An Introduction to Brain and Behavior 2nd Edition
What Is the Brain?
For his postgraduate research, our friend Harvey chose to study the electrical activity that the brain gives off. He said that he wanted to live on as a brain in a bottle after his body died. He expected that his research would allow his bottled brain to communicate with others who could â€œreadâ€ his brainâ€™s electrical signals. Harvey mastered the techniques of brain electrical activity but failed in his objective, not only because the goal was technically impossible but also because he lacked a full understanding of what â€œbrainâ€means.
Brain is the Anglo-Saxon word for the tissue that is found within the skull, and it is this tissue that Harvey wanted to put into a bottle. The brain has two almost symmetrical halves called hemispheres, one on the left and one on the right. So, just as your body is symmetrical, having two arms and two legs, so is the brain. Figure 1-1A shows the left hemisphere of a typical human brain oriented in the upright human skull. If you make a fist with your right hand and hold it up, the fist can represent the positions of the brainâ€™s broad divisions, or lobes, within the skull, with the thumb pointing toward the front (Figure 1-1B).
The entire outer layer of the human brain consists of a thin, folded layer of nerve tissue, the cerebral cortex, detailed in the sectional view in Figure 1-1A. The word cortex, Latin for the bark of a tree, is apt, considering the cortexâ€™s heavily folded surface and its location in covering most of the rest of the brain. The grooves of the cortex are called sulci and the bumps are called gyri. Unlike the bark on a tree, they are not random folds but demark functional zones. Later on, weâ€™ll provide their names and functions. The cortex of each hemisphere is divided into four lobes, named after the skull bones beneath which they lie.
The forward-pointing temporal lobe is located at the side of the brain, approximately the same place as the thumb on your upraised fist. Immediately above your thumbnail, your fingers correspond to the location of the frontal lobe, so called because it is located at the front of the brain, beneath the frontal bone of the skull. The parietal lobe is located beneath the parietal bone at the top of the skull, behind the frontal lobe and above the temporal lobe. The area at the back of each hemisphere beneath the occipital bone constitutes the occipital lobe.
Harvey clearly wanted to preserve not just his brain but his selfâ€”his consciousness, his thoughts, his intelligence. This meaning of the term brain refers to something other than the organ found inside the skull. It refers to the brain as that which exerts control over behavior.
This meaning of brain is what we intend when we talk of someone being â€œthe brainâ€ or when we speak of the computer that guides a spacecraft as being the vesselâ€™s â€œbrain.â€ The term brain, then, signifies both the organ itself and the fact that this organ controls behavior.Why could Harvey not manage to preserve his control exerting self inside a bottle? Read on to learn one answer to this question.
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|May 30, 2020|
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