100 billion nerve cells. 100 trillion synapses.
dozens of neurotransmitters. This "strength in numbers"
provides your brain's raw material. Over time, our experiences
create patterns in signal type and strength. These patterns
of activity explain how, at the cellular level, our brains
code our thoughts, memories, skills and sense of who we
The positron emission tomography (PET) scan
on the left shows typical patterns of brain activity associated
Activity is highest in red areas and then decreases through
the other colors of the rainbow from yellow to blue-violet.
Specific activity patterns change throughout life as we
meet new people, have new experiences and acquire new skills.
The patterns also change when Alzheimer's disease or a related
disorder disrupts nerve cells and their connections to one