Inside the Brain

1.1. Hacks 1-12 It's never entirely true to say, "This bit of the brain is solely responsible for function X." Take the visual system [Hack #13], for instance; it runs through many varied parts of the brain with no single area solely responsible for all of vision. Vision is made up of lots of different subfunctions, many of which will be compensated for if areas become unavailable. With some types of brain damage, it's possible to still be able to see, but not be able to figure out what's moving or maybe not be able to see what color things are. What we can do is look at which parts of the brain are active while it is performing a particular taskanything from recognizing a face to playing the pianoand make some assertions. We can provide input and see what output we getthe black box approach to the study of mind. Or we can work from the outside in, figuring out which abilities people with certain types of damaged brains lack. The latter, part of neuropsychology [Hack #6], is an important tool for psychologists. Small, isolated strokes can deactivate very specific brain regions, and also (though more rarely) accidents can damage small parts of the brain. Seeing what these people can no longer do in these pathological cases, provides good clues into the functions of those regions of the brain. Animal experimentation, purposely removing pieces of the brain to see what happens, is another. These are, however, pathology-based methodsless invasive techniques are available. Careful experimentationmeasuring response types, reaction times, and response changes to certain stimuli over timeis one such alternative. That's cognitive psychology [Hack #1], the science of making deductions about the structure of the brain through reverse engineering from the outside. It has a distinguished history. More recently we've been able to go one step further. Pairing techniques from cognitive psychology with imaging methods and stimulation techniques [Hack#2] through [Hack#5], we can manipulate and look at the brain from the outside, without having to, say, remove the skull and pull a bit of the cerebrum out. These imaging methods are so important and referred to so much in the rest of this book, we've provided an overview and short explanation for some of the most common techniques in this chapter. In order that the rest of the book make sense, after looking at the various neuroscience techniques, we take a short tour round the central nervous system [Hack #7], from the spine, to the brain [Hack #8], and then down to the individual neuron [Hack #9] itself. But what we're really interested in is how the biology manifests in everyday life. What does it really mean for our decision-making systems to be assembled from neurons rather than, well, silicon, like a computer? What it means is that we're not software running on hardware. The two are one and the same, the physical properties of our mental substrate continually leaking into everyday life: the telltale sign of our neurons is evident when we respond faster to brighter lights [Hack #11], and our biological roots show through when blood flow has to increase because we're thinking so hard [Hack #10] . And finally take a gander at a picture of the body your brain thinks you have and get in touch with your inner sensory homunculus [Hack #12] .