Neural Substrate of Cognition and Literacy: Biology as Wish Fulfillment?

Abstract

Aristotle recognized that the human brain is disproportionately large when compared with the brains of other animals but he concluded that the heart is the source of mental activity and that the large brain serves merely as aradiator which cools the blood (Kolb & Whishaw, 1985). Opin­ ions have changed during the 2,300 years that have elapsed since Aristotle's death. We no longer regard the brain as a cooling device and, our poetry and popular music notwithstanding, we no longer regard the heart as an organ of thought. Since the early nineteenth century, Western philosophy and Western science have firmly accepted the brain as the organ of the mind (Boring, 1950). Nonetheless, nearly all of our scientific knowledge about brain functioning has been acquired during the past 150 years, a brief per iod in the history of civilization. Once the brain was established unequivocally as the seat of intellect, facts about brain function began to accumulate quite rapidly. It took only a few decades for Dax, Broca, and other nineteenth-century physicians to discover the lateralized nature of speech representation. By the end of the nineteenth century, scientists such as Munk, Ferrier, Hitzig, and Fritsch had identified cortical regions responsible for specific sensory and motor functions of the mammalian brain. New investigative techniques led to the discovery of the neuron and the synapse, discoveries that pre­ pared the way for extensive examination of brain anatomy and brain physio­ logy at a more molecular level. The resultant knowledge of basic chemical and electrical mechanisms of the brain has led to rapid progress in the neurosciences during the contemporary era. Despite the remarkable advances of neuroscience, the brain functions most relevant to education are the least understood. The degrep. to which specific cognitive functions are localized in the cerebral cortex has remained a controversial issue throughout the twentieth century. The higher mental functions of the right (nondominant) cerebra 1 hemisphere were generally unappreciated until the 1940s and 50s and, even today, the 1 Preparation of this chapter was supported in part by a research grant from the Medical Research Council of Canada. The author thanks Roxanne Inch for her assistance and Dr. GIen Aikenhead for his comments on a previous version of the chapter.