I enjoy Michio Kaku in every science show he appears in on tv and he's an expert in the field of physics. And I'm no expert in neuroscience, but my Bachelor's is in it and I continue to be pretty engrossed in the medical field, so I took a critical eye to his more "wetware" discussions of the brain.

For one, he refers to parts of the inner brain like parts of the diencephalon, telencephalon, and mesencephalon as the "limbic system" throughout the entire book. While many people still use this term, it is regarded as an outdated label for all those structures by the experts in the field of neuroscience. The normal reader wouldn't care about labels and it makes sense for unifying structure and purpose under one term. But for the sake of citizen science, I don't think using outdated language helps anyone.

Kaku also flips back and forth on his views regarding animal minds and consciousness. In the very first chapter, he refers to evolution of the brain as going from the basic reptillian brain, to the mammalian brain, to the human brain. The reptillian brain is capable of responding to simple stimuli, the mammalian brain can process emotions and social structures, and the human brain achieves full consciousness by being able to plan for the future. I think this organization is overly simplistic. For one, birds would be considered to have a mammalian brain with their complex social structures and grammar used in song birds. This is pure anthropomorphization- taking our own model of mind and applying it to others. We cannot imagine what the mind of a, say, dolphin is like because we are in no way able to be a dolphin. Their reliance on sensory information is completely different than ours. I think it's wrong to insist that humans are the only ones capable of having consciousness.

But if that is Kaku's opinion, then he should stick to it. Instead, he insists on not applying anthropomorphism to imagining alien minds in Chapter 14. He finally discusses the changes in sensory input in different species like bats, dogs, and dolphins. But if this is his opinion at the end of the book in regard to aliens, it's not what he concluded earlier. Also, his argument about sensory differences in other species would have been improved if he mentioned the inferior and superior colliculi. These small structures, located on the midbrain, are centers of information related to auditory (inferior) and visual (superior) reflexes. The inferior (the labels being used to refer to placement along the midbrain, not size) colliculus is much bigger than the superior in dolphins and bats. In humans, the two colliculi are closer in size. This makes sense for echolocating animals like bats and dolphins to rely much more on auditory cues than visual ones. Mentioning these structures would have helped Kaku demonstrate how very different our brains are from other animals' and how it is indeed unfair to assume that if their consciousness doesn't resemble ours, it's therefore not a true mind.

A couple other stray misunderstandings- I'm not completely convinced of Kaku's explanations of mirror neurons as to how they're used in the brain to replicate behaviors. And his definition of a homunculus as cortical areas assigned to various body regions was unclear. But I had no criticisms of the physics, quantum theory, and engineering parts of his arguments. Some of the science seemed farfetched (like transmitting consciousness via lasers), but I'm unfamiliar with the groundbreaking work in these areas. This was still an interesting book with lots of amazing ideas about the future of robots, the mind, and where else technology can take us.