Neurology of language.

A host of recent investigations and new theoretical models have advanced our understanding of the neural underpinnings of speech and language in humans. The application of positron emission tomography (PET) techniques to the investigation of language has provided corroborating evidence regarding the role of left hemisphere structures previously associated with language, together with some intriguing new findings. Innovative ideas regarding the ontogeny of language have come from studies of deaf infants who appear to babble with signs in much the same way that hearing infants babble vocally. A number of investigators have focused on the controversial syndrome known as progressive aphasia, and new evidence has supported the importance of this syndrome from both diagnostic (e.g. providing clues regarding neuropathology) and scientific (e.g. yielding information about the organization of lexical access structures in left temporal lobe) perspectives.