Technical and conceptual difficulties abound in the effort to localize high-level cognitive functions to narrowly circumscribed regions of the brain. Some of the most serious involve the ambiguous definition of the putative mental components that are to be localized and the generally unacknowledged nonlinear complexity of both the mind and the brain. In addition, the imaging techniques themselves are replete with technical difficulties that raise additional questions about this particular application even though these wonderful machines can make extraordinary contributions to our knowledge of brain anatomy and physiology. — William Uttal