ABSTRACT
This chapter uses the structure-function relationship as a basis for exploring units of information processing. It examines the brain as a whole, first providing the non-specialist with a short overview of the structure and some of the functions or outputs of the brain. The hierarchy of spatial scales is to some degree correlated with the brain's chemical anatomy—the distribution of neurochemicals over a single cell, over groups of cells, and over layers, areas, and structures. Brain function is neither as easily quantifiable, nor as investigable, as the structure of the nervous system. Celltials cut across boundaries of layer, area, and structure. The chapter reviews three of the prominent theoretical concepts that have emerged in the last few decades: receptive fields, feature extraction, and parallel processing. It proposes some fundamental re-evaluations of structural and functional data, and their relationship. Columns as information-processing units, rather than structural entities, have numerous problems.
