Phantoms in the Brain: Probing the Mysteries of the Human Mind by V. S. Ramachandran, Sandra Blakeslee Read Free Book Online

Mind and Behavior by Bloom and Laserson (1988) by Educational Broadcasting Corporation. Used with permission from W. H. Freeman and Company.
    "Do you remember that I showed you an object? Do you remember where I put it?"
    "No." He has absolutely no recollection of my hiding the pen sixty seconds earlier.
    Such patients are, in effect, frozen in time in the sense they remember only events that took place before the accident that injured them neu−rologically. They may recall their first baseball game, first date and college graduation in elaborate detail, but nothing after the injury seems to be recorded. For example, if post accident they come upon last week's newspaper, they read it every day as if it were a brand−new paper each time. They can read a detective novel again and again, each time enjoying the plot and the surprise ending. I can tell them the same joke half a dozen times and each time I come to the punch line, they laugh heartily (actually, my graduate students do this too).
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    These patients are telling us something very important—that a tiny brain structure called the hippocampus is absolutely vital for laying down new memory traces in the brain (even though the actual memory traces are not stored in the hippocampus). They illustrate the power of the modular approach: In helping to narrow the scope of inquiry, if you want to understand memory, look at the hippocampus. And yet, as we shall see, studying the hippocampus alone will never explain all aspects of memory. To understand how memories are retrieved at a moment's notice, how they are edited, pigeonholed (sometimes even censored!), we need to look at how the hippocampus interacts with other brain structures such as the frontal lobes, the limbic system (concerned with emotions) and the structures in the brain stem (which allow you to attend selectively to specific memories).
    The role of the hippocampus in forming memories is clearly established, but are there brain regions specialized in more esoteric abilities like the "number sense" that is unique to humans? Not long ago I met a gentleman, Bill Marshall, who had suffered a stroke a week earlier. Cheerful and on his way to recovery, he was only too happy to discuss his life and medical condition. When I asked him to tell me about his family, he named each of his children, listed their occupations and gave many details about his grandchildren. He was fluent, intelligent and articulate—and not everyone is so soon after a stroke.
    "What was your occupation?" I asked Bill.
    Bill replied, "I used to be an Air Force pilot."
    "What kind of plane did you fly?"
    He named the plane and said, "It was the fastest man−made thing on this planet at that time." Then he told me how fast it flew and said that it had been made before the introduction of jet engines.
    At one point I said, "Okay, Bill, can you subtract seven from one hundred? What's one hundred minus seven?"
    He said, "Oh. One hundred minus seven?"
    "Yeah."
    "Hmmm, one hundred minus seven."
    "Yes, one hundred minus seven."
    "So," said Bill. "One hundred. You want me to take away seven from one hundred. One hundred minus seven."
    "Yes."
    "Ninety six?"
    "No."
    "Oh," he said.
    "Let's try something else. What's seventeen minus three?"
    "Seventeen minus three? You know I'm not very good at this kind of thing," said Bill.
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    "Bill," I said, "is the answer going to be a smaller number or a bigger number?"
    "Oh, a smaller number," he said, showing that he knew what subtraction is.
    "Okay, so what's seventeen minus three?"
    "Is it twelve?" he said at last.
    I started wondering whether Bill had a problem understanding what a number is or the nature of numbers.
    Indeed, the question of numbers is old and deep, going back to Pythagoras.
    I asked him, "What is infinity?"
    "Oh, that's the largest number there is."
    "Which number is bigger: one hundred and one or ninety−seven?
    He answered immediately: "One hundred and one is larger."
    "Why?"
    "Because there