8Chapter Connectionist Models of Aphasia and Other Language Impairments
Aphasia presents a bewildering variety of symptoms, both within and across individuals. In order to make sense of this variety, theorists have used models. For example, over 100 years ago, the hypothesized relation between aphasic syndromes and brain regions was elegantly expressed by Lichtheim (1885) in a diagram of a small network, with nodes for mental content and their associated brain loci (e.g., Broca’s area containing motor patterns) and directional arrows between the nodes indicating the ow of processing (see Graves, 1997 for review). A syndrome could correspond to the loss of a node, such as Wernicke’s aphasia resulting from damage to the node for auditory images, or the loss of an arrow, as in conduction aphasia where the transmission of auditory images in Wernicke’s area to the motor patterns in Broca’s area is compromised (see Figure 8.1).