| Child Neuropsychology |
| 1 | Foreword The human brain represents the product of an ongoing, six-billion-year con- struction project. In its physical form and function, the human brain represents millions upon millions of trial-and-error adaptive adjustments. Comprised of an estimated 100 billion neurons and many more glial cells it is organized into thousands of regions. The human brain, in a seamlessly integrated manner, governs body functions and movement but more importantly, regulates cogni- tion. |
| 2 | Not surprisingly, although the brains of different animals may not look exactly alike, they all work according to the same principles and mechanisms. These neurons and glial cells communicate using a nearly infinite number of synaptic connections, yet the entire organ in humans weighs only about three pounds. As authors Sandra Aamodt and Sam Wang eloquently describe in their book, Welcome to your brain, billions of years of evolution have resulted in a very complex human brain, yet one that is a jumbled, far from efficient, crowded organ. |
| 3 | They describe the neuronal pathways of the human brain as the equivalent of the New York City subway system or the streets of London with layers upon layers of routes each constructed at a different time in a different way. Yet this stunning system, for the most part, develops and works fine for most children. The adult human brain at between 1300 and 1400 cm is by far not the largest brain among mammals. |
| 4 | Consider that a sperm whale's brain is approximately 7800 cm and an elephant's brain is 4700 cm. Thus, bigger brains alone do not necessarily mean smarter or more developed organisms. Although larger brains are associated with higher intelligence to some extent, smaller brains can be advantageous from an evolutionary point of view, particularly if they are equal in intelligence to larger brains. But many additional factors beyond brain size impact intelligence. |
| 5 | Brain size in vertebrates such as humans may relate more to social rather than mechanical skills. Lower ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. For reptiles it is about 1:1500; for birds, 1:220; for most mammals, 1:180 and for humans, 1:50. MRI studies of humans have demonstrated that to some extent brain size has modest correlation with intelligence. |
| 6 | Among our ancestors, homo erectus had a brain size of about 980 cm; homo habilis a brain of about 750 cm; homo floresiensis a brain size of about 380 cm; and neanderthals a brain size slightly larger than our current brains. Consider also that an infant is born with a brain of 300-400 cm tripling in size by the adult years. Yet, between birth and the conclusion of the first two decades of life, a nearly infinite acquisition of knowl- edge and behaviors characterizes human development. |
| 7 | Gram for gram the human brain delivers an almost dazzling array of motoric, behavioral, cognitive and emotional capacities nearly impossible to fathom in light of its' size. The brain is a metabolically high cost organ consuming about 20% of the body's metabolic energy providing further evidence of its' complex operations. Further most energy use is devoted to being ready to think and respond rather than thinking per se. |
| 8 | Despite rapid and fascinating advances in our understanding of brain struc- ture, function and complex human behavior, it still remains the case that there is much more that we don't know about how the brain grows, functions and ages. Though neuroimaging techniques have allowed scientists to appreciate the relationship between the anatomy and physiology of the brain and motor functions for example, the basic cognitive operations of the brain remain elusive. |
| 9 | Beyond anatomical structure and physiology, the brain unlike any other organ in the body creates an alter ego, the conscious mind. In his fictional short story They're made out of meat, author Terry Bison describes aliens with electronic brains referring to humans as "thinking meat"! The idea that the brain can create consciousness seems like a science fiction phenomena. For thousands of years philosophers and scientists have debated and waxed poetic about the nature of the human mind. |
| 10 | The mind appears to be composed of a set of processes driven by language, organized by memory and individualized by each person's unique perception and interpretation of their lives. And yet, the human brain does not appear to possess a localized center of conscious control. Though highly dependent upon the frontal lobes, consciousness is also dependent upon sensory, processing and interpretative abilities distribu- ted throughout the brain. |
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