In the chapter the author is essentially saying that it is important that they brain is divided into two separate systems- top and bottom- separated by the Sylvian fissure. The long-range connections between the different parts of the brain determine whether the brain is in the top-brain system or the bottom brain-system. The author is also very clear to communicate that the top system and bottom system are in constant communication with each other even though they may serve different functions.
A computer program, created in the 1980s, that can recognize shape and location of objects teaches us that a system operates much more effectively when the labor is divided and organized into specific top and bottom parts that communicate with each other instead of one single system.
I find it interesting that they are using computers that simulate neural networks to support brain theory. But I understand the challenge of studying and manipulating a human brain. It is fascinating though that the computers did prove that it is much better better to divide the tasks of shape recognition and location into two different systems than just have one system try to do both tasks.
This computer simulation supported the research done by Ungerleider and Mishkin when they actually cut the top and bottom parts out to monkey's brains. This experiment showed that the top part of the brain determines location and the bottom part of the brain determines that shape.
The idea of the top and bottom brain is supported mostly by a meta-analysis done by a team of researchers in 2011. It makes me a little bit skeptical that this book seems to rely heavily on one meta-analysis. They say it is the only one done of its kind about this type of brain research. I know by the term meta-analysis a ton of different research was looked at to find the patterns they talk about in the book, but wouldn't you want more than just want study to be done to back up your book?