Iconoclast: A Neuroscientist Reveals How to Think Differently Read Online Free PDF

expect. And yet, the ability to do this is absolutely essential for iconoclastic thinking.
    FIGURE 1-1
    The “what” and the “where” pathways flowing forward from the primary visual area of the brain
     

     
    In the early stages of visual processing, such as V1, the brain performs its functions on a local scale. Neurons here do not have information about what other neurons are doing. As the information flows forward through the “what” and the “where” pathways, the information from other parts of the retina becomes increasingly integrated, to the point where the information ceases to be based on retinal location at all. By the time we become aware of what we are seeing, we perceive the visual stream not as a rectangular grid of light and dark spots, but as a landscape of stationary and moving objects, each with its own identity.
    To appreciate the transformation from local to global information processing, examine figure 1-2. The figure consists of only three Pac-Man shapes and three pairs of lines, but you perceive a white triangle floating above the background. 6 There is no triangle, but your brain, using its global processing mode, perceives one anyway. You can force yourself to drop down from global processing by staring at one of the individual elements, but this is generally a temporary state as your brain wants to make sense of what it is seeing. A flick of the eyes, and you are back to seeing the floating triangle.
    FIGURE 1-2
    The Kanizsa triangle
     

     
    Which is the true perception: Pac-Man or triangle? Regardless of which you see, the information coming from the eyes remains constant. Perception, then, is a product of the mind and brain, not the eyes. Unless you grew up in the ’70s, glued to an Atari console, the relative dominance of the triangle perception illustrates the brain’s tendency to perceive things as it expects them to be. Triangles are more common than Pac-Men. The perception of a floating triangle also provides a unified interpretation of the entire figure. At a global level, this makes more sense to the brain than the alternative perception of three Pac-Men clustering around an empty space.
    The triangle illusion demonstrates a key rule of perception: the most likely way that you perceive something will be in a manner consistent with your past experience. Commonplace perceptions feel comfortable and cost little energy to process. Conversely, uncommon perceptions force the brain into a different mode of processing in which it must figure out what exactly it is seeing, and this costs energy.
    The issue of how the brain creates perceptions from raw visual inputs is of critical importance to being an iconoclast. The iconoclast doesn’t literally see things differently than other people. More precisely, he
perceives
things differently. There are several different routes to forcing the brain out of its lazy mode of perception, but the theme linking these methods depends on the element of surprise. The brain must be provided with something that it has never before processed to force it out of predictable perceptions. When Chihuly lost an eye, his brain was forced to reinterpret visual stimuli in a new way.
    The Iconoclast Who Discovered MRI
     
    It is easy to take for granted the remarkable advances that medical technology has showered upon us. In an age of CAT scans and MRIs, the image of a human brain doesn’t carry quite the same awe-inspiring reaction that it used to. But this is a recent phenomenon. MRI is only thirtyyears old. The brain is the central player in iconoclasm, and much of what we know about the human brain comes from MRI.
    The story of MRI—magnetic resonance imaging—is itself a story of iconoclasm. The basic physical principle behind MRI was actually discovered in the 1940s. When an atom is placed in a magnetic field, the atom will start vibrating. This is called
nuclear magnetic resonance
(NMR). The rate at which the atom vibrates is determined by what kind of