This ain't your typical brain book. Writing from a physicist's perspective, Kaku focuses on the intersect between technology and neuroscience. From magnetic resonance imaging to electroencephalography, the study of the brain has undergone a revolution in recent decades as new tools have allowed scientists to probe the brain with increasing resolution and insight. Much of this technological advancement stems from our understanding of the physics of magnetic and electrical fields and applying them in novel ways to help answer the age old question of how the mind works.
But this is only the beginning of the story. When we look at the current state of art with respect to the study of the brain, a fascinating picture of the future starts to emerge. Fortunately, I possess just enough familiarity with Star Trek to get references to tricorders (cell phones with MRI capabilities) and the Borg (nanoprobe implants in the brain to enable telepathic communication). Scientists have already been able to read minds by creating a mental dictionary by matching up signals emanating from the brain when subjects focus on particular letters. This effectively allows someone to type using only the power of the mind. Needless to say, this is pretty wild. And we're just scratching the surface here...
Again taking a physicist's viewpoint, Kaku outlines a definition of consciousness that assigns "levels" which correspond to how an organism models the world according to a set of feedback loops and parameters. This is called the "space-time theory of consciousness" and it is certainly a handy way to think about the various ways in which animals are conscious. The "levels" in the theory roughly line up with stages in the evolution of the brain, from the reptilian, to the mammalian, to human. In increasing complexity, the brains of animals create models of the world in order to achieve their goals starting with simple sensory input about the environment (reptilian), then expanding their model to incorporate their relationship to others (mammalian), and ultimately including the parameter of time by evaluating the past to make predictions and plan for the future (human). Hence, the "space-time theory of consciousness".
Once thought impenetrable to scientific inquiry, the problem of consciousness is becoming less opaque by the day. With the recent news that scientists may have found the proverbial 'on/off' switch for consciousness, our lofty philosophical notions of the special place occupied by human awareness are slowly coming back down to earth. Granted, there's still a long way to go in fully comprehending how all the complexity of human mind emerges out of the traffic of the brain, but real progress is (encouragingly) being made. This is a good thing. I, for one, am perpetually enthralled and amazed by the capacity for the brain to know itself.
