The last frontier

THE CEREBRAL CODE: THINKING A THOUGHT IN THE MOSAIC OF THE MIND·William Calvin· Bradford Book, MIT Press

 
By Bhanusingha Ghosh
Published: Wednesday 30 April 1997

how does the brain function? What are memories? How does the brain perceive the difference between Bach and Anu Malik? How are the processes of sleep, dream, awareness, problem solving and creative thinking, and the dynamics of nerve cell assemblies that make consciousness possible, related? These are questions that have puzzled neurophysiologists for ages. Till the '80s, not much information was available for neurophysiologists to propose robust models on the functioning of the brain. Now, as more information comes to light, the pieces are falling in place. In this book, Calvin proposes a bold new theory of how the brain operates. According to him, the basic premise that explains the origin of species may also explain the functioning of the immune system, the development of language or even the progress of thought. c alvin proposes that the cerebral cortex works using a selection algorithm, what he refers to as a Darwin machine in analogy to the t uring machine, a hypothetical computer that can perform an infinite number of calculations.

The processes in the cerebral cortex work on the basis of 'cerebral codes' the pattern of space and time-related impulses exchanged between neurons in the cortex that are essential to represent a concept, word, image or even a metaphor the cortical level equivalent to the gene. A unique code can be contained in a unit hexagon which is the smallest unit of a Hebbian cell assembly, about 0.5 mm across, involving about 100 minicolumns of 10,000 neurons.

Written primarily for scientists, the book is of extremely sound scholarship. The 11-page glossary at the end of the book should enable lay readers to follow and enjoy this exposition on the neural basis of cognition. The book is a must read for any cognitive biologist.

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