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.

The brain "fills in" the missing information from the blind spot. Notice what you see in the location of the dot when it's in your blind spot. When the dot disappears, you do not perceive a hole of whiteness or blackness in its place; instead your brain invents a patch of the background pattern. Your brain, with no information from that particular spot in visual space, fills in with the patterns around it. You're not perceiving what's out there. You're perceiving whatever your brain tells you.

At least 15 percent of human females possess a genetic mutation that gives them an extra (fourth) type of color photoreceptor - and this allows them to discriminate between colors that look identical to the majority of us with a mere three types of color photoreceptors.

Scientists often talk of parsimony (as in "the simplest explanation is probably correct," also known as Occam's razor), but we should not get seduced by the apparent elegance of argument from parsimony; this line of reasoning has failed in the past at least as many times as it has succeeded.

Brains are like representative democracies. They are built of multiple, overlapping experts who weigh in and compete over different choices.

The deep secret of the brain is that not only the spinal cord but the entire central nervous system works this way: internally generated activity is modulated by sensory input. In this view, the difference between being awake and being asleep is merely that the data coming in from the eyes anchors the perception.

Societies would _not_ be better off if everyone were like Mr Spock, all rationality and no emotion. Instead, a balance - a teaming up of the internal rivals - is optimal for brains. ... Some balance of the emotional and rational systems is needed, and that balance may already be optimized by natural selection in human brains.