Head trauma can be caused from a wide variety of incidents: from falling and hitting your head to being in a serious accident. No two brains are exactly the same, but damage to certain areas of the brain can cause general, isolated problems. For example, damage to the occipital lobe has an increased chance of impacting vision.
In 2012, a family friend of mine was in a serious accident. He had extensive injuries to the back, as well as minor injuries to the top, of his head. He is very lucky to be alive today. He has since recovered greatly from his physical injuries. However, he still suffers from memory problems, and the effects of damage to other mental processes.
A majority of his problems with memory occur in the short-term; he forgets what he is told within thirty seconds. For example, someone can tell him to complete three simple tasks, A, B and C. After he completes task A, he cannot remember what the other two were. However, most of his existing long-term memories can be recalled with ease. It is interesting to see that he can talk about things that happened long before his accident, while having great difficulty creating new long-term memories.
The other part that was greatly affected was the parietal lobe, which is where the dorsal processing stream is located. The dorsal stream is a big part of perception and actions and is responsible for determining the location of objects, often known as the “where” pathway. His case shows dissociation, just like D.F. in the Milner and Goodale study from 1995. Dissociations are “situations in which one function is absent while another function is present.” (Goldstein, 2011, p. 73). D.F. had problems with the ventral processing stream, or the “what” processing stream. She could not identify the card slot correctly, but when an action was carried out, she knew exactly where and how to place the card into the card slot.
In the complete opposite way, the effect on my friend’s dorsal stream allows him to be able to identify objects, but not know where or how to reach for or grab them. A simple example is trying to pick up a saltshaker at dinner. He can identify the item, but cannot locate it in perspective to him to pick it up. He described it in a simple way. It is like running your hand over a wall in search for a light switch without looking; even though you know it is a light switch you search for, you will have a tough time finding it because you do not know where it is.
Before lesson three, I had no real idea that anything like this could happen: that there were specific parts of the brain that directly influenced how one perceives objects and their locations. As a friend, it is a good feeling to know what is happening with the brain when someone is going through this situation. A better understanding of something allows one to be more sympathetic.
Goldstein, E. B. (2011). Cognitive Psychology: Connecting Mind, Research, and Everyday Experience. Wadsworth: Cengage Learning.
Photo From: http://sciencewise.anu.edu.au/articles/dyslexia
**The above source is also an interesting article about the visual pathways being connected to dyslexia.**