It's a Jungle in There: How Competition and Cooperation in the Brain Shape the Mind Read Online Free

scientists make use of powerful quantitative tools like those employed in statistics to analyze the group as a whole. The population approach is useful not just in studies of evolutionary biology but also in studies of neural ensembles. 8
Competition, Cooperation, and Levels of Control
    If it makes sense to speak of populations, why speak about individual mental fellows—those demons and elves to which I’ve referred? The reason isdidactic (for teaching). As I’ve already mentioned, this way of speaking about the brain can make the material fun and engaging, which is not to diminish the profundity of the questions to be addressed about the brain, nor to sidestep the often sad consequences of brain damage. In addition, and just to emphasize what I’ve already said, I don’t mean to ascribe full-bodied ambitions, hopes, or desires to the cranial creatures I’ll credit with undergirding cognition. On the contrary, I want to emphasize that every mental elf is totally dumb, doing just what it does with no awareness of how it fits into the larger scheme of things. No mental gnome has any more idea of the neural ecosystem of which it’s a part than does an amoeba in a lake or a fungus on a tree. But like conglomerates of amoebas or fungi, populations of neural demons have emergent properties, and that is where things get interesting.
    How can those emergent properties arise from the collective actions of individual neural elves that, on their own, are clueless to their places in the neural ecosystem? Though the elves are ignorant of where or how they fit in, they’re not clueless about who their “friends” and who their “foes” are. With their friends they cooperate; with their foes they compete. The way they express cooperation, mechanistically, is through excitation, and the way they express competition, mechanistically, is through inhibition. If a neuron is friends with another neuron, it excites that other neuron. If a neuron is enemies with another neuron, it inhibits that other neuron. These two simple mechanisms—excitation and inhibition—allow for amity and animus, respectively, in the neural jungle.
    One way that cooperation and competition are manifested is in levels of control. Much as there are dominance hierarchies in nature—pecking orders among poultry, for example—there are dominance hierarchies in the brain. The idea that neural ensembles dominate other neural ensembles is widespread in neuroscience. Oddly, though, there has been little discussion of how the levels of control come into being or why they exist. Thinking about these questions helps clarify the brain’s (and so the mind’s) dynamics.
    Consider what it means to have dominant and less dominant mechanisms in the brain—to have “big guns” and “little pistols,” if you will. The bigger the guns, the fewer of them there can be. This may help explain why attention is limited, and why it exists at all. The defining feature of attention—a topic covered in Chapter 4 —is selectivity, and the ultimate result of selectivity is being able to think of only one thing at once. 9 Your mind may flit back and forth from one idea to the next, but it’s impossible to have more than one thought at a time. If you’re thinking hard about this paragraph, for example, you can’t think equally intensively about what you’ll do on Saturday night. You might momentarily jump to that topic now that I’ve just mentioned it,but for you to think as carefully about the topic of this paragraph as you did before, you have to return to it, leaving Saturday night to another time.
    The fact that only one idea can be kept in mind suggests that some mental function is taken over by that idea. Whatever that mental function is, it’s the top spot in the mental milieu, the spot where competition is most intense.
    Why should there be a top spot? To survive, mental creatures need helpful inputs. One way they can get helpful inputs is by affecting the output