The brain consists of 456 trillion trillion atoms. These are found in the 3 parts of the brain. The cerebrum filling up most of your head contains the cerebral cortex (the two cerebral hemispheres) this is where most of your thought processes come from. The cerebrum at the back and underneath the Cerebrum is responsible for motor control and the brain stem is responsible for things like blood/brain barrier.
“The human brain has often been viewed as outstanding among mammalian brains: the most cognitively able, the largest-than-expected from body size, endowed with an overdeveloped cerebral cortex that represents over 80% of brain mass, and purportedly containing 100 billion neurons“