Brain Computation as Hierarchical Abstraction
Dana H. Ballard
The MIT Press
<P>The vast differences between the brain's neural circuitry and a                 computer's silicon circuitry might suggest that they have nothing in common. In                 fact, as Dana Ballard argues in this book, computational tools are essential for                 understanding brain function. Ballard shows that the hierarchical organization of                 the brain has many parallels with the hierarchical organization of computing; as in                 silicon computing, the complexities of brain computation can be dramatically                 simplified when its computation is factored into different levels of                 abstraction.</P><P>Drawing on several decades of progress in                 computational neuroscience, together with recent results in Bayesian and                 reinforcement learning methodologies, Ballard factors the brain's principal                 computational issues in terms of their natural place in an overall hierarchy. Each                 of these factors leads to a fresh perspective. A neural level focuses on the basic                 forebrain functions and shows how processing demands dictate the extensive use of                 timing-based circuitry and an overall organization of tabular memories. An                 embodiment level organization works in reverse, making extensive use of multiplexing                 and on-demand processing to achieve fast parallel computation. An awareness level                 focuses on the brain's representations of emotion, attention and consciousness,                 showing that they can operate with great economy in the context of the neural and                 embodiment substrates.</P>