A note for Lesson no. 2, "Your Brain Is a Network," in Lisa Feldman Barrett.
Some context from page 37 is:
Neuromodulators and neurotransmitters together allow your brain’s single structure to take on trillions of different patterns of activity.
Your brain has the potential to create a vast number of distinct neural configurations. The philosopher Paul Churchland estimates the number at 10100,000,000,000. That's a 1 followed by 100 billion zeroes, a figure that supposedly dwarfs the number of atoms in the universe.
- Churchland, Paul M. 2012. Plato’s Camera: How the Physical Brain Captures a Landscape of Abstract Universals, 17 Cambridge, MA: MIT Press.