If choices and decisions derive from hidden mental processes, then free choice is either an illusion or, at minimum, more tightly constrained than previously considered.

A typical neuron makes about ten thousand connections to neighboring neurons. Given the billions of neurons, this means there are as many connections in a single cubic centimeter of brain tissue as there are stars in the Milky Way galaxy.

Even while it's true that we are tied to our molecules and proteins and neurons - as strokes and hormones and drugs and microorganisms indisputably tell us - it does not logically follow that humans are best described only as pieces and parts.

The left hemisphere acts as an "interpreter," watching the actions and behaviors of the body and assigning a coherent narrative to these events. And the left hemisphere works this way even in normal, intact brains. Hidden programs drive actions, and the left hemisphere makes justifications. This idea of retrospective storytelling suggests that we come to know our own attitudes and emotions, at least partially, by inferring them from observations of our own behavior.

The main thing known about secrets is that keeping them is unhealthy for the brain.

We spend our lives on a thin slice between the unimaginably small scales of the atoms that compose us and the infinitely large scales of galaxies.

Who you are depends on the sum total of your neurobiology.