Science writer Allport has taken on the dual challenge of explaining a frontier area of neuroscience as well as the highly competitive frontiersmen (and women). She succeeds admirably on both counts. First the frontier. In the past few decades, neuroscientists have seized upon species of aplysia--unlovable marine slugs capable of exuding inky bad smells as the test animals of choice. Why? The slug's abdominal ganglion contains only a few thousand super-sized nerve cells. Among the first on board was Eric Kandel, who now presides over a research empire at Columbia University. Kandel has published seminal papers on the nerve cell biochemical and electrophysiological changes he believes underlie habituation (the nerve cell turns off to a repeated stimulus), sensitization (the cell gets more excited with repeated stimulation), and associative learning. Meanwhile, other aplysia camps have cropped up, some spun off from Kandel's lab, some representing early rivals like Daniel Alkon, who has contended and contested with Kandel every step of the way. It appears that a shaky truce was Formed when the principals were confronted with Allport's invasion into the sociology of science--and that, too, she reports with verve. (Why, since The Double Helix and other insider tales, scientists persist in denying the importance of competition is in itself an interesting sociological question Allport discusses.) As for the facts and issues, Allport handles these masterfully. Whether or not findings in marine invertebrates apply to man (another bone of contention), it is clear that the new cell-centered approach is yielding a wealth of molecular-level information on how environmental stimuli cause an individual neuron to change its tune--to adapt, to learn, perhaps even to remember.