Sunday, September 27, 2009

Michael Gazzaniga, Human (2008)

In the September 18th post, I concluded that a grander treatment of the subject of mirror neurons should be forthcoming someday, a volume that more completely integrates the role of mirror neurons with the biological operations of the mind and body and discusses consciousness memory, and evolution. I did not expect that such a book was already on The Bookshelf and was the next book to come off the shelf. Human, by U.C. Santa Barbara neuroscientist and psychology professor, Michael Gazzaniga , is such a book. While not specifically about mirror neurons, this larger look at the landscape of language, memory, emotion, perception, primate evolution and behavior, infant behavior and development of the human brain gives due recognition to discovery and role of mirror neurons.

In the Mystery of Consciousness, University of California philosophy professor, John Searle, writes, "The mystery of consciousness will gradually be removed when we solve the biological problem of consciousness." That's a remarkable statement from the philosophical community, where for millenia its leading lights have been debating and struggling with non-biological metaphysical ideas about what form reality takes and how we know reality. For Searle, who rejects the mind-body dualism of Descartes, "The 'problem of consciousness' is the problem of explaining exactly how the neurobiological processes in the brain cause our subjective states of awareness or sentience. . . the problem of consciousness is a scientific research project like any other." And that is a task that Gazzaniga embarks upon in Human.

While Searle appears ready to jettison philosophy of the mind for the biology of the mind, it is my belief that understanding the human mind is primarily biology and chemistry and physics (neuronal activity after all is electro-chemical), but it is also empirical anthropology, paleontology, research about other species, sociology, and psychology too. The human brain is the most important feature that distinguishes humans from other species. Gazzaniga would agree, and Human is engaging on all disciplines. There is a growing body of research that recognizes this interdisciplinary approach including Pascal Boyer's Religion Explained , Paul Bloom's Descartes' Baby , Steven Rose's The Future of the Brain , and Marc Hauser's Moral Minds. Each of these books explores one or more of the aspects of Gazzaniga's inquiry: what is unique about being human? which explores the answer inside the human mind.

Philosopher Searle and neuroscientist Antonio Damassio reject Cartesian dualism, but neuroscientist Gazzaniga says: we all act like dualists. "We are animate objects, which are the subject to the physical laws of animate objects, but we also have nonperceptual psychological properties not subject to physical laws." It is the latter that is one of the unique of attributes of being human: "we are the only animals that reason about unobservable forces ... we alone ... try to explain an effect as having been caused by something." That we may "act like" there is an unseen world separate from the physical world does not axiomatically lead to the conclusion that there is a dual world of the mental forms separate from a physical world of the senses. Pascal Boyer has provided one cogent explanation why the human mind is uniquely willing to recognize unseen agents, but he does not conclude that our psychological properties are not subject to physical laws. In the end, Gazzaniga does not appear to disagree. Gazzaniga is well-known for his split-brain research of patients suffering from severe epilepsy and the only treatment is to sever the corpus collosum that connects the right side of the brain from the left side. The right side of the brain is not a problem solver; it is good at perceiving, attentional skills, and emotions, but it is the cognitive left side of the brain that takes all the input coming into the brain and makes sense of it. The left side of the brain, says Gazzaniga, is the "interpreter" of our conscious experience, and in the course of acting as an "interpreter" this biological organ organizes information in a way to create a self-conscious self (an image of ourselves in our mind, separate from our physical self, or as Antonio Damassio calls it, our "movie within a movie"), another unique attribute of what makes us human. But this is the outcome of biological processes, not a feature of a separate world of the mind.

Enough of dualism or not! There are important nuggets of information in Human. The human brain is unique, not merely because of its size relative to our body weight or size, but because the way it is organized into modules and its connectivity. We learn of two genes that are regulators of brain size: microencephalin and ASPM. There is evidence of accelerated evolution of microencephalin in primates, and a variant of microencephalin appeared about 37,000 years ago about the same time that corresponds with culturally modern humans. A variant of ASPM appeared in humans about 5800 years ago, which coincides with the establishment of cities, agriculture, and written language. We don't know whether these genetic developments are in fact linked with cultural development and language, but it is certainly suggestive.

At the end of the book, we meet Merlin Donald who developed what is called mimesis theory: that the ability to imitate motor action is the foundation of language, human consciousness, and human culture. Language and gesture, the subject of the August 31 post on Christine Kennealy's The First Word, requires fine motor skills, which must be flexible enough to involve a voluntary control of muscles to mimic or rehearse an action undertaken by some other animate object, observe its consequences, store it in memory, and then change what must be changed. Donald calls this a "rehearsal loop," which he says is uniquely human. This requires feedback loops in the brain --- part of the brain's connectivity --- whereby the brain's ability to perceive (the right side) is connected the brain's cognitive capacity (in the left side) to connect to the action, and in order for the brain to imitate another animate object (such as another human), the brain must be self-aware. Is it this connectivity that is tied to the genetic developments in humans thousands of years ago?

Finally, we meet Jeff Hawkins, a creator of the Palm Pilot, who has co-authored a book called On Intelligence. Hawkins rejects the idea that the human brain is "computational." The brain does not compute the answers to problems; the neocortex is a memory system, which differs from a computer. The brain uses stored memory from past experience to make predictions -- which Hawkins asserts is the primary function of the neocortex and the foundation of human intelligence. Recall from the September 18 post on Marco Iacoboni's Mirroring People, that the part of the brain where mirror neurons are found is a part of the neocortex, which is responsible for planning and execution. The neocortex is the center or our attentive capacity, and we come to attention when we fail to accurately predict something. So it is here that motor coordination, drawing on memory, planning and execution all occur, with help from other, evolutionarily older parts of the brain tied to the senses. This is a key part of the brain responsible for attention and self-awareness, forming what Damassio characterizes as our "extended consciousness." Hawkins' model of the brain depends on feedback loops where information must flow back and forth comparing what is happening to what is predicted to happen. Information about what is happening flows in one direction; information about what memory tells you is expected to happen flows in another direction. This is not how a computer operates, which relies heavily on parallel processes, and arguably it suggests that robots will never replace us.

I said in a previous post that one of the big three areas for human inquiry is the human mind. Human delineates why this is true. Mirror neurons, fine motor skills that enable us to imitate, connectivity among modules in the brain and feedback loops, extended consciousness, language, and self-awareness are some of the important attributes of what make humans unique. To comprehend how the human mind works is really the key to understanding what makes us unique in the animal kingdom. Not all of the answers are here, but there is a lot in one book to fathom this huge question.

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