Robert Sapolsky has spent decades researching primate brains, and in this book, he explains in detail how electric signals in different parts of the brain accumulate into emotions, cognition, and automaticity.
If you want to understand how people do, say, and feel various things, this book will certainly help.
Read the sample on Amazon (click the picture of the book)
Book: Behave: The Biology of Humans at Our Best and Worst by Robert M. Sapolsky
you can find his lessons on this book on youtube or as a podcast (search for "human behavioral biology).
I strongly recommend them