Thinking is traveling
The brain-train metaphor is a double metaphor. On the one hand, it relates the trajectory of neural activity with a passenger boarding a specific train of thought, similar to the brain-sled metaphor. On the other hand, it relates the brain structure with the rigid railway infrastructure which supports traveling. The brain-train metaphor highlights the rigid nature of brain structure, while also hinting at the possibility of switching patterns of thought by switching trains. It’s important to note that the brain-train metaphor doesn’t invoke structural neural pathways, but rather abstract high-dimensional connectivity which supports the aggregate functional dynamic.