References 88


One of the central goals of the neurosciences is to describe perception, action, and thought in terms of brain processes. Near the middle of the 19th century it was felt that such a reductionist research program could not hope to succeed unless the behavior of any one animal were completely described in terms of its neurons (this is a demand that bears the name of Thomas Huxley). So far, the most successful affirmative answer to Huxley’s demand rests on evidence collected in invertebrates, in particular the marine snail Aplysia californica.1 Experimental work in this species offers several advantages (eloquently summarized in the early chapters of Reference 1) including a fairly simple central nervous system made of a relatively small number of neurons. Mammalian neurons are more numerous (by seven orders of magnitude or more) and display a large number of interconnections and discharge patterns. It is therefore not surprising that progress in satisfying Huxley’s demand has been and remains much slower in mammals.