Free Keeper: One House, Three Generations, and a Journey Into Alzheimer's by Andrea Gillies

expected to be contradicted, that “from the brain and the brain alone comes pleasure, happiness, laughter, as well as sorrow and pain.” The ancient Egyptians discarded the brains of those they were mummifying, removing them in bits through the nose with long hooks and binning them, though they preserved the hearts of their kings for the kings’ later use.
    The brain is a big thing and heavy. It can weigh three pounds. The outer layer, the cortex (from the Latin for tree bark) , is wrinkled so as to cram more surface area into the limited space. The cauliflower shape is actually a twinned half-cauliflower pair, two halves, left and right, with functions allocated, divided, and shared. People who’ve had the connection between the two halves severed medically experience a troubling dual consciousness in which one hand really doesn’t know what the other one’s doing.
    Brain use is tiring work. Whether purposely trying to think or not, conscious or unconscious, the system takes a lot of energy. Up to a fifth of food energy is dedicated to fueling brain functions. Glucose is the brain’s gasoline, and brain glucose levels plummet in Alzheimer’s; one of the newer diagnostic tests measures these levels in living subjects. Aside from the 100,000 million neurons, there are ten times as many neuroglia (from the Greek for glue) , cells that form the support network, feeding and repairing the lead actors. This support network also suffers devastating cell loss in the Alzheimer’s forest fire.
    They’re gray, these neurons, Hercule Poirot’s leetle gray cells —gray with white axons. And so many of them: 100,000 million is a big number. There are fewer than 7,000 million people in the world. I read somewhere that the phone system covering the whole planet, with all its connections and interconnections, parts of it at rest and parts of it firing with calls, is nowhere nearly as complicated as the interior of one human brain.
    While neurons are different shapes according to function, those illustrated in neurology texts are generally star shaped. Neurons are microscopic, but an axon can be as much as half an inch long, directing its communications network in particular sequences, though most stay very local, passing information along like firemen passing water in buckets (albeit huge numbers of firemen and buckets), passing water too fast for the naked eye to see.
    The neurons are packed tight in the cortex, and the cortex divides into four main areas, or lobes. The frontal lobe , the front third of the brain, in and behind the forehead, is where we think in the most obvious, self-conscious sense, plan, imagine, debate, decide. It’s the area that develops last in the growing child. It’s the area that best distinguishes us from the rest of the animal kingdom. It’s our executive center, the seat of the executive I. It has vital secondary roles in all kinds of brain function and is crucial in the retrieval of memory.
    The temporal lobes , worn like earmuffs at the sides of the head, are memory banks and instrumental in language and the comprehension of language. They analyze sensory input and, with the auditory cortex, interpret sound. The temporal lobes work in emotion as well as memory. The so-called God spot is here, the mysterious brain area that may give us our sense of the divine. In an experiment done with nuns, it was the same small location in the right temporal lobe that lit up within each, shown on a scanner, when they were asked to focus on communication with the Almighty. Richard Dawkins, the biological theorist who wrote The God Delusion , thinks that this God spot, in evolutionary terms, has to do with belonging to a tribe and the socially unifying effects of tribal genuflection. The bishop of Oxford thinks it’s provided by the Lord as an interface.
    The parietal lobe , at the upper part of the back of the head, helps orient us, giving us spatial awareness, our three-dimensional sense of the world, our own