Visual Thinking: The Hidden Gifts of People Who Think in Pictures, Patterns, and Abstractions

by Temple Grandin

In both humans and animals, the PAG (periaqueductal gray) has a network of connections to numerous brain areas in both higher cortical areas and lower brain centers. When the PAG is destroyed, whether in a human or in a cat, they will enter a comatose state, ceasing to react to things around them. Another hub for consciousness is located in the middle lower-brain area. Both areas serve as hubs for processing emotions. The information that is stored in the brain can mingle and associate there, like delegates entering the rotunda of a large convention center. The research points to a consensus that consciousness is a hierarchy. As brain systems become more complex, consciousness becomes more complex, with emotions and sensory information being processed in larger and larger association areas more densely packed with neurons. The lower PAG area acts like the master of a railway switching yard or an air traffic controller. This system enables either an animal or a person to interact both with the environment and with other individuals. For humans and most animals, the PAG is also involved in assessing possible danger. A deer will suddenly raise its head and point both its eyes and ears at a strange noise or sight. This is an innate response to a possible threat. However, the deer still needs to decide how to respond. I have observed this behavior many times. There is a pause while the brain decides whether to flee, keep watching, or continue grazing. This is the beginning of f...