Localization and Distribution of Function in the Brain

Abstract

'-, , -Triroughout his research career, Karl Lashley remained puzzled by-the relationship between brain, behavior, and experience. On one hand, his experiments showed the brain to be put together with exquisite anatomical precision, which was to 'some degree reflected in the separation by behavioral function of the several sensorimotor systems and even regional differences within the so-called association areas, On the other hand, results of other experiments and observations made it clear that engrams, memory traces, could not be localized and that perceptual images and motor panerns displayed constancies and equivalences for which it was difficult to conceive any permanent "wiring diagram. " Lashley is best known for his continuing attention to these nonlocalizable aspects of brain function that he formalized in the laws of mass action and equipotentiality. But it should be remembered that these aspects were puzzling to Lashley in large part because he was so keenly aware of the anatomical precision of the connectivity th'at gave rise to nonlocal characteristics in function. Had the brain been shown to be essentially a randomly connected network (as was so often assumed by those then working in the field of artificial intelligence), the problem might not have loomed so insurmountable. In this chapter I present data that fill out a theoretical frame that was proposed by Lashley as a possible resolution of the localizationlnonlocalization puzzle. These data have accumulated during the quarter century that has intervened since his last paper. The data have been gathered without reference to the frame, and the frame itself was derived, not from brain-behavior studies, but from the