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

detailed body map, and our orientation to left and right. Number recognition, and the ability to manipulate numbers, is worked on here also.
    The occipital lobe , at the lower rear of the head, is responsible for vision. Vision takes up a lot of space and energy. Other centers in the brain collaborate to process visual information. Among its visual tasks, the occipital lobe helps interpret writing.
    Across the top of the head like a stretchy headband runs the motor cortex , and behind it lies a second headband-type strip, known as the somatosensory cortex , where messages from the nerve endings in the body arrive for processing and analysis from the spine.
    Deep beneath the cortex, the limbic system , folded away in its own compartment, includes the hippocampus and amygdala and our sense of smell. A dulled sense of smell (like Nancy’s) may be a predictor of Alzheimer’s and contributes to problems with appetite. The amygdala has been described as the fear zone, the seat of primitive emotions, instinctive, fearful, and aggressive. The egglike thalamus, at the center of the system, acts as mediator between the limbic system and the cortex, between instinct and abstract thought, and may be the brain area that most specifically corresponds to the experience of consciousness. The hippocampus processes short-term memory, which may or may not then be laid down into long-term memory. It’s called hippocampus because it’s supposed to look like a sea horse.
    The brain stem is in evolutionary terms the original organ and resembles the whole brain of simpler animals like lizards. It handles all the basic regulatory functions, the heart rate, hormones, sleep, breathing, blinking, blood pressure. It’s a bulbous small area at the top of the spine.
    The cerebellum , at the base and back of the skull, is an onion-shaped organ that’s thought to be a minibrain in itself, a minicomputer, and may be a sort of backup generator for the rest. Traditionally, its main responsibilities are thought to be for movement, coordination, posture, balance. It’s also the seat of our most secure, most deeply embedded memories. How to walk, for instance. Automatic actions, the kind we don’t need to think about anymore—cleaning our teeth, riding a bike—are handled from here. The cortex learns things and then delegates, once we have the thing mastered. Forty million fibers connect the cerebellum to the cortex.
    The romantic view of the brain as an interior landscape predated the Romantic movement by over two thousand years, in its using cave and weather and smoke metaphors. “Caverns there were in my mind,” Wordsworth writes, “which sun could never penetrate.” Coleridge’s “intellectual breeze, / At once the soul of each and god of all.” Erasistratus, born three hundred years before Christ, talked about “vital spirit,” the pneuma , a liquid life force flowing around our bodies like blood. The second-century doctor-scientist Galen thought the cerebrospinal fluid to be the pneuma and discounted the hard-boiled-egg-consistency, gray-and-white matter that surrounded it as merely protective.
    J. K. Rowling uses this antique idea of selfhood as something vaporous, silvery, swirling through the caverns of the mind like mist. In the Harry Potter books, memories can be decanted, studied, held in a pensieve . The dying Snape’s memories emanate with his final breath and are caught by Harry in a flask, to be reviewed later. Nurses on intensive care wards open windows to let the souls of the just-deceased escape the walls of the hospital. Absurd though the idea of memory as a silver mist might be, it’s in truth far closer to our own idea of the workings of our thoughts than the actual mechanism is. The actual mechanism has all to do with electricity made by the body. How can a body make an electrical impulse? Chemistry provides the answer, down at the cellular level—the fact that chemical molecules carry electrical charges that react with