing, and bad, disorders we’ve talked about in the whole class. We can never really know what it is to see the world with a disorder like this, but it must be so confusing and disorienting. I’d almost rather be blind than be in such a scary world where everything is moving about you but it is impossible to tell how. It seems like we take much of vision for granted, but really a deficit in any aspect could be pretty debilitating whether it is in color, motion processing, or object recognition. The least harmful condition would be a problem with depth perception. It was a different world when we wore the eye patches for our third paper, but after a few minutes I was able to get used to it. I wonder how plastic the brain is when it comes to losing something like motion processing. It seems to me that higher cortical areas have higher plasticity than sensory processing areas. Maybe because these are so hard-wired from an early age. Either way, a problem in any area of the visual system could cause a large array of problems.